title: Flutter Export Container with widgets to png/jpg
body: <p>I want to export an 1000 x 1000 Container or something like that with perhaps a Text, which changes, and multiple Containers inside which can change their color. When pressed a button, I want to export/share this 1000 x 1000 Container with its current widgets as an 1000 x 1000 PNG or JPG. To be honest, I have no idea how to do it. Every suggestion is appreciated :)</p>
  <p>(I want to do it in Flutter Web)</p>