feature: supports preview and diff with image files

src/SourceGit/Commands/GetImageFileAsBitmap.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Diagnostics;
+using System.IO;
+
+using Avalonia.Media.Imaging;
+
+namespace SourceGit.Commands
+{
+    public static class GetImageFileAsBitmap
+    {
+        public static Bitmap Run(string repo, string revision, string file)
+        {
+            var starter = new ProcessStartInfo();
+            starter.WorkingDirectory = repo;
+            starter.FileName = Native.OS.GitInstallPath;
+            starter.Arguments = $"show {revision}:\"{file}\"";
+            starter.UseShellExecute = false;
+            starter.CreateNoWindow = true;
+            starter.WindowStyle = ProcessWindowStyle.Hidden;
+            starter.RedirectStandardOutput = true;
+
+            try
+            {
+                var stream = new MemoryStream();
+                var proc = new Process() { StartInfo = starter };
+                proc.Start();
+                proc.StandardOutput.BaseStream.CopyTo(stream);
+                proc.WaitForExit();
+                proc.Close();
+
+                stream.Position = 0;
+                return new Bitmap(stream);
+            }
+            catch
+            {
+                return null;
+            }
+        }
+    }
+}

src/SourceGit/Models/DiffResult.cs

@@ -2,6 +2,8 @@
 using System.Text;
 using System.Text.RegularExpressions;
 
+using Avalonia.Media.Imaging;
+
 namespace SourceGit.Models
 {
     public enum TextDiffLineType
@@ -547,6 +549,12 @@ namespace SourceGit.Models
         public long NewSize { get; set; } = 0;
     }
 
+    public class ImageDiff
+    {
+        public Bitmap Old { get; set; } = null;
+        public Bitmap New { get; set; } = null;
+    }
+
     public class NoOrEOLChange
     {
     }

src/SourceGit/Models/RevisionFile.cs

@@ -1,10 +1,17 @@
-namespace SourceGit.Models
+using Avalonia.Media.Imaging;
+
+namespace SourceGit.Models
 {
     public class RevisionBinaryFile
     {
         public long Size { get; set; } = 0;
     }
 
+    public class RevisionImageFile
+    {
+        public Bitmap Image { get; set; } = null;
+    }
+
     public class RevisionTextFile
     {
         public string FileName { get; set; }

src/SourceGit/ViewModels/CommitDetail.cs

@@ -432,11 +432,24 @@ namespace SourceGit.ViewModels
                         var isBinary = new Commands.IsBinary(_repo, _commit.SHA, file.Path).Result();
                         if (isBinary)
                         {
-                            var size = new Commands.QueryFileSize(_repo, file.Path, _commit.SHA).Result();
+                            var ext = Path.GetExtension(file.Path);
-                            Dispatcher.UIThread.Invoke(() =>
+                            if (IMG_EXTS.Contains(ext))
                             {
-                                ViewRevisionFileContent = new Models.RevisionBinaryFile() { Size = size };
+                                var bitmap = Commands.GetImageFileAsBitmap.Run(_repo, _commit.SHA, file.Path);
-                            });
+                                Dispatcher.UIThread.Invoke(() =>
+                                {
+                                    ViewRevisionFileContent = new Models.RevisionImageFile() { Image = bitmap };
+                                });
+                            }
+                            else
+                            {
+                                var size = new Commands.QueryFileSize(_repo, file.Path, _commit.SHA).Result();
+                                Dispatcher.UIThread.Invoke(() =>
+                                {
+                                    ViewRevisionFileContent = new Models.RevisionBinaryFile() { Size = size };
+                                });
+                            }
+                            
                             return;
                         }
 
@@ -485,6 +498,11 @@ namespace SourceGit.ViewModels
             }
         }
 
+        private static readonly HashSet<string> IMG_EXTS = new HashSet<string>()
+        {
+            ".ico", ".bmp", ".jpg", ".png", ".jpeg"
+        };
+
         private string _repo = string.Empty;
         private int _activePageIndex = 0;
         private Models.Commit _commit = null;

src/SourceGit/ViewModels/DiffContext.cs

@@ -1,4 +1,5 @@
-using System.IO;
+using System.Collections.Generic;
+using System.IO;
 using System.Threading.Tasks;
 
 using Avalonia;
@@ -46,12 +47,6 @@ namespace SourceGit.ViewModels
             private set => SetProperty(ref _isLoading, value);
         }
 
