From 2bd215c91a9ebf13b98a6f86c173055b0a3473fb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mat=C4=9Bj=20Kub=C3=AD=C4=8Dek?= <kubicekm23@spstrutnov.cz>
Date: Sun, 29 Mar 2026 11:05:30 +0200
Subject: [PATCH] "Infinite" workspace for diagrams

---
 NetworkDiagram/MainWindow.xaml    | 17 +++++-
 NetworkDiagram/MainWindow.xaml.cs | 97 +++++++++++++++++++++++++++++++
 2 files changed, 111 insertions(+), 3 deletions(-)

diff --git a/NetworkDiagram/MainWindow.xaml b/NetworkDiagram/MainWindow.xaml
index 3e6a5b4..b36c3ec 100644
--- a/NetworkDiagram/MainWindow.xaml
+++ b/NetworkDiagram/MainWindow.xaml
@@ -73,12 +73,23 @@
         </Border>
 
         <!-- Canvas Area -->
-        <ScrollViewer Grid.Row="1" Grid.Column="1" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" Background="Transparent">
-            <Canvas x:Name="DiagramCanvas" Width="2000" Height="2000" AllowDrop="True"
+        <Grid Grid.Row="1" Grid.Column="1" x:Name="CanvasViewport" ClipToBounds="True" Background="Transparent"
+              MouseDown="Viewport_MouseDown"
+              MouseMove="Viewport_MouseMove"
+              MouseUp="Viewport_MouseUp"
+              MouseWheel="Viewport_MouseWheel">
+            <!-- Increased size to 40k to provide plenty of space in all directions -->
+            <Canvas x:Name="DiagramCanvas" Width="40000" Height="40000" AllowDrop="True"
                     Drop="DiagramCanvas_Drop" DragOver="DiagramCanvas_DragOver"
                     MouseDown="DiagramCanvas_MouseDown"
                     MouseMove="DiagramCanvas_MouseMove"
                     MouseUp="DiagramCanvas_MouseUp">
+                <Canvas.RenderTransform>
+                    <TransformGroup>
+                        <ScaleTransform x:Name="CanvasScale" ScaleX="1" ScaleY="1"/>
+                        <TranslateTransform x:Name="CanvasTranslate" X="-20000" Y="-20000"/>
+                    </TransformGroup>
+                </Canvas.RenderTransform>
                 <Canvas.Background>
                     <VisualBrush TileMode="Tile" Viewport="0,0,40,40" ViewportUnits="Absolute">
                         <VisualBrush.Visual>
@@ -122,6 +133,6 @@
                 <Rectangle x:Name="SelectionRect" Stroke="{StaticResource AccentBlue}" StrokeThickness="1.5" StrokeDashArray="3,3" 
                            Fill="#220078D7" Visibility="Collapsed" Panel.ZIndex="9999" RadiusX="2" RadiusY="2" IsHitTestVisible="False"/>
             </Canvas>
-        </ScrollViewer>
+        </Grid>
     </Grid>
 </Window>
diff --git a/NetworkDiagram/MainWindow.xaml.cs b/NetworkDiagram/MainWindow.xaml.cs
index 63272ec..4bdaca8 100644
--- a/NetworkDiagram/MainWindow.xaml.cs
+++ b/NetworkDiagram/MainWindow.xaml.cs
@@ -30,12 +30,85 @@ namespace NetworkDiagram
         private readonly Dictionary<Connection, Line> _connectionLines = new();
         private readonly Dictionary<PlacedDevice, FrameworkElement> _deviceElements = new();
 
+        // Panning and Zooming
+        private Point _lastPanPoint;
+        private bool _isPanning;
+
         public MainWindow()
         {
             InitializeComponent();
             LoadTemplates();
+            this.Loaded += MainWindow_Loaded;
         }
 
