sdk/android/src/java/org/webrtc/TextureBufferImpl.java

/*
 *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

package org.webrtc;

import android.graphics.Matrix;
import java.nio.ByteBuffer;

/**
 * Android texture buffer backed by a SurfaceTextureHelper's texture. The buffer calls
 * |releaseCallback| when it is released.
 */
class TextureBufferImpl implements VideoFrame.TextureBuffer {
  private final int width;
  private final int height;
  private final Type type;
  private final int id;
  private final Matrix transformMatrix;
  private final SurfaceTextureHelper surfaceTextureHelper;
  private final Runnable releaseCallback;
  private final Object refCountLock = new Object();
  private int refCount;

  public TextureBufferImpl(int width, int height, Type type, int id, Matrix transformMatrix,
      SurfaceTextureHelper surfaceTextureHelper, Runnable releaseCallback) {
    this.width = width;
    this.height = height;
    this.type = type;
    this.id = id;
    this.transformMatrix = transformMatrix;
    this.surfaceTextureHelper = surfaceTextureHelper;
    this.releaseCallback = releaseCallback;
    this.refCount = 1; // Creator implicitly holds a reference.
  }

  @Override
  public VideoFrame.TextureBuffer.Type getType() {
    return type;
  }

  @Override
  public int getTextureId() {
    return id;
  }

  @Override
  public Matrix getTransformMatrix() {
    return transformMatrix;
  }

  @Override
  public int getWidth() {
    return width;
  }

  @Override
  public int getHeight() {
    return height;
  }

  @Override
  public VideoFrame.I420Buffer toI420() {
    if (type == Type.RGB) {
      throw new RuntimeException("toI420 for RGB frames not implemented yet");
    }
    // SurfaceTextureHelper requires a stride that is divisible by 8.  Round width up.
    // See SurfaceTextureHelper for details on the size and format.
    int stride = ((width + 7) / 8) * 8;
    int uvHeight = (height + 1) / 2;
    // Due to the layout used by SurfaceTextureHelper, vPos + stride * uvHeight would overrun the
    // buffer.  Add one row at the bottom to compensate for this.  There will never be data in the
    // extra row, but now other code does not have to deal with v stride * v height exceeding the
    // buffer's capacity.
    int size = stride * (height + uvHeight + 1);
    ByteBuffer buffer = ByteBuffer.allocateDirect(size);
    surfaceTextureHelper.textureToYUV(buffer, width, height, stride, id,
        RendererCommon.convertMatrixFromAndroidGraphicsMatrix(transformMatrix));

    int yPos = 0;
    int uPos = yPos + stride * height;
    // Rows of U and V alternate in the buffer, so V data starts after the first row of U.
    int vPos = uPos + stride / 2;

    buffer.position(yPos);
    buffer.limit(yPos + stride * height);
    ByteBuffer dataY = buffer.slice();

    buffer.position(uPos);
    buffer.limit(uPos + stride * uvHeight);
    ByteBuffer dataU = buffer.slice();

    buffer.position(vPos);
    buffer.limit(vPos + stride * uvHeight);
    ByteBuffer dataV = buffer.slice();

    // SurfaceTextureHelper uses the same stride for Y, U, and V data.
    return new I420BufferImpl(width, height, dataY, stride, dataU, stride, dataV, stride, null);
  }

  @Override
  public void retain() {
    synchronized (refCountLock) {
      ++refCount;
    }
  }

  @Override
  public void release() {
    synchronized (refCountLock) {
      if (--refCount == 0 && releaseCallback != null) {
        releaseCallback.run();
      }
    }
  }

  @Override
  public VideoFrame.Buffer cropAndScale(
      int cropX, int cropY, int cropWidth, int cropHeight, int scaleWidth, int scaleHeight) {
    retain();
    Matrix newMatrix = new Matrix(transformMatrix);
    newMatrix.postScale(cropWidth / (float) width, cropHeight / (float) height);
    newMatrix.postTranslate(cropX / (float) width, cropY / (float) height);

    return new TextureBufferImpl(
        scaleWidth, scaleHeight, type, id, newMatrix, surfaceTextureHelper, new Runnable() {
          @Override
          public void run() {
            release();
          }
        });
  }
}