-        public bool IsNoChange
-        {
-            get => _isNoChange;
-            private set => SetProperty(ref _isNoChange, value);
-        }
-
         public bool IsTextDiff
         {
             get => _isTextDiff;
@@ -77,7 +72,6 @@ namespace SourceGit.ViewModels
 
             if (previous != null)
             {
-                _isNoChange = previous._isNoChange;
                 _isTextDiff = previous._isTextDiff;
                 _content = previous._content;
             }
@@ -89,53 +83,62 @@ namespace SourceGit.ViewModels
             Task.Run(() =>
             {
                 var latest = new Commands.Diff(repo, option).Result();
-                var binaryDiff = null as Models.BinaryDiff;
+                var rs = null as object;
 
-                if (latest.IsBinary)
+                if (latest.TextDiff != null)
+                {
+                    latest.TextDiff.File = _option.Path;
+                    rs = latest.TextDiff;
+                }
+                else if (latest.IsBinary)
                 {
-                    binaryDiff = new Models.BinaryDiff();
-
                     var oldPath = string.IsNullOrEmpty(_option.OrgPath) ? _option.Path : _option.OrgPath;
-                    if (option.Revisions.Count == 2)
+                    var ext = Path.GetExtension(oldPath);
+
+                    if (IMG_EXTS.Contains(ext))
                     {
-                        binaryDiff.OldSize = new Commands.QueryFileSize(repo, oldPath, option.Revisions[0]).Result();
+                        var imgDiff = new Models.ImageDiff();
-                        binaryDiff.NewSize = new Commands.QueryFileSize(repo, _option.Path, option.Revisions[1]).Result();
+                        if (option.Revisions.Count == 2)
+                        {
+                            imgDiff.Old = Commands.GetImageFileAsBitmap.Run(repo, option.Revisions[0], oldPath);
+                            imgDiff.New = Commands.GetImageFileAsBitmap.Run(repo, option.Revisions[1], oldPath);
+                        }
+                        else
+                        {
+                            imgDiff.Old = Commands.GetImageFileAsBitmap.Run(repo, "HEAD", oldPath);
+                            imgDiff.New = File.Exists(_option.Path) ? new Avalonia.Media.Imaging.Bitmap(_option.Path) : null;
+                        }
+                        rs = imgDiff;
                     }
                     else
                     {
-                        binaryDiff.OldSize = new Commands.QueryFileSize(repo, oldPath, "HEAD").Result();
+                        var binaryDiff = new Models.BinaryDiff();
-                        binaryDiff.NewSize = new FileInfo(Path.Combine(repo, _option.Path)).Length;
+                        if (option.Revisions.Count == 2)
-                    }
+                        {
+                            binaryDiff.OldSize = new Commands.QueryFileSize(repo, oldPath, option.Revisions[0]).Result();
+                            binaryDiff.NewSize = new Commands.QueryFileSize(repo, _option.Path, option.Revisions[1]).Result();
+                        }
+                        else
+                        {
+                            binaryDiff.OldSize = new Commands.QueryFileSize(repo, oldPath, "HEAD").Result();
+                            binaryDiff.NewSize = new FileInfo(Path.Combine(repo, _option.Path)).Length;
+                        }
+                        rs = binaryDiff;
+                    }                    
+                } 
+                else if (latest.IsLFS)
+                {
+                    rs = latest.LFSDiff;
+                }
+                else
+                {
+                    rs = new Models.NoOrEOLChange();
                 }
 
