extract pixels returns black image

[Fnapsi]

Hi.

I have a newbie question. So I create a new PIXI application, draw a blue square onto it, wait a couple of seconds, and then manually start a function to extract the pixels. The extracted pixels are always black. If anybody could help me find out why this is the case, that would be great.

The blue square is correctly drawn and visible, and the extract function gives me a correct array of data, but all pixel information in it is black. As I execute the extract function right now manually, it's not possible that it's extracted too early or something like that.

Here are the important bits of the code:
 

initPixi() {
  let type = "WebGL";
  if(!PIXI.utils.isWebGLSupported()){
    type = "canvas";
  }

  this.pixi = new PIXI.Application({
        width: 0,
        height: 0,
        antialias: false,
        transparent: false,
        resolution: 1,
        autoResize: true,
        view: $('.imgCurrent')[0]
      }
  );
}

updatePixi() {
  this.pixi.renderer.resize(this.imgWidth, this.imgHeight);
  this.pixiDraw();
}

pixiDraw() {
  let rectangle = new PIXI.Graphics();
  rectangle.beginFill(0x66CCFF);
  rectangle.drawRect(0, 0, 200, 200);
  rectangle.endFill();
  rectangle.x = 0;
  rectangle.y = 0;
  this.pixi.stage.addChild(rectangle);
}

pixiExtract {
  this.pixi.renderer.extract.pixels();
}

 

[ivan.popelyshev]

It may happen, there's no guarantee that browser stores correct framebuffer between frames. You have to pass "this.pixi.app.stage" to pixels().