Objective:
I have a WPF project which shall be themed using DevExpress Themes. There is a Login-UserControl that shall have a themable background image.
Implementation
I made a custom Theme. In that theme I have a Folder "CustomResources" in which there is an Image, let's call it "Background.png" and a "Brushes.xaml" that defines an ImageBrush like this:
<ResourceDictionary ...> <ImageBrush x:Key="{CustomThemeKeyAssembly:CustomThemeResourcesThemeKey ResourceKey=LoginBackgroundImageBrush, ThemeName=CustomTheme}" ImageSource="Background.png" /> </ResourceDictionary> Accordingly, I have a shared Assembly CustomThemeKeyAssembly that derives a Custom ResourceThemeKey.
In the Project, I register and set the Theme using ApplicationThemeHelper
var theme = new Theme("CustomTheme") { AssemblyName = "DevExpress.Xpf.Themes.CustomTheme.v17.2" }; Theme.RegisterTheme(theme); ApplicationThemeHelper.ApplicationThemeName = "CustomTheme"; and I reference the Resource through
Background="{dxci:ThemeResource ThemeKey={CustomThemeKeyAssembly:CustomThemeResourcesThemeKey ResourceKey=LoginBackgroundImageBrush}}" As advised by DevExpress Knowledgebase / Support.
Problem
The Resource is only found and displayed, if I add a Merged Resource Dictionary like this:
ResourceDictionary loginBackgroundDictionary = new ResourceDictionary { Source = new Uri($"pack://application:,,,/{MyProject.Properties.Settings.Default.ThemeAssembly};Component/CustomResources/Brushes.xaml", UriKind.Absolute) }; //Add LoginBackgroundImageBrush Dictionary Resources.MergedDictionaries.Add(loginBackgroundDictionary); No article or example mentions having to do this, though. So my impression is that I either am doing something wrong or I am missing some simple step like merging the Brushes.xaml into some ResourceDictionary.
Without that snippet I get a warning that the resource could not be found.
Question
Has anybody an idea where I am going wrong or what I am missing to get this working without that last snippet?
FYI: I am using DevExpress 17.2.3 and the ResourceKey Assembly is targeted to .net Framework 4.0
EDIT
Meanwhile, I tried adding the Brushes.xaml to Themes/Generic.xaml in the theme assembly like this:
<ResourceDictionary.MergedDictionaries> <dxt:ResourceDictionaryEx Source="/DevExpress.Xpf.Themes.Office2016WhiteSE.v17.2;component/Themes/ControlStyles.xaml" /> <dxt:ResourceDictionaryEx Source="/DevExpress.Xpf.Themes.Office2016WhiteSE.v17.2;component/CustomResources/Brushes.xaml" /> </ResourceDictionary.MergedDictionaries> It didn't make any difference. Same behavior as before.
1 Answers
Answers 1
Problem solved!
The problem was in the CustomThemeKeyAssembly
The wrong implementation was
public class CustomThemeResourcesThemeKey : ThemeKeyExtensionBase { public override Assembly Assembly => TypeInTargetAssembly != null ? TypeInTargetAssembly.Assembly : GetType().Assembly; } The working implementation is
public class CustomThemeResourcesThemeKey : ThemeKeyExtensionBase<ThemeResourcesThemeKeys> { } The breaking difference is the override of the Assembly property. The default implementation makes it work. I did that because it was done so in an example. Support told me to stick with the default implementation and it worked.
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