Add Feature/auto scrolling

Dashboard/Helpers/ScrollPanBehavior.cs

@@ -0,0 +1,271 @@
+/*
+ * Copyright (c) 2026 Erik Darling, Darling Data LLC
+ *
+ * This file is part of the SQL Server Performance Monitor.
+ *
+ * Licensed under the MIT License. See LICENSE file in the project root for full license information.
+ */
+
+using System;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Controls.Primitives;
+using System.Windows.Input;
+using System.Windows.Media;
+
+namespace PerformanceMonitorDashboard.Helpers;
+
+/// <summary>
+/// Enables middle-mouse drag panning for scrollable controls such as DataGrid and ListView.
+/// </summary>
+public static class ScrollPanBehavior
+{
+    public static readonly DependencyProperty EnableMiddleClickPanningProperty =
+        DependencyProperty.RegisterAttached(
+            "EnableMiddleClickPanning",
+            typeof(bool),
+            typeof(ScrollPanBehavior),
+            new PropertyMetadata(false, OnEnableMiddleClickPanningChanged));
+
+    private static readonly DependencyProperty PanStateProperty =
+        DependencyProperty.RegisterAttached(
+            "PanState",
+            typeof(PanState),
+            typeof(ScrollPanBehavior),
+            new PropertyMetadata(null));
+
+    public static bool GetEnableMiddleClickPanning(DependencyObject obj) => (bool)obj.GetValue(EnableMiddleClickPanningProperty);
+    public static void SetEnableMiddleClickPanning(DependencyObject obj, bool value) => obj.SetValue(EnableMiddleClickPanningProperty, value);
+
+    private static PanState GetOrCreatePanState(FrameworkElement element)
+    {
+        if (element.GetValue(PanStateProperty) is not PanState state)
+        {
+            state = new PanState();
+            element.SetValue(PanStateProperty, state);
+        }
+
+        return state;
+    }
+
+    private static void OnEnableMiddleClickPanningChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+    {
+        if (d is not FrameworkElement element)
+        {
+            return;
+        }
+
+        var isEnabled = (bool)e.NewValue;
+
+        if (isEnabled)
+        {
+            element.Loaded += OnLoaded;
+            element.Unloaded += OnUnloaded;
+            element.PreviewMouseDown += OnPreviewMouseDown;
+            element.PreviewMouseMove += OnPreviewMouseMove;
+            element.PreviewMouseUp += OnPreviewMouseUp;
+            element.LostMouseCapture += OnLostMouseCapture;
+        }
+        else
+        {
+            element.Loaded -= OnLoaded;
+            element.Unloaded -= OnUnloaded;
+            element.PreviewMouseDown -= OnPreviewMouseDown;
+            element.PreviewMouseMove -= OnPreviewMouseMove;
+            element.PreviewMouseUp -= OnPreviewMouseUp;
+            element.LostMouseCapture -= OnLostMouseCapture;
+            StopPanning(element, restoreCursor: true);
+        }
+    }
+
+    private static void OnLoaded(object sender, RoutedEventArgs e)
+    {
+        if (sender is FrameworkElement element)
+        {
+            GetOrCreatePanState(element).ScrollViewer = FindVisualChild<ScrollViewer>(element);
+        }
+    }
+
+    private static void OnUnloaded(object sender, RoutedEventArgs e)
+    {
+        if (sender is FrameworkElement element)
+        {
+            StopPanning(element, restoreCursor: false);
+            GetOrCreatePanState(element).ScrollViewer = null;
+        }
+    }
+
+    private static void OnPreviewMouseDown(object sender, MouseButtonEventArgs e)
+    {
+        if (e.ChangedButton != MouseButton.Middle
+            || sender is not FrameworkElement element
+            || !CanStartPanning(e.OriginalSource as DependencyObject))
+        {
+            return;
+        }
+
+        var state = GetOrCreatePanState(element);
+        state.ScrollViewer ??= FindVisualChild<ScrollViewer>(element);
+
+        if (state.ScrollViewer is null)
+        {
+            return;
+        }
+
+        if (state.ScrollViewer.ScrollableWidth <= 0 && state.ScrollViewer.ScrollableHeight <= 0)
+        {
+            return;
+        }
+
+        state.IsPanning = true;
+        state.StartPoint = e.GetPosition(state.ScrollViewer);
+        state.StartHorizontalOffset = state.ScrollViewer.HorizontalOffset;
