From e5913b6ff6d5a14eb9bb65e44a5eb71af5892170 Mon Sep 17 00:00:00 2001
From: leo <longshuang@msn.cn>
Date: Wed, 25 Nov 2020 20:51:33 +0800
Subject: [PATCH] optimize<Diff>: improve update layout performance

---
 src/UI/DiffViewer.xaml    | 129 +++--------------------
 src/UI/DiffViewer.xaml.cs | 210 ++++++++++++++++++++++++--------------
 2 files changed, 149 insertions(+), 190 deletions(-)

diff --git a/src/UI/DiffViewer.xaml b/src/UI/DiffViewer.xaml
index 41dbe78d..e06db277 100644
--- a/src/UI/DiffViewer.xaml
+++ b/src/UI/DiffViewer.xaml
@@ -6,30 +6,28 @@
              xmlns:sourcegit="clr-namespace:SourceGit"
              mc:Ignorable="d"
              FontFamily="Consolas">
+    <UserControl.Resources>
+        <Style x:Key="Style.DataGridRow.TextChange" TargetType="{x:Type DataGridRow}" BasedOn="{StaticResource Style.DataGridRow}">
+            <EventSetter Event="RequestBringIntoView" Handler="OnLineRequestBringIntoView"/>
+        </Style>
+
+        <Style x:Key="Style.DataGridText.LineNumber" TargetType="{x:Type TextBlock}">
+            <Setter Property="FontFamily" Value="Consolas"/>
+            <Setter Property="Foreground" Value="{StaticResource Brush.FG}"/>
+            <Setter Property="HorizontalAlignment" Value="Right"/>
+            <Setter Property="VerticalAlignment" Value="Center"/>
+            <Setter Property="Padding" Value="8,0"/>
+            <Setter Property="FontSize" Value="12"/>
+        </Style>
+    </UserControl.Resources>
+    
     <Border BorderThickness="1" BorderBrush="{StaticResource Brush.Border2}">
-        <Grid x:Name="area" SizeChanged="OnSizeChanged">
+        <Grid>
             <Grid.RowDefinitions>
                 <RowDefinition Height="26"/>
                 <RowDefinition Height="*"/>
             </Grid.RowDefinitions>
 
-            <Grid.Resources>
-                <Style x:Key="Style.DataGridText.LineNumber" TargetType="{x:Type TextBlock}">
-                    <Setter Property="FontFamily" Value="Consolas"/>
-                    <Setter Property="Foreground" Value="{StaticResource Brush.FG}"/>
-                    <Setter Property="HorizontalAlignment" Value="Right"/>
-                    <Setter Property="VerticalAlignment" Value="Center"/>
-                    <Setter Property="Padding" Value="8,0"/>
-                </Style>
-
-                <Style x:Key="Style.DataGridText.Block" TargetType="{x:Type TextBlock}">
-                    <Setter Property="FontFamily" Value="Consolas"/>
-                    <Setter Property="Foreground" Value="{StaticResource Brush.FG}"/>
-                    <Setter Property="VerticalAlignment" Value="Center"/>
-                    <Setter Property="Padding" Value="0"/>
-                </Style>
-            </Grid.Resources>
-
             <Border Grid.Row="0" BorderBrush="{StaticResource Brush.Border2}" BorderThickness="0,0,0,1">
                 <Grid Margin="8,4">
                     <Grid.ColumnDefinitions>
@@ -69,106 +67,13 @@
                 </Grid>
             </Border>
 
