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

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.

Button Pressed Background is Transparent Before Clicked

I have implement Ripple Animation after the button is pressed. Everything works great except before I Click the Button is Transparent makes it impossible to be visible.
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
android:color="?android:colorControlHighlight">
<item android:id="#android:id/mask">
<shape android:shape="rectangle">
<corners android:radius="3dp"/>
<solid android:color="?android:colorAccent" />
</shape>
</item>
</ripple>
This is the Custom Button Class I have created.
public class MyButton extends Button {
public MyButton(final Context context) {
super(context);
init();
}
public MyButton(final Context context, final AttributeSet attrs) {
super(context, attrs);
init();
}
public MyButton(final Context context, final AttributeSet attrs,
final int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
mPaint = new Paint();
mPaint.setAlpha(100);
}
#Override
public boolean onTouchEvent(#NonNull final MotionEvent event) {
if (event.getActionMasked() == MotionEvent.ACTION_UP) {
mDownX = event.getX();
mDownY = event.getY();
ObjectAnimator animator = ObjectAnimator.ofFloat(this, "radius", 0,
getWidth() * 3.0f);
animator.setInterpolator(new AccelerateInterpolator());
animator.setDuration(400);
animator.start();
}
return super.onTouchEvent(event);
}
public void setRadius(final float radius) {
mRadius = radius;
if (mRadius > 0) {
RadialGradient radialGradient = new RadialGradient(mDownX, mDownY,
mRadius * 3, Color.TRANSPARENT, getResources().getColor(R.color.colorPrimaryDark),
Shader.TileMode.MIRROR);
mPaint.setShader(radialGradient);
}
invalidate();
}
private Path mPath = new Path();
private Path mPath2 = new Path();
#Override
protected void onDraw(#NonNull final Canvas canvas) {
super.onDraw(canvas);
mPath2.reset();
mPath2.addCircle(mDownX, mDownY, mRadius, Path.Direction.CW);
canvas.clipPath(mPath2);
mPath.reset();
mPath.addCircle(mDownX, mDownY, mRadius / 3, Path.Direction.CW);
canvas.clipPath(mPath, Region.Op.DIFFERENCE);
canvas.drawCircle(mDownX, mDownY, mRadius, mPaint);
}
}
Here is where I have used the myButton class
<io.wyntr.peepster.MyButton
android:layout_width="325dp"
android:layout_height="60dp"
android:layout_marginTop="10dp"
android:textSize="20dp"
android:textAllCaps="false"
android:text="Continue"
android:id="#+id/sendCodeButton"
style="#style/Widget.AppCompat.Button.Borderless"
android:clickable="true"
android:background="#drawable/ripple"
android:textColor="#color/icons"
android:layout_gravity="center_horizontal" />
Screenshots:

Was waiting for you to respond to my comment, but gonna go on ahead and add my answer:
You can set the color of the button that will be using your ripple animation by adding the
<item android:drawable="#android:color/holo_blue_bright" />
Like so:
<?xml version="1.0" encoding="utf-8"?>
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
android:color="?android:colorControlHighlight">
<item android:id="#android:id/mask">
<shape android:shape="rectangle">
<corners android:radius="3dp" />
<solid android:color="?android:colorAccent" />
</shape>
</item>
<item android:drawable="#android:color/holo_blue_bright" />
</ripple>
Tested this. And when used, the default color (unpressed) for the button turns to holo_blue_bright. Here's a post that I think is useful for you. :)
Hope this helps. Cheers. :)

This line removes the border of your button so of course it will be invisible
try changing it to something else
style="#style/Widget.AppCompat.Button.Borderless"

how to draw a half circle in android

I'm using this code to draw a half in my app:
<?xml version="1.0" encoding="utf-8" ?>
<layer-list
xmlns:android="http://schemas.android.com/apk/res/android"
>
<item
android:left="35dp"
android:top="40dp"
android:bottom="40dp"
android:right="0dp">
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval" android:innerRadius="30dp" android:thickness="0dp">
<solid android:color="#color/transparent"/>
<stroke android:width="3dp" android:color="#color/White"/>
</shape>
</item>
</layer-list>
output :
but i need something like below :
how to draw this ?

