Function fromPixels

tfjs-backend-webgl/src/kernels/FromPixels.ts:36–89

(args: {
  inputs: FromPixelsInputs,
  backend: MathBackendWebGL,
  attrs: FromPixelsAttrs
})

let willReadFrequently = env().getBool('CANVAS2D_WILL_READ_FREQUENTLY_FOR_GPU');

function fromPixels(args: {
  inputs: FromPixelsInputs,
  backend: MathBackendWebGL,
  attrs: FromPixelsAttrs
}): TensorInfo {
  const {inputs, backend, attrs} = args;
  let {pixels} = inputs;
  const {numChannels} = attrs;

  const isVideo = typeof (HTMLVideoElement) !== 'undefined' &&
      pixels instanceof HTMLVideoElement;
  const isImage = typeof (HTMLImageElement) !== 'undefined' &&
      pixels instanceof HTMLImageElement;
  const [width, height] = isVideo ?
      [
        (pixels as HTMLVideoElement).videoWidth,
        (pixels as HTMLVideoElement).videoHeight
      ] :
      [pixels.width, pixels.height];

  const texShape: [number, number] = [height, width];
  const outShape = [height, width, numChannels];

  if (isImage || isVideo) {
    const newWillReadFrequently =
        env().getBool('CANVAS2D_WILL_READ_FREQUENTLY_FOR_GPU');
    if (fromPixels2DContext == null ||
        newWillReadFrequently !== willReadFrequently) {
      willReadFrequently = newWillReadFrequently;
      fromPixels2DContext =
          document.createElement('canvas').getContext(
              '2d', {willReadFrequently});
    }

    fromPixels2DContext.canvas.width = width;
    fromPixels2DContext.canvas.height = height;
    fromPixels2DContext.drawImage(
        pixels as HTMLVideoElement | HTMLImageElement | ImageBitmap, 0, 0,
        width, height);
    pixels = fromPixels2DContext.canvas;
  }

  const tempPixelHandle = backend.makeTensorInfo(texShape, 'int32');
  // This is a byte texture with pixels.
  backend.texData.get(tempPixelHandle.dataId).usage = TextureUsage.PIXELS;
  backend.gpgpu.uploadPixelDataToTexture(
      backend.getTexture(tempPixelHandle.dataId), pixels as ImageData);
  const program = env().getBool('WEBGL_PACK') ?
      new FromPixelsPackedProgram(outShape) :
      new FromPixelsProgram(outShape);
  const res = backend.runWebGLProgram(program, [tempPixelHandle], 'int32');
  backend.disposeData(tempPixelHandle.dataId);
  return res;
}