Function downloadTextureData

tfjs-react-native/src/camera/camera_webgl_util.ts:59–97

(
    gl: WebGL2RenderingContext, texture: WebGLTexture,
    dims: Dimensions)

 * @param dims
 */
export function downloadTextureData(
    gl: WebGL2RenderingContext, texture: WebGLTexture,
    dims: Dimensions): Uint8Array {
  const {width, height, depth} = dims;
  const pixels = new Uint8Array(width * height * depth);

  if (!fboCache.has(gl)) {
    fboCache.set(gl, createFrameBuffer(gl));
  }
  const fbo = fboCache.get(gl);

  webgl_util.callAndCheck(gl, () => {
    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
  });

  webgl_util.callAndCheck(gl, () => {
    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(gl.TEXTURE_2D, texture);
  });

  webgl_util.callAndCheck(gl, () => {
    const level = 0;
    gl.framebufferTexture2D(
        gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, level);
  });

  webgl_util.callAndCheck(gl, () => {
    const format = depth === 3 ? gl.RGB : gl.RGBA;
    const x = 0;
    const y = 0;
    gl.readPixels(x, y, width, height, format, gl.UNSIGNED_BYTE, pixels);
  });

  // Unbind framebuffer
  webgl_util.callAndCheck(gl, () => {
    gl.bindFramebuffer(gl.FRAMEBUFFER, null);
  });
  return pixels;
}

/**
 * Upload image data to a texture.