Question

I am having a problem with filling a ShapeDrawable containing a custom PathShape using the drawable’s setShaderFactory() method. The following code works perfectly when drawing a RectShape:

ShapeDrawable shape = new ShapeDrawable();
shape.setShape(new RectShape());
shape.setShaderFactory(new ShaderFactory() {
    @Override
    public Shader resize(int width, int height) {
        LinearGradient gradient = new LinearGradient (0, 0,
                width, height, Color.Red, Color.Blue,
                TileMode.REPEAT);
        return gradient;
    }
});

When I change the RectShape to any custom PathShape, however, the drawable fills the entire shape with the gradient start color (red) only. In other words, the custom shapes draw correctly but the color is completely wrong. Has anyone seen this before and know what might be the problem?

Answer 1

After experimenting I found that the size of the gradient must be related to the standard width and standard height of the PathShape, when it is created and has nothing to do with the height and width of the ShapeDrawable. This means you must keep track of the standard width / height you assign to your PathShape for the entire life of the ShapeDrawable in the event it is ever resized.

Though somewhat inelegant, here is a solution:

public static final int STD_WIDTH = 20;
public static final int STD_HEIGHT = 20;

PathShape shape = new PathShape(myPath, STD_WIDTH,
        STD_HEIGHT);
ShapeDrawable drawable = new ShapeDrawable();
drawable.setShape(myPathShape);
drawable.setShaderFactory(new ShaderFactory() {
    @Override
    public Shader resize(int width, int height) {
        LinearGradient gradient = new LinearGradient (0, 0,
                STD_WIDTH, STD_HEIGHT, Color.Red, Color.Blue,
                TileMode.REPEAT);
        return gradient;
    }
});