protected override void onDraw (Canvas canvas)
{
Paint paint = mPaint;
float x = 20;
float y = 20;
canvas.drawColor (Color.WHITE);
paint.setColorFilter (null);
canvas.drawBitmap (mBitmap, x, y, paint);
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 / 180.0f;
setContrast (cm, contrast);
paint.setColorFilter (new ColorMatrixColorFilter (cm));
canvas.drawBitmap (mBitmap, x + mBitmap.getWidth () + 10, y, paint);
setContrastScaleOnly (cm, contrast);
paint.setColorFilter (new ColorMatrixColorFilter (cm));
canvas.drawBitmap (mBitmap, x, y + mBitmap.getHeight () + 10, paint);
setContrastTranslateOnly (cm, contrast);
paint.setColorFilter (new ColorMatrixColorFilter (cm));
canvas.drawBitmap (mBitmap, x, y + 2 * (mBitmap.getHeight () + 10), paint);
}
static void setTranslate (ColorMatrix cm, float dr, float dg, float db, float da)
{
cm.set (new float[] {
2, 0, 0, 0, dr,
0, 2, 0, 0, dg,
0, 0, 2, 0, db,
0, 0, 0, 1, da
});
}
static void setContrastScaleOnly (ColorMatrix cm, float contrast)
{
float scale = contrast + 1.0f;
// float translate = (-.5f * scale + .5f) * 255.0f;
cm.set (new float[] {
scale, 0, 0, 0, 0,
0, scale, 0, 0, 0,
0, 0, scale, 0, 0,
0, 0, 0, 1, 0
});
}
private static void setContrastTranslateOnly (ColorMatrix cm, float contrast)
{
float scale = contrast + 1.0f;
float translate = (-.5f * scale + .5f) * 255.0f;
cm.set (new float[] {
1, 0, 0, 0, translate,
0, 1, 0, 0, translate,
0, 0, 1, 0, translate,
0, 0, 0, 1, 0
});
}