More natural scroll behaviour

QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs

@@ -56,6 +56,7 @@ namespace QuickLook.Plugin.ImageViewer
             viewPanel.MouseLeftButtonDown += ViewPanel_MouseLeftButtonDown;
             viewPanel.MouseMove += ViewPanel_MouseMove;
 
+            viewPanel.ManipulationInertiaStarting += ViewPanel_ManipulationInertiaStarting;
             viewPanel.ManipulationStarting += ViewPanel_ManipulationStarting;
             viewPanel.ManipulationDelta += ViewPanel_ManipulationDelta;
         }
@@ -128,7 +129,16 @@ namespace QuickLook.Plugin.ImageViewer
         private void ImagePanel_SizeChanged(object sender, SizeChangedEventArgs e)
         {
             if (ZoomToFit)
-                DoZoomToFit(false);
+                DoZoomToFit();
+        }
+
+        private void ViewPanel_ManipulationInertiaStarting(object sender, ManipulationInertiaStartingEventArgs e)
+        {
+            e.TranslationBehavior = new InertiaTranslationBehavior
+            {
+                InitialVelocity = e.InitialVelocities.LinearVelocity,
+                DesiredDeceleration = 10.0 * 96.0 / (1000.0 * 1000.0)
+            };
         }
 
         private void ViewPanel_ManipulationStarting(object sender, ManipulationStartingEventArgs e)
@@ -220,7 +230,7 @@ namespace QuickLook.Plugin.ImageViewer
             viewPanel.ScrollToVerticalOffset(point.Y);
         }
 
-        public void DoZoomToFit(bool suppressEvent)
+        public void DoZoomToFit()
         {
             if (viewPanelImage.Source == null)
                 return;
@@ -228,7 +238,7 @@ namespace QuickLook.Plugin.ImageViewer
             var factor = Math.Min(viewPanel.ActualWidth / viewPanelImage.Source.Width,
                 viewPanel.ActualHeight / viewPanelImage.Source.Height);
 
-            Zoom(factor, true, suppressEvent);
+            Zoom(factor, true);
         }
 
         public void ResetZoom()

QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml.cs

@@ -34,6 +34,8 @@ namespace QuickLook.Plugin.PDFViewer
     {
         private const double MinZoomFactor = 0.1d;
         private const double MaxZoomFactor = 3d;
+        private int _changePageDeltaSum;
+
         private bool _pdfLoaded;
         private double _viewRenderFactor = 1d;
 
@@ -103,9 +105,23 @@ namespace QuickLook.Plugin.PDFViewer
 
             const double tolerance = 0.0001d;
             if (Math.Abs(pos.Y) < tolerance && delta > 0)
+            {
+                _changePageDeltaSum += delta;
+                if (Math.Abs(_changePageDeltaSum) < 20)
+                    return;
+
                 PrevPage();
-            else if (Math.Abs(pos.Y - size.Height) < tolerance && delta < 0)
+                _changePageDeltaSum = 0;
+            }
+            else if (Math.Abs(pos.Y - size.Height) < tolerance && delta < -0)
+            {
+                _changePageDeltaSum += delta;
+                if (Math.Abs(_changePageDeltaSum) < 20)
+                    return;
+
                 NextPage();
+                _changePageDeltaSum = 0;
+            }
         }
 
         private void NextPage()
@@ -193,7 +209,7 @@ namespace QuickLook.Plugin.PDFViewer
             OnPropertyChanged("PageIds");
 
             CurrentPage = 0;
-            pagePanel.DoZoomToFit(true);
+            pagePanel.DoZoomToFit();
         }
 
         protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)

QuickLook.Plugin/QuickLook.Plugin.TextViewer/TextViewerPanel.xaml

@@ -11,6 +11,6 @@
              UseLayoutRounding="True">
     <Grid>
         <avalonEdit:TextEditor x:Name="viewer" Background="#00FFFFFF" FontSize="14" ShowLineNumbers="True"
-                               WordWrap="True" IsReadOnly="True" />
+                               WordWrap="True" IsReadOnly="True" IsManipulationEnabled="True" />
     </Grid>
 </UserControl>

QuickLook.Plugin/QuickLook.Plugin.TextViewer/TextViewerPanel.xaml.cs

@@ -18,6 +18,7 @@
 using System.IO;
 using System.Text;
 using System.Windows.Controls;
+using System.Windows.Input;
 using System.Windows.Media;
 using ICSharpCode.AvalonEdit.Highlighting;
 
@@ -32,12 +33,48 @@ namespace QuickLook.Plugin.TextViewer
         {
             InitializeComponent();
 
+            viewer.ManipulationInertiaStarting += Viewer_ManipulationInertiaStarting;
+            viewer.ManipulationStarting += Viewer_ManipulationStarting;
+            viewer.ManipulationDelta += Viewer_ManipulationDelta;
+
+            viewer.PreviewMouseWheel += Viewer_MouseWheel;
+
             viewer.FontFamily =
                 new FontFamily(context.GetString("Editor_FontFamily", failsafe: "Consolas"));
 
             LoadFile(path);
         }
 
+        private void Viewer_ManipulationInertiaStarting(object sender, ManipulationInertiaStartingEventArgs e)
+        {
+            e.TranslationBehavior = new InertiaTranslationBehavior
+            {
+                InitialVelocity = e.InitialVelocities.LinearVelocity,
+                DesiredDeceleration = 10.0 * 96.0 / (1000.0 * 1000.0)
+            };
+        }
+
+        private void Viewer_MouseWheel(object sender, MouseWheelEventArgs e)
+        {
+            e.Handled = true;
+
+            viewer.ScrollToVerticalOffset(viewer.VerticalOffset - e.Delta);
+        }
+
+        private void Viewer_ManipulationDelta(object sender, ManipulationDeltaEventArgs e)
+        {
+            e.Handled = true;
+
+            var delta = e.DeltaManipulation;
+            viewer.ScrollToVerticalOffset(viewer.VerticalOffset - delta.Translation.Y);
+        }
+
+        private void Viewer_ManipulationStarting(object sender, ManipulationStartingEventArgs e)
+        {
+            e.ManipulationContainer = this;
+            e.Mode = ManipulationModes.Translate;
+        }
+
         private void LoadFile(string path)
         {
             using (var s = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))