                 Dispatcher.UIThread.Post(() =>
                 {
-                    if (latest.IsBinary)
+                    Content = rs;
-                    {
+                    IsTextDiff = latest.TextDiff != null;
-                        Content = binaryDiff;
-                        IsTextDiff = false;
-                        IsNoChange = false;
-                    }
-                    else if (latest.IsLFS)
-                    {
-                        Content = latest.LFSDiff;
-                        IsTextDiff = false;
-                        IsNoChange = false;
-                    }
-                    else if (latest.TextDiff != null)
-                    {
-                        latest.TextDiff.File = _option.Path;
-                        Content = latest.TextDiff;
-                        IsTextDiff = true;
-                        IsNoChange = false;
-                    }
-                    else
-                    {
-                        Content = new Models.NoOrEOLChange();
-                        IsTextDiff = false;
-                        IsNoChange = true;
-                    }
-
                     IsLoading = false;
                 });
             });
@@ -157,10 +160,14 @@ namespace SourceGit.ViewModels
             await Task.Run(() => Commands.MergeTool.OpenForDiff(_repo, exec, args, _option));
         }
 
+        private static readonly HashSet<string> IMG_EXTS = new HashSet<string>()
+        {
+            ".ico", ".bmp", ".jpg", ".png", ".jpeg"
+        };
+
         private readonly string _repo = string.Empty;
         private readonly Models.DiffOption _option = null;
         private bool _isLoading = true;
-        private bool _isNoChange = false;
         private bool _isTextDiff = false;
         private object _content = null;
         private Vector _syncScrollOffset = Vector.Zero;

src/SourceGit/Views/DiffView.axaml

@@ -109,6 +109,36 @@
             </StackPanel>
           </DataTemplate>
 
+          <!-- Image Diff -->
+          <DataTemplate DataType="m:ImageDiff">
+            <Grid Margin="8,8,8,8" RowDefinitions="*,Auto" HorizontalAlignment="Center">
+              <Border Grid.Row="0" BorderThickness="1" BorderBrush="{DynamicResource Brush.Border1}">
+                <v:ImageDiffView Alpha="{Binding #ImageDiffSlider.Value}" 
+                                 OldImage="{Binding Old}" 
+                                 NewImage="{Binding New}"/>
+              </Border>
+
+              <Slider Grid.Row="1" 
+                      x:Name="ImageDiffSlider" 
+                      Minimum="0" Maximum="1"
+                      VerticalAlignment="Top"
+                      TickPlacement="BottomRight"
+                      TickFrequency="0.1"
+                      Margin="0,8,0,0"
+                      Foreground="{DynamicResource Brush.Border1}"
+                      Value="0.5">
+                <Slider.Resources>
+                  <Thickness x:Key="SliderTopHeaderMargin">0,0,0,4</Thickness>
+                  <GridLength x:Key="SliderPreContentMargin">0</GridLength>
+                  <GridLength x:Key="SliderPostContentMargin">0</GridLength>
+                  <CornerRadius x:Key="SliderThumbCornerRadius">8</CornerRadius>
+                  <x:Double x:Key="SliderHorizontalThumbWidth">16</x:Double>
+                  <x:Double x:Key="SliderHorizontalThumbHeight">16</x:Double>
+                </Slider.Resources>
+              </Slider>
+            </Grid>
+          </DataTemplate>
+
           <!-- Text Diff -->
           <DataTemplate DataType="m:TextDiff">
             <v:TextDiffView TextDiff="{Binding}" UseSideBySideDiff="{Binding Source={x:Static vm:Preference.Instance}, Path=UseSideBySideDiff, Mode=OneWay}"/>

src/SourceGit/Views/DiffView.axaml.cs

@@ -1,7 +1,111 @@
+using System;
+
+using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Media;
+using Avalonia.Media.Imaging;
 
