Android how to create triangle and rectangle shape programmatically?

Android how to create triangle and rectangle shape programmatically? - android

How can we create ballon drawable shape as below. where we can change the color of it dynamically.

Here it is XML for triangle and rectangle. save it inside drawable folder.
triangle.xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item >
<rotate
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="-40%"
android:pivotY="87%" >
<shape
android:shape="rectangle" >
<stroke android:color="#android:color/transparent" android:width="10dp"/>
<solid
android:color="#000000" />
</shape>
</rotate>
</item>
</layer-list>
rectangle.xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<shape android:shape="rectangle">
<solid android:color="#B2E3FA" />
</shape>
</item>
</layer-list>
and layout for shape you require.
<RelativeLayout
android:id="#+id/rlv1"
android:layout_width="150dp"
android:layout_height="50dp"
android:background="#drawable/rectangle" />
<RelativeLayout
android:id="#+id/rlv2"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_below="#+id/rlv1"
android:background="#drawable/triangle"
android:rotation="180" />
set margin according you required.
Source

If you want a border for your layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linear_root"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
>
<TextView
android:id="#+id/text_message"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:background="#drawable/bg_rectangle"
android:layout_marginLeft="20dp"
android:layout_marginRight="20dp"
android:layout_marginTop="20dp"
android:padding="8dp"
android:text="Abc"
/>
<ImageView
android:id="#+id/image_arrow"
android:layout_marginTop="-1.5dp"
android:layout_width="16dp"
android:layout_height="16dp"
android:layout_gravity="center_horizontal"
android:background="#drawable/icon_arrow_down"
/>
</LinearLayout>
bg_rectangle
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="#eaeaea" />
<stroke
android:width="1dp"
android:color="#f00" />
<corners android:radius="8dp" />
</shape>
icon_arrow_down, or you can create triangle by vector like here
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<rotate
android:fromDegrees="45"
android:pivotX="135%"
android:pivotY="15%"
android:toDegrees="45"
>
<shape android:shape="rectangle">
<solid android:color="#eaeaea"/>
<stroke
android:width="1dp"
android:color="#f00" />
</shape>
</rotate>
</item>
</layer-list>

The clean and right way to do this whilst keeping it dynamic is to extend the View class.
Then in the onDraw you would do something like this:
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
drawBackground(canvas);
}
private void drawBackground(Canvas canvas) {
int width = (int) mWidth;
int height = (int) mHeight;
Point a = new Point(0, 0);
Point b = new Point(width, 0);
Point c = new Point(width, height - mPointHeight);//mPointedHeight is the length of the triangle... in this case we have it dynamic and can be changed.
Point d = new Point((width/2)+(mPointedHeight/2), height - mPointHeight);
Point e = new Point((width/2), height);// this is the sharp point of the triangle
Point f = new Point((width/2)-(mPointedHeight/2), height - mPointHeight);
Point g = new Point(0, height - mPointHeight);
Path path = new Path();
path.moveTo(a.x, a.y);
path.lineTo(b.x, b.y);
path.lineTo(c.x, c.y);
path.lineTo(d.x, d.y);
path.lineTo(e.x, e.y);
path.lineTo(f.x, f.y);
path.lineTo(g.x, g.y);
canvas.drawPath(path, mPointedBackgroundPaint);// mPointedBackgroundPaint is whatever color you want as the fill.
}
There you go, no unnecessary layering or code that isn't dynamic or clean. You could also add the text in the box too.

Use a triangle image and a rectangular image and mathematically align them in the above mentioned format. Use color filtering to dynamically change its color.
You can even draw them on a custom view, using vector graphics, using custom colors, and that would be another way of solving this problem.

Create custom view and draw traingle with canvas
package com.example.dickbutt;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.View;
public class TriangleShapeView extends View {
public int colorCode = Color.MAGENTA;
public int getColorCode() {
return colorCode;
}
public void setColorCode(int colorCode) {
this.colorCode = colorCode;
}
public TriangleShapeView(Context context) {
super(context);
}
public TriangleShapeView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public TriangleShapeView(Context context, AttributeSet attrs) {
super(context, attrs);
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int w = getWidth() / 2;
int h = getHeight() / 2;
Path path = new Path();
path.moveTo(0, 0);
path.lineTo(w, 2 * h);
path.lineTo(2 * w, 0);
path.lineTo(0, 0);
path.close();
Paint p = new Paint();
p.setColor(colorCode);
p.setAntiAlias(true);
canvas.drawPath(path, p);
}
}
Result
Usage
<TextView
android:id="#+id/progress_value"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:background="#android:color/holo_purple"
android:gravity="center_horizontal"
android:text="200,0000000"
android:textColor="#fff" />
<com.example.dickbutt.TriangleShapeView
android:id="#+id/textView1"
android:layout_width="10dp"
android:layout_height="20dp"
android:layout_below="#+id/progress_value"
android:layout_centerHorizontal="true"
android:background="#drawable/rectangle"
android:gravity="center_horizontal"
android:textSize="10sp" />
Advantages
Change shape according to width and height of view .
Highly customization possible.
Look cleaner

Use Canvas in onDraw method inside custom View class.
Other way is to use Path class.

First you can create one xml inside drawable folder
That xml will be responsible for the border color of rectangle shape
You can create such border shape with below code
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape android:shape="rectangle">
<solid android:color="#B2E3FA" />
</shape>
</item>
<item android:left="5dp" android:bottom="5dp" android:top="5dp" >
<shape android:shape="rectangle">
<solid android:color="#D8D8D8" />
</shape>
</item>
</layer-list>
well this will create a required border to rectangle shape, you need to assign background of that rectangle shape with this drawable like this
android:background="#drawable/bg"
where bg is xml file name which has been saved on drawable folder
After that you need to put that triangle exactly below to rectangle object.
I hope you understood my logic

Related

Generate specific xml drawable [duplicate]

Is there a way that I can specify a triangle shape in an XML file?
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="triangle">
<stroke android:width="1dip" android:color="#FFF" />
<solid android:color="#FFF" />
</shape>
Can we do this with a path shape or something? I just need an equilateral triangle.
Thanks

In this post I describe how to do it. And here is the XML defining triangle:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<rotate
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="-40%"
android:pivotY="87%" >
<shape
android:shape="rectangle" >
<stroke android:color="#color/transparent" android:width="10dp"/>
<solid
android:color="#color/your_color_here" />
</shape>
</rotate>
</item>
</layer-list>
Refer to my post if something is unclear or you need explanation how it is built. It is rotated an cutout rectangle :) it is very smart and well working solution.
EDIT:
to create an arrow pointing like --> use:
...
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="13%"
android:pivotY="-40%" >
...
And to create an arrow pointing like <-- use:
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="87%"
android:pivotY="140%" >

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="▼"/>
You can get here more options.

You can use vector to make triangle like this
ic_triangle_right.xml
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="24dp"
android:height="24dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
<path
android:pathData="M0,12l0,12 11.5,-5.7c6.3,-3.2 11.5,-6 11.5,-6.3 0,-0.3 -5.2,-3.1 -11.5,-6.3l-11.5,-5.7 0,12z"
android:strokeColor="#00000000"
android:fillColor="#000000"/>
</vector>
Then use it like
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="#drawable/ic_triangle_right"
/>
For change the color and direction, use android:tint and android:rotation
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="#drawable/ic_triangle_right"
android:rotation="180" // change direction
android:tint="#00f" // change color
/>
Result
For change the shape of vector, you can change the width/height of vector. Example change width to 10dp
<vector
android:width="10dp"
android:height="24dp"
>
...
</vector>

You can use vector drawables.
If your minimum API is lower than 21, Android Studio automatically creates PNG bitmaps for those lower versions at build time (see Vector Asset Studio). If you use the support library, Android even manages "real vectors" down to API 7 (more on that in the update of this post at the bottom).
A red upwards pointing triangle would be:
<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:height="100dp"
android:width="100dp"
android:viewportHeight="100"
android:viewportWidth="100" >
<group
android:name="triableGroup">
<path
android:name="triangle"
android:fillColor="#FF0000"
android:pathData="m 50,0 l 50,100 -100,0 z" />
</group>
</vector>
Add it to your layout and remember to set clipChildren="false" if you rotate the triangle.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipChildren="false">
<ImageView
android:layout_width="130dp"
android:layout_height="100dp"
android:rotation="0"
android:layout_centerInParent="true"
android:background="#drawable/triangle"/>
</RelativeLayout>
Change the size (width/height) of the triangle by setting the Views layout_width/layout_height attributes. This way you can also get an eqilateral triagle if you do the math correct.
UPDATE 25.11.2017
If you use the support library you can use real vectors (instead if bitmap creation) as far back as API 7. Simply add:
vectorDrawables.useSupportLibrary = true
do your defaultConfig in your module's build.gradle.
Then set the (vector xml) drawable like this:
<ImageView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
app:srcCompat="#drawable/triangle" />
Everything is documented very nicely on the Vector Asset Studio page.
Ever since this feature I've been working entirely without bitmaps in terms of icons. This also reduces APK size quite a bit.

