Custom background for transparent image about pica

[puzrin]

Sorry, that's out of package scope. It's for resize only.

[DZakh]

Well, I've just found why my solution doesn't work. It's in the __extractTileData method because of tmpCtx.globalCompositeOperation = 'copy';. I see your point that it's for resize only, but I don't like the idea to do the processing logic twice just to set another color for background when converting png to jpeg. Ok, I'll try to figure out some rational solution, thanks for your fast response.

this.debug('Draw tile imageBitmap/image to temporary canvas');
  var tmpCanvas = this.options.createCanvas(tile.width, tile.height);
  var tmpCtx = tmpCanvas.getContext('2d', {
    alpha: Boolean(opts.alpha)
  });
  tmpCtx.globalCompositeOperation = 'copy';
  tmpCtx.drawImage(stageEnv.srcImageBitmap || from, tile.x, tile.y, tile.width, tile.height, 0, 0, tile.width, tile.height);
  this.debug('Get tile pixel data');
  extractTo.src = tmpCtx.getImageData(0, 0, tile.width, tile.height).data; // Safari 12 workaround
  // https://github.com/nodeca/pica/issues/199