Develop Reference

Android Layout transparent layout background with underline

I am trying to have a layout background drawable, which will be only gradient underline with 1-2 dp height and rest is transparent, so the upper part will have the parent's background.
Here is what I have.
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android>
<!-- underline color -->
<item>
<shape>
<gradient
android:startColor="#color/colorPrimaryDark"
android:endColor="#FFFFFFFF"
android:centerY="0.5"
android:angle="0"/>
</shape>
</item>
<!-- main color -->
<item android:bottom="2.5dp">
<shape android:shape="rectangle">
<solid android:color="#color/white" />
<padding
android:top="4dp"
android:bottom="4dp" />
</shape>
</item>
If I change the solid color in "main color" to transparent, whole background will be using "underline color" settings.

The technique you use to create a line on the bottom of the view works if the color of the layer overlaying the gradient layer is opaque. What you are trying to do is to apply a transparent layer that replaces (erases) the underlying gradient. That is not how it works: A transparent overlay leaves the underlying color, here a gradient, untouched.
Here is an alternate layer-list drawable that you can use for API 23+:
underline_drawable.xml
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:gravity="bottom">
<shape>
<size android:height="2dp" />
<gradient
android:angle="0"
android:centerY="0.5"
android:endColor="#FFFFFFFF"
android:startColor="#color/colorPrimaryDark" />
</shape>
</item>
</layer-list>
Here is what it looks like:
Prior to API 23, you can use the following custom drawable, but it must be set in code.
GradientUnderline.java
public class GradientUnderline extends Drawable {
private Shader mShader;
private final Paint mPaint;
private int mHeight = -1;
private int mStartColor = Color.BLACK;
private int mEndColor = Color.WHITE;
private int mLastWidth;
public GradientUnderline() {
mPaint = new Paint();
}
public GradientUnderline(int lineHeight, int startColor, int endColor) {
mPaint = new Paint();
mHeight = lineHeight;
mStartColor = startColor;
mEndColor = endColor;
}
#Override
public void draw(#NonNull Canvas canvas) {
if (mShader == null || getBounds().width() != mLastWidth) {
mLastWidth = getBounds().width();
mShader = new LinearGradient(0, 0, getBounds().width(), mHeight, mStartColor,
mEndColor, Shader.TileMode.CLAMP);
mPaint.setShader(mShader);
}
canvas.drawRect(0, getBounds().height() - mHeight, getBounds().width(),
getBounds().height(), mPaint);
}
#Override
public void setAlpha(int alpha) {
}
#Override
public void setColorFilter(#Nullable ColorFilter colorFilter) {
}
#Override
public int getOpacity() {
return PixelFormat.OPAQUE;
}
}
I missed the availability of android:gravity initially because it is not mentioned on the "Drawable Resources" page. It is mentioned, however, in the LayerDrawable documentation.

Why problem occurs: Shape at first item will draw the gradient in entire region. After setting colour to second item will hide the top item region except ay 2.5dp at bottom. So whenever you set transparent colour to second item it automatically show the top level item that is gradient region..
Here i suggest the way to use but you can set to fixed height in view.
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:top="47dp">
<shape>
<gradient
android:startColor="#color/colorPrimaryDark"
android:endColor="#FFFFFFFF"
android:centerY="0.5"
android:angle="0"/>
</shape>
</item>
</layer-list>
View.xml
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#drawable/bottom_line">
</RelativeLayout>
Change size according to your needs..!
OUTPUT

Android CardView - How to fold corner

I want to get a CardView with the top-right corner like you can see in the image below, but I have no idea how to do so. It is like a folded paper (with no animation). I don't know if I should make a custom background drawable or how to manage the corner radius to get the desired result. Any help will be greatly appreciated, thanks