The solution of Jacek Milewski works for me and, based on his solution, if you need and inversed triangle you can use this:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<rotate
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="135%"
android:pivotY="15%">
<shape android:shape="rectangle">
<solid android:color="#color/aquamarine" />
</shape>
</rotate>
</item>
</layer-list>

I would definetely go for implementing a View in this case:
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.View;
public class TriangleShapeView extends View {
public TriangleShapeView(Context context) {
super(context);
}
public TriangleShapeView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public TriangleShapeView(Context context, AttributeSet attrs) {
super(context, attrs);
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int w = getWidth() / 2;
Path path = new Path();
path.moveTo( w, 0);
path.lineTo( 2 * w , 0);
path.lineTo( 2 * w , w);
path.lineTo( w , 0);
path.close();
Paint p = new Paint();
p.setColor( Color.RED );
canvas.drawPath(path, p);
}
}
Make use of it in your layouts as follows:
<TriangleShapeView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ff487fff">
</TriangleShapeView>
Using this implementation will give you the following result:

See answer here:
Custom arrows without image: Android
<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="32dp"
android:height="24dp"
android:viewportWidth="32.0"
android:viewportHeight="24.0">
<path android:fillColor="#e4e4e8"
android:pathData="M0 0 h32 l-16 24 Z"/>
</vector>

Using vector drawable:
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="24dp"
android:height="24dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
<path
android:pathData="M0,0 L24,0 L0,24 z"
android:strokeColor="#color/color"
android:fillColor="#color/color"/>
</vector>

May I help you without using XML ?
Simply,
Custom Layout ( Slice ) :
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Path;
import android.graphics.Point;
import android.util.AttributeSet;
import android.view.View;
public class Slice extends View {
Paint mPaint;
Path mPath;
public enum Direction {
NORTH, SOUTH, EAST, WEST
}
public Slice(Context context) {
super(context);
create();
}
public Slice(Context context, AttributeSet attrs) {
super(context, attrs);
create();
}
public void setColor(int color) {
mPaint.setColor(color);
invalidate();
}
private void create() {
mPaint = new Paint();
mPaint.setStyle(Style.FILL);
mPaint.setColor(Color.RED);
}
#Override
protected void onDraw(Canvas canvas) {
mPath = calculate(Direction.SOUTH);
canvas.drawPath(mPath, mPaint);
}
private Path calculate(Direction direction) {
Point p1 = new Point();
p1.x = 0;
p1.y = 0;
Point p2 = null, p3 = null;
int width = getWidth();
if (direction == Direction.NORTH) {
p2 = new Point(p1.x + width, p1.y);
p3 = new Point(p1.x + (width / 2), p1.y - width);
} else if (direction == Direction.SOUTH) {
p2 = new Point(p1.x + width, p1.y);
p3 = new Point(p1.x + (width / 2), p1.y + width);
} else if (direction == Direction.EAST) {
p2 = new Point(p1.x, p1.y + width);
p3 = new Point(p1.x - width, p1.y + (width / 2));
} else if (direction == Direction.WEST) {
p2 = new Point(p1.x, p1.y + width);
p3 = new Point(p1.x + width, p1.y + (width / 2));
}
Path path = new Path();
path.moveTo(p1.x, p1.y);
path.lineTo(p2.x, p2.y);
path.lineTo(p3.x, p3.y);
return path;
}
}
Your Activity ( Example ) :
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.ViewGroup.LayoutParams;
import android.widget.LinearLayout;
public class Layout extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Slice mySlice = new Slice(getApplicationContext());
mySlice.setBackgroundColor(Color.WHITE);
setContentView(mySlice, new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
}
}
Working Example :
Another absolutely simple Calculate function you may interested in ..
private Path Calculate(Point A, Point B, Point C) {
Path Pencil = new Path();
Pencil.moveTo(A.x, A.y);
Pencil.lineTo(B.x, B.y);
Pencil.lineTo(C.x, C.y);
return Pencil;
}

You can add following triangle in background using following xml
<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:height="100dp"
android:width="100dp"
android:viewportHeight="100"
android:viewportWidth="100" >
<group
android:name="triableGroup">
<path
android:name="triangle"
android:fillColor="#848af8"
android:pathData="M 0,20 L 0,0 L 100,0 L 100,20 L 54,55 l -1,0.6 l -1,0.4 l -1,0.2 l -1,0 l -1,-0 l -1,-0.2 l -1,-0.4 l -1,-0.6 L 46,55 L 0,20 -100,-100 Z" />
</group>
</vector>
The whole logic to customize xml design is in pathData. Consider top-left as (0,0) and design the layout as per your requirement.
Check this answer.

For those who want a right triangle arrow, here you go:
STEP 1: Create a drawable XML file, copy and paste the following XML content into your drawable XML. (Please be informed that you can use any name for your drawable XML file. For my case, I name it "v_right_arrow")
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item >
<rotate
android:fromDegrees="45"
android:toDegrees="-45"
android:pivotX="15%"
android:pivotY="-36%" >
<shape
android:shape="rectangle" >
<stroke android:color="#android:color/transparent" android:width="1dp"/>
<solid
android:color="#000000" />
</shape>
</rotate>
</item>
</layer-list>
STEP 2: In your layout's XML, create a View and bind its background to the drawable XML that you have just created in STEP 1. For my case, I bind v_right_arrow to my View's background property.
<View
android:layout_width="200dp"
android:layout_height="200dp"
android:background="#drawable/v_right_arrow">
</View>
Sample output:
Hope this helps, good luck!

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<rotate
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="-40%"
android:pivotY="87%" >
<shape
android:shape="rectangle" >
<stroke android:color="#android:color/transparent" android:width="0dp"/>
<solid
android:color="#fff" />
</shape>
</rotate>
</item>
</layer-list>

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<rotate
android:fromDegrees="45"
android:pivotX="135%"
android:pivotY="1%"
android:toDegrees="45">
<shape android:shape="rectangle">
<stroke
android:width="-60dp"
android:color="#android:color/transparent" />
<solid android:color="#color/orange" />
</shape>
</rotate>
</item>
</layer-list>

I try to create triangle image like back button of android navigation bar but I haven't found any solution.
Now, I found the solution with myself and would like to share it.
use xml below
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:bottom="20dp"
android:left="480dp"
android:right="60dp"
android:top="20dp">
<shape>
<size android:width="60dp" />
<corners android:radius="80dp"/>
<solid android:color="#AAA" />
</shape>
</item>
<item
android:bottom="480dp"
android:right="70dp"
android:top="20dp">
<rotate
android:fromDegrees="-28"
android:pivotX="96%"
android:pivotY="50%"
android:toDegrees="-20">
<shape>
<corners android:radius="80dp"/>
<size android:height="60dp" />
<solid android:color="#AAA" />
</shape>
</rotate>
</item>
<item
android:bottom="20dp"
android:right="70dp"
android:top="480dp">
<rotate
android:fromDegrees="28"
android:pivotX="96%"
android:pivotY="50%"
android:toDegrees="-20">
<shape>
<corners android:radius="80dp"/>
<size android:height="60dp" />
<solid android:color="#AAA" />
</shape>
</rotate>
</item>

I have never done this, but from what I understand you can use the PathShape class:
http://developer.android.com/reference/android/graphics/drawable/shapes/PathShape.html

I my be late to party and I came across same problem and Google pointed me to this StackOverflow thread as first result.
I tried using xml way to add triangle and find out a problem that the triangle
shape via xml approach is taking more space than it appears.
See screen shot with layout bounds on
So ended up making this custom view class which can draws Triangle of any of following types:-
up pointing
down pointing
left pointing &
right pointing
asas
package com.hiteshsahu.materialupvotewidget;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.support.annotation.NonNull;
import android.util.AttributeSet;
import android.view.View;
public class TriangleShapeView extends View {
private int colorCode = Color.DKGRAY;
public int getColorCode() {
return colorCode;
}
public void setColorCode(int colorCode) {
this.colorCode = colorCode;
}
public TriangleShapeView(Context context) {
super(context);
if (isInEditMode())
return;
}
public TriangleShapeView(Context context, AttributeSet attrs) {
super(context, attrs);
if (isInEditMode())
return;
}
public TriangleShapeView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
if (isInEditMode())
return;
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int w = getWidth() / 2;
int h = getHeight() / 2;
//Choose what type of triangle you want here
Path path = getLeftTriangle(w, h);
path.close();
Paint p = new Paint();
p.setColor(colorCode);
p.setAntiAlias(true);
canvas.drawPath(path, p);
}
#NonNull
/**
* Return Path for down facing triangle
*/
private Path getInvertedTriangle(int w, int h) {
Path path = new Path();
path.moveTo(0, 0);
path.lineTo(w, 2 * h);
path.lineTo(2 * w, 0);
path.lineTo(0, 0);
return path;
}
#NonNull
/**
* Return Path for Up facing triangle
*/
private Path getUpTriangle(int w, int h) {
Path path = new Path();
path.moveTo(0, 2 * h);
path.lineTo(w, 0);
path.lineTo(2 * w, 2 * h);
path.lineTo(0, 2 * h);
return path;
}
#NonNull
/**
* Return Path for Right pointing triangle
*/
private Path getRightTriangle(int w, int h) {
Path path = new Path();
path.moveTo(0, 0);
path.lineTo(2 * w, h);
path.lineTo(0, 2 * h);
path.lineTo(0, 0);
return path;
}
#NonNull
/**
* Return Path for Left pointing triangle
*/
private Path getLeftTriangle(int w, int h) {
Path path = new Path();
path.moveTo(2 * w, 0);
path.lineTo(0, h);
path.lineTo(2 * w, 2 * h);
path.lineTo(2 * w, 0);
return path;
}
}
You can Simply use it in xml layout like this
<com.hiteshsahu.materialupvote.TriangleShapeView
android:layout_width="50dp"
android:layout_height="50dp"></com.hiteshsahu.materialupvote.TriangleShapeView>
I know OP want solutions in xml solution but as I pointed out problem with xml approach . I Hope it might help somebody.

