project: reorganize the structure of the project.

* remove dotnet-tool.json because the project does not rely on any dotnet tools.
* remove Directory.Build.props because the solution has only one project.
* move src/SourceGit to src. It's not needed to put all sources into a subfolder of src since there's only one project.

src/Views/RevisionFiles.axaml.cs

@@ -0,0 +1,226 @@
+using System;
+
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
+using Avalonia.Interactivity;
+using Avalonia.Media;
+using Avalonia.Media.Imaging;
+using Avalonia.Styling;
+
+using AvaloniaEdit;
+using AvaloniaEdit.Document;
+using AvaloniaEdit.Editing;
+using AvaloniaEdit.TextMate;
+
+namespace SourceGit.Views
+{
+    public class RevisionImageFileView : Control
+    {
+        public static readonly StyledProperty<Bitmap> SourceProperty =
+            AvaloniaProperty.Register<RevisionImageFileView, Bitmap>(nameof(Source), null);
+
+        public Bitmap Source
+        {
+            get => GetValue(SourceProperty);
+            set => SetValue(SourceProperty, value);
+        }
+
+        static RevisionImageFileView()
+        {
+            AffectsMeasure<RevisionImageFileView>(SourceProperty);
+        }
+
+        public override void Render(DrawingContext context)
+        {
+            if (_bgBrush == null)
+            {
+                var maskBrush = new SolidColorBrush(ActualThemeVariant == ThemeVariant.Dark ? 0xFF404040 : 0xFFBBBBBB);
+                var bg = new DrawingGroup()
+                {
+                    Children =
+                    {
+                        new GeometryDrawing() { Brush = maskBrush, Geometry = new RectangleGeometry(new Rect(0, 0, 12, 12)) },
+                        new GeometryDrawing() { Brush = maskBrush, Geometry = new RectangleGeometry(new Rect(12, 12, 12, 12)) },
+                    }
+                };
+
+                _bgBrush = new DrawingBrush(bg)
+                {
+                    AlignmentX = AlignmentX.Left,
+                    AlignmentY = AlignmentY.Top,
+                    DestinationRect = new RelativeRect(new Size(24, 24), RelativeUnit.Absolute),
+                    Stretch = Stretch.None,
+                    TileMode = TileMode.Tile,
+                };
+            }
+
+            context.FillRectangle(_bgBrush, new Rect(Bounds.Size));
+
+            var source = Source;
+            if (source != null)
+            {
+                context.DrawImage(source, new Rect(source.Size), new Rect(8, 8, Bounds.Width - 16, Bounds.Height - 16));
+            }
+        }
+
+        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property.Name == "ActualThemeVariant")
+            {
+                _bgBrush = null;
+                InvalidateVisual();
+            }
+        }
+
+        protected override Size MeasureOverride(Size availableSize)
+        {
+            var source = Source;
+            if (source == null)
+            {
+                return availableSize;
+            }
+
+            var w = availableSize.Width - 16;
+            var h = availableSize.Height - 16;
+            var size = source.Size;
+            if (size.Width <= w)
+            {
+                if (size.Height <= h)
+                {
+                    return new Size(size.Width + 16, size.Height + 16);
+                }
+                else
+                {
+                    return new Size(h * size.Width / size.Height + 16, availableSize.Height);
+                }
+            }
+            else
+            {
+                var scale = Math.Max(size.Width / w, size.Height / h);
+                return new Size(size.Width / scale + 16, size.Height / scale + 16);
+            }
+        }
+
+        private DrawingBrush _bgBrush = null;
+    }
+
+    public class RevisionTextFileView : TextEditor
+    {
+        protected override Type StyleKeyOverride => typeof(TextEditor);
+
+        public RevisionTextFileView() : base(new TextArea(), new TextDocument())
+        {
+            IsReadOnly = true;
+            ShowLineNumbers = true;
+            WordWrap = false;
+            HorizontalScrollBarVisibility = ScrollBarVisibility.Auto;
+            VerticalScrollBarVisibility = ScrollBarVisibility.Auto;
+
+            TextArea.LeftMargins[0].Margin = new Thickness(8, 0);
+            TextArea.TextView.Margin = new Thickness(4, 0);
+        }
+
+        protected override void OnLoaded(RoutedEventArgs e)
+        {
+            base.OnLoaded(e);
+
+            TextArea.TextView.ContextRequested += OnTextViewContextRequested;
+
+            _textMate = Models.TextMateHelper.CreateForEditor(this);
+            if (DataContext is Models.RevisionTextFile source)
+            {
+                Models.TextMateHelper.SetGrammarByFileName(_textMate, source.FileName);
+            }
+        }
+
+        protected override void OnUnloaded(RoutedEventArgs e)
+        {
+            base.OnUnloaded(e);
+
+            TextArea.TextView.ContextRequested -= OnTextViewContextRequested;
+
+            if (_textMate != null)
+            {
+                _textMate.Dispose();
+                _textMate = null;
+            }
+
+            GC.Collect();
+        }
+
+        protected override void OnDataContextChanged(EventArgs e)
+        {
+            base.OnDataContextChanged(e);
+
+            var source = DataContext as Models.RevisionTextFile;
+            if (source != null)
+            {
+                Text = source.Content;
+                Models.TextMateHelper.SetGrammarByFileName(_textMate, source.FileName);
+            }
+        }
+
+        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property.Name == "ActualThemeVariant" && change.NewValue != null)
+            {
+                Models.TextMateHelper.SetThemeByApp(_textMate);
+            }
+        }
+
+        private void OnTextViewContextRequested(object sender, ContextRequestedEventArgs e)
+        {
+            var selected = SelectedText;
+            if (string.IsNullOrEmpty(selected))
+                return;
+
+            var icon = new Avalonia.Controls.Shapes.Path();
+            icon.Width = 10;
+            icon.Height = 10;
+            icon.Stretch = Stretch.Uniform;
+            icon.Data = App.Current?.FindResource("Icons.Copy") as StreamGeometry;
+
+            var copy = new MenuItem();
+            copy.Header = App.Text("Copy");
+            copy.Icon = icon;
+            copy.Click += (o, ev) =>
+            {
+                App.CopyText(selected);
+                ev.Handled = true;
+            };
+
+            var menu = new ContextMenu();
+            menu.Items.Add(copy);
+            menu.Open(TextArea.TextView);
+            e.Handled = true;
+        }
+
+        private TextMate.Installation _textMate = null;
+    }
+
+    public partial class RevisionFiles : UserControl
+    {
+        public RevisionFiles()
+        {
+            InitializeComponent();
+        }
+
+        private void OnTreeViewContextRequested(object sender, ContextRequestedEventArgs e)
+        {
+            var detail = DataContext as ViewModels.CommitDetail;
+            var node = detail.SelectedRevisionFileNode;
+            if (!node.IsFolder)
+            {
+                var menu = detail.CreateRevisionFileContextMenu(node.Backend as Models.Object);
+                menu.Open(sender as Control);
+            }
+
+            e.Handled = true;
+        }
+    }
+}