Implemented cancelling ContextMenu opening/closing. (#1781)

src/Avalonia.Controls/ContextMenu.cs

@@ -7,11 +7,20 @@ namespace Avalonia.Controls
     using System;
     using System.Reactive.Linq;
     using System.Linq;
+    using System.ComponentModel;
+
     public class ContextMenu : SelectingItemsControl
     {
         private bool _isOpen;
         private Popup _popup;
 
+        /// <summary>
+        /// Defines the <see cref="IsOpen"/> property.
+        /// </summary>
+        public static readonly DirectProperty<ContextMenu, bool> IsOpenProperty =
+                            AvaloniaProperty.RegisterDirect<ContextMenu, bool>(nameof(IsOpen), o => o.IsOpen);
+
+
         /// <summary>
         /// Initializes static members of the <see cref="ContextMenu"/> class.
         /// </summary>
@@ -22,6 +31,26 @@ namespace Avalonia.Controls
             MenuItem.ClickEvent.AddClassHandler<ContextMenu>(x => x.OnContextMenuClick, handledEventsToo: true);
         }
 
+        /// <summary>
+        /// Gets a value indicating whether the popup is open
+        /// </summary>
+        public bool IsOpen => _isOpen;
+
+        /// <summary>
+        /// Occurs when the value of the
+        /// <see cref="P:Avalonia.Controls.ContextMenu.IsOpen" />
+        /// property is changing from false to true.
+        /// </summary>
+        public event CancelEventHandler ContextMenuOpening;
+
+        /// <summary>
+        /// Occurs when the value of the
+        /// <see cref="P:Avalonia.Controls.ContextMenu.IsOpen" />
+        /// property is changing from true to false.
+        /// </summary>
+        public event CancelEventHandler ContextMenuClosing;
+
+
         /// <summary>
         /// Called when the <see cref="Control.ContextMenu"/> property changes on a control.
         /// </summary>
@@ -59,12 +88,12 @@ namespace Avalonia.Controls
         {
             if (_popup != null && _popup.IsVisible)
             {
-                _popup.Close();
+                _popup.IsOpen = false;
             }
 
             SelectedIndex = -1;
 
-            _isOpen = false;
+            SetAndRaise(IsOpenProperty, ref _isOpen, false);
         }
 
         /// <summary>
@@ -89,11 +118,11 @@ namespace Avalonia.Controls
                 }
 
                 ((ISetLogicalParent)_popup).SetParent(control);
-                _popup.Child = control.ContextMenu;
+                _popup.Child = this;
 
-                _popup.Open();
+                _popup.IsOpen = true;
 
-                control.ContextMenu._isOpen = true;
+                SetAndRaise(IsOpenProperty, ref _isOpen, true);
             }
         }
 
@@ -118,21 +147,37 @@ namespace Avalonia.Controls
             var control = (Control)sender;
             var contextMenu = control.ContextMenu;
 
-            if (e.MouseButton == MouseButton.Right)
+            if (control.ContextMenu._isOpen)
             {
-                if (control.ContextMenu._isOpen)
-                {
-                    control.ContextMenu.Hide();
-                }
+                if (contextMenu.CancelClosing())
+                    return;
 
-                contextMenu.Show(control);
+                control.ContextMenu.Hide();
                 e.Handled = true;
             }
-            else if (contextMenu._isOpen)
+
+            if (e.MouseButton == MouseButton.Right)
             {
-                control.ContextMenu.Hide();
+                if (contextMenu.CancelOpening())
+                    return;
+
+                contextMenu.Show(control);
                 e.Handled = true;
             }
         }
+
+        private bool CancelClosing()
+        {
+            var eventArgs = new CancelEventArgs();
+            ContextMenuClosing?.Invoke(this, eventArgs);
+            return eventArgs.Cancel;
+        }
+
+        private bool CancelOpening()
+        {
+            var eventArgs = new CancelEventArgs();
+            ContextMenuOpening?.Invoke(this, eventArgs);
+            return eventArgs.Cancel;
+        }
     }
 }