Using the solution of Jacek Milewski I made an oriented down angle with a transparent background.
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<rotate
android:fromDegrees="135"
android:pivotX="65%"
android:pivotY="20%"
android:toDegrees="135"
>
<shape android:shape="rectangle">
<stroke
android:width="1dp"
android:color="#color/blue"
/>
<solid android:color="#color/transparent" />
</shape>
</rotate>
</item>
</layer-list>
You can change android:pivotX and android:pivotY to shift the angle.
Usage:
<ImageView
android:layout_width="10dp"
android:layout_height="10dp"
android:src="#drawable/ic_angle_down"
/>
Parameters depend on the size of the image. For instance, if ImageView has size 100dp*80dp, you should use these constants:
<rotate
android:fromDegrees="135"
android:pivotX="64.5%"
android:pivotY="19%"
android:toDegrees="135"
>

I provide this customView below if you don't want to hack xml.
Please have a try.
/**
* TriangleView
*
* #author Veer
* #date 2020-09-03
*/
class TriangleView #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {
private var triangleColor: Int = 0
private var direction = Direction.Bottom
private val paint by lazy {
Paint().apply {
isAntiAlias = true
style = Paint.Style.FILL
color = triangleColor
}
}
init {
initStyle(context, attrs, defStyleAttr)
}
private fun initStyle(
context: Context,
attrs: AttributeSet?,
defStyleAttr: Int
) {
val ta = context.obtainStyledAttributes(attrs, R.styleable.TriangleView, defStyleAttr, 0)
with(ta) {
triangleColor =
getColor(R.styleable.TriangleView_triangle_background, Color.parseColor("#000000"))
val directionValue =
getInt(R.styleable.TriangleView_triangle_direction, Direction.Bottom.value)
direction = when (directionValue) {
Direction.Top.value -> Direction.Top
Direction.Bottom.value -> Direction.Bottom
Direction.Left.value -> Direction.Left
Direction.Right.value -> Direction.Right
else -> Direction.Bottom
}
recycle()
}
}
override fun onDraw(canvas: Canvas) {
calculatePath(direction).let {
canvas.drawPath(it, paint)
}
}
private fun calculatePath(direction: Direction): Path {
var p1: Point? = null
var p2: Point? = null
var p3: Point? = null
val width = width
val height = height
when (direction) {
Direction.Top -> {
p1 = Point(0, height)
p2 = Point(width / 2, 0)
p3 = Point(width, height)
}
Direction.Bottom -> {
p1 = Point(0, 0)
p2 = Point(width / 2, height)
p3 = Point(width, 0)
}
Direction.Left -> {
p1 = Point(width, 0)
p2 = Point(0, height / 2)
p3 = Point(width, height)
}
Direction.Right -> {
p1 = Point(0, 0)
p2 = Point(width, height / 2)
p3 = Point(0, height)
}
}
val path = Path()
path.moveTo(p1.x.toFloat(), p1.y.toFloat())
path.lineTo(p2.x.toFloat(), p2.y.toFloat())
path.lineTo(p3.x.toFloat(), p3.y.toFloat())
return path
}
private enum class Direction(val value: Int) {
Top(0),
Bottom(1),
Left(2),
Right(3)
}
}
<declare-styleable name="TriangleView">
<attr name="triangle_direction" format="enum">
<enum name="top" value="0" />
<enum name="bottom" value="1" />
<enum name="left" value="2" />
<enum name="right" value="3" />
</attr>
<attr name="triangle_background" format="reference|color" />
</declare-styleable>

<LinearLayout
android:id="#+id/ly_fill_color_shape"
android:layout_width="300dp"
android:layout_height="300dp"
android:layout_gravity="center"
android:background="#drawable/shape_triangle"
android:gravity="center"
android:orientation="horizontal" >
</LinearLayout>
<item>
<rotate
android:fromDegrees="45"
android:pivotX="-15%"
android:pivotY="77%"
android:toDegrees="45" >
<shape android:shape="rectangle" >
<stroke
android:width="2dp"
android:color="#color/black_color" />
<solid android:color="#color/white" />
<padding android:left="1dp" />
</shape>
</rotate>
</item>
<item android:top="200dp">
<shape android:shape="line" >
<stroke
android:width="1dp"
android:color="#color/black_color" />
<solid android:color="#color/white" />
</shape>
</item>

Google provides a Equilateral triangle here.
Choose VectorDrawable so the size is flexible.
It' integrated into Android Studio as plugin.
If you have an SVG image, you can use this to convert it to VectorDrawable too.
Once you have a VectorDrawable, changing its colour and rotation is easy like others have mentioned.

Images with rounded corners in a ListView

I have developed an rss application. I want the ListView which contains the titles and images to have the images with rounded corners. I have taken a sample code online, but the problem is that the images are still rectangular. The weird part is that I have a sliding menu, when toggled it pushes the rss ListView away, while it's being pushed the images have round corners! when they stop their pushing animation the become rectangular again. It's a pretty weird problem for me so any help?
Rounded Image class:
public class RoundedImageView extends ImageView
{
private float radius = 20.0f;
public RoundedImageView(Context context)
{
super(context);
}
public RoundedImageView(Context context,AttributeSet attrs)
{
super(context,attrs);
}
public RoundedImageView(Context context,AttributeSet attrs,int defStyle)
{
super(context,attrs,defStyle);
}
#SuppressLint("DrawAllocation")
#Override
protected void onDraw(Canvas canvas)
{
Path clipPath = new Path();
RectF rect = new RectF(0,0,getWidth(), getHeight());
clipPath.addRoundRect(rect, radius, radius, Path.Direction.CW);
canvas.clipPath(clipPath);
super.onDraw(canvas);
}
}

Try this way: create rounded_corner.xml file into drawable\rounded_corner.xml
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="#101010" />
<stroke
android:width="1dp"
android:color="#808080" />
<corners android:radius="15dp" />
And set as Background to your ImageView like
android:background="#drawable\rounded_corner"
And also set your RSS image to ImageView as a Src or a Bitmap like:
imageview.setBitmap(yourrssimage);

use rounded corner image or create xml and set as background image on imageview.

Create one XML like below in your drawable folder.
button_back.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:state_enabled="false"
android:drawable="#color/grey">
<shape>
<solid
android:color="#ef4444" />
<stroke
android:width="1dp"
android:color="#992f2f" />
<corners
android:radius="16dp" />
</shape>
</item>
and then apply to your button like this.
<Button
android:text="#string/press_me"
android:layout_margin="12dp"
android:layout_width="fill_parent"
android:layout_height="30dp"
android:background="#drawable/button_back"
/>

Create a stroke and list it as your imageview background
<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#android:color/transparent"/>
<stroke android:width="5dip" android:color="#android:color/transparent" />
<corners android:radius="5dip"/>
<padding android:left="0dip" android:top="0dip" android:right="0dip" android:bottom="0dip" />
</shape>
And in your imageview xml
android:background="#drawable/your_stroke_xml"

How to make layout with rounded corners..?

How can I make a layout with rounded corners? I want to apply rounded corners to my LinearLayout.

1: Define layout_bg.xml in drawables:
<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#FFFFFF"/>
<stroke android:width="3dp" android:color="#B1BCBE" />
<corners android:radius="10dp"/>
<padding android:left="0dp" android:top="0dp" android:right="0dp" android:bottom="0dp" />
</shape>
2: Add layout_bg.xml as background to your layout
android:background="#drawable/layout_bg"

For API 21+, Use Clip Views
Rounded outline clipping was added to the View class in API 21. See this training doc or this reference for more info.
This in-built feature makes rounded corners very easy to implement. It works on any view or layout and supports proper clipping.
Here's What To Do:
Create a rounded shape drawable and set it as your view's background:
android:background="#drawable/round_outline"
Clip to outline in code: setClipToOutline(true)
The documentation used to say that you can set android:clipToOutline="true" the XML, but this bug is now finally resolved and the documentation now correctly states that you can only do this in code.
What It Looks Like:
Special Note About ImageViews
setClipToOutline() only works when the View's background is set to a shape drawable. If this background shape exists, View treats the background's outline as the borders for clipping and shadowing purposes.
This means that if you want to round the corners on an ImageView with setClipToOutline(), your image must come from android:src instead of android:background (since background is used for the rounded shape). If you MUST use background to set your image instead of src, you can use this nested views workaround:
Create an outer layout with its background set to your shape drawable
Wrap that layout around your ImageView (with no padding)
The ImageView (including anything else in the layout) will now be clipped to the outer layout's rounded shape.

Here's a copy of a XML file to create a drawable with a white background, black border and rounded corners:
<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#ffffffff"/>
<stroke android:width="3dp"
android:color="#ff000000"
/>
<padding android:left="1dp"
android:top="1dp"
android:right="1dp"
android:bottom="1dp"
/>
<corners android:bottomRightRadius="7dp" android:bottomLeftRadius="7dp"
android:topLeftRadius="7dp" android:topRightRadius="7dp"/>
</shape>
save it as a xml file in the drawable directory,
Use it like you would use any drawable background(icon or resource file) using its resource name (R.drawable.your_xml_name)

Use CardView in android v7 support library.
Though it's a bit heavy, it solves all problem, and easy enough.
Not like the set drawable background method, it could clip subviews successfully.
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
card_view:cardBackgroundColor="#android:color/transparent"
card_view:cardCornerRadius="5dp"
card_view:cardElevation="0dp"
card_view:contentPadding="0dp">
<YOUR_LINEARLAYOUT_HERE>
</android.support.v7.widget.CardView>

I have done this way:
Check Screenshot:
Create drawable file named with custom_rectangle.xml in drawable folder:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="#android:color/white" />
<corners android:radius="10dip" />
<stroke
android:width="1dp"
android:color="#android:color/white" />
</shape>
Now apply Rectangle background on View:
mView.setBackground(R.drawlable.custom_rectangle);
Done