-            <Grid Grid.Row="1" x:Name="textChangeTwoSides">
+            <Grid Grid.Row="1" x:Name="editorContainer" SizeChanged="OnSizeChanged">
                 <Grid.ColumnDefinitions>
                     <ColumnDefinition Width="*"/>
                     <ColumnDefinition Width="*"/>
                 </Grid.ColumnDefinitions>
-
-                <DataGrid
-                    Grid.Column="0"
-                    x:Name="textChangeOldSide"
-                    GridLinesVisibility="Vertical"
-                    VerticalGridLinesBrush="{StaticResource Brush.Border2}"
-                    FrozenColumnCount="1"
-                    ScrollViewer.ScrollChanged="OnTwoSidesScroll"
-                    ContextMenuOpening="OnTextChangeContextMenuOpening">
-                    
-                    <DataGrid.RowStyle>
-                        <Style TargetType="{x:Type DataGridRow}" BasedOn="{StaticResource Style.DataGridRow}">
-                            <EventSetter Event="RequestBringIntoView" Handler="OnLineRequestBringIntoView"/>
-                        </Style>
-                    </DataGrid.RowStyle>
-
-                    <DataGrid.Columns>
-                        <DataGridTextColumn Width="Auto" IsReadOnly="True" Binding="{Binding OldLine}" ElementStyle="{StaticResource Style.DataGridText.LineNumber}"/>
-
-                        <DataGridTemplateColumn Width="Auto" IsReadOnly="True">
-                            <DataGridTemplateColumn.CellTemplate>
-                                <DataTemplate>
-                                    <Grid>
-                                        <Border Background="{Binding BG}" BorderThickness="0"/>
-                                        <TextBlock Text="{Binding Content}" Background="Transparent" Foreground="{Binding FG}" FontFamily="Consolas" FontSize="12" FontStyle="{Binding Style}" Margin="0" Padding="0"/>
-                                    </Grid>
-                                </DataTemplate>
-                            </DataGridTemplateColumn.CellTemplate>
-                        </DataGridTemplateColumn>
-                    </DataGrid.Columns>
-                </DataGrid>
-
-                <DataGrid
-                    Grid.Column="1"
-                    x:Name="textChangeNewSide"
-                    GridLinesVisibility="Vertical"
-                    VerticalGridLinesBrush="{StaticResource Brush.Border2}"
-                    FrozenColumnCount="1"
-                    ScrollViewer.ScrollChanged="OnTwoSidesScroll"
-                    ContextMenuOpening="OnTextChangeContextMenuOpening">
-
-                    <DataGrid.RowStyle>
-                        <Style TargetType="{x:Type DataGridRow}" BasedOn="{StaticResource Style.DataGridRow}">
-                            <EventSetter Event="RequestBringIntoView" Handler="OnLineRequestBringIntoView"/>
-                        </Style>
-                    </DataGrid.RowStyle>
-
-                    <DataGrid.Columns>
-                        <DataGridTextColumn Width="Auto" IsReadOnly="True" Binding="{Binding NewLine}" ElementStyle="{StaticResource Style.DataGridText.LineNumber}"/>
-
-                        <DataGridTemplateColumn Width="Auto" IsReadOnly="True">
-                            <DataGridTemplateColumn.CellTemplate>
-                                <DataTemplate>
-                                    <Grid>
-                                        <Border Background="{Binding BG}" BorderThickness="0"/>
-                                        <TextBlock Text="{Binding Content}" Background="Transparent" Foreground="{Binding FG}" FontFamily="Consolas" FontSize="12" FontStyle="{Binding Style}" Margin="0" Padding="0"/>
-                                    </Grid>
-                                </DataTemplate>
-                            </DataGridTemplateColumn.CellTemplate>
-                        </DataGridTemplateColumn>
-                    </DataGrid.Columns>
-                </DataGrid>
             </Grid>
 
-            <DataGrid
-                Grid.Row="1"
-                x:Name="textChangeOneSide"                
-                GridLinesVisibility="Vertical"
-                VerticalGridLinesBrush="{StaticResource Brush.Border2}"
-                FrozenColumnCount="2"
-                ContextMenuOpening="OnTextChangeContextMenuOpening">
-
-                <DataGrid.RowStyle>
-                    <Style TargetType="{x:Type DataGridRow}" BasedOn="{StaticResource Style.DataGridRow}">
-                        <EventSetter Event="RequestBringIntoView" Handler="OnLineRequestBringIntoView"/>
-                    </Style>
-                </DataGrid.RowStyle>
-                
-                <DataGrid.Columns>
-                    <DataGridTextColumn Width="Auto" IsReadOnly="True" Binding="{Binding OldLine}" ElementStyle="{StaticResource Style.DataGridText.LineNumber}"/>
-                    <DataGridTextColumn Width="Auto" IsReadOnly="True" Binding="{Binding NewLine}" ElementStyle="{StaticResource Style.DataGridText.LineNumber}"/>
-
-                    <DataGridTemplateColumn Width="Auto" IsReadOnly="True">
-                        <DataGridTemplateColumn.CellTemplate>
-                            <DataTemplate>
-                                <Grid>
-                                    <Border Background="{Binding BG}" BorderThickness="0"/>
-                                    <TextBlock Text="{Binding Content}" Background="Transparent" Foreground="{Binding FG}" FontFamily="Consolas" FontSize="12" FontStyle="{Binding Style}" Margin="0" Padding="0"/>
-                                </Grid>
-                            </DataTemplate>
-                        </DataGridTemplateColumn.CellTemplate>
-                    </DataGridTemplateColumn>
-                </DataGrid.Columns>                
-            </DataGrid>
-                
             <Border x:Name="sizeChange" Grid.Row="1" ClipToBounds="True" Background="{StaticResource Brush.BG3}" Visibility="Collapsed">
                 <StackPanel Orientation="Vertical" VerticalAlignment="Center">
                     <Label x:Name="txtSizeChangeTitle" Content="BINARY DIFF" Margin="0,0,0,32" FontSize="18" FontWeight="UltraBold" Foreground="{StaticResource Brush.FG2}" HorizontalAlignment="Center"/>
diff --git a/src/UI/DiffViewer.xaml.cs b/src/UI/DiffViewer.xaml.cs
index 57d38f83..4e444eeb 100644
--- a/src/UI/DiffViewer.xaml.cs
+++ b/src/UI/DiffViewer.xaml.cs
@@ -1,9 +1,11 @@
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Data;
 using System.Windows.Media;
 using System.Windows.Threading;
 
