wpf 库的图片不呈现

When an image in a WPF library (DLL) does not display in the consuming application, the primary issues are incorrect Build Action settings and improper Pack URI syntax for accessing resources across assemblies. 

Here are the steps to fix the problem:

1. Verify Project SDK (for .NET Core/.NET 5+)

If you are using modern .NET (Core, 5, 6+), the library project's SDK must be set correctly to handle WPF resources. 

• In your library's .csproj file, ensure the Sdk attribute is set to Microsoft.NET.Sdk.WindowsDesktop. 

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2. Set the Image Build Action to 'Resource' 

This is the most common fix. The image file must be compiled into the library's managed resources. 

• In Visual Studio, right-click the image file in the Solution Explorer.
• Select Properties.
• In the Properties window, change the Build Action from Content or Embedded Resource to Resource.
• Ensure Copy to Output Directory is set to Do not copy (or left blank). 

3. Use the Correct Pack URI Syntax in the Consuming Application 

When referencing an image from an external library, you must use a full Pack URI that specifies the assembly name. 

The correct format in XAML is:
Source="pack://application:,,,/AssemblyName;component/FolderPath/ImageName.ext"

• Replace AssemblyName with the actual name of your library project (e.g., MyControlsLibrary).
• Replace FolderPath/ImageName.ext with the path to your image within the library project (e.g., Images/logo.png). 

Example XAML:

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A shorthand syntax is also common and typically works:

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4. Rebuild the Solution

After making changes, especially to the build actions or project file, perform a full Rebuild Solution (Build -> Rebuild Solution) to ensure the images are properly compiled into the resulting DLL. 

5. Check for Z-Index or Layout Issues 

Sometimes the image loads correctly, but it is hidden behind another UI element in your layout. 

• Verify your layout containers (like Grid, StackPanel, Canvas) to ensure the Image control is visible and not obscured by an element with a higher Z-index or an opaque background.