tests/Avalonia.Controls.UnitTests/ContextMenuTests.cs

@@ -0,0 +1,179 @@
+using System;
+using System.Windows.Input;
+using Avalonia.Controls.Primitives;
+using Avalonia.Data;
+using Avalonia.Input;
+using Avalonia.Markup.Data;
+using Avalonia.Platform;
+using Avalonia.UnitTests;
+using Moq;
+using Xunit;
+
+namespace Avalonia.Controls.UnitTests
+{
+    public class ContextMenuTests
+    {
+        private Mock<IPopupImpl> popupImpl;
+
+        [Fact]
+        public void Clicking_On_Control_Toggles_ContextMenu()
+        {
+            using (Application())
+            {
+                popupImpl.Setup(x => x.Show()).Verifiable();
+                popupImpl.Setup(x => x.Hide()).Verifiable();
+
+                var sut = new ContextMenu();
+                var target = new Panel
+                {
+                    ContextMenu = sut
+                };
+
+                new Window { Content = target };
+
+                target.RaiseEvent(new PointerReleasedEventArgs
+                {
+                    RoutedEvent = InputElement.PointerReleasedEvent,
+                    MouseButton = MouseButton.Right
+                });
+
+                Assert.True(sut.IsOpen);
+
+                target.RaiseEvent(new PointerReleasedEventArgs
+                {
+                    RoutedEvent = InputElement.PointerReleasedEvent,
+                    MouseButton = MouseButton.None
+                });
+
+                Assert.False(sut.IsOpen);
+                popupImpl.Verify(x => x.Show(), Times.Once);
+                popupImpl.Verify(x => x.Hide(), Times.Once);
+            }
+        }
+
+        [Fact]
+        public void Right_Clicking_On_Control_Twice_Re_Opens_ContextMenu()
+        {
+            using (Application())
+            {
+                popupImpl.Setup(x => x.Show()).Verifiable();
+                popupImpl.Setup(x => x.Hide()).Verifiable();
+
+                var sut = new ContextMenu();
+                var target = new Panel
+                {
+                    ContextMenu = sut
+                };
+                new Window { Content = target };
+
+                target.RaiseEvent(new PointerReleasedEventArgs
+                {
+                    RoutedEvent = InputElement.PointerReleasedEvent,
+                    MouseButton = MouseButton.Right
+                });
+
+                Assert.True(sut.IsOpen);
+
+                target.RaiseEvent(new PointerReleasedEventArgs
+                {
+                    RoutedEvent = InputElement.PointerReleasedEvent,
+                    MouseButton = MouseButton.Right
+                });
+
+                Assert.True(sut.IsOpen);
+                popupImpl.Verify(x => x.Hide(), Times.Once);
+                popupImpl.Verify(x => x.Show(), Times.Exactly(2));
+            }
+        }
+
+        [Fact]
+        public void Cancelling_Opening_Does_Not_Show_ContextMenu()
+        {
+            using (Application())
+            {
+                popupImpl.Setup(x => x.Show()).Verifiable();
+
+                bool eventCalled = false;
+                var sut = new ContextMenu();
+                var target = new Panel
+                {
+                    ContextMenu = sut
+                };
+                new Window { Content = target };
+
+                sut.ContextMenuOpening += (c, e) => { eventCalled = true; e.Cancel = true; };
+
+                target.RaiseEvent(new PointerReleasedEventArgs
+                {
+                    RoutedEvent = InputElement.PointerReleasedEvent,
+                    MouseButton = MouseButton.Right
+                });
+
+                Assert.True(eventCalled);
+                Assert.False(sut.IsOpen);
+                popupImpl.Verify(x => x.Show(), Times.Never);
+            }
+        }
+
+        [Fact]
+        public void Cancelling_Closing_Leaves_ContextMenuOpen()
+        {
+            using (Application())
+            {
+                popupImpl.Setup(x => x.Show()).Verifiable();
+                popupImpl.Setup(x => x.Hide()).Verifiable();
+
+                bool eventCalled = false;
+                var sut = new ContextMenu();
+                var target = new Panel
+                {
+                    ContextMenu = sut
+                };
+                new Window { Content = target };
+
+                sut.ContextMenuClosing += (c, e) => { eventCalled = true; e.Cancel = true; };
+
+                target.RaiseEvent(new PointerReleasedEventArgs
+                {
+                    RoutedEvent = InputElement.PointerReleasedEvent,
+                    MouseButton = MouseButton.Right
+                });
+
+                Assert.True(sut.IsOpen);
+
+                target.RaiseEvent(new PointerReleasedEventArgs
+                {
+                    RoutedEvent = InputElement.PointerReleasedEvent,
+                    MouseButton = MouseButton.None
+                });
+
+                Assert.True(eventCalled);
+                Assert.True(sut.IsOpen);
+
+                popupImpl.Verify(x => x.Show(), Times.Once());
+                popupImpl.Verify(x => x.Hide(), Times.Never);
+            }
+        }
+
+        private IDisposable Application()
+        {
+            var screen = new Rect(new Point(), new Size(100, 100));
+            var screenImpl = new Mock<IScreenImpl>();
+            screenImpl.Setup(x => x.ScreenCount).Returns(1);
+            screenImpl.Setup(X => X.AllScreens).Returns( new[] { new Screen(screen, screen, true) });
+
+            var windowImpl = new Mock<IWindowImpl>();
+            windowImpl.Setup(x => x.Screen).Returns(screenImpl.Object);
+
+            popupImpl = new Mock<IPopupImpl>();
+            popupImpl.SetupGet(x => x.Scaling).Returns(1);
+
+            var services = TestServices.StyledWindow.With(
+                                        inputManager: new InputManager(),
+                                        windowImpl: windowImpl.Object,
+                                        windowingPlatform: new MockWindowingPlatform(() => windowImpl.Object, () => popupImpl.Object));
+
+            return UnitTestApplication.Start(services);
+        }
+    }
+}