TextBlock foreground being reset to inherited value after dynamic resource from merged dictionary is applied

问题

EDIT: I was able to reproduce this in a very stripped-down version of the application. Here is a link to the .zip file

http://www.mediafire.com/?cn918gi15uph1xe

I have the module add the view to two different regions - the status bar region along the top is where the issue occurs. The weird part is, when the same view type is added to the main region, there are no problems. The status bar region is an ItemsControl and the main region is a ContentPresenter. That is the only difference.

Please let me know if you have any insight! Thanks.

-----Original Post-----

Hello all,

I am seeing some weird behavior with WPF. I'm using .NET 4 and PRISM v4. The way we have our application structured is that the skin resource dictionaries exist in their own assembly. The modules do not reference this assembly - instead we have a skin manager class that reads from a config file which skin we want and loads the appropriate components into a merged dictionary. The merged dictionary is set in the Application resources (we clear out the Application.Resources.MergedDictionaries before we add it). The idea is that we can later switch skins at runtime if needed, and the modules don't need to know about the skins until runtime.

Then in our xaml we are referencing styles using DynamicResource. The problem has to do with a TextBlock style defined in the skin and referenced by key, such as

<TextBlock Style="{DynamicResource someKey}" ... />

The style defines the font family, font size, and foreground. The font family and size are applied correctly (I verified this). The foreground, however, is always black. I used Snoop and WPF Inspector to see that the foreground value is "inherited" instead of coming from the style.

I also have a control that inherits from TextBlock and all it does is add some properties that determine what the text value should be (it doesn't affect the style at all). I was able to add a property changed override for the Foreground property and found out that the style's foreground value gets applied, and then the inherited value gets applied after that. I wasn't able to get the .NET source debugging to work so I couldn't figure out why/where it was being called from the second time...

Here is a link to an old, old post from a guy with the exact same problem - he did not find the answer, but instead a workaround. Unfortunately the workaround only works on the inherited control (I can't set InheritanceBehavior for TextBlocks).

http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/3501ed19-ab40-4064-81b5-e9b7b9d35b56

回答1:

My guess is that for TextBlock the foreground property is inherited from its parent unless you explicitly set it on your TextBlock instane. For example if you change the Window or UserControl that this Textblock is in to have a Foreground of blue does it work? One thing you can try doing is in the style instead of setting just Foreground to a color, set TextElement.Foreground. See if that works.