Add property to access the main window's width and height

[PanCakeConnaisseur]

Feature Description

Please add a global way to access the main window's width and height. AFAIU root only accesses the main components width/height and therefore the main windows's dimensions are not accessible from within a nested component. I imageine, that this would be useful for many scenarios but for me it would be useful to prevent elements from moving out of the window, such as in tooltips.

By main window I mean the thing that windows decorators are applied onto and which can be moved around, minimized, maximized, etc.

Example

component ToolTipArea inherits Window {
  in property <string> text;
  Rectangle {
    // The expression of `x` needs to know how wide the main window is to not
    // let the rectangle leave the main window. `root` here refers to
    // ToolTipArea, but I would like to have the value of MainWindow.width in
    // the variable `mainwindow-width`
    x: max(-parent.absolute-position.x, min(ta.mouse-x + root.x-offset, - parent.absolute-position.x + mainwindow-width - self.width));
    Text {
      text <=> root.text;
    }
  }
  ta := TouchArea {
    HorizontalLayout {
        @children
    }
}
}

component MainWindow inherits Window {
  ToolTipArea {
    text : "This is additional information"
  }
}

Product Impact

No response

[Vadoola]

Perhaps not for a more complicated example, but for the one you presented couldn't you do something like below:

component ToolTipArea inherits Window {
  in property <string> text;
  in property <int> parent-width;
  in property <int> parent-height;
  Rectangle {
    x: max(-parent.absolute-position.x, min(ta.mouse-x + root.x-offset, - parent.absolute-position.x + parent-width - self.width));
    Text {
      text <=> root.text;
    }
  }
  ta := TouchArea {
    HorizontalLayout {
        @children
    }
}
}

component MainWindow inherits Window {
  ToolTipArea {
    text : "This is additional information"
    parent-width = parent.width;
    parent-height = parent.height;
  }
}

[PanCakeConnaisseur]

@Vadoola, this is the workaround I am using right now. The suggested feature would make it possible to avoid this boilerplate code.

[ogoffart]

Another workaround would be to use a global and use changed event to keep it in sync.

global Helper {
    in property<length> win-height;
}

export component MainWindow inherits Window {
    changed height => {
      Helper.win-height = self.height;
    } 
}

Given all the workarounds, i'm not sure it makes sense to add this feature in Slint.

[PanCakeConnaisseur]

IMHO this is a fundamental property that should be built-in and not rely on workarounds or helpers.