I think a better way to do it is to merge 2 things:
make a bitmap of the layout, as shown here.
make a rounded drawable from the bitmap, as shown here
set the drawable on an imageView.
This will handle cases that other solutions have failed to solve, such as having content that has corners.
I think it's also a bit more GPU-friendly, as it shows a single layer instead of 2 .
The only better way is to make a totally customized view, but that's a lot of code and might take a lot of time. I think that what I suggested here is the best of both worlds.
Here's a snippet of how it can be done:
RoundedCornersDrawable.java
/**
* shows a bitmap as if it had rounded corners. based on :
* http://rahulswackyworld.blogspot.co.il/2013/04/android-drawables-with-rounded_7.html
* easy alternative from support library: RoundedBitmapDrawableFactory.create( ...) ;
*/
public class RoundedCornersDrawable extends BitmapDrawable {
private final BitmapShader bitmapShader;
private final Paint p;
private final RectF rect;
private final float borderRadius;
public RoundedCornersDrawable(final Resources resources, final Bitmap bitmap, final float borderRadius) {
super(resources, bitmap);
bitmapShader = new BitmapShader(getBitmap(), Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
final Bitmap b = getBitmap();
p = getPaint();
p.setAntiAlias(true);
p.setShader(bitmapShader);
final int w = b.getWidth(), h = b.getHeight();
rect = new RectF(0, 0, w, h);
this.borderRadius = borderRadius < 0 ? 0.15f * Math.min(w, h) : borderRadius;
}
#Override
public void draw(final Canvas canvas) {
canvas.drawRoundRect(rect, borderRadius, borderRadius, p);
}
}
CustomView.java
public class CustomView extends ImageView {
private View mMainContainer;
private boolean mIsDirty=false;
// TODO for each change of views/content, set mIsDirty to true and call invalidate
#Override
protected void onDraw(final Canvas canvas) {
if (mIsDirty) {
mIsDirty = false;
drawContent();
return;
}
super.onDraw(canvas);
}
/**
* draws the view's content to a bitmap. code based on :
* http://nadavfima.com/android-snippet-inflate-a-layout-draw-to-a-bitmap/
*/
public static Bitmap drawToBitmap(final View viewToDrawFrom, final int width, final int height) {
// Create a new bitmap and a new canvas using that bitmap
final Bitmap bmp = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
final Canvas canvas = new Canvas(bmp);
viewToDrawFrom.setDrawingCacheEnabled(true);
// Supply measurements
viewToDrawFrom.measure(MeasureSpec.makeMeasureSpec(canvas.getWidth(), MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(canvas.getHeight(), MeasureSpec.EXACTLY));
// Apply the measures so the layout would resize before drawing.
viewToDrawFrom.layout(0, 0, viewToDrawFrom.getMeasuredWidth(), viewToDrawFrom.getMeasuredHeight());
// and now the bmp object will actually contain the requested layout
canvas.drawBitmap(viewToDrawFrom.getDrawingCache(), 0, 0, new Paint());
return bmp;
}
private void drawContent() {
if (getMeasuredWidth() <= 0 || getMeasuredHeight() <= 0)
return;
final Bitmap bitmap = drawToBitmap(mMainContainer, getMeasuredWidth(), getMeasuredHeight());
final RoundedCornersDrawable drawable = new RoundedCornersDrawable(getResources(), bitmap, 15);
setImageDrawable(drawable);
}
}
EDIT: found a nice alternative, based on "RoundKornersLayouts" library. Have a class that will be used for all of the layout classes you wish to extend, to be rounded:
//based on https://github.com/JcMinarro/RoundKornerLayouts
class CanvasRounder(cornerRadius: Float, cornerStrokeColor: Int = 0, cornerStrokeWidth: Float = 0F) {
private val path = android.graphics.Path()
private lateinit var rectF: RectF
private var strokePaint: Paint?
var cornerRadius: Float = cornerRadius
set(value) {
field = value
resetPath()
}
init {
if (cornerStrokeWidth <= 0)
strokePaint = null
else {
strokePaint = Paint()
strokePaint!!.style = Paint.Style.STROKE
strokePaint!!.isAntiAlias = true
strokePaint!!.color = cornerStrokeColor
strokePaint!!.strokeWidth = cornerStrokeWidth
}
}
fun round(canvas: Canvas, drawFunction: (Canvas) -> Unit) {
val save = canvas.save()
canvas.clipPath(path)
drawFunction(canvas)
if (strokePaint != null)
canvas.drawRoundRect(rectF, cornerRadius, cornerRadius, strokePaint)
canvas.restoreToCount(save)
}
fun updateSize(currentWidth: Int, currentHeight: Int) {
rectF = android.graphics.RectF(0f, 0f, currentWidth.toFloat(), currentHeight.toFloat())
resetPath()
}
private fun resetPath() {
path.reset()
path.addRoundRect(rectF, cornerRadius, cornerRadius, Path.Direction.CW)
path.close()
}
}
Then, in each of your customized layout classes, add code similar to this one:
class RoundedConstraintLayout : ConstraintLayout {
private lateinit var canvasRounder: CanvasRounder
constructor(context: Context) : super(context) {
init(context, null, 0)
}
constructor(context: Context, attrs: AttributeSet) : super(context, attrs) {
init(context, attrs, 0)
}
constructor(context: Context, attrs: AttributeSet, defStyle: Int) : super(context, attrs, defStyle) {
init(context, attrs, defStyle)
}
private fun init(context: Context, attrs: AttributeSet?, defStyle: Int) {
val array = context.obtainStyledAttributes(attrs, R.styleable.RoundedCornersView, 0, 0)
val cornerRadius = array.getDimension(R.styleable.RoundedCornersView_corner_radius, 0f)
val cornerStrokeColor = array.getColor(R.styleable.RoundedCornersView_corner_stroke_color, 0)
val cornerStrokeWidth = array.getDimension(R.styleable.RoundedCornersView_corner_stroke_width, 0f)
array.recycle()
canvasRounder = CanvasRounder(cornerRadius,cornerStrokeColor,cornerStrokeWidth)
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR2) {
setLayerType(FrameLayout.LAYER_TYPE_SOFTWARE, null)
}
}
override fun onSizeChanged(currentWidth: Int, currentHeight: Int, oldWidth: Int, oldheight: Int) {
super.onSizeChanged(currentWidth, currentHeight, oldWidth, oldheight)
canvasRounder.updateSize(currentWidth, currentHeight)
}
override fun draw(canvas: Canvas) = canvasRounder.round(canvas) { super.draw(canvas) }
override fun dispatchDraw(canvas: Canvas) = canvasRounder.round(canvas) { super.dispatchDraw(canvas) }
}
If you wish to support attributes, use this as written on the library:
<resources>
<declare-styleable name="RoundedCornersView">
<attr name="corner_radius" format="dimension"/>
<attr name="corner_stroke_width" format="dimension"/>
<attr name="corner_stroke_color" format="color"/>
</declare-styleable>
</resources>
Another alternative, which might be easier for most uses: use MaterialCardView . It allows customizing the rounded corners, stroke color and width, and elevation.
Example:
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:clipChildren="false" android:clipToPadding="false"
tools:context=".MainActivity">
<com.google.android.material.card.MaterialCardView
android:layout_width="100dp" android:layout_height="100dp" android:layout_gravity="center"
app:cardCornerRadius="8dp" app:cardElevation="8dp" app:strokeColor="#f00" app:strokeWidth="2dp">
<ImageView
android:layout_width="match_parent" android:layout_height="match_parent" android:background="#0f0"/>
</com.google.android.material.card.MaterialCardView>
</FrameLayout>
And the result:
Do note that there is a slight artifacts issue at the edges of the stroke (leaves some pixels of the content there), if you use it. You can notice it if you zoom in. I've reported about this issue here.
EDIT: seems to be fixed, but not on the IDE. Reported here.

Step 1: Define bg_layout.xml in drawables folder, and put the below code in it.
Step 2: Add that bg_layout.xml as background to your layout, Done.
<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid
android:color="#EEEEEE"/> <!--your desired colour for solid-->
<stroke
android:width="3dp"
android:color="#EEEEEE" /> <!--your desired colour for border-->
<corners
android:radius="50dp"/> <!--shape rounded value-->
</shape>

If you would like to make your layout rounded, it is best to use the CardView, it provided many features to make the design beautiful.
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
card_view:cardCornerRadius="5dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight=".3"
android:text="#string/quote_code"
android:textColor="#color/white"
android:textSize="#dimen/text_head_size" />
</LinearLayout>
</android.support.v7.widget.CardView>
With this card_view:cardCornerRadius="5dp", you can change the radius.

Try this...
1.create drawable xml(custom_layout.xml):
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
<solid android:color="#FFFFFF" />
<stroke
android:width="2dp"
android:color="#FF785C" />
<corners android:radius="10dp" />
</shape>
2.add your view background
android:background="#drawable/custom_layout"

With the Material Components Library you can use the MaterialShapeDrawable to draw custom shapes.
Just put the LinearLayout in your xml layout:
<LinearLayout
android:id="#+id/linear_rounded"
android:layout_width="match_parent"
android:layout_height="wrap_content"
..>
<!-- content ..... -->
</LinearLayout>
Then in your code you can apply a ShapeAppearanceModel. Something like:
float radius = getResources().getDimension(R.dimen.default_corner_radius);
LinearLayout linearLayout= findViewById(R.id.linear_rounded);
ShapeAppearanceModel shapeAppearanceModel = new ShapeAppearanceModel()
.toBuilder()
.setAllCorners(CornerFamily.ROUNDED,radius)
.build();
MaterialShapeDrawable shapeDrawable = new MaterialShapeDrawable(shapeAppearanceModel);
//Fill the LinearLayout with your color
shapeDrawable.setFillColor(ContextCompat.getColorStateList(this,R.color.secondaryLightColor));
ViewCompat.setBackground(linearLayout,shapeDrawable);
Note:: it requires the version 1.1.0 of the material components library.

