Develop Reference

Android - How to apply gradient color to bitmap?

I need to apply dynamically a gradient color to a bitmap (it looks like a scratch with some transparent parts) that will be draw over another bitmap: this is the result i need.
This is my code:
Bitmap bitmapbackground = bitmaporiginal.copy(bitmaporiginal.getConfig(), true);
Bitmap bitmaptocolor = BitmapFactory.decodeResource(activity.getResources(), R.drawable.scratch);
LinearGradient gradient = new LinearGradient(0, 0, 0, bitmaptocolor.getHeight(), Color.parseColor("#D81B60"), Color.parseColor("#F48FB1"), Shader.TileMode.CLAMP);
Paint paint = new Paint();
paint.setShader(gradient);
Canvas canvas = new Canvas(bitmapbackground);
canvas.drawBitmap(bitmaptocolor, 0, 0, paint);
But in this way it does not apply the gradient color to the scratch (it remains always black). What am i doing wrong ?

Make sure bitmaptocolor.getHeight() is actually returning height.
Use hexadecimal equivalent for color.
LinearGradient gradient = new LinearGradient(0, 0, 0, bitmaptocolor.getHeight(), 0xD81B60, 0xD81B60, Shader.TileMode.CLAMP);

Why doesn't this argument of the LinearGradient constructor seem to work?

I want to set a custom drawable with a linear gradient as the background drawable of the bar in my SeekBar. I am creating the LinearGradient in the second statement in the following snippet, and doing it like so:
// Creating the drawable:
ShapeDrawable shapeDrawable = new ShapeDrawable(new RectShape());
Shader linearGradientShader = new LinearGradient(0, 0, 300, 20, new int[] { Color.RED, Color.BLUE },
new float[] { 0, 1 }, Shader.TileMode.CLAMP);
shapeDrawable.getPaint().setShader(linearGradientShader);
shapeDrawable.setBounds(10, 10, 300, 30);
seekBar.setProgressDrawable(shapeDrawable);
The problem here is that, according to the specification, the 6th parameter is defined as
May be null. The relative positions [0..1] of each corresponding color in the colors array. If this is null, the the colors are distributed evenly along the gradient line.
I wanted both the red and blue colors to be distributed evenly, i.e. half the shape should appear redish and half should appear bluish (like the following image).
So I tried null, new float[] {0, 0.5f}, and new float[] {0, 1} as values of the 6th argument. I got the following three results respectively.
For null:
For new float[] {0, 0.5f}:
For new float[] {0, 1}:
Show where am I going wrong? How should I fix this?

use
ShapeDrawable#setShaderFactory(ShapeDrawable.ShaderFactory factory)
the factory has a method Shader resize(int width, int height) which is called every time your drawable bounds change and this is a place where you should return your LinearGradient shader based on width / height parameters
as you will see you can now just pass null positions and colors will be distributed evenly

Giving LinearGradient Shade From Bottom of the TextView in Android

TextView secondTextView = new TextView(this);
Shader textShader=new LinearGradient(0, 0, 0, 20,
new int[]{Color.GREEN,Color.BLUE},
new float[]{0, 1}, TileMode.CLAMP);
secondTextView.getPaint().setShader(textShader);
The above particular code giving me green shade at the top and blue as text color but my requirement is absolutely in reverse order all i need is green color shade from the bottom and blue as text color. can someone please help me out to achieve this.

Hope this will work for you.
Shader myShader = new LinearGradient(
0, 0, 0, 100,
Color.WHITE, Color.BLACK,
Shader.TileMode.CLAMP);
secondTextView.getPaint().setShader(myShader);

Programmatically add Gradient with solid color and stroke

Currently I am using this code to add color:
ShapeDrawable drawable = new ShapeDrawable(new OvalShape());
drawable.getPaint().setColor(color);
Now I need to apply some gradient colors to it along with stroke(like border with different color). I am setting this as background to button.
Here is what I am expecting, I need to do it programmatically.

Add a RadialGradient to your drawable like this:
Shader shader = new RadialGradient(x, y, radius, color0, color1, Shader.TileMode.REPEAT);
drawable.getPaint().setShader(shader);
Obviously, you can interchange LinearGradient, SweepGradient, and any of the parameters.
Here is how to add the stroke:
drawable.getPaint().setStrokeWidth(3);
drawable.getPaint().setColor(Color.WHITE);
drawable.getPaint().setStyle(Paint.Style.FILL_AND_STROKE);
Hmmm, I think I have to defer to #StinePike with the GradientDrawable:
GradientDrawable gd = new GradientDrawable();
gd.setColor(Color.RED);
gd.setCornerRadius(10);
gd.setStroke(2, Color.WHITE);
gd.setShape(GradientDrawable.OVAL);

use GradientDrawable to create gradient
or
you can see this answer

How to add a stroke to ShapeDrawable

Hi
I want to create a shape drawable and fill it with gradient color with white stroke
here is my code
ShapeDrawable greenShape = new ShapeDrawable(new RectShape());
Shader shader1 = new LinearGradient(0, 0, 0, 50, new int[] {
0xFFBAF706, 0xFF4CD52F }, null, Shader.TileMode.CLAMP);
greenShape.getPaint().setShader(shader1);
greenShape.getPaint().setStrokeWidth(3);
greenShape.getPaint().setColor(Color.WHITE);
greenShape.getPaint().setStyle(Paint.Style.FILL_AND_STROKE);`
The problem is the rectangle appears with gradient fill but without stroke

The ShapeDrawable does not allow you to easily draw a stroke around it.
If you really want then this would be a nice place to look at.
OR
You could use a GradientDrawable
GradientDrawable gd = new GradientDrawable();
gd.setColor(Color.RED);
gd.setCornerRadius(10);
gd.setStroke(2, Color.WHITE);
(PS: This is given as a comment in the same page!)

It looks like this person struggled with the same issue and the only way they found was to subclass the ShapeDrawable:
Trying to draw a button: how to set a stroke color and how to "align" a gradient to the bottom without knowing the height?

<stroke
android:width="2dp"
android:color="#808080" />
try it, it will work definitely

Change the style to greenShape.getPaint().setStyle(Paint.Style.STROKE)
and
greenShape.setShaderFactory(new ShapeDrawable.ShaderFactory() {
#Override
public Shader resize(int width, int height) {
return new LinearGradient(0, 0, 0, 0, Color.WHITE, Color.WHITE, Shader.TileMode.REPEAT);