content: /*
   * Copyright (C) 2017 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package android.graphics;
  
  import android.annotation.NonNull;
  import android.graphics.drawable.AnimatedImageDrawable;
  import android.graphics.drawable.Drawable;
  
  /**
   *  Helper interface for adding custom processing to an image.
   *
   *  <p>The image being processed may be a {@link Drawable}, a {@link Bitmap}, or
   *  a frame of an {@link AnimatedImageDrawable} produced by {@link ImageDecoder}.
   *  This is called before the requested object is returned.</p>
   *
   *  <p>This custom processing can even be applied to images that will be returned
   *  as immutable objects, such as a {@link Bitmap} with {@code Config}
   *  {@link Bitmap.Config#HARDWARE} returned by {@link ImageDecoder}.</p>
   *
   *  <p>On an {@link AnimatedImageDrawable}, the callback will only be called once,
   *  but the drawing commands will be applied to each frame, as if the {@link Canvas}
   *  had been returned by {@link Picture#beginRecording Picture.beginRecording}.<p>
   *
   *  <p>Supplied to ImageDecoder via {@link ImageDecoder#setPostProcessor setPostProcessor}.</p>
   */
  public interface PostProcessor {
      /**
       *  Do any processing after (for example) decoding.
       *
       *  <p>Drawing to the {@link Canvas} will behave as if the initial processing
       *  (e.g. decoding) already exists in the Canvas. An implementation can draw
       *  effects on top of this, or it can even draw behind it using
       *  {@link PorterDuff.Mode#DST_OVER PorterDuff.Mode.DST_OVER}. A common
       *  effect is to add transparency to the corners to achieve rounded corners.
       *  That can be done with the following code:</p>
       *
       *  <pre class="prettyprint">
       *  Path path = new Path();
       *  path.setFillType(Path.FillType.INVERSE_EVEN_ODD);
       *  int width = canvas.getWidth();
       *  int height = canvas.getHeight();
       *  path.addRoundRect(0, 0, width, height, 20, 20, Path.Direction.CW);
       *  Paint paint = new Paint();
       *  paint.setAntiAlias(true);
       *  paint.setColor(Color.TRANSPARENT);
       *  paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
       *  canvas.drawPath(path, paint);
       *  return PixelFormat.TRANSLUCENT;
       *  </pre>
       *
       *
       *  @param canvas The {@link Canvas} to draw to.
       *  @return Opacity of the result after drawing.
       *      {@link PixelFormat#UNKNOWN PixelFormat.UNKNOWN} means that the
       *      implementation did not change whether the image has alpha. Return
       *      this unless you added transparency (e.g. with the code above, in
       *      which case you should return
       *      {@link PixelFormat#TRANSLUCENT PixelFormat.TRANSLUCENT}) or you
       *      forced the image to be opaque (e.g. by drawing everywhere with an
       *      opaque color and {@link PorterDuff.Mode#DST_OVER PorterDuff.Mode.DST_OVER},
       *      in which case you should return {@link PixelFormat#OPAQUE PixelFormat.OPAQUE}).
       *      {@link PixelFormat#TRANSLUCENT PixelFormat.TRANSLUCENT} means that
       *      the implementation added transparency. This is safe to return even
       *      if the image already had transparency. This is also safe to return
       *      if the result is opaque, though it may draw more slowly.
       *      {@link PixelFormat#OPAQUE PixelFormat.OPAQUE} means that the
       *      implementation forced the image to be opaque. This is safe to return
       *      even if the image was already opaque.
       *      {@link PixelFormat#TRANSPARENT PixelFormat.TRANSPARENT} (or any other
       *      integer) is not allowed, and will result in throwing an
       *      {@link java.lang.IllegalArgumentException}.
       */
      @PixelFormat.Opacity
      public int onPostProcess(@NonNull Canvas canvas);
  }
  