feature: supports to view .tiff images

Signed-off-by: leo <longshuang@msn.cn>

src/Models/ImageDecoder.cs

@@ -4,6 +4,7 @@
     {
         None = 0,
         Builtin,
-        Pfim
+        Pfim,
+        Tiff,
     }
 }

src/SourceGit.csproj

@@ -47,6 +47,7 @@
     <PackageReference Include="Avalonia.AvaloniaEdit" Version="11.2.0" />
     <PackageReference Include="AvaloniaEdit.TextMate" Version="11.2.0" />
     <PackageReference Include="Azure.AI.OpenAI" Version="2.2.0-beta.4" />
+    <PackageReference Include="BitMiracle.LibTiff.NET" Version="2.4.660" />
     <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.0" />
     <PackageReference Include="LiveChartsCore.SkiaSharpView.Avalonia" Version="2.0.0-rc5.4" />
     <PackageReference Include="OpenAI" Version="2.2.0-beta.4" />

src/ViewModels/ImageSource.cs

@@ -7,6 +7,7 @@ using Avalonia;
 using Avalonia.Media.Imaging;
 using Avalonia.Platform;
 
+using BitMiracle.LibTiff.Classic;
 using Pfim;
 
 namespace SourceGit.ViewModels
@@ -39,6 +40,9 @@ namespace SourceGit.ViewModels
                 case ".tga":
                 case ".dds":
                     return Models.ImageDecoder.Pfim;
+                case ".tif":
+                case ".tiff":
+                    return Models.ImageDecoder.Tiff;
                 default:
                     return Models.ImageDecoder.None;
             }
@@ -70,31 +74,34 @@ namespace SourceGit.ViewModels
             var size = stream.Length;
             if (size > 0)
             {
-                if (decoder == Models.ImageDecoder.Builtin)
+                try
+                {
+                    switch (decoder)
+                    {
+                        case Models.ImageDecoder.Builtin:
                             return DecodeWithAvalonia(stream, size);
-                else if (decoder == Models.ImageDecoder.Pfim)
+                        case Models.ImageDecoder.Pfim:
                             return DecodeWithPfim(stream, size);
+                        case Models.ImageDecoder.Tiff:
+                            return DecodeWithTiff(stream, size);
+                    }
+                }
+                catch (Exception e)
+                {
+                    Console.Out.WriteLine(e.Message);
+                }                
             }
 
             return new ImageSource(null, 0);
         }
 
         private static ImageSource DecodeWithAvalonia(Stream stream, long size)
-        {
-            try
         {
             var bitmap = new Bitmap(stream);
             return new ImageSource(bitmap, size);
         }
-            catch
-            {
-                return new ImageSource(null, 0);
-            }
-        }
 
         private static ImageSource DecodeWithPfim(Stream stream, long size)
-        {
-            try
         {
             using (var pfiImage = Pfimage.FromStream(stream))
             {
@@ -147,9 +154,26 @@ namespace SourceGit.ViewModels
                 return new ImageSource(bitmap, size);
             }
         }
-            catch
+    
+        private static ImageSource DecodeWithTiff(Stream stream, long size)
         {
+            using (var tiff = Tiff.ClientOpen($"{Guid.NewGuid()}.tif", "r", stream, new TiffStream()))
+            {
+                if (tiff == null)
                     return new ImageSource(null, 0);
+
+                var width = tiff.GetField(TiffTag.IMAGEWIDTH)[0].ToInt();
+                var height = tiff.GetField(TiffTag.IMAGELENGTH)[0].ToInt();
+                var pixels = new int[width * height];
+
+                // Currently only supports image when its `BITSPERSAMPLE` is one in [1,2,4,8,16] 
+                tiff.ReadRGBAImageOriented(width, height, pixels, Orientation.TOPLEFT);
+
+                var ptr = Marshal.UnsafeAddrOfPinnedArrayElement(pixels, 0);
+                var pixelSize = new PixelSize(width, height);
+                var dpi = new Vector(96, 96);
+                var bitmap = new Bitmap(PixelFormats.Rgba8888, AlphaFormat.Premul, ptr, pixelSize, dpi, width * 4);
+                return new ImageSource(bitmap, size);
             }
         }
     }