public void renderFrame(int frameNumber, Bitmap bitmap) {
    if (mIsNewRenderImplementation) {
      renderDeltas(frameNumber, bitmap);
      return;
    }

    Canvas canvas = new Canvas(bitmap);
    canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.SRC);

    // If blending is required, prepare the canvas with the nearest cached frame.
    int nextIndex;
    if (!isKeyFrame(frameNumber)) {
      // Blending is required. nextIndex points to the next index to render onto the canvas.
      nextIndex = prepareCanvasWithClosestCachedFrame(frameNumber - 1, canvas);
    } else {
      // Blending isn't required. Start at the frame we're trying to render.
      nextIndex = frameNumber;
    }

    // Iterate from nextIndex to the frame number just preceding the one we're trying to render
    // and composite them in order according to the Disposal Method.
    for (int index = nextIndex; index < frameNumber; index++) {
      AnimatedDrawableFrameInfo frameInfo = mAnimatedDrawableBackend.getFrameInfo(index);
      DisposalMethod disposalMethod = frameInfo.disposalMethod;
      if (disposalMethod == DisposalMethod.DISPOSE_TO_PREVIOUS) {
        continue;
      }
      if (frameInfo.blendOperation == BlendOperation.NO_BLEND) {
        disposeToBackground(canvas, frameInfo);
      }
      mAnimatedDrawableBackend.renderFrame(index, canvas);
      mCallback.onIntermediateResult(index, bitmap);
      if (disposalMethod == DisposalMethod.DISPOSE_TO_BACKGROUND) {
        disposeToBackground(canvas, frameInfo);
      }
    }

    AnimatedDrawableFrameInfo frameInfo = mAnimatedDrawableBackend.getFrameInfo(frameNumber);
    if (frameInfo.blendOperation == BlendOperation.NO_BLEND) {
      disposeToBackground(canvas, frameInfo);
    }
    // Finally, we render the current frame. We don't dispose it.
    mAnimatedDrawableBackend.renderFrame(frameNumber, canvas);
    maybeApplyTransformation(bitmap);
  }
Renders the specified frame. Only should be called on the rendering thread.

@param frameNumber the frame to render
@param bitmap the bitmap to render into
animated-base/src/main/java/com/facebook/imagepipeline/animated/impl/AnimatedImageCompositor.java