title: Offset origin of tiled Image in Flutter
body: <p>I'm trying to create a parallax background in a Flutter app, and the most efficient way to build it is to use a <code>Stack</code> with the image filling the screen as a background and then my list on top. The image is tiled with an <code>ImageRepeat</code> set on the Y axis. The plan is to then offset the origin of the tile in sync with the <code>ScrollController</code> I'm using for my list. I can then adjust the origin of the tiled image to create the parallax effect. It should be really simple. Here's some code for context:</p>
  <pre><code>Stack(
            children: [
              SizedBox.expand(
                child: Image(
                  image: AssetImage('assets/images/tiled_background_leaf.jpg'),
                  repeat: ImageRepeat.repeatY,
                ),
              ),
              CustomScrollView(
                controller: _controller,
                slivers: [ ...
  </code></pre>
  <p>My problem is that Image does not have an <code>offset</code> property, or an <code>origin</code> position. I need some advice on the easiest way to do this. I've seen that there are custom painters, canvas methods etc, but they all seem massively over-complicated when there should be a more elegant solution within the <code>Image</code> widget, or possibly within another widget that would give me the same parallax effect.</p>