android画图——颜色过滤

颜色的过滤 不是很懂，牵扯到颜色的数组配置吧，只把简单的代码写下吧：
mBitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.balloons);
             mDrawable = context.getResources().getDrawable(R.drawable.balloons);
上面两个代码 分别得到一个Bitmap，和Drawable
private static void setContrastTranslateOnly(ColorMatrix cm, float contrast) {
            float scale = contrast + 1.f;
               float translate = (-.5f * scale + .5f) * 255.f;
            cm.set(new float[] {
                   1, 0, 0, 0, translate,
                   0, 1, 0, 0, translate,
                   0, 0, 1, 0, translate,
                   0, 0, 0, 1, 0,
                   });
        }

private static void setContrastScaleOnly(ColorMatrix cm, float contrast) {
            float scale = contrast + 1.f;
             //  float translate = (-.5f * scale + .5f) * 255.f;
            cm.set(new float[] {
                   scale, 0, 0, 0, 0,
                   0, scale, 0, 0, 0,
                   0, 0, scale, 0, 0,
                   0, 0, 0, 1, 0 });
          
        }
设置一个矩阵 进行颜色变化吧 只是没搞懂设置数值和颜色的关系
ColorMatrix cm = new ColorMatrix();
  mAngle += 2;
            if (mAngle > 180) {
                mAngle = 0;
            }
           
            //convert our animated angle [-180...180] to a contrast value of [-1..1]
            float contrast = mAngle / 180.f;

setContrastTranslateOnly(cm, contrast);
// 画笔设置颜色过滤
            paint.setColorFilter(new ColorMatrixColorFilter(cm));
            canvas.drawBitmap(mBitmap, x, y + 2*(mBitmap.getHeight() + 10),
                              paint);
//图片设置颜色过滤
// setContrastTranslateOnly(cm, contrast);
    //        mDrawable.setColorFilter(new ColorMatrixColorFilter(cm));
mDrawable.setColorFilter(new PorterDuffColorFilter(  0xffff00,PorterDuff.Mode.LIGHTEN));
            mDrawable.setBounds(new Rect(25, 330,150,430));
            mDrawable.draw(canvas);
画笔设置过滤 和图片设置过滤我没看出区别有多大，但是这里有两种方法设置颜色过滤
mDrawable.setColorFilter(new PorterDuffColorFilter(  0xffff00,PorterDuff.Mode.LIGHTEN));
mDrawable.setColorFilter(new ColorMatrixColorFilter(cm));
一个针对单色彩一个针对一个颜色矩阵