 namespace SourceGit.Views
 {
+    public class ImageDiffView : Control
+    {
+        public static readonly StyledProperty<double> AlphaProperty =
+            AvaloniaProperty.Register<ImageDiffView, double>(nameof(Alpha), 0.5);
+
+        public double Alpha
+        {
+            get => GetValue(AlphaProperty);
+            set => SetValue(AlphaProperty, value);
+        }
+
+        public static readonly StyledProperty<Bitmap> OldImageProperty =
+            AvaloniaProperty.Register<ImageDiffView, Bitmap>(nameof(OldImage), null);
+
+        public Bitmap OldImage
+        {
+            get => GetValue(OldImageProperty);
+            set => SetValue(OldImageProperty, value);
+        }
+
+        public static readonly StyledProperty<Bitmap> NewImageProperty =
+            AvaloniaProperty.Register<ImageDiffView, Bitmap>(nameof(NewImage), null);
+
+        public Bitmap NewImage
+        {
+            get => GetValue(NewImageProperty);
+            set => SetValue(NewImageProperty, value);
+        }
+
+        static ImageDiffView()
+        {
+            AffectsMeasure<ImageDiffView>(OldImageProperty, NewImageProperty);
+            AffectsRender<ImageDiffView>(AlphaProperty);
+        }
+
+        public override void Render(DrawingContext context)
+        {
+            var alpha = Alpha;
+            var x = Bounds.Width * Alpha;
+
+            var left = OldImage;
+            if (left != null && alpha > 0)
+            {
+                var src = new Rect(0, 0, left.Size.Width * Alpha, left.Size.Height);
+                var dst = new Rect(0, 0, x, Bounds.Height);
+                context.DrawImage(left, src, dst);
+            }
+
+            var right = NewImage;
+            if (right != null)
+            {
+                var src = new Rect(right.Size.Width * Alpha, 0, right.Size.Width - right.Size.Width * Alpha, right.Size.Height);
+                var dst = new Rect(x, 0, Bounds.Width - x, Bounds.Height);
+                context.DrawImage(right, src, dst);
+            }
+            
+            context.DrawLine(new Pen(Brushes.DarkGreen, 2), new Point(x, 0), new Point(x, Bounds.Height));
+        }
+
+        protected override Size MeasureOverride(Size availableSize)
+        {
+            var left = OldImage;
+            var right = NewImage;
+
+            if (left != null)
+            {
+                return GetDesiredSize(left.Size, availableSize);
+            } 
+            else if (right != null)
+            {
+                return GetDesiredSize(right.Size, availableSize);
+            }
+            else
+            {
+                return availableSize;
+            }
+        }
+
+        private Size GetDesiredSize(Size img, Size available)
+        {
+            if (img.Width <= available.Width)
+            {
+                if (img.Height <= available.Height)
+                {
+                    return img;
+                }
+                else
+                {
+                    return new Size(available.Height * img.Width / img.Height, available.Height);
+                }
+            }
+            else
+            {
+                var s = Math.Max(img.Width / available.Width, img.Height / available.Height);
+                return new Size(img.Width / s, img.Height / s);
+            }
+        }
+    }
+
     public partial class DiffView : UserControl
     {
         public DiffView()

src/SourceGit/Views/NameHighlightedTextBlock.cs

@@ -9,7 +9,6 @@ namespace SourceGit.Views
 {
     public class NameHighlightedTextBlock : Control
     {
-
         public static readonly StyledProperty<string> TextProperty =
             AvaloniaProperty.Register<NameHighlightedTextBlock, string>(nameof(Text));
 

src/SourceGit/Views/RevisionFiles.axaml

@@ -91,6 +91,10 @@
               <v:RevisionTextFileView FontFamily="{Binding Source={x:Static vm:Preference.Instance}, Path=MonospaceFont}" Background="{DynamicResource Brush.Contents}"/>
             </DataTemplate>
 
+            <DataTemplate DataType="m:RevisionImageFile">
+              <Image Source="{Binding Image}" Margin="8"/>
+            </DataTemplate>
+
             <DataTemplate DataType="m:RevisionLFSObject">
               <StackPanel Orientation="Vertical" HorizontalAlignment="Center" VerticalAlignment="Center">
                 <TextBlock Text="{DynamicResource Text.CommitDetail.Files.LFS}" FontSize="18" FontWeight="Bold" HorizontalAlignment="Center" Foreground="{DynamicResource Brush.FG2}"/>