I was wondering if WebGL is considered stable enough to be enabled by default. It makes some PDFs render much faster and it has been off by default for a while now, so we have had quite some time to test it.

If we decide to enable WebGL by default, we should not forget to update https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/preferences_schema.json#L39 as well.

/cc @yurydelendik 
/cc @Snuffleupagus (because IIRC you were testing WebGL too)

transform,
      viewport,
      transparency = false,
      background = null,
    }) {
      
      
      
      
      
      const width = this.ctx.canvas.width;
      const height = this.ctx.canvas.height;
      this.ctx.save();
      this.ctx.fillStyle = background || "rgb(255, 255, 255)";
      this.ctx.fillRect(0, 0, width, height);
      this.ctx.restore();
      if (transparency) {
        const transparentCanvas = this.cachedCanvases.getCanvas(
          "transparent",
          width,