Android: Change center of linear GradientDrawable

问题:

EDIT: LOOK AT SOLUTION ABOVE

i m freaking out. all i just want to do, is setting a linear GradientDrawable, which changes the vertical center of the gradient... drawing the gradient works fine, but how can i change the center of it?!?

RelativeLayout bgScreen = (RelativeLayout) findViewById(R.id.player_screen);

GradientDrawable gd = new GradientDrawable(
     GradientDrawable.Orientation.TOP_BOTTOM,
     new int[] {startColor,endColor});

gd.setCornerRadius(0f);
gd.setAlpha(200);
bgScreen.setBackground(gd); 


public void redrawOrChangeBackgroundGradient(){
    //??? either change center of existing
    gd.setGradientCenter(float x, float y) //ONLY works in RADIAL_GRADIENT or SWEEP_GRADIENT.

    //??? or complete redraw Gradient with different center

}

here s a picture example of how i want to change the gradient via code

cannot be that hard, can it?

回答1:

The lacking ability to set the center programmatically for linear GradientDrawables is a registered issue already.

But there is a workaround described here. Basically, you should create a PaintDrawable from a LinearGradient and set it as your view's background drawable. Following this solution, you can set the center in your LinearGradient constructor by mapping the colors to the positions array:

float[] positions

May be null. The relative positions [0..1] of each corresponding color in the colors array. If this is null, the colors are distributed evenly along the gradient line.

(not tested, but it should do the trick for you)