WPF : Extend Theme's style - StackOverflowException

Question

I want every button to have 5 points margin, in addition to Royale theme style.

Window1.xaml:

<Window x:Class="_styles.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
  <Window.Resources>
    <ResourceDictionary>
      <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="/PresentationFramework.Royale;component/themes/royale.normalcolor.xaml" />
      </ResourceDictionary.MergedDictionaries>
      <Style TargetType="{x:Type Button}" BasedOn="{StaticResource {x:Type Button}}">
        <Setter Property="Margin" Value="5"/>
      </Style>
    </ResourceDictionary>
  </Window.Resources>
  <StackPanel>
    <Button Content="Button A"/>
    <Button Content="Button B"/>
  </StackPanel>
</Window>

It compiles but I get:

An unhandled exception of type 'System.StackOverflowException' occurred in PresentationFramework.dll

public Window1() {
    InitializeComponent(); // <-- getting exception here
}

There are no exception details because:

{Cannot evaluate expression because the current thread is in a stack overflow state.}

Can you give us any indication of where the exception is raised? — ChrisF, May 29 '09 at 17:45

Stanislav Kniazev · Accepted Answer · 2009-10-09T14:48:48.710

This seems to be a circular reference between your style and the one defined in PresentationFramework.Royale. A workaroud would be to place resources at different levels:

<Window x:Class="_styles.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    Title="Window1" Height="300" Width="300">
<Window.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="/PresentationFramework.Royale;component/themes/royale.normalcolor.xaml" />
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
</Window.Resources>
<StackPanel>
    <StackPanel.Resources>
        <Style TargetType="{x:Type Button}" BasedOn="{StaticResource {x:Type Button}}">
            <Setter Property="Margin" Value="5"/>
        </Style>
    </StackPanel.Resources>
    <Button Content="Button A"/>
</StackPanel>
</Window>

Can anyone explain how was this causing circular reference and why changing the scope has resolved it? — teenup, Mar 07 '15 at 04:19

score 0 · Answer 2 · edited May 23 '17 at 12:30

0

Please see this question and my answer for another solution that doesn't require you to specify a resource dictionary in every window and allows you to resolve the BasedOn style dynamically.

edited May 23 '17 at 12:30

Community

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answered Jun 23 '10 at 07:26

Andre Luus

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score 0 · Answer 3 · answered May 29 '09 at 18:02

0

I would remove the BasedOn attribute - it's not necessary. Think of it this way, merging the Royale theme will apply the button theme, and you just want to change the margin - styles are additive in nature, so it will combine the Royale theme and your own button theme without specifying the BasedOn attribute - does that make sense?

Cheers!

answered May 29 '09 at 18:02

Charles

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I was under impression that closer-scoped style *overwrites* previous style, i.e. at most one style can be applied. And BasedOn attribute is the way to *extend* a style. – THX-1138 May 29 '09 at 18:50
Ah, you're absolutely right. That's interesting - I tried the suggestion I gave you using the Aero theme, and leaving out the BasedOn="..." resets the buttons style back to the original XP theme. Woops :) If you can share more of the source, perhaps I could take a look. – Charles Jun 02 '09 at 15:50

WPF : Extend Theme's style - StackOverflowException

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