Touch support in PlotBase

Author: VisualMelon

Source/Examples/Avalonia/AvaloniaExamples/Examples/ControllerDemo/CustomPlotController.cs

@@ -18,6 +18,7 @@ public CustomPlotController()
             this.UnbindAll();
             this.BindKeyDown(OxyKey.Left, PlotCommands.PanRight);
             this.BindKeyDown(OxyKey.Right, PlotCommands.PanLeft);
+            this.BindTouchDown(PlotCommands.PanZoomByTouch);
         }
     }
 }

Source/OxyPlot.Avalonia/PlotBase.Events.cs

@@ -13,6 +13,8 @@ namespace OxyPlot.Avalonia
 {
     using global::Avalonia.Input;
     using System;
+    using System.Collections.Generic;
+    using System.Linq;
 
     /// <summary>
     /// Represents a control that displays a <see cref="PlotModel" />.
@@ -35,53 +37,6 @@ protected override void OnKeyDown(KeyEventArgs e)
             e.Handled = ActualController.HandleKeyDown(this, args);
         }
 
-        /*
-        /// <summary>
-        /// Called when the <see cref="E:System.Windows.UIElement.ManipulationStarted" /> event occurs.
-        /// </summary>
-        /// <param name="e">The data for the event.</param>
-        protected override void OnManipulationStarted(ManipulationStartedEventArgs e)
-        {
-            base.OnManipulationStarted(e);
-            if (e.Handled)
-            {
-                return;
-            }
-
-            e.Handled = ActualController.HandleTouchStarted(this, e.ToTouchEventArgs(this));
-        }
-
-        /// <summary>
-        /// Called when the <see cref="E:System.Windows.UIElement.ManipulationDelta" /> event occurs.
-        /// </summary>
-        /// <param name="e">The data for the event.</param>
-        protected override void OnManipulationDelta(ManipulationDeltaEventArgs e)
-        {
-            base.OnManipulationDelta(e);
-            if (e.Handled)
-            {
-                return;
-            }
-
-            e.Handled = ActualController.HandleTouchDelta(this, e.ToTouchEventArgs(this));
-        }
-
-        /// <summary>
-        /// Called when the <see cref="E:System.Windows.UIElement.ManipulationCompleted" /> event occurs.
-        /// </summary>
-        /// <param name="e">The data for the event.</param>
-        protected override void OnManipulationCompleted(ManipulationCompletedEventArgs e)
-        {
-            base.OnManipulationCompleted(e);
-            if (e.Handled)
-            {
-                return;
-            }
-
-            e.Handled = ActualController.HandleTouchCompleted(this, e.ToTouchEventArgs(this));
-        }
-        */
-
         /// <summary>
         /// Called before the <see cref="E:System.Windows.UIElement.MouseWheel" /> event occurs to provide handling for the event in a derived class without attaching a delegate.
         /// </summary>
@@ -97,6 +52,11 @@ protected override void OnPointerWheelChanged(PointerWheelEventArgs e)
             e.Handled = ActualController.HandleMouseWheel(this, e.ToMouseWheelEventArgs(this));
         }
 
+        /// <summary>
+        /// Gets the dictionary of locations of touch pointers.
+        /// </summary>
+        private SortedDictionary<int, ScreenPoint> TouchPositions { get; } = new SortedDictionary<int, ScreenPoint>();
+
         /// <summary>
         /// Invoked when an unhandled MouseDown attached event reaches an element in its route that is derived from this class. Implement this method to add class handling for this event.
         /// </summary>
@@ -112,10 +72,32 @@ protected override void OnPointerPressed(PointerPressedEventArgs e)
             Focus();
             e.Pointer.Capture(this);
 
-            // store the mouse down point, check it when mouse button is released to determine if the context menu should be shown
-            mouseDownPoint = e.GetPosition(this).ToScreenPoint();
+            if (e.Pointer.Type == PointerType.Touch)
+            {
+                var position = e.GetPosition(this).ToScreenPoint();
+
+                var touchEventArgs = new OxyTouchEventArgs()
+                {
+                    ModifierKeys = e.KeyModifiers.ToModifierKeys(),
+                    Position = position,
+                    DeltaTranslation = new ScreenVector(0, 0),
+                    DeltaScale = new ScreenVector(1, 1),
+                };
+
+                TouchPositions[e.Pointer.Id] = position;
+
+                if (TouchPositions.Count == 1)
+                {
+                    e.Handled = ActualController.HandleTouchStarted(this, touchEventArgs);
+                }
+            }
+            else
+            {
+                // store the mouse down point, check it when mouse button is released to determine if the context menu should be shown
+                mouseDownPoint = e.GetPosition(this).ToScreenPoint();
 
