Using an embedded resource Image from code in a WPF application.

In WinForms or standard ASP.Net coding getting a reference to an embedded resource image is as simple as “My.Resources.ImageName” but alas this is not the case in WPF or even in Silverlight. You can access the Image resource in code using the previous examples, but as the saying  goes, you can’t get there from here. What you will get is a Bitmap reference that is just not usable by the ImageSource object.

There are many examples of how to use an embedded resource image directly in the XAML script such as ImageSource="/{AssemblyName};component/Images/MyImage.png" where {Assemblyname} is the name of the containing assembly.  But what if your requirements include the need to set these image properties during runtime in the Visueal Basic code instead of during XAML design time?

What you are going to have to do is use reflection to extract the embedded resource file from the containing assembly and stream it into a decoder object and then pass the decoder’s frame object to the ImageSource object and you are done.   Below is a code example that retrieves A PNG image from the assembly’s embedded resources.  The method takes the name of the image as an argument including the root namespace of the assembly and the file extension of the image as an argument. As written this method is specifically designed for a PNG type of image file since the image decoders are specific to an image type. The steps include getting a reference to the containing assembly, opening a memory stream that points to the image resource and decode the stream using a BitMapDecoder that is specific to an image type to decode the image into a System.Windows.Media.ImageSource object. You extract the Image Source from Frame(0) of the decoder.  Why is the image source placed in a frame array? Because in some cases such as an animated GIF, you will have several frames that make up the animation. In such a case you will have to create a method that returns an array of ImageSource objects.

'''     ''' Given a valid resource image name that includes [namespace].[imagename].[extension]     ''' this function returns an PNG image source that can be programatically used as a     ''' WPF ImageSource object.     '''     '''     '''     '''     '''     Public Shared Function GetPNGResourceImage(ByVal Imagename As String) _                                                As ImageSource           Dim MyStream As System.IO.Stream = Nothing         Dim MyDecoder As PngBitmapDecoder = Nothing         Dim MyImage As ImageSource = Nothing         Dim MyAssembly As System.Reflection.Assembly = Nothing           Try             'get a reference to the containing assembly             MyAssembly = System.Reflection.Assembly.GetExecutingAssembly             'get a memory stream of the embedded image             MyStream = MyAssembly.GetManifestResourceStream(Imagename)             'make sure we have a valid stream instance             If MyStream IsNot Nothing Then                   'decode the image into a imagesource object                 MyDecoder = New PngBitmapDecoder(MyStream, _                                                  BitmapCreateOptions.PreservePixelFormat, _                                                  BitmapCacheOption.Default)                 MyImage = MyDecoder.Frames(0)               End If           Catch ex As Exception             ’handle your exceptions here         Finally             MyStream.Close()         End Try           Return MyImage       End Function

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The code above extracts a PNG type of image from an assembly’s resource cache.  For this to work properly you have to set the resource image’s Build Action property to Embedded Resource.  To call the function you might do something like this:

Me.Logo.Source = Utilities.GetPNGResourceImage(Me, "PPCSalesManagement.PPCSpider.png")

 The above function method works fine if all of your images are of PNG type.  That is not always the case and perhaps a more flexible method would be in order to accommodate any of the image types. You can approach it many ways but in the example below I use an enumerator in the argument for selecting the image type and then a select case to instantiate an image type specific decoder from the generic base class declaration.

Public Enum eImageType         PNG = 0         JPG = 1         BMP = 2         GIF = 3         Icon = 4         WMF = 5         TIFF = 6     End Enum         '''     '''  Given a valid resource image name that includes [namespace].[imagename].[extension]     '''  and the proper image type selection this function returns an image source that can be      '''  prgramatically used as a WPF ImageSource object.     '''     '''     '''     '''     ''' Given a valid resource image name that includes [namespace].[imagename].[extension]     '''  and the proper image type selection this function returns an image source that can be      '''  prgramatically used as a WPF ImageSource object.     Public Shared Function GetResourceImage(ByVal ImageNameIn As String, ByVal TypeIn As eImageType) As ImageSource           Dim MyStream As System.IO.Stream = Nothing         Dim MyDecoder As BitmapDecoder = Nothing 'PngBitmapDecoder = Nothing         Dim MyImage As ImageSource = Nothing         Dim MyAssembly As System.Reflection.Assembly = Nothing           Try               'get a reference to the containing assembly             MyAssembly = System.Reflection.Assembly.GetExecutingAssembly             'get a memory stream of the embedded image             MyStream = MyAssembly.GetManifestResourceStream(ImageNameIn)             'make sure we have a valid stream instance             If MyStream IsNot Nothing Then                   'get the appropriate decoder                 Select Case TypeIn                       Case eImageType.BMP                         MyDecoder = New BmpBitmapDecoder(MyStream, _                                                  BitmapCreateOptions.PreservePixelFormat, _                                                  BitmapCacheOption.Default)                     Case eImageType.GIF                         MyDecoder = New GifBitmapDecoder(MyStream, _                                                  BitmapCreateOptions.PreservePixelFormat, _                                                  BitmapCacheOption.Default)                       Case eImageType.Icon                         MyDecoder = New IconBitmapDecoder(MyStream, _                                                  BitmapCreateOptions.PreservePixelFormat, _                                                  BitmapCacheOption.Default)                       Case eImageType.JPG                         MyDecoder = New JpegBitmapDecoder(MyStream, _                                                  BitmapCreateOptions.PreservePixelFormat, _                                                  BitmapCacheOption.Default)                       Case eImageType.PNG                         MyDecoder = New PngBitmapDecoder(MyStream, _                                                  BitmapCreateOptions.PreservePixelFormat, _                                                  BitmapCacheOption.Default)                       Case eImageType.TIFF                         MyDecoder = New TiffBitmapDecoder(MyStream, _                                                  BitmapCreateOptions.PreservePixelFormat, _                                                  BitmapCacheOption.Default)                       Case eImageType.WMF                         MyDecoder = New WmpBitmapDecoder(MyStream, _                                                  BitmapCreateOptions.PreservePixelFormat, _                                                  BitmapCacheOption.Default)                   End Select                   MyImage = MyDecoder.Frames(0)               End If           Catch ex As Exception             ProcessException(ex, eExceptionsOptions.ShowMessageAndLog)         Finally             MyStream.Close()         End Try           Return MyImage       End Function

A call to this function is would look like the example below:

Me.HeaderBorder.Background = New ImageBrush(Utilities.GetResourceImage("PPCSalesManagement.ppcBanner1.png", Utilities.eImageType.PNG))

Well, that wraps up this article.  If you have comments or suggestions please feel free to post them here.

Ibrahim