@@ -18,6 +20,7 @@ namespace SourceGit.UI {
         private Brush bgAdded = new SolidColorBrush(Color.FromArgb(60, 0, 255, 0));
         private Brush bgDeleted = new SolidColorBrush(Color.FromArgb(60, 255, 0, 0));
         private Brush bgNormal = Brushes.Transparent;
+        private List<DataGrid> editors = new List<DataGrid>();
 
         /// <summary>
         ///     Diff options.
@@ -69,11 +72,12 @@ namespace SourceGit.UI {
 
             loading.Visibility = Visibility.Visible;
             mask.Visibility = Visibility.Collapsed;
-            textChangeOneSide.Visibility = Visibility.Collapsed;
-            textChangeTwoSides.Visibility = Visibility.Collapsed;
             sizeChange.Visibility = Visibility.Collapsed;
             noChange.Visibility = Visibility.Collapsed;
 
+            foreach (var editor in editors) editorContainer.Children.Remove(editor);
+            editors.Clear();
+
             Task.Run(() => {
                 var args = $"{opts.ExtraArgs} ";
                 if (opts.RevisionRange.Length > 0) args += $"{opts.RevisionRange[0]} ";
@@ -132,6 +136,8 @@ namespace SourceGit.UI {
 
             var fgCommon = FindResource("Brush.FG") as Brush;
             var fgIndicator = FindResource("Brush.FG2") as Brush;
+            var lastOldLine = "";
+            var lastNewLine = "";
 
             if (App.Preference.UIUseOneSideDiff) {
                 var blocks = new List<ChangeBlock>();
@@ -146,18 +152,31 @@ namespace SourceGit.UI {
                     block.OldLine = line.OldLine;
                     block.NewLine = line.NewLine;
 
+                    if (line.OldLine.Length > 0) lastOldLine = line.OldLine;
+                    if (line.NewLine.Length > 0) lastNewLine = line.NewLine;
+
                     blocks.Add(block);
                 }
 
                 Dispatcher.Invoke(() => {
                     loading.Visibility = Visibility.Collapsed;
                     textChangeOptions.Visibility = Visibility.Visible;
-                    textChangeOneSide.Visibility = Visibility.Visible;
-                    textChangeTwoSides.Visibility = Visibility.Collapsed;
 
-                    ResetDataGrid(textChangeOneSide);
-                    textChangeOneSide.ItemsSource = blocks;
-                    OnSizeChanged(null, null);
+                    var formatted = new FormattedText(
+                        lastOldLine + lastNewLine,
+                        CultureInfo.CurrentCulture,
+                        FlowDirection.LeftToRight,
+                        new Typeface(FontFamily, FontStyles.Normal, FontWeights.Normal, FontStretches.Normal),
+                        12.0,
+                        fgCommon);
+
+                    var minWidth = editorContainer.ActualWidth - formatted.Width - 16 - 12;
+                    var editor = CreateTextEditor(new string[] { "OldLine", "NewLine" });
+                    editor.Columns[2].MinWidth = minWidth;
+                    editor.ItemsSource = blocks;
+                    editor.SetValue(Grid.ColumnSpanProperty, 2);
+                    editorContainer.Children.Add(editor);
+                    editors.Add(editor);
                 });
             } else {
                 var oldSideBlocks = new List<ChangeBlock>();
@@ -173,6 +192,9 @@ namespace SourceGit.UI {
                     block.OldLine = line.OldLine;
                     block.NewLine = line.NewLine;
 