The best and simplest method would be to make use of card_background drawable in your layout. This also follows Google's material design guidelines. Just include this in you LinearLayout:
android:background="#drawable/card_background"
Add this to your drawable directory and name it card_background.xml:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape android:shape="rectangle">
<solid android:color="#BDBDBD"/>
<corners android:radius="5dp"/>
</shape>
</item>
<item
android:left="0dp"
android:right="0dp"
android:top="0dp"
android:bottom="2dp">
<shape android:shape="rectangle">
<solid android:color="#ffffff"/>
<corners android:radius="5dp"/>
</shape>
</item>
</layer-list>

Function for set corner radius programmatically
static void setCornerRadius(GradientDrawable drawable, float topLeft,
float topRight, float bottomRight, float bottomLeft) {
drawable.setCornerRadii(new float[] { topLeft, topLeft, topRight, topRight,
bottomRight, bottomRight, bottomLeft, bottomLeft });
}
static void setCornerRadius(GradientDrawable drawable, float radius) {
drawable.setCornerRadius(radius);
}
Using
GradientDrawable gradientDrawable = new GradientDrawable();
gradientDrawable.setColor(Color.GREEN);
setCornerRadius(gradientDrawable, 20f);
//or setCornerRadius(gradientDrawable, 20f, 40f, 60f, 80f);
view.setBackground(gradientDrawable);

Use CardView to get rounded edges for any layouts.
Use card_view:cardCornerRadius="5dp" for cardview to get rounded layout edges.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
card_view:cardCornerRadius="5dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:padding="15dp"
android:weightSum="1">
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight=".3"
android:text="#string/quote_code"
android:textColor="#color/white"
android:textSize="#dimen/text_head_size" />
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight=".7"
android:text="#string/quote_details"
android:textColor="#color/white"
android:textSize="#dimen/text_head_size" />
</LinearLayout>
</android.support.v7.widget.CardView>
</LinearLayout>

A better way to do it would be:
background_activity.xml
<?xml version="1.0" encoding="UTF-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:gravity="fill">
<color android:color="#color/black"/>
</item>
<item>
<shape android:gravity="fill">
<solid android:color="#color/white"/>
<corners android:radius="10dip"/>
<padding android:left="0dip" android:top="0dip" android:right="0dip" android:bottom="0dip" />
</shape>
</item>
</layer-list>
This will work below API 21 also, and give you something like this:
If you are willing to make a little more effort more better control, then use android.support.v7.widget.CardView with its cardCornerRadius attribute (and set elevation attribute to 0dp to get rid of any accompanying drop shadow with the cardView). Also, this will work from API level as low as 15.

Create your xml in drawable, layout_background.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
<solid android:color="#color/your_colour" />
<stroke
android:width="2dp"
android:color="#color/your_colour" />
<corners android:radius="10dp" />
</shape>
<--width, color, radius should be as per your requirement-->
and then, add this in your layout.xml
android:background="#drawable/layout_background"

<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#FFFFFF"/>
<stroke android:width="3dip" android:color="#B1BCBE" />
<corners android:radius="10dip"/>
<padding android:left="3dip" android:top="3dip" android:right="3dip" android:bottom="3dip" />
</shape>
#David, just put padding same value as stroke, so border can be visible, regardeless image size

<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:padding="#dimen/_10sdp"
android:shape="rectangle">
<solid android:color="#color/header" />
<corners
android:bottomLeftRadius="#dimen/_5sdp"
android:bottomRightRadius="#dimen/_5sdp"
android:topLeftRadius="#dimen/_5sdp"
android:topRightRadius="#dimen/_5sdp" />

I've taken #gauravsapiens answer with my comments inside to give you a reasonable apprehension of what the parameters will effect.
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Background color -->
<solid android:color="#color/white" />
<!-- Stroke around the background, width and color -->
<stroke android:width="4dp" android:color="#color/drop_shadow"/>
<!-- The corners of the shape -->
<corners android:radius="4dp"/>
<!-- Padding for the background, e.g the Text inside a TextView will be
located differently -->
<padding android:left="10dp" android:right="10dp"
android:bottom="10dp" android:top="10dp" />
</shape>
If you're just looking to create a shape that rounds the corners, removing the padding and the stroke will do. If you remove the solid as well you will, in effect, have created rounded corners on a transparent background.
For the sake of being lazy I have created a shape underneath, which is just a solid white background with rounded corners - enjoy! :)
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Background color -->
<solid android:color="#color/white" />
<!-- The corners of the shape -->
<corners android:radius="4dp"/>
</shape>

I'm a bit late to the party, but this is still a problem. So I wrote a set of OutlineProviders and BindingAdapters for data binding that enables you to clip corners from xml.
NOTE: Clipping with outline does not support corners to be different sizes!
I wrote a detailed response with code on this stackoverflow post
What you will get with code + binding adapter:
<androidx.constraintlayout.widget.ConstraintLayout
clipRadius="#{#dimen/some_radius}"
clipBottomLeft="#{#dimen/some_radius}"
clipBottomRight="#{#dimen/some_radius}"
clipTopLeft="#{#dimen/some_radius}"
clipTopRight="#{#dimen/some_radius}"
clipCircle="#{#bool/clip}"
This enables you to clip the view to a circle, round all corners, round corners in one direction (left, top, right, bottom) or single corners.

If what you want is just a simple rounded rectangle, cut the long story short.
float r=8;
ShapeDrawable shape =
new ShapeDrawable (new RoundRectShape(new float[] { r, r, r, r, r, r, r, r },null,null));
shape.getPaint().setColor(Color.RED);
view.setBackground(shape);
The first two floats are for the top-left corner (remaining pairs correspond clockwise).
for more details read this answer

You can do it with a custom view, like this RoundAppBar and RoundBottomAppBar.
Here a path is used to clipPath the canvas.

How to show shadow around the linearlayout in Android?

How can I show shadow for my linear layout. I want white colored rounded background with shadow around the linearlayout. I have done this so far.
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:background="#xml/rounded_rect_shape"
android:orientation="vertical"
android:padding="10dp">
<-- My buttons, textviews, Imageviews go here -->
</LinearLayout>
And rounded_rect_shape.xml under xml directory
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="#ffffff" />
<corners
android:bottomLeftRadius="3dp"
android:bottomRightRadius="3dp"
android:topLeftRadius="3dp"
android:topRightRadius="3dp" />
</shape>

There is also another solution to the problem by implementing a layer-list that will act as the background for the LinearLayoout.
Add background_with_shadow.xml file to res/drawable. Containing:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item >
<shape
android:shape="rectangle">
<solid android:color="#android:color/darker_gray" />
<corners android:radius="5dp"/>
</shape>
</item>
<item android:right="1dp" android:left="1dp" android:bottom="2dp">
<shape
android:shape="rectangle">
<solid android:color="#android:color/white"/>
<corners android:radius="5dp"/>
</shape>
</item>
</layer-list>
Then add the the layer-list as background in your LinearLayout.
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/background_with_shadow"/>

Well, this is easy to achieve .
Just build a GradientDrawable that comes from black and goes to a transparent color, than use parent relationship to place your shape close to the View that you want to have a shadow, then you just have to give any values to height or width .
Here is an example, this file have to be created inside res/drawable , I name it as shadow.xml :
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<gradient
android:startColor="#9444"
android:endColor="#0000"
android:type="linear"
android:angle="90"> <!-- Change this value to have the correct shadow angle, must be multiple from 45 -->
</gradient>
</shape>
Place the following code above from a LinearLayout , for example, set the android:layout_width and android:layout_height to fill_parent and 2.3dp, you'll have a nice shadow effect on your LinearLayout .
<View
android:id="#+id/shadow"
android:layout_width="fill_parent"
android:layout_height="2.3dp"
android:layout_above="#+id/id_from_your_LinearLayout"
android:background="#drawable/shadow">
</View>
Note 1: If you increase android:layout_height more shadow will be shown .
Note 2: Use android:layout_above="#+id/id_from_your_LinearLayout" attribute if you are placing this code inside a RelativeLayout, otherwise ignore it.
Hope it help someone.

There is no such attribute in Android, to show a shadow. But possible ways to do it are:
Add a plain LinearLayout with grey color, over which add your actual layout, with margin at bottom and right equal to 1 or 2 dp
Have a 9-patch image with a shadow and set it as the background to your Linear layout

For lollipop and above you can use elevation.
For older versions:
Here is a lazy hack from:
http://odedhb.blogspot.com/2013/05/android-layout-shadow-without-9-patch.html
(toast_frame does not work on KitKat, shadow was removed from toasts)
just use:
android:background="#android:drawable/toast_frame"
or:
android:background="#android:drawable/dialog_frame"
as a background
examples:
<TextView
android:layout_width="fill_parent"
android:text="I am a simple textview with a shadow"
android:layout_height="wrap_content"
android:textSize="18sp"
android:padding="16dp"
android:textColor="#fff"
android:background="#android:drawable/toast_frame"
/>
and with different bg color:
<LinearLayout
android:layout_height="64dp"
android:layout_width="fill_parent"
android:gravity="center"
android:background="#android:drawable/toast_frame"
android:padding="4dp"
>
<Button
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="Button shadow"
android:background="#33b5e5"
android:textSize="24sp"
android:textStyle="bold"
android:textColor="#fff"
android:layout_gravity="center|bottom"
/>
</LinearLayout>

Try this.. layout_shadow.xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape android:shape="rectangle">
<solid android:color="#CABBBBBB"/>
<corners android:radius="2dp" />
</shape>
</item>
<item
android:left="0dp"
android:right="0dp"
android:top="0dp"
android:bottom="2dp">
<shape android:shape="rectangle">
<solid android:color="#android:color/white"/>
<corners android:radius="2dp" />
</shape>
</item>
</layer-list>
Apply to your layout like this
android:background="#drawable/layout_shadow"

I know this is old, but most of these answers require a ton of extra code.
If you have a light colored background, you can simply use this:
android:elevation="25dp"

Actually I agree with #odedbreiner but I put the dialog_frame inside the first layer and hide the black background under the white layer.
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:drawable="#android:drawable/dialog_frame"
android:right="2dp" android:left="2dp" android:bottom="2dp" android:top="5dp" >
<shape android:shape="rectangle">
<corners android:radius="5dp"/>
</shape>
</item>
<item>
<shape
android:shape="rectangle">
<solid android:color="#android:color/white"/>
<corners android:radius="5dp"/>
</shape>
</item>
</layer-list>

save this 9.png. (change name it to 9.png)
2.save it in your drawable.
3.set it to your layout.
4.set padding.
For example :
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#drawable/shadow"
android:paddingBottom="6dp"
android:paddingLeft="5dp"
android:paddingRight="5dp"
android:paddingTop="6dp"
>
.
.
.
</LinearLayout>

