refactor: only redraw commit graph when it is necessary

Signed-off-by: leo <[email protected]>

Author: love-linger

src/Models/CommitGraph.cs

@@ -6,6 +6,13 @@
 
 namespace SourceGit.Models
 {
+    public record CommitGraphLayout(double startY, double clipWidth, double rowHeight)
+    {
+        public double StartY { get; set; } = startY;
+        public double ClipWidth { get; set; } = clipWidth;
+        public double RowHeight { get; set; } = rowHeight;
+    }
+
     public class CommitGraph
     {
         public static List<Pen> Pens { get; } = [];

src/Views/CommitGraph.cs

@@ -1,8 +1,6 @@
 using Avalonia;
 using Avalonia.Controls;
-using Avalonia.Controls.Primitives;
 using Avalonia.Media;
-using Avalonia.VisualTree;
 
 namespace SourceGit.Views
 {
@@ -35,57 +33,39 @@ public bool OnlyHighlightCurrentBranch
             set => SetValue(OnlyHighlightCurrentBranchProperty, value);
         }
 
+        public static readonly StyledProperty<Models.CommitGraphLayout> LayoutProperty =
+            AvaloniaProperty.Register<CommitGraph, Models.CommitGraphLayout>(nameof(Layout));
+
+        public Models.CommitGraphLayout Layout
+        {
+            get => GetValue(LayoutProperty);
+            set => SetValue(LayoutProperty, value);
+        }
+
         static CommitGraph()
         {
-            AffectsRender<CommitGraph>(GraphProperty, DotBrushProperty, OnlyHighlightCurrentBranchProperty);
+            AffectsRender<CommitGraph>(
+                GraphProperty, 
+                DotBrushProperty, 
+                OnlyHighlightCurrentBranchProperty,
+                LayoutProperty);
         }
 
         public override void Render(DrawingContext context)
         {
             base.Render(context);
 
-            var graph = Graph;
-            if (graph == null)
-                return;
-
-            var histories = this.FindAncestorOfType<Histories>();
-            if (histories == null)
-                return;
-
-            var grid = histories.CommitListContainer;
-            if (grid == null)
-                return;
-
-            var rowsPresenter = grid.FindDescendantOfType<DataGridRowsPresenter>();
-            if (rowsPresenter == null)
+            if (Graph is not { } graph || Layout is not { } layout)
                 return;
 
-            double rowHeight = grid.RowHeight;
-            double startY = 0;
-            foreach (var child in rowsPresenter.Children)
-            {
-                var row = child as DataGridRow;
-                if (row.IsVisible)
-                {
-                    if (rowHeight != row.Bounds.Height)
-                        rowHeight = row.Bounds.Height;
-
-                    if (row.Bounds.Top <= 0 && row.Bounds.Top > -rowHeight)
-                    {
-                        var test = rowHeight * row.Index - row.Bounds.Top;
-                        if (startY < test)
-                            startY = test;
-                    }
-                }
-            }
-
-            var headersHeight = grid.ColumnHeaderHeight;
-            var width = histories.CommitListContainer.Columns[0].ActualWidth;
-            var height = Bounds.Height - headersHeight;
-            var endY = startY + height + 28;
+            var startY = layout.StartY;
+            var clipWidth = layout.ClipWidth;
+            var clipHeight = Bounds.Height;
+            var rowHeight = layout.RowHeight;
+            var endY = startY + clipHeight + 28;
 
-            using (context.PushClip(new Rect(0, headersHeight, width, height)))
-            using (context.PushTransform(Matrix.CreateTranslation(0, headersHeight - startY)))
+            using (context.PushClip(new Rect(0, 0, clipWidth, clipHeight)))
+            using (context.PushTransform(Matrix.CreateTranslation(0, -startY)))
             {
                 DrawCurves(context, graph, startY, endY, rowHeight);
                 DrawAnchors(context, graph, startY, endY, rowHeight);

src/Views/Histories.axaml

@@ -226,6 +226,7 @@
       </DataGrid>
 
       <v:CommitGraph x:Name="CommitGraph"
+                     Margin="0,24,0,0"
                      Graph="{Binding Graph}"
                      DotBrush="{DynamicResource Brush.Contents}"
                      OnlyHighlightCurrentBranch="{Binding $parent[v:Histories].OnlyHighlightCurrentBranch}"

src/Views/Histories.axaml.cs

@@ -4,6 +4,7 @@
 using Avalonia;
 using Avalonia.Collections;
 using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
 using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.VisualTree;
@@ -137,14 +138,59 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
 
         private void OnCommitListLoaded(object sender, RoutedEventArgs e)
         {
-            if (CommitListContainer is { SelectedItems.Count: 1 } dataGrid)
+            var dataGrid = CommitListContainer;
+            if (dataGrid.SelectedItems.Count == 1)
+            {
                 dataGrid.ScrollIntoView(dataGrid.SelectedItem, null);
+            }
+            else
+            {
+                var rowsPresenter = dataGrid.FindDescendantOfType<DataGridRowsPresenter>();
+                if (rowsPresenter is { Children: { Count: > 0 } rows })
+                    CommitGraph.Layout = new(0, dataGrid.Columns[0].ActualWidth, rows[0].Bounds.Height);
+            }
         }
 
         private void OnCommitListLayoutUpdated(object _1, EventArgs _2)
         {
-            if (IsLoaded)
-                CommitGraph.InvalidateVisual();
+            if (!IsLoaded)
+                return;
+
+            var dataGrid = CommitListContainer;
+            var rowsPresenter = dataGrid.FindDescendantOfType<DataGridRowsPresenter>();
+            if (rowsPresenter == null)
+                return;
+
+            double rowHeight = dataGrid.RowHeight;
+            double startY = 0;
+            foreach (var child in rowsPresenter.Children)
+            {
+                var row = child as DataGridRow;
+                if (row.IsVisible)
+                {
+                    if (rowHeight != row.Bounds.Height)
+                        rowHeight = row.Bounds.Height;
+
+                    if (row.Bounds.Top <= 0 && row.Bounds.Top > -rowHeight)
+                    {
+                        var test = rowHeight * row.Index - row.Bounds.Top;
+                        if (startY < test)
+                            startY = test;
+                    }
+                }
+            }
+
+            var clipWidth = dataGrid.Columns[0].ActualWidth;
+            if (_lastGraphStartY != startY ||
+                _lastGraphClipWidth != clipWidth ||
+                _lastGraphRowHeight != rowHeight)
+            {
+                _lastGraphStartY = startY;
+                _lastGraphClipWidth = clipWidth;
+                _lastGraphRowHeight = rowHeight;
+
+                CommitGraph.Layout = new(startY, clipWidth, rowHeight);
+            }
         }
 
         private void OnCommitListSelectionChanged(object _, SelectionChangedEventArgs e)
@@ -228,5 +274,9 @@ sender is DataGrid grid &&
                     histories.CheckoutBranchByCommit(c);
             }
         }
+
+        private double _lastGraphStartY = 0;
+        private double _lastGraphClipWidth = 0;
+        private double _lastGraphRowHeight = 0;
     }
 }