Question

I’m making a WPF/C# program with a Polygon to make a triangle. When the size of my window changes, I want it to be redraw, so here is my WPF :

<Polygon  Name="Plg" Grid.Row="1" Grid.Column="1" Stroke="Red" StrokeThickness="1">
    <Polygon.Fill>
        <SolidColorBrush Color="White" />
    </Polygon.Fill>
</Polygon>

And here is my code in the Window_SizeChanged Event:

private void Window_SizeChanged(object sender, SizeChangedEventArgs e)
{        
    Plg.Points.Clear(); 
    Plg.Points.Add(new Point(Plg.ActualWidth / 2 , 0));
    Plg.Points.Add(new Point(2, Plg.ActualHeight));
    Plg.Points.Add(new Point(Plg.ActualWidth, Plg.ActualHeight));         
}

If i increase the size of the window, it works well, but if I try to reduce it, the triangle keeps the biggest size that it has. I also try with RenderSize, but the result is the same.

Is it a bug, or did i make something wrong ?

Answer 1

with this XAML, it works: (the grid is in the window)

<Grid Name="myGrid">
    <Polygon  Name="Plg" Grid.Row="1" Grid.Column="1" Stroke="Red" StrokeThickness="1">
        <Polygon.Fill>
            <SolidColorBrush Color="Black" />
        </Polygon.Fill>
    </Polygon>
</Grid>

Change your code like this:

private void Window_SizeChanged(object sender, SizeChangedEventArgs e)
{        
    Plg.Points.Clear(); 
    Plg.Points.Add(new Point(myGrid.ActualWidth / 2 , 0));
    Plg.Points.Add(new Point(2, myGrid.ActualHeight));
    Plg.Points.Add(new Point(myGrid.ActualWidth, this.ActualHeight));         
}