-            e.Handled = ActualController.HandleMouseDown(this, e.ToMouseDownEventArgs(this));
+                e.Handled = ActualController.HandleMouseDown(this, e.ToMouseDownEventArgs(this));
+            }
         }
 
         /// <summary>
@@ -130,7 +112,21 @@ protected override void OnPointerMoved(PointerEventArgs e)
                 return;
             }
 
-            e.Handled = ActualController.HandleMouseMove(this, e.ToMouseEventArgs(this));
+            if (e.Pointer.Type == PointerType.Touch)
+            {
+                var point = e.GetPosition(this).ToScreenPoint();
+                var oldTouchPoints = TouchPositions.Values.ToArray();
+                TouchPositions[e.Pointer.Id] = point;
+                var newTouchPoints = TouchPositions.Values.ToArray();
+
+                var touchEventArgs = new OxyTouchEventArgs(newTouchPoints, oldTouchPoints);
+
+                e.Handled = ActualController.HandleTouchDelta(this, touchEventArgs);
+            }
+            else
+            {
+                e.Handled = ActualController.HandleMouseMove(this, e.ToMouseEventArgs(this));
+            }
         }
 
         /// <summary>
@@ -149,28 +145,50 @@ protected override void OnPointerReleased(PointerReleasedEventArgs e)
 
             e.Pointer.Capture(null);
 
-            e.Handled = ActualController.HandleMouseUp(this, releasedArgs.ToMouseReleasedEventArgs(this));
+            if (e.Pointer.Type == PointerType.Touch)
+            {
+                var position = e.GetPosition(this).ToScreenPoint();
 
-            // Open the context menu
-            var p = e.GetPosition(this).ToScreenPoint();
-            var d = p.DistanceTo(mouseDownPoint);
+                var touchEventArgs = new OxyTouchEventArgs()
+                {
+                    ModifierKeys = e.KeyModifiers.ToModifierKeys(),
+                    Position = position,
+                    DeltaTranslation = new ScreenVector(0, 0),
+                    DeltaScale = new ScreenVector(1, 1),
+                };
 
-            if (ContextMenu != null)
-            {
-                if (Math.Abs(d) < 1e-8 && releasedArgs.InitialPressMouseButton == MouseButton.Right)
+                TouchPositions.Remove(e.Pointer.Id);
+
+                if (TouchPositions.Count == 0)
                 {
-                    ContextMenu.DataContext = DataContext;
-                    ContextMenu.IsVisible = true;
+                    e.Handled = ActualController.HandleTouchCompleted(this, touchEventArgs);
                 }
-                else
+            }
+            else
+            {
+                e.Handled = ActualController.HandleMouseUp(this, releasedArgs.ToMouseReleasedEventArgs(this));
+
+                // Open the context menu
+                var p = e.GetPosition(this).ToScreenPoint();
+                var d = p.DistanceTo(mouseDownPoint);
+
+                if (ContextMenu != null)
                 {
-                    ContextMenu.IsVisible = false;
+                    if (Math.Abs(d) < 1e-8 && releasedArgs.InitialPressMouseButton == MouseButton.Right)
+                    {
+                        ContextMenu.DataContext = DataContext;
+                        ContextMenu.IsVisible = true;
+                    }
+                    else
+                    {
+                        ContextMenu.IsVisible = false;
+                    }
                 }
             }
         }
 
         /// <summary>
-        /// Invoked when an unhandled <see cref="E:System.Windows.Input.Mouse.MouseEnter" /> attached event is raised on this element. Implement this method to add class handling for this event.
+        /// Invoked when an unhandled <see cref="E:System.Windows.Input.Mouse.MouseEnter" /> attached event is raised on this element. Implement this method to add class handling for this event.
         /// </summary>
         /// <param name="e">The <see cref="T:System.Windows.Input.MouseEventArgs" /> that contains the event data.</param>
         protected override void OnPointerEnter(PointerEventArgs e)
@@ -185,7 +203,7 @@ protected override void OnPointerEnter(PointerEventArgs e)
         }
 
         /// <summary>
-        /// Invoked when an unhandled <see cref="E:System.Windows.Input.Mouse.MouseLeave" /> attached event is raised on this element. Implement this method to add class handling for this event.
+        /// Invoked when an unhandled <see cref="E:System.Windows.Input.Mouse.MouseLeave" /> attached event is raised on this element. Implement this method to add class handling for this event.
         /// </summary>
         /// <param name="e">The <see cref="T:System.Windows.Input.MouseEventArgs" /> that contains the event data.</param>
         protected override void OnPointerLeave(PointerEventArgs e)
@@ -199,4 +217,4 @@ protected override void OnPointerLeave(PointerEventArgs e)
             e.Handled = ActualController.HandleMouseLeave(this, e.ToMouseEventArgs(this));
         }
     }
-}
+}