Create a new XML by example named "shadow.xml" at DRAWABLE with the following code (you can modify it or find another better):
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape android:shape="rectangle">
<solid android:color="#color/middle_grey"/>
</shape>
</item>
<item android:left="2dp"
android:right="2dp"
android:bottom="2dp">
<shape android:shape="rectangle">
<solid android:color="#color/white"/>
</shape>
</item>
</layer-list>
After creating the XML in the LinearLayout or another Widget you want to create shade, you use the BACKGROUND property to see the efect. It would be something like :
<LinearLayout
android:orientation="horizontal"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:paddingRight="#dimen/margin_med"
android:background="#drawable/shadow"
android:minHeight="?attr/actionBarSize"
android:gravity="center_vertical">

You can use following class for xml tag:
import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BlurMaskFilter;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.Rect;
import android.os.Build;
import android.support.annotation.FloatRange;
import android.util.AttributeSet;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.widget.FrameLayout;
import com.webappmate.weeassure.R;
/**
* Created by GIGAMOLE on 13.04.2016.
*/
public class ShadowLayout extends FrameLayout {
// Default shadow values
private final static float DEFAULT_SHADOW_RADIUS = 30.0F;
private final static float DEFAULT_SHADOW_DISTANCE = 15.0F;
private final static float DEFAULT_SHADOW_ANGLE = 45.0F;
private final static int DEFAULT_SHADOW_COLOR = Color.DKGRAY;
// Shadow bounds values
private final static int MAX_ALPHA = 255;
private final static float MAX_ANGLE = 360.0F;
private final static float MIN_RADIUS = 0.1F;
private final static float MIN_ANGLE = 0.0F;
// Shadow paint
private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG) {
{
setDither(true);
setFilterBitmap(true);
}
};
// Shadow bitmap and canvas
private Bitmap mBitmap;
private final Canvas mCanvas = new Canvas();
// View bounds
private final Rect mBounds = new Rect();
// Check whether need to redraw shadow
private boolean mInvalidateShadow = true;
// Detect if shadow is visible
private boolean mIsShadowed;
// Shadow variables
private int mShadowColor;
private int mShadowAlpha;
private float mShadowRadius;
private float mShadowDistance;
private float mShadowAngle;
private float mShadowDx;
private float mShadowDy;
public ShadowLayout(final Context context) {
this(context, null);
}
public ShadowLayout(final Context context, final AttributeSet attrs) {
this(context, attrs, 0);
}
public ShadowLayout(final Context context, final AttributeSet attrs, final int defStyleAttr) {
super(context, attrs, defStyleAttr);
setWillNotDraw(false);
setLayerType(LAYER_TYPE_HARDWARE, mPaint);
// Retrieve attributes from xml
final TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.ShadowLayout);
try {
setIsShadowed(typedArray.getBoolean(R.styleable.ShadowLayout_sl_shadowed, true));
setShadowRadius(
typedArray.getDimension(
R.styleable.ShadowLayout_sl_shadow_radius, DEFAULT_SHADOW_RADIUS
)
);
setShadowDistance(
typedArray.getDimension(
R.styleable.ShadowLayout_sl_shadow_distance, DEFAULT_SHADOW_DISTANCE
)
);
setShadowAngle(
typedArray.getInteger(
R.styleable.ShadowLayout_sl_shadow_angle, (int) DEFAULT_SHADOW_ANGLE
)
);
setShadowColor(
typedArray.getColor(
R.styleable.ShadowLayout_sl_shadow_color, DEFAULT_SHADOW_COLOR
)
);
} finally {
typedArray.recycle();
}
}
#Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
// Clear shadow bitmap
if (mBitmap != null) {
mBitmap.recycle();
mBitmap = null;
}
}
public boolean isShadowed() {
return mIsShadowed;
}
public void setIsShadowed(final boolean isShadowed) {
mIsShadowed = isShadowed;
postInvalidate();
}
public float getShadowDistance() {
return mShadowDistance;
}
public void setShadowDistance(final float shadowDistance) {
mShadowDistance = shadowDistance;
resetShadow();
}
public float getShadowAngle() {
return mShadowAngle;
}
#SuppressLint("SupportAnnotationUsage")
#FloatRange
public void setShadowAngle(#FloatRange(from = MIN_ANGLE, to = MAX_ANGLE) final float shadowAngle) {
mShadowAngle = Math.max(MIN_ANGLE, Math.min(shadowAngle, MAX_ANGLE));
resetShadow();
}
public float getShadowRadius() {
return mShadowRadius;
}
public void setShadowRadius(final float shadowRadius) {
mShadowRadius = Math.max(MIN_RADIUS, shadowRadius);
if (isInEditMode()) return;
// Set blur filter to paint
mPaint.setMaskFilter(new BlurMaskFilter(mShadowRadius, BlurMaskFilter.Blur.NORMAL));
resetShadow();
}
public int getShadowColor() {
return mShadowColor;
}
public void setShadowColor(final int shadowColor) {
mShadowColor = shadowColor;
mShadowAlpha = Color.alpha(shadowColor);
resetShadow();
}
public float getShadowDx() {
return mShadowDx;
}
public float getShadowDy() {
return mShadowDy;
}
// Reset shadow layer
private void resetShadow() {
// Detect shadow axis offset
mShadowDx = (float) ((mShadowDistance) * Math.cos(mShadowAngle / 180.0F * Math.PI));
mShadowDy = (float) ((mShadowDistance) * Math.sin(mShadowAngle / 180.0F * Math.PI));
// Set padding for shadow bitmap
final int padding = (int) (mShadowDistance + mShadowRadius);
setPadding(padding, padding, padding, padding);
requestLayout();
}
private int adjustShadowAlpha(final boolean adjust) {
return Color.argb(
adjust ? MAX_ALPHA : mShadowAlpha,
Color.red(mShadowColor),
Color.green(mShadowColor),
Color.blue(mShadowColor)
);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
// Set ShadowLayout bounds
mBounds.set(
0, 0, MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.getSize(heightMeasureSpec)
);
}
#Override
public void requestLayout() {
// Redraw shadow
mInvalidateShadow = true;
super.requestLayout();
}
#Override
protected void dispatchDraw(final Canvas canvas) {
// If is not shadowed, skip
if (mIsShadowed) {
// If need to redraw shadow
if (mInvalidateShadow) {
// If bounds is zero
if (mBounds.width() != 0 && mBounds.height() != 0) {
// Reset bitmap to bounds
mBitmap = Bitmap.createBitmap(
mBounds.width(), mBounds.height(), Bitmap.Config.ARGB_8888
);
// Canvas reset
mCanvas.setBitmap(mBitmap);
// We just redraw
mInvalidateShadow = false;
// Main feature of this lib. We create the local copy of all content, so now
// we can draw bitmap as a bottom layer of natural canvas.
// We draw shadow like blur effect on bitmap, cause of setShadowLayer() method of
// paint does`t draw shadow, it draw another copy of bitmap
super.dispatchDraw(mCanvas);
// Get the alpha bounds of bitmap
final Bitmap extractedAlpha = mBitmap.extractAlpha();
// Clear past content content to draw shadow
mCanvas.drawColor(0, PorterDuff.Mode.CLEAR);
// Draw extracted alpha bounds of our local canvas
mPaint.setColor(adjustShadowAlpha(false));
mCanvas.drawBitmap(extractedAlpha, mShadowDx, mShadowDy, mPaint);
// Recycle and clear extracted alpha
extractedAlpha.recycle();
} else {
// Create placeholder bitmap when size is zero and wait until new size coming up
mBitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.RGB_565);
}
}
// Reset alpha to draw child with full alpha
mPaint.setColor(adjustShadowAlpha(true));
// Draw shadow bitmap
if (mCanvas != null && mBitmap != null && !mBitmap.isRecycled())
canvas.drawBitmap(mBitmap, 0.0F, 0.0F, mPaint);
}
// Draw child`s
super.dispatchDraw(canvas);
}
}
use Tag in xml like this:
<yourpackagename.ShadowLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_gravity="center_horizontal"
app:sl_shadow_color="#9e000000"
app:sl_shadow_radius="4dp">
<child views>
</yourpackagename.ShadowLayout>
UPDATE
put the below code in attrs.xml in resource>>values
<declare-styleable name="ShadowLayout">
<attr name="sl_shadowed" format="boolean"/>
<attr name="sl_shadow_distance" format="dimension"/>
<attr name="sl_shadow_angle" format="integer"/>
<attr name="sl_shadow_radius" format="dimension"/>
<attr name="sl_shadow_color" format="color"/>
</declare-styleable>

