Re: WPF Background issue

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Here's some code to reproduce this problem:

Window1.xaml:

<Window x:Class="BackgroundIssue.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation";
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml";
xmlns:test="clr-namespace:BackgroundIssue"
Title="Background Issue" Height="375" Width="464"
xmlns:my="clr-namespace:System;assembly=mscorlib">
<Grid>
<test:CustomViewer x:Name="customViewer1" HorizontalAlignment="Left"
Width="238" Background="Red" />
</Grid>
</Window>


CustomWindow.cs:

using System;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows;

namespace BackgroundIssue
{
public class CustomViewer : ScrollViewer
{
public CustomViewer()
{
this.VerticalScrollBarVisibility = ScrollBarVisibility.Hidden;
}

protected override void OnRender(System.Windows.Media.DrawingContext
drawingContext)
{
drawingContext.DrawRectangle(null, new Pen(new
SolidColorBrush(Colors.Navy), 10), new Rect(20, 20, 400, 300));
}

}
}


This will create a window with the control on half of it. A rectangle is
drawn larger than the control so you can see that the red background is
covering what is drawn in the OnRender method.

-Glenn



"Bob Powell [MVP]" wrote:

Post some code...

--
Bob Powell [MVP]
Visual C#, System.Drawing

Ramuseco Limited .NET consulting
http://www.ramuseco.com

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Glenn wrote:
Hi,

I've created a control that derives from ScrollViewer and override the
OnRender method to draw onto the control. However, if the Background
property is set, the background always draws on top of whatever I draw.

Even if I don't call base.OnRender the background is drawn, so I'm not sure
what is drawing the background or why it would be drawn after OnRender is
called. Does anyone have any ideas?

.

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