+        state.StartVerticalOffset = state.ScrollViewer.VerticalOffset;
+        state.OriginalCursor = element.Cursor;
+
+        element.Cursor = Cursors.ScrollAll;
+        element.CaptureMouse();
+        e.Handled = true;
+    }
+
+    private static void OnPreviewMouseMove(object sender, MouseEventArgs e)
+    {
+        if (sender is not FrameworkElement element)
+        {
+            return;
+        }
+
+        var state = GetOrCreatePanState(element);
+        if (!state.IsPanning || state.ScrollViewer is null)
+        {
+            return;
+        }
+
+        var currentPoint = e.GetPosition(state.ScrollViewer);
+        var deltaX = currentPoint.X - state.StartPoint.X;
+        var deltaY = currentPoint.Y - state.StartPoint.Y;
+
+        state.ScrollViewer.ScrollToHorizontalOffset(ClampOffset(state.StartHorizontalOffset - deltaX, state.ScrollViewer.ScrollableWidth));
+        state.ScrollViewer.ScrollToVerticalOffset(ClampOffset(state.StartVerticalOffset - deltaY, state.ScrollViewer.ScrollableHeight));
+        e.Handled = true;
+    }
+
+    private static void OnPreviewMouseUp(object sender, MouseButtonEventArgs e)
+    {
+        if (e.ChangedButton != MouseButton.Middle || sender is not FrameworkElement element)
+        {
+            return;
+        }
+
+        if (!GetOrCreatePanState(element).IsPanning)
+        {
+            return;
+        }
+
+        StopPanning(element, restoreCursor: true);
+        e.Handled = true;
+    }
+
+    private static void OnLostMouseCapture(object sender, MouseEventArgs e)
+    {
+        if (sender is FrameworkElement element)
+        {
+            StopPanning(element, restoreCursor: true);
+        }
+    }
+
+    private static void StopPanning(FrameworkElement element, bool restoreCursor)
+    {
+        var state = GetOrCreatePanState(element);
+        if (!state.IsPanning)
+        {
+            if (restoreCursor)
+            {
+                element.ClearValue(FrameworkElement.CursorProperty);
+            }
+
+            return;
+        }
+
+        state.IsPanning = false;
+
+        if (restoreCursor)
+        {
+            if (state.OriginalCursor is null)
+            {
+                element.ClearValue(FrameworkElement.CursorProperty);
+            }
+            else
+            {
+                element.Cursor = state.OriginalCursor;
+            }
+        }
+
+        state.OriginalCursor = null;
+
+        if (Mouse.Captured == element)
+        {
+            element.ReleaseMouseCapture();
+        }
+    }
+
+    private static bool CanStartPanning(DependencyObject? source)
+    {
+        while (source is not null)
+        {
+            if (source is ScrollBar
+                || source is Thumb
+                || source is DataGridColumnHeader
+                || source is GridViewColumnHeader
+                || source is TextBoxBase
+                || source is PasswordBox
+                || source is ComboBox
+                || source is ComboBoxItem
+                || source is ButtonBase)
+            {
+                return false;
+            }
+
+            source = VisualTreeHelper.GetParent(source);
+        }
+
+        return true;
+    }
+
+    private static double ClampOffset(double value, double maxValue) => Math.Max(0, Math.Min(maxValue, value));
+
+    private static T? FindVisualChild<T>(DependencyObject? parent) where T : DependencyObject
+    {
+        if (parent is null)
+        {
+            return null;
+        }
+
+        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
+        {
+            var child = VisualTreeHelper.GetChild(parent, i);
+            if (child is T target)
+            {
+                return target;
+            }
+
+            var nested = FindVisualChild<T>(child);
+            if (nested is not null)
+            {
+                return nested;
+            }
+        }
+
+        return null;
+    }
+
+    private sealed class PanState
+    {
+        public bool IsPanning { get; set; }
+        public Point StartPoint { get; set; }
+        public double StartHorizontalOffset { get; set; }
+        public double StartVerticalOffset { get; set; }
+        public Cursor? OriginalCursor { get; set; }
+        public ScrollViewer? ScrollViewer { get; set; }
+    }
+}