+                    if (line.OldLine.Length > 0) lastOldLine = line.OldLine;
+                    if (line.NewLine.Length > 0) lastNewLine = line.NewLine;
+
                     switch (line.Mode) {
                     case Git.Diff.LineMode.Added:
                         newSideBlocks.Add(block);
@@ -210,16 +232,38 @@ namespace SourceGit.UI {
                 Dispatcher.Invoke(() => {
                     loading.Visibility = Visibility.Collapsed;
                     textChangeOptions.Visibility = Visibility.Visible;
-                    textChangeOneSide.Visibility = Visibility.Collapsed;
-                    textChangeTwoSides.Visibility = Visibility.Visible;
 
-                    ResetDataGrid(textChangeOldSide);
-                    ResetDataGrid(textChangeNewSide);
+                    var number = lastOldLine;
+                    if (lastOldLine.Length > lastNewLine.Length) number = lastNewLine;
 
-                    textChangeOldSide.ItemsSource = oldSideBlocks;
-                    textChangeNewSide.ItemsSource = newSideBlocks;
+                    var formatted = new FormattedText(
+                        number,
+                        CultureInfo.CurrentCulture,
+                        FlowDirection.LeftToRight,
+                        new Typeface(FontFamily, FontStyles.Normal, FontWeights.Normal, FontStretches.Normal),
+                        12.0,
+                        fgCommon);
 
-                    OnSizeChanged(null, null);
+                    var minWidth = editorContainer.ActualWidth / 2 - formatted.Width - 16 - 12;
+
+                    var oldEditor = CreateTextEditor(new string[] { "OldLine" });
+                    oldEditor.SetValue(Grid.ColumnProperty, 0);
+                    oldEditor.ContextMenuOpening += OnTextChangeContextMenuOpening;
+                    oldEditor.AddHandler(ScrollViewer.ScrollChangedEvent, new ScrollChangedEventHandler(OnTwoSidesScroll));
+                    oldEditor.Columns[1].MinWidth = minWidth;
+                    oldEditor.ItemsSource = oldSideBlocks;
+                    var newEditor = CreateTextEditor(new string[] { "NewLine" });
+                    newEditor.SetValue(Grid.ColumnProperty, 1);
+                    newEditor.ContextMenuOpening += OnTextChangeContextMenuOpening;
+                    newEditor.AddHandler(ScrollViewer.ScrollChangedEvent, new ScrollChangedEventHandler(OnTwoSidesScroll));
+                    newEditor.Columns[1].MinWidth = minWidth;
+                    newEditor.ItemsSource = newSideBlocks;
+
+                    editorContainer.Children.Add(oldEditor);
+                    editorContainer.Children.Add(newEditor);
+
+                    editors.Add(oldEditor);
+                    editors.Add(newEditor);
                 });
             }
         }
@@ -310,14 +354,47 @@ namespace SourceGit.UI {
             return child;
         }
 
-        private void ResetDataGrid(DataGrid dg) {
-            dg.ItemsSource = null;
-            dg.Items.Clear();
+        private DataGrid CreateTextEditor(string[] lineNumbers) {
+            var grid = new DataGrid();
+            grid.SetValue(Grid.RowProperty, 1);
+            grid.GridLinesVisibility = DataGridGridLinesVisibility.Vertical;
+            grid.VerticalGridLinesBrush = FindResource("Brush.Border2") as Brush;
+            grid.FrozenColumnCount = lineNumbers.Length;
+            grid.ContextMenuOpening += OnTextChangeContextMenuOpening;
+            grid.RowStyle = FindResource("Style.DataGridRow.TextChange") as Style;
 
