feature<Diff>: highlights differences for modified lines (both added and removed)

src/Views/Controls/HighlightableTextBlock.cs

@@ -0,0 +1,63 @@
+using System.Collections.Generic;
+using System.Windows;
+using System.Windows.Media;
+using System.Windows.Controls;
+using System.Windows.Documents;
+
+namespace SourceGit.Views.Controls {
+    /// <summary>
+    ///     支持部分高亮的文本组件
+    /// </summary>
+    public class HighlightableTextBlock : TextBlock {
+
+        public class Data {
+            public string Text { get; set; } = "";
+            public List<Models.TextChanges.HighlightRange> Highlights { get; set; } = new List<Models.TextChanges.HighlightRange>();
+            public Brush HighlightBrush { get; set; } = Brushes.Transparent;
+        }
+
+        public static readonly DependencyProperty ContentProperty = DependencyProperty.Register(
+            "Content", 
+            typeof(Data),
+            typeof(HighlightableTextBlock), 
+            new PropertyMetadata(null, OnContentChanged));
+
+        public Data Content {
+            get { return (Data)GetValue(ContentProperty); }
+            set { SetValue(ContentProperty, value); }
+        }
+
+        private static void OnContentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) {
+            var txt = d as HighlightableTextBlock;
+            if (txt == null) return;
+
+            txt.Inlines.Clear();
+            txt.Text = null;
+            if (txt.Content == null) return;
+
+            if (txt.Content.Highlights == null || txt.Content.Highlights.Count == 0) {
+                txt.Text = txt.Content.Text;
+                return;
+            }
+
+            var started = 0;
+            foreach (var highlight in txt.Content.Highlights) {
+                if (started < highlight.Start) {
+                    txt.Inlines.Add(new Run(txt.Content.Text.Substring(started, highlight.Start - started)));
+                }
+
+                txt.Inlines.Add(new TextBlock() {
+                    Background = txt.Content.HighlightBrush,
+                    LineHeight = txt.LineHeight,
+                    Text = txt.Content.Text.Substring(highlight.Start, highlight.Count),
+                });
+
+                started = highlight.Start + highlight.Count;
+            }
+
+            if (started < txt.Content.Text.Length) {
+                txt.Inlines.Add(new Run(txt.Content.Text.Substring(started)));
+            }
+        }
+    }
+}