Dashboard/Themes/CoolBreezeTheme.xaml

@@ -649,6 +649,7 @@
     <!-- ============================================ -->
     <Style TargetType="DataGrid">
         <Setter Property="helpers:DataGridClipboardBehavior.FixHeaderCopy" Value="True"/>
+        <Setter Property="helpers:ScrollPanBehavior.EnableMiddleClickPanning" Value="True"/>
         <Setter Property="Background" Value="{StaticResource BackgroundDarkBrush}"/>
         <Setter Property="Foreground" Value="{StaticResource ForegroundBrush}"/>
         <Setter Property="BorderBrush" Value="{StaticResource BorderBrush}"/>
@@ -793,6 +794,7 @@
     <!-- ListView Style                               -->
     <!-- ============================================ -->
     <Style TargetType="ListView">
+        <Setter Property="helpers:ScrollPanBehavior.EnableMiddleClickPanning" Value="True"/>
         <Setter Property="Background" Value="{StaticResource BackgroundDarkBrush}"/>
         <Setter Property="Foreground" Value="{StaticResource ForegroundBrush}"/>
         <Setter Property="BorderBrush" Value="{StaticResource BorderBrush}"/>

Dashboard/Themes/DarkTheme.xaml

@@ -648,6 +648,7 @@
     <!-- ============================================ -->
     <Style TargetType="DataGrid">
         <Setter Property="helpers:DataGridClipboardBehavior.FixHeaderCopy" Value="True"/>
+        <Setter Property="helpers:ScrollPanBehavior.EnableMiddleClickPanning" Value="True"/>
         <Setter Property="Background" Value="{StaticResource BackgroundDarkBrush}"/>
         <Setter Property="Foreground" Value="{StaticResource ForegroundBrush}"/>
         <Setter Property="BorderBrush" Value="{StaticResource BorderBrush}"/>
@@ -792,6 +793,7 @@
     <!-- ListView Style                               -->
     <!-- ============================================ -->
     <Style TargetType="ListView">
+        <Setter Property="helpers:ScrollPanBehavior.EnableMiddleClickPanning" Value="True"/>
         <Setter Property="Background" Value="{StaticResource BackgroundDarkBrush}"/>
         <Setter Property="Foreground" Value="{StaticResource ForegroundBrush}"/>
         <Setter Property="BorderBrush" Value="{StaticResource BorderBrush}"/>

Dashboard/Themes/LightTheme.xaml

@@ -649,6 +649,7 @@
     <!-- ============================================ -->
     <Style TargetType="DataGrid">
         <Setter Property="helpers:DataGridClipboardBehavior.FixHeaderCopy" Value="True"/>
+        <Setter Property="helpers:ScrollPanBehavior.EnableMiddleClickPanning" Value="True"/>
         <Setter Property="Background" Value="{StaticResource BackgroundDarkBrush}"/>
         <Setter Property="Foreground" Value="{StaticResource ForegroundBrush}"/>
         <Setter Property="BorderBrush" Value="{StaticResource BorderBrush}"/>
@@ -793,6 +794,7 @@
     <!-- ListView Style                               -->
     <!-- ============================================ -->
     <Style TargetType="ListView">
+        <Setter Property="helpers:ScrollPanBehavior.EnableMiddleClickPanning" Value="True"/>
         <Setter Property="Background" Value="{StaticResource BackgroundDarkBrush}"/>
         <Setter Property="Foreground" Value="{StaticResource ForegroundBrush}"/>
         <Setter Property="BorderBrush" Value="{StaticResource BorderBrush}"/>