-            foreach (var col in dg.Columns) {
-                col.MinWidth = 0;
-                col.Width = 0;
+            foreach (var number in lineNumbers) {
+                var colLineNumber = new DataGridTextColumn();
+                colLineNumber.Width = DataGridLength.Auto;
+                colLineNumber.IsReadOnly = true;
+                colLineNumber.Binding = new Binding(number);
+                colLineNumber.ElementStyle = FindResource("Style.DataGridText.LineNumber") as Style;
+                grid.Columns.Add(colLineNumber);
             }
+
+            var borderContent = new FrameworkElementFactory(typeof(Border));
+            borderContent.SetBinding(Border.BackgroundProperty, new Binding("BG"));
+
+            var textContent = new FrameworkElementFactory(typeof(TextBlock));
+            textContent.SetBinding(TextBlock.TextProperty, new Binding("Content"));
+            textContent.SetBinding(TextBlock.ForegroundProperty, new Binding("FG"));
+            textContent.SetBinding(TextBlock.FontStyleProperty, new Binding("Style"));
+            textContent.SetValue(TextBlock.BackgroundProperty, Brushes.Transparent);
+            textContent.SetValue(TextBlock.FontSizeProperty, 12.0);
+            textContent.SetValue(TextBlock.MarginProperty, new Thickness(0));
+            textContent.SetValue(TextBlock.PaddingProperty, new Thickness(0));
+
+            var visualTree = new FrameworkElementFactory(typeof(Grid));
+            visualTree.AppendChild(borderContent);
+            visualTree.AppendChild(textContent);
+
+            var colContent = new DataGridTemplateColumn();
+            colContent.CellTemplate = new DataTemplate();
+            colContent.CellTemplate.VisualTree = visualTree;
+            colContent.Width = DataGridLength.SizeToCells;
+            grid.Columns.Add(colContent);
+
+            return grid;
         }
         #endregion
 
@@ -329,52 +406,35 @@ namespace SourceGit.UI {
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void OnSizeChanged(object sender, SizeChangedEventArgs e) {
-            var total = area.ActualWidth;
+            if (editors.Count == 0) return;
 
+            var total = editorContainer.ActualWidth;
             if (App.Preference.UIUseOneSideDiff) {
-                textChangeOneSide.Columns[0].Width = DataGridLength.Auto;
-                textChangeOneSide.Columns[1].Width = DataGridLength.Auto;
-                textChangeOneSide.Columns[2].MinWidth = 1;
-                textChangeOneSide.Columns[2].Width = 1;
-                textChangeOneSide.UpdateLayout();
-
-                var offset = textChangeOneSide.NonFrozenColumnsViewportHorizontalOffset;
-                var minWidth = total - offset;
-
-                var scroller = GetVisualChild<ScrollViewer>(textChangeOneSide);
-                if (scroller.ComputedVerticalScrollBarVisibility == Visibility.Visible) minWidth -= 8;
-
-                textChangeOneSide.Columns[2].MinWidth = minWidth;
-                textChangeOneSide.Columns[2].Width = DataGridLength.Auto;
-                textChangeOneSide.UpdateLayout();
+                var editor = editors[0];
+                var minWidth = total - editor.NonFrozenColumnsViewportHorizontalOffset;
+                var scroller = GetVisualChild<ScrollViewer>(editor);
+                if (scroller != null && scroller.ComputedVerticalScrollBarVisibility == Visibility.Visible) minWidth -= 8;
+                editor.Columns[2].MinWidth = minWidth;
+                editor.Columns[2].Width = DataGridLength.SizeToCells;
+                editor.UpdateLayout();
             } else {
-                textChangeOldSide.Columns[0].Width = DataGridLength.Auto;
-                textChangeOldSide.Columns[1].MinWidth = 1;
-                textChangeOldSide.Columns[1].Width = 1;
-                textChangeOldSide.UpdateLayout();
+                var offOld = editors[0].NonFrozenColumnsViewportHorizontalOffset;
+                var offNew = editors[1].NonFrozenColumnsViewportHorizontalOffset;
 