I would suggest to draw it through code.
1- Create class MyView and put below code.
public class MyView extends View {
public MyView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
#Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
float width = (float) getWidth();
float height = (float) getHeight();
float radius;
if (width > height) {
radius = height / 4;
} else {
radius = width / 4;
}
Path path = new Path();
path.addCircle(width / 2,
height / 2, radius,
Path.Direction.CW);
Paint paint = new Paint();
paint.setColor(Color.BLACK);
paint.setStrokeWidth(5);
paint.setStyle(Paint.Style.FILL);
float center_x, center_y;
final RectF oval = new RectF();
paint.setStyle(Paint.Style.STROKE);
center_x = width / 2;
center_y = height / 2;
oval.set(center_x - radius,
center_y - radius,
center_x + radius,
center_y + radius);
canvas.drawArc(oval, 90, 180, false, paint);
}
}
2-Initialize this class inside you activity or fragment:-
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new MyView(this));
}

Your can use a rectangle shape .xml file and edit the corners on one side only.
Example:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<size android:height="30dp"
android:width="30dp"/>
<solid android:color="#color/black"/>
<corners android:topLeftRadius="15dp"
android:bottomLeftRadius="15dp"/>
</shape>

You can use <clip /> drawable in order to cut-off part of your circle.
http://developer.android.com/guide/topics/resources/drawable-resource.html#Clip

this is how i created my semi circle in a drawable xml file.
<size
android:width="180dp"
android:height="90dp"></size>
<corners
android:topLeftRadius="200dp"
android:topRightRadius="200dp"></corners>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<size
android:width="180dp"
android:height="90dp"></size>
<corners
android:topLeftRadius="200dp"
android:topRightRadius="200dp"></corners>
<stroke android:width="5px" android:color="#color/black" />
</shape>

Rectangle shape with two solid colors

I'd like to create a rectangle shape with two solid colors (horizontally) to achieve something like this:
I heard about layer-list, i though i could use it to contains two rectangle with a different color but it seems that it only lays shapes vertically.
Is there a way to achieve this using lalyer-list or should i use something totally different? I'd like to keep it simple with ability to change the shape colors at runtime.
Thanks.

this will surely draw the shape as per your Requirement :
Adjust size of <item> as you need !
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item
android:left="50dip">
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="#0000FF" />
</shape>
</item>
<item android:right="50dip">
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="#ff0000" />
</shape>
</item>
</layer-list>

You can create custom drawable for this. Just extend Drawable class.
Here is a sample code which draws a rectangle like you wanted, you can provide any number of colors.
public class ColorBarDrawable extends Drawable {
private int[] themeColors;
public ColorBarDrawable(int[] themeColors) {
this.themeColors = themeColors;
}
#Override
public void draw(Canvas canvas) {
// get drawable dimensions
Rect bounds = getBounds();
int width = bounds.right - bounds.left;
int height = bounds.bottom - bounds.top;
// draw background gradient
Paint backgroundPaint = new Paint();
int barWidth = width / themeColors.length;
int barWidthRemainder = width % themeColors.length;
for (int i = 0; i < themeColors.length; i++) {
backgroundPaint.setColor(themeColors[i]);
canvas.drawRect(i * barWidth, 0, (i + 1) * barWidth, height, backgroundPaint);
}
// draw remainder, if exists
if (barWidthRemainder > 0) {
canvas.drawRect(themeColors.length * barWidth, 0, themeColors.length * barWidth + barWidthRemainder, height, backgroundPaint);
}
}
#Override
public void setAlpha(int alpha) {
}
#Override
public void setColorFilter(ColorFilter cf) {
}
#Override
public int getOpacity() {
return PixelFormat.OPAQUE;
}
}

This will give you two colors half and half vertically. Put this code in a drawable resource.
<item
android:top="320dip">
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="#color/red" />
</shape>
</item>
<item android:bottom="320dip">
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="#color/yellow" />
</shape>
</item>