+        private void MainWindow_Loaded(object sender, RoutedEventArgs e)
+        {
+            CenterView();
+        }
+
+        private void CenterView()
+        {
+            // Center logically on (20000, 20000) minus half the viewport size to put 0,0 in the middle
+            CanvasTranslate.X = -20000 + (CanvasViewport.ActualWidth / 2);
+            CanvasTranslate.Y = -20000 + (CanvasViewport.ActualHeight / 2);
+            CanvasScale.ScaleX = 1.0;
+            CanvasScale.ScaleY = 1.0;
+        }
+
+        #region Panning and Zooming
+        private void Viewport_MouseDown(object sender, MouseButtonEventArgs e)
+        {
+            if (e.ChangedButton == MouseButton.Middle)
+            {
+                _isPanning = true;
+                _lastPanPoint = e.GetPosition(CanvasViewport);
+                CanvasViewport.CaptureMouse();
+            }
+        }
+
+        private void Viewport_MouseMove(object sender, MouseEventArgs e)
+        {
+            if (_isPanning)
+            {
+                Point currentPoint = e.GetPosition(CanvasViewport);
+                double deltaX = currentPoint.X - _lastPanPoint.X;
+                double deltaY = currentPoint.Y - _lastPanPoint.Y;
+
+                CanvasTranslate.X += deltaX;
+                CanvasTranslate.Y += deltaY;
+
+                _lastPanPoint = currentPoint;
+            }
+        }
+
+        private void Viewport_MouseUp(object sender, MouseButtonEventArgs e)
+        {
+            if (e.ChangedButton == MouseButton.Middle)
+            {
+                _isPanning = false;
+                CanvasViewport.ReleaseMouseCapture();
+            }
+        }
+
+        private void Viewport_MouseWheel(object sender, MouseWheelEventArgs e)
+        {
+            double zoom = e.Delta > 0 ? 1.1 : 0.9;
+            
+            double newScale = CanvasScale.ScaleX * zoom;
+            if (newScale < 0.1 || newScale > 5) return;
+
+            Point mousePos = e.GetPosition(DiagramCanvas);
+
+            // Zoom centered on mouse
+            CanvasScale.ScaleX = newScale;
+            CanvasScale.ScaleY = newScale;
+
+            Point newMousePos = e.GetPosition(DiagramCanvas);
+            CanvasTranslate.X += (newMousePos.X - mousePos.X) * CanvasScale.ScaleX;
+            CanvasTranslate.Y += (newMousePos.Y - mousePos.Y) * CanvasScale.ScaleY;
+        }
+        #endregion
+
         private void LoadTemplates()
         {
             try
@@ -457,9 +530,13 @@ namespace NetworkDiagram
         {
             _currentDiagram = new Diagram();
             DiagramCanvas.Children.Clear();
+            // Re-add selection rectangle after clearing
+            if (SelectionRect != null) DiagramCanvas.Children.Add(SelectionRect);
+            
             _connectionLines.Clear();
             _deviceElements.Clear();
             ClearSelection();
+            CenterView();
         }
 
         private void SaveDiagram_Click(object sender, RoutedEventArgs e)
@@ -497,15 +574,35 @@ namespace NetworkDiagram
             }
 
             DiagramCanvas.Children.Clear();
+            // Re-add selection rectangle after clearing
+            if (SelectionRect != null) DiagramCanvas.Children.Add(SelectionRect);
+            
             _connectionLines.Clear();
             _deviceElements.Clear();
             ClearSelection();
+
             foreach (var device in _currentDiagram.Devices) RenderDevice(device);
             foreach (var conn in model.Connections.Select(cModel => new Connection { StartDevice = _currentDiagram.Devices[cModel.StartIndex], EndDevice = _currentDiagram.Devices[cModel.EndIndex], Type = cModel.Type }))
             {
                 _currentDiagram.Connections.Add(conn);
                 RenderConnection(conn);
             }
+
+            // Center on loaded content
+            if (_currentDiagram.Devices.Count > 0)
+            {
+                double minX = _currentDiagram.Devices.Min(d => d.X);
+                double minY = _currentDiagram.Devices.Min(d => d.Y);
+                double maxX = _currentDiagram.Devices.Max(d => d.X);
+                double maxY = _currentDiagram.Devices.Max(d => d.Y);
+
+                CanvasTranslate.X = -((minX + maxX) / 2) * CanvasScale.ScaleX + (CanvasViewport.ActualWidth / 2);
+                CanvasTranslate.Y = -((minY + maxY) / 2) * CanvasScale.ScaleY + (CanvasViewport.ActualHeight / 2);
+            }
+            else
+            {
+                CenterView();
+            }
         }
 
         private void WireTool_Click(object sender, RoutedEventArgs e) => _activeTool = ConnectionType.Wire;