One possible solution is using nine patch image like this http://developer.android.com/guide/topics/graphics/2d-graphics.html#nine-patch
OR
I have done this in the following way. This is my main layout in which round_corner.xml and drop_shadow.xml used as background resource. round_corner_two is same like round_corner.xml only the color attribute is different. copy the round_corner.xml,drop_shadow.xml and round_conere_two.xml into drawable folder.
<RelativeLayout
android:id="#+id/facebook_id"
android:layout_width="250dp"
android:layout_height="52dp"
android:layout_centerHorizontal="true"
android:layout_marginTop="28dp"
android:background="#drawable/round_corner" >
<LinearLayout
android:id="#+id/shadow_id"
android:layout_width="match_parent"
android:layout_height="48dp"
android:layout_margin="1dp"
android:background="#drawable/drop_shadow" >
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:layout_marginBottom="2dp"
android:background="#drawable/round_corner_two"
android:gravity="center"
android:text="#string/fb_butn_text"
android:textColor="#color/white" >
</TextView>
</LinearLayout>
</RelativeLayout>
round_corner.xml:
<?xml version="1.0" encoding="utf-8"?>
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<!-- view background color -->
<solid
android:color="#ffffff" >
</solid>
<!-- view border color and width -->
<stroke
android:width="0dp"
android:color="#3b5998" >
</stroke>
<!-- If you want to add some padding -->
<padding
android:left="1dp"
android:top="1dp"
android:right="1dp"
android:bottom="1dp" >
</padding>
<!-- Here is the corner radius -->
<corners
android:radius="10dp" >
</corners>
</shape>
drop_shadow.xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item >
<shape
android:shape="rectangle">
<solid android:color="#android:color/darker_gray" />
<corners android:radius="12dp"/>
</shape>
</item>
<item android:right="1dp" android:left="1dp" android:bottom="5dp">
<shape
android:shape="rectangle">
<solid android:color="#android:color/white"/>
<corners android:radius="5dp"/>
</shape>
</item>
</layer-list>

i know this is way too late. but i had the same requirement. i solved like this
<android.support.v7.widget.CardView
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:cardUseCompatPadding="true"
app:cardElevation="4dp"
app:cardCornerRadius="3dp" >
<!-- put whatever you want -->
</android.support.v7.widget.CardView>
you need to add dependency:
compile 'com.android.support:cardview-v7:25.0.1'

set this xml drwable as your background;---
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<!-- Bottom 2dp Shadow -->
<item>
<shape android:shape="rectangle" >
<solid android:color="#d8d8d8" />-->Your shadow color<--
<corners android:radius="15dp" />
</shape>
</item>
<!-- White Top color -->
<item android:bottom="3px" android:left="3px" android:right="3px" android:top="3px">-->here you can customize the shadow size<---
<shape android:shape="rectangle" >
<solid android:color="#FFFFFF" />
<corners android:radius="15dp" />
</shape>
</item>
</layer-list>

Making a triangle shape using XML definitions?

Is there a way that I can specify a triangle shape in an XML file?
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="triangle">
<stroke android:width="1dip" android:color="#FFF" />
<solid android:color="#FFF" />
</shape>
Can we do this with a path shape or something? I just need an equilateral triangle.
Thanks

In this post I describe how to do it. And here is the XML defining triangle:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<rotate
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="-40%"
android:pivotY="87%" >
<shape
android:shape="rectangle" >
<stroke android:color="#color/transparent" android:width="10dp"/>
<solid
android:color="#color/your_color_here" />
</shape>
</rotate>
</item>
</layer-list>
Refer to my post if something is unclear or you need explanation how it is built. It is rotated an cutout rectangle :) it is very smart and well working solution.
EDIT:
to create an arrow pointing like --> use:
...
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="13%"
android:pivotY="-40%" >
...
And to create an arrow pointing like <-- use:
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="87%"
android:pivotY="140%" >

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="▼"/>
You can get here more options.

You can use vector to make triangle like this
ic_triangle_right.xml
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="24dp"
android:height="24dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
<path
android:pathData="M0,12l0,12 11.5,-5.7c6.3,-3.2 11.5,-6 11.5,-6.3 0,-0.3 -5.2,-3.1 -11.5,-6.3l-11.5,-5.7 0,12z"
android:strokeColor="#00000000"
android:fillColor="#000000"/>
</vector>
Then use it like
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="#drawable/ic_triangle_right"
/>
For change the color and direction, use android:tint and android:rotation
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="#drawable/ic_triangle_right"
android:rotation="180" // change direction
android:tint="#00f" // change color
/>
Result
For change the shape of vector, you can change the width/height of vector. Example change width to 10dp
<vector
android:width="10dp"
android:height="24dp"
>
...
</vector>

You can use vector drawables.
If your minimum API is lower than 21, Android Studio automatically creates PNG bitmaps for those lower versions at build time (see Vector Asset Studio). If you use the support library, Android even manages "real vectors" down to API 7 (more on that in the update of this post at the bottom).
A red upwards pointing triangle would be:
<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:height="100dp"
android:width="100dp"
android:viewportHeight="100"
android:viewportWidth="100" >
<group
android:name="triableGroup">
<path
android:name="triangle"
android:fillColor="#FF0000"
android:pathData="m 50,0 l 50,100 -100,0 z" />
</group>
</vector>
Add it to your layout and remember to set clipChildren="false" if you rotate the triangle.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipChildren="false">
<ImageView
android:layout_width="130dp"
android:layout_height="100dp"
android:rotation="0"
android:layout_centerInParent="true"
android:background="#drawable/triangle"/>
</RelativeLayout>
Change the size (width/height) of the triangle by setting the Views layout_width/layout_height attributes. This way you can also get an eqilateral triagle if you do the math correct.
UPDATE 25.11.2017
If you use the support library you can use real vectors (instead if bitmap creation) as far back as API 7. Simply add:
vectorDrawables.useSupportLibrary = true
do your defaultConfig in your module's build.gradle.
Then set the (vector xml) drawable like this:
<ImageView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
app:srcCompat="#drawable/triangle" />
Everything is documented very nicely on the Vector Asset Studio page.
Ever since this feature I've been working entirely without bitmaps in terms of icons. This also reduces APK size quite a bit.

The solution of Jacek Milewski works for me and, based on his solution, if you need and inversed triangle you can use this:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<rotate
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="135%"
android:pivotY="15%">
<shape android:shape="rectangle">
<solid android:color="#color/aquamarine" />
</shape>
</rotate>
</item>
</layer-list>

I would definetely go for implementing a View in this case:
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.View;
public class TriangleShapeView extends View {
public TriangleShapeView(Context context) {
super(context);
}
public TriangleShapeView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public TriangleShapeView(Context context, AttributeSet attrs) {
super(context, attrs);
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int w = getWidth() / 2;
Path path = new Path();
path.moveTo( w, 0);
path.lineTo( 2 * w , 0);
path.lineTo( 2 * w , w);
path.lineTo( w , 0);
path.close();
Paint p = new Paint();
p.setColor( Color.RED );
canvas.drawPath(path, p);
}
}
Make use of it in your layouts as follows:
<TriangleShapeView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ff487fff">
</TriangleShapeView>
Using this implementation will give you the following result:

See answer here:
Custom arrows without image: Android
<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="32dp"
android:height="24dp"
android:viewportWidth="32.0"
android:viewportHeight="24.0">
<path android:fillColor="#e4e4e8"
android:pathData="M0 0 h32 l-16 24 Z"/>
</vector>

Using vector drawable:
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="24dp"
android:height="24dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
<path
android:pathData="M0,0 L24,0 L0,24 z"
android:strokeColor="#color/color"
android:fillColor="#color/color"/>
</vector>

May I help you without using XML ?
Simply,
Custom Layout ( Slice ) :
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Path;
import android.graphics.Point;
import android.util.AttributeSet;
import android.view.View;
public class Slice extends View {
Paint mPaint;
Path mPath;
public enum Direction {
NORTH, SOUTH, EAST, WEST
}
public Slice(Context context) {
super(context);
create();
}
public Slice(Context context, AttributeSet attrs) {
super(context, attrs);
create();
}
public void setColor(int color) {
mPaint.setColor(color);
invalidate();
}
private void create() {
mPaint = new Paint();
mPaint.setStyle(Style.FILL);
mPaint.setColor(Color.RED);
}
#Override
protected void onDraw(Canvas canvas) {
mPath = calculate(Direction.SOUTH);
canvas.drawPath(mPath, mPaint);
}
private Path calculate(Direction direction) {
Point p1 = new Point();
p1.x = 0;
p1.y = 0;
Point p2 = null, p3 = null;
int width = getWidth();
if (direction == Direction.NORTH) {
p2 = new Point(p1.x + width, p1.y);
p3 = new Point(p1.x + (width / 2), p1.y - width);
} else if (direction == Direction.SOUTH) {
p2 = new Point(p1.x + width, p1.y);
p3 = new Point(p1.x + (width / 2), p1.y + width);
} else if (direction == Direction.EAST) {
p2 = new Point(p1.x, p1.y + width);
p3 = new Point(p1.x - width, p1.y + (width / 2));
} else if (direction == Direction.WEST) {
p2 = new Point(p1.x, p1.y + width);
p3 = new Point(p1.x + width, p1.y + (width / 2));
}
Path path = new Path();
path.moveTo(p1.x, p1.y);
path.lineTo(p2.x, p2.y);
path.lineTo(p3.x, p3.y);
return path;
}
}
Your Activity ( Example ) :
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.ViewGroup.LayoutParams;
import android.widget.LinearLayout;
public class Layout extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Slice mySlice = new Slice(getApplicationContext());
mySlice.setBackgroundColor(Color.WHITE);
setContentView(mySlice, new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
}
}
Working Example :
Another absolutely simple Calculate function you may interested in ..
private Path Calculate(Point A, Point B, Point C) {
Path Pencil = new Path();
Pencil.moveTo(A.x, A.y);
Pencil.lineTo(B.x, B.y);
Pencil.lineTo(C.x, C.y);
return Pencil;
}

You can add following triangle in background using following xml
<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:height="100dp"
android:width="100dp"
android:viewportHeight="100"
android:viewportWidth="100" >
<group
android:name="triableGroup">
<path
android:name="triangle"
android:fillColor="#848af8"
android:pathData="M 0,20 L 0,0 L 100,0 L 100,20 L 54,55 l -1,0.6 l -1,0.4 l -1,0.2 l -1,0 l -1,-0 l -1,-0.2 l -1,-0.4 l -1,-0.6 L 46,55 L 0,20 -100,-100 Z" />
</group>
</vector>
The whole logic to customize xml design is in pathData. Consider top-left as (0,0) and design the layout as per your requirement.
Check this answer.

For those who want a right triangle arrow, here you go:
STEP 1: Create a drawable XML file, copy and paste the following XML content into your drawable XML. (Please be informed that you can use any name for your drawable XML file. For my case, I name it "v_right_arrow")
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item >
<rotate
android:fromDegrees="45"
android:toDegrees="-45"
android:pivotX="15%"
android:pivotY="-36%" >
<shape
android:shape="rectangle" >
<stroke android:color="#android:color/transparent" android:width="1dp"/>
<solid
android:color="#000000" />
</shape>
</rotate>
</item>
</layer-list>
STEP 2: In your layout's XML, create a View and bind its background to the drawable XML that you have just created in STEP 1. For my case, I bind v_right_arrow to my View's background property.
<View
android:layout_width="200dp"
android:layout_height="200dp"
android:background="#drawable/v_right_arrow">
</View>
Sample output:
Hope this helps, good luck!

