Scrolling content in a masked container behaving differently after 1.3 upgrade

mayorbyrne commented 6 years ago

I am part of a project which involves scrolling lists of DisplayObjects. I have code that behaves drastically different between 1.1.0 (working) and 1.3.0 (breaking, I believe as of 1.2). Was wondering if you could give me insight into the issue, and how I might be able to resolve it.

Previously (1.1.0), I added a mask to the wrapper, and added the items to the wrapper, adjusting the Y position of the wrapper itself depending on scroll direction. Doing the same thing in 1.3.0 displays differently, and I am unable to adjust the Y positioning of the wrapper content.

It seems to be breaking on relativeToParent, as taking that line wrapperMask.relativeToParent = true; out allows me to scroll again, albeit with incorrect mask positioning.

Please let me know what I am doing wrong!

  Shape bg = new Shape()
    ..graphics.rect(0, 0, 500, 500)
    ..graphics.fillColor(Color.Green)
    ..x = 50
    ..y = 50
    ..addTo(stage);

  _wrapper = new Sprite()
    ..x = 50
    ..y = 50
    ..addTo(stage);

  Mask wrapperMask = new Mask.rectangle(50, 50, 500, 500);
  wrapperMask.relativeToParent = true;
  _wrapper.mask = wrapperMask;

  int posY = 10;
  for (int i = 0; i < 20; i++)
  {
    new TextField("HELLO WORLD $i", new TextFormat("Arial", 24, Color.Black)
      ..align = TextFormatAlign.CENTER)
      ..width = 500
      ..height = 50
      ..y = posY
      ..border = true
      ..addTo(_wrapper);

    posY += 50;
  }

Here's a screenshot of the initial load of the page, with the exact same code on each browser window.

capture