Set static resource in code

Question

I have a few styles in my App.xaml file:

<SolidColorBrush x:Key="styleBlue" Color="#FF4B77BE"/>
<SolidColorBrush x:Key="styleRed" Color="#FFF64747"/>
<SolidColorBrush x:Key="styleOrange" Color="#FFF89406"/>
<SolidColorBrush x:Key="styleGreen" Color="#FF1BBC9B"/>
<SolidColorBrush x:Key="styleYellow" Color="#FFF9BF3B"/>

<Style x:Key="stackpanelBackground" TargetType="StackPanel">
    <Setter Property="Background" Value="{StaticResource styleBlue}"/>
</Style>

I want to change the BackgroundProperty in the code of my mainpage.xaml.cs.

I tried using this:

Style style = Application.Current.Resources["stackpanelBackground"] as Style;          
style.Setters.SetValue(StackPanel.BackgroundProperty, "{StaticResource styleRed}");

But I get a catastrophic failure exception. I think it has to do with {StaticResource styleRed}. Is there a better way to do this?

Patrick Hofman · Accepted Answer · 2014-11-24T14:53:18.063

29

A StaticResource is static. You can't change them once the application has compiled.

For this purpose, there is DynamicResource:

A DynamicResource will create a temporary expression during the initial compilation and thus defer lookup for resources until the requested resource value is actually required in order to construct an object.

Also note that you can find the reference to the other resource better using FindResource. Try something like this (full working sample):

In MainPage.xaml:

<Window.Resources>
    <Color R="255" x:Key="styleRed" />
    <Style x:Key="abc" TargetType="StackPanel">
        <Setter Property="Background" Value="Blue" />
    </Style>
</Window.Resources>

In MainPage.xaml.cs:

Style style = this.FindResource("abc") as Style;
var r = this.FindResource("styleRed");

foreach (Setter s in style.Setters)
{
    if (s.Property == StackPanel.BackgroundProperty)
    {
        s.Value = r;
    }
}

edited Nov 24 '14 at 14:53

answered Nov 24 '14 at 14:17

Patrick Hofman

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I tried using DynamicResource but it says "The name "DynamicResource" does not exist in the namespace "http://schemas.microsoft.com/client/2007"." – Arn Vanhoutte Nov 24 '14 at 14:19
@ArnVanhoutte: See the edit. Does this help? Any information in the `Output` pane in Visual Studio when you run the project? – Patrick Hofman Nov 24 '14 at 14:25
I tried to use the method in your edit, but it didn't work. It can't resolve FindResource – Arn Vanhoutte Nov 24 '14 at 14:28
@ArnVanhoutte: Try `Application.FindResource` then. – Patrick Hofman Nov 24 '14 at 14:29
Tried it too. And also App.FindResource. Output just show that it failed to build. Error is this: 'System.Windows.Application' does not contain a definition for 'FindResource' – Arn Vanhoutte Nov 24 '14 at 14:31
Try to place that code in the `Window.xaml.cs` class. – Patrick Hofman Nov 24 '14 at 14:48
I don't have that class. It is a Windows Phone app. There is by default an App.xaml (with App.xaml.cs) and MainPage.xaml (with MainPage.xaml.cs) – Arn Vanhoutte Nov 24 '14 at 14:51
In `App.xaml.cs` then? – Patrick Hofman Nov 24 '14 at 14:51
Same problem. I think that there is no FindResource for windows phone. That's why I used Application.Current.Resources – Arn Vanhoutte Nov 24 '14 at 15:00
Okay. If you change that in the code, and use the XAML I provided, does it work then? – Patrick Hofman Nov 24 '14 at 15:00
Like this: Style style = App.Current.Resources["stackpanelBackground"] as Style; style.Setters.SetValue(StackPanel.BackgroundProperty, App.Current.Resources["styleRed"]); I get the same exception then as in the original post. – Arn Vanhoutte Nov 24 '14 at 15:04
Any info in the Output Window? – Patrick Hofman Nov 24 '14 at 15:05
"A first chance exception of type 'System.Exception' occurred in System.Windows.ni.dll The program '[5328] AgHost.exe' has exited with code -1 (0xffffffff)." – Arn Vanhoutte Nov 24 '14 at 15:06
Can you put a `try catch` around it and check the exception? – Patrick Hofman Nov 24 '14 at 15:22
the Exception Message is "Catastrophic failure (Exception from HRESULT: 0x8000FFFF (E_UNEXPECTED))" – Arn Vanhoutte Nov 24 '14 at 15:25
Any inner exceptions? Call stack? – Patrick Hofman Nov 24 '14 at 15:28
No not really. Just that. I can send you the code if you want – Arn Vanhoutte Nov 24 '14 at 15:29
@ArnVanhoutte: I switched from testing this in a Desktop app to WP. It breaks there indeed. Here it says: "Access is denied" on setting the property. Maybe this is not allowed? – Patrick Hofman Nov 24 '14 at 15:39
I don't get that access is denied error. Could be that it is not allowed though. – Arn Vanhoutte Nov 24 '14 at 16:26

score 12 · Answer 2 · answered Nov 24 '14 at 14:35

Why are you modifying the Style instead of setting the Background-Property of your targeted StackPanel directly? Since a 'Local value' has a higher precedence than 'Style setters' the value that you write into Background from code behind would be used

Means:

(1) Give a name to your stackpanel x:Name="spBla"

(2) Assign the Brush to the Background of spBla ( something like spBla.Background=Application.Current.Resources["styleRed"] as SolidColorBrush; )

You can learn more about value precedence here:

http://msdn.microsoft.com/en-us/library/ms743230(v=vs.110).aspx

Because I have a lot of stackpanels in my different views. So instead of changing them all, I can just assign the ones I want to change to a specific style and then changing that style. — Arn Vanhoutte, Nov 24 '14 at 14:36

score 1 · Answer 3 · answered Jun 29 '21 at 15:06

xaml resource

    <Window.Resources>
        <LinearGradientBrush x:Key="GrayBlueGardientBrush"  
                                StartPoint="0,0" EndPoint="1,1">
            <GradientStop Color="DarkCyan" Offset="0"/>
            <GradientStop Color="#CCCCFF" Offset="0.5"/>
            <GradientStop Color="DarkCyan" Offset="1"/>
        </LinearGradientBrush>
    </Window.Resources>

CS

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        var r = this.FindResource("GrayBlueGardientBrush");
        (sender as Button).Background = r as LinearGradientBrush;
    }

score 0 · Answer 4 · answered Nov 24 '14 at 16:42

If I understand correctly, you are wanting to set up a style that allows you to only change specific stackpanels, so you don't have to set them all. Give this suggestion a try (note: it is a suggestion and I have not tested it, but hopefully it is in the right direction)

<SolidColorBrush x:Key="styleBlue" Color="#FF4B77BE"/>
<SolidColorBrush x:Key="styleRed" Color="#FFF64747"/>
<SolidColorBrush x:Key="styleOrange" Color="#FFF89406"/>
<SolidColorBrush x:Key="styleGreen" Color="#FF1BBC9B"/>
<SolidColorBrush x:Key="styleYellow" Color="#FFF9BF3B"/>

<Style x:Key="stackpanelBackground" TargetType="StackPanel">
    <Setter Property="Background" Value="{Binding Background, FallbackValue={StaticResource styleBlue}}"/>
</Style>

Or try TemplateBinding instead of Binding, like I said it is a suggestion and I haven't tested it. This would give you a binding for the background, and a fallback value for a stackpanel that you haven't set a background color for. Let me know how or if this works for you :)

Set static resource in code

4 Answers4

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