Maintaining fixed-thickness lines in WPF with Viewbox scaling/stretching

Question

I have a which contains some vertical and horizontal s. I want the grid to be scalable with the window size, and retain i

Answer 1

A Viewbox can only "visually" scale its child element, including the thickness of any rendered stroke. What you need is a scaling that only applies to the geometry of the lines (or other shapes), but leaves the stroke unaffected.

Instead of using Line objects, you could draw your lines by Path objects that use transformed LineGeometries for their Data property. You could create a ScaleTransform that scales from logical coordinates to viewport coordinates by using the Grid's width and height as scaling factors in x and y direction. Each LineGeometry (or any other Geometry) would use logical coordinates in the range 0..1:

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In order to get a uniform scaling you may simply bind both the ScaleTransform's ScaleX and ScaleY properties to either the ActualWidth or ActualHeight of the Grid:

    
        
    
    ...

You may also calculate the uniform scaling factor from the minimum value of the width and height, with a bit of code behind:

    
        
    
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with a SizeChanged handler like this:

private void grid_SizeChanged(object sender, SizeChangedEventArgs e)
{
    var transform = grid.Resources["transform"] as ScaleTransform;
    var minScale = Math.Min(grid.ActualWidth, grid.ActualHeight);
    transform.ScaleX = minScale;
    transform.ScaleY = minScale;
}