dynamic WPF theme by zip

• Download ThemeInZip.zip - 1.6 MB

Introduction

WPF provide many ways to theme the application, i provide a new way to theme the application dynamically, neither AppDomain, nor loose xaml

Background

Make sure you are familar with the common WPF theme, maybe you can refer to the other great article at first

• WPF Themes and Skins Engine

Using the code

Before present my theme way, let's see what's cons & pros on the classic theme way

Theme strategy	Load Speed	Native support( not require additional code)	Support code themed(bundle code & resource into single file)	Support resource hierarchy navigation	Load dynamically	Unload dynamically	Easily edit and compile(not require VS installed)
Direct Load	Fast	Y	Y	Y	Y	N	N
Loose Xaml	Low	Y	N	Y	Y	Y	Y
AppDomain	Fast	N	Y	N	Y	Y	N

Let's see some fact

• Xaml support pack protocol Uri
• pack protocol support custom parser( System.IO.Packaging.PackageStore)
• WPF support Zip file parser ( System.IO.Packaging.ZipPackage)

Now let's combine these fact into a new theme way

1. add/remove custom parser for pack protocol
   C#

   PackageStore.AddPackage(new Uri("customtheme://"), Package.Open("123.zip"));
   PackageStore.RemovePackage(new Uri("customtheme://"));
   

2. embed resources files/folders to single zip file, i use the 7za.exe (from 7zip command line tools )

   7za.exe	a	-tzip	theme1.customtheme	.\Themes\theme1\*	-mm=copy
   	Add/ Replace files in zip	Use zip compress algorithm	Destination zip file, extension can be changed	The source files to compressed	The compress strategy, just copy , don’t do compress to improve the decompress speed

3. Because ZipPackage is designed for XPS, and XPS require to include a file named [Content_types].xml to identify the content type, so make sure always present a valid [Content_types].xml besides the resource files in the destination zip file
   XML

   <?xml version="1.0" encoding="utf-8" ?>
   <Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">
     <Default Extension="png" ContentType="image/png" />
     <Default Extension="tiff" ContentType="image/tiff" />
     <Default Extension="jpg" ContentType="image/jpeg" />
     <Default Extension="gif" ContentType="image/gif" />
     <Default Extension="bmp" ContentType="image/bmp" />
     <Default Extension="txt" ContentType="text/plain" />
     <Default Extension="xaml" ContentType="application/xaml+xml" />
     <Default Extension="xml" ContentType="application/xml" />
     <Default Extension="avi" ContentType="video/avi" />
     <Default Extension="mp4" ContentType="video/mp4" />
     <Default Extension="mp3" ContentType="audio/mp3" />
   </Types> 

4. i use MemoryMappedFile to improve IO access speed, because there are many little-size IO access when Xaml load theme files

   Stream fileMapViewStream;
   try
   {
       fileMapViewStream = MemoryMappedFile.OpenExisting(item.Replace("\\", ":"), MemoryMappedFileRights.Read).CreateViewStream(0, new FileInfo(item).Length, MemoryMappedFileAccess.Read);
   }
   catch(IOException)
   {
       fileMapViewStream = MemoryMappedFile.CreateFromFile(item, FileMode.Open, item.Replace("\\", ":"), new FileInfo(item).Length, MemoryMappedFileAccess.Read).CreateViewStream(0, new FileInfo(item).Length, MemoryMappedFileAccess.Read);
   }
   

5. At last, we got the most important code for this article
   C#

   private void cmbThemes_SelectionChanged(object sender, SelectionChangedEventArgs e)
     {
         if (e.RemovedItems != null)
         {
             foreach (var item in e.RemovedItems.OfType<string>())
             {
                 PackageStore.RemovePackage(new Uri(System.IO.Path.GetFileName(item) + "://"));
             }
         }
   
   
   
   
         if (e.AddedItems != null)
         {
             foreach (var item in e.AddedItems.OfType<string>())
             {
                 Stream fileMapViewStream;
                 try
                 {
                     fileMapViewStream = MemoryMappedFile.OpenExisting(item.Replace("\\", ":"), MemoryMappedFileRights.Read).CreateViewStream(0, new FileInfo(item).Length, MemoryMappedFileAccess.Read);
                 }
                 catch(IOException)
                 {
                     fileMapViewStream = MemoryMappedFile.CreateFromFile(item, FileMode.Open, item.Replace("\\", ":"), new FileInfo(item).Length, MemoryMappedFileAccess.Read).CreateViewStream(0, new FileInfo(item).Length, MemoryMappedFileAccess.Read);
                 }
                 PackageStore.AddPackage(new Uri(System.IO.Path.GetFileName(item) + "://"), Package.Open(fileMapViewStream, FileMode.Open, FileAccess.Read));
                 Application.Current.Resources.MergedDictionaries[0] = new ResourceDictionary() { Source = new Uri("pack://" + System.IO.Path.GetFileName(item) + ":,,,/ResourceDictionary.xaml") };
             }
         }
     }
   

At last, let's see the comparison between the three classic theme ways

Theme strategy	Load Speed	Native support( not require additional code)	Support code themed(bundle code & resource into single file)	Support resource hierarchy navigation	Load dynamically	Unload dynamically	Easily edit and compile(not require VS installed)
Direct Load	Fast	Y	Y	Y	Y	N	N
Loose Xaml	Low	Y	N	Y	Y	Y	Y
AppDomain	Fast	N	Y	N	Y	Y	N
Zip file	Fast(*)	N	N	Y	Y	Y	Y

* Though Zip file don't compile the Xaml to baml, but consider the MemoryMappedFile, so will require less IO operation theoretically, speed should be faster

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