Also you can create such a drawable programmatically like this:
public static final class FoldCornerCard extends Shape {
private final float foldPart;
private final Path cardPath = new Path();
private final Path foldPath = new Path();
private final Paint foldPaint;
public FoldCornerCard(int foldColor, float foldPart) {
if (foldPart <= 0 || foldPart >= 1) {
throw new IllegalArgumentException("Fold part must be in (0,1)");
}
this.foldPart = foldPart;
this.foldPaint = new Paint();
foldPaint.setAntiAlias(true);
foldPaint.setColor(foldColor);
}
#Override
protected void onResize(float width, float height) {
super.onResize(width, height);
this.cardPath.reset();
final float leftFold = width - width * foldPart;
final float bottomFold = height * foldPart;
cardPath.lineTo(leftFold, 0);
cardPath.lineTo(width, bottomFold);
cardPath.lineTo(width, height);
cardPath.lineTo(0, height);
cardPath.close();
foldPath.reset();
foldPath.moveTo(leftFold, 0);
foldPath.lineTo(leftFold, bottomFold);
foldPath.lineTo(width, bottomFold);
foldPath.close();
}
#Override
public void draw(Canvas canvas, Paint paint) {
canvas.drawPath(cardPath, paint);
canvas.drawPath(foldPath, foldPaint);
}
}
And usage example:
final ShapeDrawable shapeDrawable = new ShapeDrawable(
new FoldCornerCard(Color.GREEN, 0.1f));
shapeDrawable.getPaint().setColor(Color.WHITE);
shapeDrawable.setIntrinsicHeight(-1);
shapeDrawable.setIntrinsicWidth(-1);
You just need to modify my snippet a bit to add round corners.

Look at here https://developer.android.com/studio/write/draw9patch.html
I think this is righ way to use custom layout. You could draw it on xml, or use 9-patch png.
Also you can create own class MyCardView and extends from CardView, then override method onDraw and draw CardView like you want, but it is not good idea.
I would reccomend you use 9-patch image

You can achieve this using your xml:
Lets Assume our xml shape is called shape.xml
In shape.xml(Which you have to create in your drawable folder..drawable/shape.xml)..
Create your layer list element with its square shape as the background of your xml:
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<!--Paper-Back-->
<item
android:bottom="30dp"
android:left="18dp"
android:right="1dp"
android:top="0dp">
<shape android:shape="rectangle">
<solid android:color="#color/paperBack"/>
<corners
android:bottomLeftRadius="10dp"
android:bottomRightRadius="10dp"
android:topLeftRadius="10dp"
android:topRightRadius="78dp"/>
</shape>
</item>
<!--Paper-Back End-->
<!--Fold-->
<item
android:bottom="650dp"
android:top="0dp"
android:left="300dp"
android:right="1dp">
<shape android:shape="rectangle">
<solid android:color="#color/paperFold"/>
<corners
android:bottomLeftRadius="0dp"
android:bottomRightRadius="0dp"
android:topLeftRadius="0dp"
android:topRightRadius="100dp"
/>
</shape>
</item>
<!--Fold End-->
</layer-list>
Then in your colours.xml resource:
Add your colours:
color.xml
<color name="PaperBack">#A6F5F5F5</color>
<color name="paperFold">#A6DDDDDD</color>
In order to achieve the best results:The opacity of your colours as well as the type of colour combination for your paper background and fold colours will have to be taken into great consideration.
Now to apply the paper fold shape..in your main xml, use the shape.xml as the background in your main.xml.
using shape.xml as the background
android:background="#drawable/shape.xml"
main.xml
<androidx.constraintlayout.widget.ConstraintLayout 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:id="#+id/main_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#drawable/shape.xml"
android:orientation="vertical"
android:weightSum="4">
.....................

Enlarge the center of an Android gradient drawable

I created an Android gradient drawable where the top and bottom are black and the center is transparent:
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<gradient
android:startColor="#android:color/black"
android:centerColor="#android:color/transparent"
android:endColor="#android:color/black"
android:angle="90"/>
</shape>
The rendered gradient looks like this:
As you can see, the black parts spread to most of the screen. I want the black to show only on a small portion of the top and bottom. Is there a way I can make the transparent center larger, or make the top and bottom black stripes smaller?
I tried playing around with some of the other XML attributes mentioned in the linked GradientDrawable documentation, yet none of them seem to make and difference.