-                textChangeNewSide.Columns[0].Width = DataGridLength.Auto;
-                textChangeNewSide.Columns[1].MinWidth = 1;
-                textChangeNewSide.Columns[1].Width = 1;
-                textChangeNewSide.UpdateLayout();
-
-                var oldOffset = textChangeOldSide.NonFrozenColumnsViewportHorizontalOffset;
-                var newOffset = textChangeNewSide.NonFrozenColumnsViewportHorizontalOffset;
-                var minWidth = total - Math.Min(oldOffset, newOffset);
-
-                var scroller = GetVisualChild<ScrollViewer>(textChangeNewSide);
-                if (scroller.ComputedVerticalScrollBarVisibility == Visibility.Visible) minWidth -= 8;
-
-                textChangeOldSide.Columns[1].MinWidth = minWidth;
-                textChangeOldSide.Columns[1].Width = DataGridLength.Auto;
-                textChangeOldSide.UpdateLayout();
-
-                textChangeNewSide.Columns[1].MinWidth = minWidth;
-                textChangeNewSide.Columns[1].Width = DataGridLength.Auto;
-                textChangeNewSide.UpdateLayout();
+                var minWidth = total / 2 - Math.Min(offOld, offNew);
+                var scroller = GetVisualChild<ScrollViewer>(editors[0]);
+                if (scroller != null && scroller.ComputedVerticalScrollBarVisibility == Visibility.Visible) minWidth -= 8;
+                editors[0].Columns[1].MinWidth = minWidth;
+                editors[0].Columns[1].Width = DataGridLength.SizeToCells;
+                editors[1].Columns[1].MinWidth = minWidth;
+                editors[1].Columns[1].Width = DataGridLength.SizeToCells;
+                editors[0].UpdateLayout();
+                editors[1].UpdateLayout();
             }
         }
 
+
+
         /// <summary>
         ///     Prevent default auto-scrolling when click row in DataGrid.
         /// </summary>
@@ -390,24 +450,15 @@ namespace SourceGit.UI {
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void OnTwoSidesScroll(object sender, ScrollChangedEventArgs e) {
-            var oldSideScroller = GetVisualChild<ScrollViewer>(textChangeOldSide);
-            var newSideScroller = GetVisualChild<ScrollViewer>(textChangeNewSide);
-
             if (e.VerticalChange != 0) {
-                if (oldSideScroller.VerticalOffset != e.VerticalOffset) {
-                    oldSideScroller.ScrollToVerticalOffset(e.VerticalOffset);
-                }
-
-                if (newSideScroller.VerticalOffset != e.VerticalOffset) {
-                    newSideScroller.ScrollToVerticalOffset(e.VerticalOffset);
+                foreach (var editor in editors) {
+                    var scroller = GetVisualChild<ScrollViewer>(editor);
+                    if (scroller.VerticalOffset != e.VerticalOffset) scroller.ScrollToVerticalOffset(e.VerticalOffset);
                 }
             } else {
-                if (oldSideScroller.HorizontalOffset != e.HorizontalOffset) {
-                    oldSideScroller.ScrollToHorizontalOffset(e.HorizontalOffset);
-                }
-
-                if (newSideScroller.HorizontalOffset != e.HorizontalOffset) {
-                    newSideScroller.ScrollToHorizontalOffset(e.HorizontalOffset);
+                foreach (var editor in editors) {
+                    var scroller = GetVisualChild<ScrollViewer>(editor);
+                    if (scroller.HorizontalOffset != e.HorizontalOffset) scroller.ScrollToHorizontalOffset(e.HorizontalOffset);
                 }
             }
         }
@@ -418,9 +469,9 @@ namespace SourceGit.UI {
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void Go2Next(object sender, RoutedEventArgs e) {
-            var grid = textChangeOneSide;
-            if (!App.Preference.UIUseOneSideDiff) grid = textChangeNewSide;
+            if (editors.Count == 0) return;
 
+            var grid = editors[0];
             var scroller = GetVisualChild<ScrollViewer>(grid);
             var firstVisible = (int)scroller.VerticalOffset;
             var firstModeEnded = false;
@@ -444,9 +495,9 @@ namespace SourceGit.UI {
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void Go2Prev(object sender, RoutedEventArgs e) {
-            var grid = textChangeOneSide;
-            if (!App.Preference.UIUseOneSideDiff) grid = textChangeNewSide;
+            if (editors.Count == 0) return;
 
+            var grid = editors[0];
             var scroller = GetVisualChild<ScrollViewer>(grid);
             var firstVisible = (int)scroller.VerticalOffset;
             var firstModeEnded = false;
@@ -470,6 +521,9 @@ namespace SourceGit.UI {
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void ChangeDiffMode(object sender, RoutedEventArgs e) {
+            foreach (var editor in editors) editorContainer.Children.Remove(editor);
+            editors.Clear();
+
             SetTextChange();
         }