How to draw a smooth/dithered gradient on a canvas in Android

问题

Several answers mention to use GradientDrawable.setDither(true) to draw smooth gradients in Android. That has no effect in my code. Any idea what I have to change to get a well looking gradient in my live wallpaper?

GradientDrawable gradient = new GradientDrawable(Orientation.TL_BR, colors);
gradient.setGradientType(GradientDrawable.RADIAL_GRADIENT);
gradient.setGradientRadius(canvas.getWidth() * 2);
gradient.setDither(true);
gradient.setGradientCenter(-0.1f, -0.1f);
gradient.setBounds(cb);
gradient.draw(canvas);

回答1:

Seeing as you have a Canvas to work with. Here is one option.

private Bitmap makeRadGrad() {
    RadialGradient gradient = new RadialGradient(200, 200, 200, 0xFFFFFFFF,
            0xFF000000, android.graphics.Shader.TileMode.CLAMP);
    Paint p = new Paint();
    p.setDither(true);
    p.setShader(gradient);

    Bitmap bitmap = Bitmap.createBitmap(400, 400, Config.ARGB_8888);
    Canvas c = new Canvas(bitmap);
    c.drawCircle(200, 200, 200, p);

    return bitmap;
}

Result:

来源：https://stackoverflow.com/questions/2936803/how-to-draw-a-smooth-dithered-gradient-on-a-canvas-in-android