For an XML only solution, you can create a layer-list with two separate gradient objects.
The following code creates two overlapping gradient objects and uses centerY with centerColor to offset the black section. Here, the centerY attributes are set to 0.9 and 0.1, so the black color is restricted to the top and bottom 10% of the view height.
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape>
<gradient
android:angle="90"
android:centerColor="#android:color/transparent"
android:centerY="0.9"
android:endColor="#android:color/black"
android:startColor="#android:color/transparent" />
</shape>
</item>
<item>
<shape>
<gradient
android:angle="90"
android:centerColor="#android:color/transparent"
android:centerY="0.1"
android:endColor="#android:color/transparent"
android:startColor="#android:color/black" />
</shape>
</item>
</layer-list>
For API level 23 or higher, the following solution will also work, using android:height. This solution can work even if you don't know the total height of your view, as long as you know how large you want the gradient to be.
This code creates two separate gradients, each with a height of 60sp, and then uses android:gravity to float the gradients to the top and bottom of the view.
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:height="60sp"
android:gravity="top">
<shape android:shape="rectangle">
<gradient
android:angle="90"
android:endColor="#android:color/black"
android:startColor="#android:color/transparent" />
</shape>
</item>
<item
android:height="65sp"
android:gravity="bottom">
<shape android:shape="rectangle">
<gradient
android:angle="90"
android:endColor="#android:color/transparent"
android:startColor="#android:color/black" />
</shape>
</item>
</layer-list>
Thank you #Luksprog for the code help, and #thenaoh for the start of the idea.
The above solutions work and it is nice that they are pure XML. If your gradient is showing with stripes, you may want to try a programmatic solution, like shown in #lelloman's answer, to create a smoother gradient.

Here is how it could be done with a custom Drawable. You can tune the LinearGradient as you want, and then set it as the view's background with view.setBackground(new CustomDrawable());.
public class CustomDrawable extends Drawable {
private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
private int[] colors;
private float[] positions;
public CustomDrawable() {
paint.setStyle(Paint.Style.FILL);
this.colors = new int[]{0xff000000, 0xffaaaaaa, 0xffffffff, 0xffaaaaaa, 0xff000000};
this.positions = new float[]{.0f, .2f, .5f, .8f, 1.f};
}
#Override
public void setBounds(int left, int top, int right, int bottom) {
super.setBounds(left, top, right, bottom);
LinearGradient linearGradient = new LinearGradient(left, top,left, bottom, colors, positions, Shader.TileMode.CLAMP);
paint.setShader(linearGradient);
}
#Override
public void draw(#NonNull Canvas canvas) {
canvas.drawRect(getBounds(), paint);
}
#Override
public void setAlpha(#IntRange(from = 0, to = 255) int alpha) {
paint.setAlpha(alpha);
}
#Override
public void setColorFilter(#Nullable ColorFilter colorFilter) {
paint.setColorFilter(colorFilter);
}
#Override
public int getOpacity() {
return PixelFormat.TRANSPARENT;
}
}

There is a solution, assuming that you know in advance the height of your view (let's say here 60dp):
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:bottom="40dp">
<shape android:shape="rectangle">
<gradient
android:type="linear"
android:angle="90"
android:startColor="#FFFFFF"
android:endColor="#000000"/>
</shape>
</item>
<item
android:top="20dp"
android:bottom="20dp"
android:gravity="center_vertical">
<shape android:shape="rectangle">
<solid android:color="#FFFFFF"/>
</shape>
</item>
<item
android:top="40dp"
android:gravity="bottom">
<shape android:shape="rectangle">
<gradient
android:type="linear"
android:angle="90"
android:startColor="#000000"
android:endColor="#FFFFFF"/>
</shape>
</item>
</layer-list>
But if you don't know the height in advance, another solution would be to make your own custom view, like this:
public class MyView extends ImageView
{
private Paint paint = null;
public MyView(Context context, AttributeSet attrs)
{
super(context, attrs);
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
}
#Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
paint.setShader(getLinearGradient(0, getHeight()));
canvas.drawPaint(paint);
}
private LinearGradient getLinearGradient(float y0, float y1)
{
// colors :
int[] listeColors = new int[3];
listeColors[0] = 0xFF000000;
listeColors[1] = 0xFFFFFFFF;
listeColors[2] = 0xFFFFFFFF;
// positions :
float[] listPositions = new float[3];
listPositions[0] = 0;
listPositions[1] = 0.25F;
listPositions[2] = 1;
// gradient :
return new LinearGradient(0, y0, 0, y0 + (y1 - y0) / 2, listeColors, listPositions, Shader.TileMode.MIRROR);
}
}
Hope it helps.

Android how to create triangle and rectangle shape programmatically?

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

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>