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<rotate
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="-40%"
android:pivotY="87%" >
<shape
android:shape="rectangle" >
<stroke android:color="#android:color/transparent" android:width="0dp"/>
<solid
android:color="#fff" />
</shape>
</rotate>
</item>
</layer-list>

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<rotate
android:fromDegrees="45"
android:pivotX="135%"
android:pivotY="1%"
android:toDegrees="45">
<shape android:shape="rectangle">
<stroke
android:width="-60dp"
android:color="#android:color/transparent" />
<solid android:color="#color/orange" />
</shape>
</rotate>
</item>
</layer-list>

I try to create triangle image like back button of android navigation bar but I haven't found any solution.
Now, I found the solution with myself and would like to share it.
use xml below
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:bottom="20dp"
android:left="480dp"
android:right="60dp"
android:top="20dp">
<shape>
<size android:width="60dp" />
<corners android:radius="80dp"/>
<solid android:color="#AAA" />
</shape>
</item>
<item
android:bottom="480dp"
android:right="70dp"
android:top="20dp">
<rotate
android:fromDegrees="-28"
android:pivotX="96%"
android:pivotY="50%"
android:toDegrees="-20">
<shape>
<corners android:radius="80dp"/>
<size android:height="60dp" />
<solid android:color="#AAA" />
</shape>
</rotate>
</item>
<item
android:bottom="20dp"
android:right="70dp"
android:top="480dp">
<rotate
android:fromDegrees="28"
android:pivotX="96%"
android:pivotY="50%"
android:toDegrees="-20">
<shape>
<corners android:radius="80dp"/>
<size android:height="60dp" />
<solid android:color="#AAA" />
</shape>
</rotate>
</item>

I have never done this, but from what I understand you can use the PathShape class:
http://developer.android.com/reference/android/graphics/drawable/shapes/PathShape.html

I my be late to party and I came across same problem and Google pointed me to this StackOverflow thread as first result.
I tried using xml way to add triangle and find out a problem that the triangle
shape via xml approach is taking more space than it appears.
See screen shot with layout bounds on
So ended up making this custom view class which can draws Triangle of any of following types:-
up pointing
down pointing
left pointing &
right pointing
asas
package com.hiteshsahu.materialupvotewidget;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.support.annotation.NonNull;
import android.util.AttributeSet;
import android.view.View;
public class TriangleShapeView extends View {
private int colorCode = Color.DKGRAY;
public int getColorCode() {
return colorCode;
}
public void setColorCode(int colorCode) {
this.colorCode = colorCode;
}
public TriangleShapeView(Context context) {
super(context);
if (isInEditMode())
return;
}
public TriangleShapeView(Context context, AttributeSet attrs) {
super(context, attrs);
if (isInEditMode())
return;
}
public TriangleShapeView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
if (isInEditMode())
return;
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int w = getWidth() / 2;
int h = getHeight() / 2;
//Choose what type of triangle you want here
Path path = getLeftTriangle(w, h);
path.close();
Paint p = new Paint();
p.setColor(colorCode);
p.setAntiAlias(true);
canvas.drawPath(path, p);
}
#NonNull
/**
* Return Path for down facing triangle
*/
private Path getInvertedTriangle(int w, int h) {
Path path = new Path();
path.moveTo(0, 0);
path.lineTo(w, 2 * h);
path.lineTo(2 * w, 0);
path.lineTo(0, 0);
return path;
}
#NonNull
/**
* Return Path for Up facing triangle
*/
private Path getUpTriangle(int w, int h) {
Path path = new Path();
path.moveTo(0, 2 * h);
path.lineTo(w, 0);
path.lineTo(2 * w, 2 * h);
path.lineTo(0, 2 * h);
return path;
}
#NonNull
/**
* Return Path for Right pointing triangle
*/
private Path getRightTriangle(int w, int h) {
Path path = new Path();
path.moveTo(0, 0);
path.lineTo(2 * w, h);
path.lineTo(0, 2 * h);
path.lineTo(0, 0);
return path;
}
#NonNull
/**
* Return Path for Left pointing triangle
*/
private Path getLeftTriangle(int w, int h) {
Path path = new Path();
path.moveTo(2 * w, 0);
path.lineTo(0, h);
path.lineTo(2 * w, 2 * h);
path.lineTo(2 * w, 0);
return path;
}
}
You can Simply use it in xml layout like this
<com.hiteshsahu.materialupvote.TriangleShapeView
android:layout_width="50dp"
android:layout_height="50dp"></com.hiteshsahu.materialupvote.TriangleShapeView>
I know OP want solutions in xml solution but as I pointed out problem with xml approach . I Hope it might help somebody.

Using the solution of Jacek Milewski I made an oriented down angle with a transparent background.
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<rotate
android:fromDegrees="135"
android:pivotX="65%"
android:pivotY="20%"
android:toDegrees="135"
>
<shape android:shape="rectangle">
<stroke
android:width="1dp"
android:color="#color/blue"
/>
<solid android:color="#color/transparent" />
</shape>
</rotate>
</item>
</layer-list>
You can change android:pivotX and android:pivotY to shift the angle.
Usage:
<ImageView
android:layout_width="10dp"
android:layout_height="10dp"
android:src="#drawable/ic_angle_down"
/>
Parameters depend on the size of the image. For instance, if ImageView has size 100dp*80dp, you should use these constants:
<rotate
android:fromDegrees="135"
android:pivotX="64.5%"
android:pivotY="19%"
android:toDegrees="135"
>

I provide this customView below if you don't want to hack xml.
Please have a try.
/**
* TriangleView
*
* #author Veer
* #date 2020-09-03
*/
class TriangleView #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {
private var triangleColor: Int = 0
private var direction = Direction.Bottom
private val paint by lazy {
Paint().apply {
isAntiAlias = true
style = Paint.Style.FILL
color = triangleColor
}
}
init {
initStyle(context, attrs, defStyleAttr)
}
private fun initStyle(
context: Context,
attrs: AttributeSet?,
defStyleAttr: Int
) {
val ta = context.obtainStyledAttributes(attrs, R.styleable.TriangleView, defStyleAttr, 0)
with(ta) {
triangleColor =
getColor(R.styleable.TriangleView_triangle_background, Color.parseColor("#000000"))
val directionValue =
getInt(R.styleable.TriangleView_triangle_direction, Direction.Bottom.value)
direction = when (directionValue) {
Direction.Top.value -> Direction.Top
Direction.Bottom.value -> Direction.Bottom
Direction.Left.value -> Direction.Left
Direction.Right.value -> Direction.Right
else -> Direction.Bottom
}
recycle()
}
}
override fun onDraw(canvas: Canvas) {
calculatePath(direction).let {
canvas.drawPath(it, paint)
}
}
private fun calculatePath(direction: Direction): Path {
var p1: Point? = null
var p2: Point? = null
var p3: Point? = null
val width = width
val height = height
when (direction) {
Direction.Top -> {
p1 = Point(0, height)
p2 = Point(width / 2, 0)
p3 = Point(width, height)
}
Direction.Bottom -> {
p1 = Point(0, 0)
p2 = Point(width / 2, height)
p3 = Point(width, 0)
}
Direction.Left -> {
p1 = Point(width, 0)
p2 = Point(0, height / 2)
p3 = Point(width, height)
}
Direction.Right -> {
p1 = Point(0, 0)
p2 = Point(width, height / 2)
p3 = Point(0, height)
}
}
val path = Path()
path.moveTo(p1.x.toFloat(), p1.y.toFloat())
path.lineTo(p2.x.toFloat(), p2.y.toFloat())
path.lineTo(p3.x.toFloat(), p3.y.toFloat())
return path
}
private enum class Direction(val value: Int) {
Top(0),
Bottom(1),
Left(2),
Right(3)
}
}
<declare-styleable name="TriangleView">
<attr name="triangle_direction" format="enum">
<enum name="top" value="0" />
<enum name="bottom" value="1" />
<enum name="left" value="2" />
<enum name="right" value="3" />
</attr>
<attr name="triangle_background" format="reference|color" />
</declare-styleable>

<LinearLayout
android:id="#+id/ly_fill_color_shape"
android:layout_width="300dp"
android:layout_height="300dp"
android:layout_gravity="center"
android:background="#drawable/shape_triangle"
android:gravity="center"
android:orientation="horizontal" >
</LinearLayout>
<item>
<rotate
android:fromDegrees="45"
android:pivotX="-15%"
android:pivotY="77%"
android:toDegrees="45" >
<shape android:shape="rectangle" >
<stroke
android:width="2dp"
android:color="#color/black_color" />
<solid android:color="#color/white" />
<padding android:left="1dp" />
</shape>
</rotate>
</item>
<item android:top="200dp">
<shape android:shape="line" >
<stroke
android:width="1dp"
android:color="#color/black_color" />
<solid android:color="#color/white" />
</shape>
</item>

Google provides a Equilateral triangle here.
Choose VectorDrawable so the size is flexible.
It' integrated into Android Studio as plugin.
If you have an SVG image, you can use this to convert it to VectorDrawable too.
Once you have a VectorDrawable, changing its colour and rotation is easy like others have mentioned.

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.

Android how to create triangle and rectangle shape programmatically? - android

How can we create ballon drawable shape as below. where we can change the color of it dynamically.

Use a triangle image and a rectangular image and mathematically align them in the above mentioned format. Use color filtering to dynamically change its color. You can even draw them on a custom view, using vector graphics, using custom colors, and that would be another way of solving this problem.

Use Canvas in onDraw method inside custom View class. Other way is to use Path class.

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Generate specific xml drawable [duplicate]

Images with rounded corners in a ListView

How to make layout with rounded corners..?

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Making a triangle shape using XML definitions?

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