GrayscaleTransformation.java 文件源码

@Override
public Resource<Bitmap> transform(Resource<Bitmap> resource, int outWidth, int outHeight) {
  Bitmap source = resource.get();

  int width = source.getWidth();
  int height = source.getHeight();

  Bitmap.Config config =
      source.getConfig() != null ? source.getConfig() : Bitmap.Config.ARGB_8888;
  Bitmap bitmap = mBitmapPool.get(width, height, config);
  if (bitmap == null) {
    bitmap = Bitmap.createBitmap(width, height, config);
  }

  Canvas canvas = new Canvas(bitmap);
  ColorMatrix saturation = new ColorMatrix();
  saturation.setSaturation(0f);
  Paint paint = new Paint();
  paint.setColorFilter(new ColorMatrixColorFilter(saturation));
  canvas.drawBitmap(source, 0, 0, paint);

  return BitmapResource.obtain(bitmap, mBitmapPool);
}