Add gestures events to View (#39)

samples/ControlGallery/AppShell.razor

@@ -2,6 +2,7 @@
 @using ControlGallery.Views.Collections
 @using ControlGallery.Views.Collections.CollectionView
 @using ControlGallery.Views.EditText
+@using ControlGallery.Views.Gestures
 @using ControlGallery.Views.InitiateCommands
 @using ControlGallery.Views.Layouts
 @using ControlGallery.Views.PresentData
@@ -51,6 +52,7 @@
     <ShellItemsPage />
 
     @*Other*@
-    <GesturesPage />
     <SkiaCanvasPage />
+    <GestureEvents />
+    <GestureRecognizersPage />
 </Shell>

samples/ControlGallery/Views/Gestures/GestureEvents.razor

@@ -0,0 +1,28 @@
+@using System.Collections.ObjectModel
+
+<ContentPage Title="Gesture Events">
+    <VerticalStackLayout>
+        <Label>Try tapping, double tapping, or swiping items.</Label>
+        <Button Text="Add" OnClick="AddItem" />
+        @foreach (var item in _items)
+        {
+            <GestureItem @key="item" Item="item" OnRemoving="RemoveItem" />
+        }
+    </VerticalStackLayout>
+</ContentPage>
+
+
+@code {
+    List<int> _items = new(Enumerable.Range(0, 10));
+
+    void RemoveItem(int i)
+    {
+        _items.Remove(i);
+    }
+
+    void AddItem()
+    {
+        var i = _items.DefaultIfEmpty(0).Max() + 1;
+        _items.Add(i);
+    }
+}

samples/ControlGallery/Views/Gestures/GestureItem.razor

@@ -0,0 +1,43 @@
+<Frame @ref="_element" BackgroundColor="Colors.LightCyan" CornerRadius="7" Padding="20" Margin="4"
+       OnTap="OnTap"
+       OnDoubleTap="OnDoubleTap"
+       OnPanUpdate="OnPanUpdate">
+
+    <Label TextColor="Colors.Black">@Item - @status</Label>
+</Frame>
+
+@code {
+    [Parameter] public int Item { get; set; }
+    [Parameter] public EventCallback<int> OnRemoving { get; set; }
+
+    Frame _element;
+    string status = "Pending";
+    double _lastX;
+
+    void OnTap() => status = "Tapped";
+    void OnDoubleTap() => status = "Double Tapped";
+
+    async Task OnPanUpdate(PanUpdatedEventArgs args)
+    {
+        if (args.StatusType == GestureStatus.Running)
+        {
+            _lastX = args.TotalX;
+            _element.NativeControl.TranslationX = args.TotalX;
+        }
+        else if (args.StatusType == GestureStatus.Completed)
+        {
+            if (Math.Abs(_lastX) > 50)
+            {
+                var screenWidth = DeviceDisplay.MainDisplayInfo.Width;
+
+                var translateTo = Math.Sign(_lastX) * screenWidth;
+                await _element.NativeControl.TranslateTo(translateTo, 0);
+                await OnRemoving.InvokeAsync(Item);
+            }
+            else
+            {
+                _element.NativeControl.TranslationX = args.TotalX;
+            }
+        }
+    }
+}

samples/ControlGallery/Views/GesturesPage.razor → samples/ControlGallery/Views/Gestures/GestureRecognizersPage.razor

@@ -1,6 +1,6 @@
 @page "/gestureplayground"
 
-<ContentPage Title="Gestures">
+<ContentPage Title="Gesture Recognizers">
     <StackLayout Margin="new Thickness(20)">
 
         <Label Text="Tap me or pan me"

src/BlazorBindings.Maui/Elements/View.cs

@@ -0,0 +1,160 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+using Microsoft.AspNetCore.Components;
+using Microsoft.Maui.Controls;
+using System;
+using System.Linq;
+using MC = Microsoft.Maui.Controls;
+
+namespace BlazorBindings.Maui.Elements
+{
+    public abstract partial class View : VisualElement
+    {
+        [Parameter] public EventCallback OnTap { get; set; }
+        [Parameter] public EventCallback OnDoubleTap { get; set; }
+        [Parameter] public EventCallback<SwipedEventArgs> OnSwipe { get; set; }
+        [Parameter] public EventCallback<PinchGestureUpdatedEventArgs> OnPinchUpdate { get; set; }
+        [Parameter] public EventCallback<PanUpdatedEventArgs> OnPanUpdate { get; set; }
+
+        protected override bool HandleAdditionalParameter(string name, object value)
+        {
+            switch (name)
+            {
+                case nameof(OnTap):
+                    if (!Equals(value, OnTap))
+                    {
+                        HandleTap();
+                        OnTap = (EventCallback)value;
+                    }
+                    return true;
+
+                case nameof(OnDoubleTap):
+                    if (!Equals(value, OnDoubleTap))
+                    {
+                        HandleDoubleTap();
+                        OnDoubleTap = (EventCallback)value;
+                    }
+                    return true;
+
+                case nameof(OnSwipe):
+                    if (!Equals(value, OnSwipe))
+                    {
+                        HandleSwipe();
+                        OnSwipe = (EventCallback<SwipedEventArgs>)value;
+                    }
+                    return true;
+
+                case nameof(OnPinchUpdate):
+                    if (!Equals(value, OnPinchUpdate))
+                    {
+                        HandlePinch();
+                        OnPinchUpdate = (EventCallback<PinchGestureUpdatedEventArgs>)value;
+                    }
+                    return true;
+
+                case nameof(OnPanUpdate):
+                    if (!Equals(value, OnPanUpdate))
+                    {
+                        HandlePan();
+                        OnPanUpdate = (EventCallback<PanUpdatedEventArgs>)value;
+                    }
+                    return true;
+
+                default:
+                    return base.HandleAdditionalParameter(name, value);
+
+            }
+        }
+
+        private void HandleTap()
+        {
+            void GestureRecognizerTapped(object sender, EventArgs e) => OnTap.InvokeAsync();
+
+            var tapGestureRecognizer = NativeControl.GestureRecognizers
+                .OfType<MC.TapGestureRecognizer>()
+                .FirstOrDefault(gr => gr.NumberOfTapsRequired == 1);
+
+            if (tapGestureRecognizer is null)
+            {
+                tapGestureRecognizer = new MC.TapGestureRecognizer();
+                NativeControl.GestureRecognizers.Add(tapGestureRecognizer);
+            }
+
+            tapGestureRecognizer.Tapped -= GestureRecognizerTapped;
+            tapGestureRecognizer.Tapped += GestureRecognizerTapped;
+        }
+
+        private void HandleDoubleTap()
+        {
+            void GestureRecognizerTapped(object sender, EventArgs e) => OnDoubleTap.InvokeAsync();
+
+            var tapGestureRecognizer = NativeControl.GestureRecognizers
+                .OfType<MC.TapGestureRecognizer>()
+                .FirstOrDefault(gr => gr.NumberOfTapsRequired == 2);
+
+            if (tapGestureRecognizer is null)
+            {
+                tapGestureRecognizer = new MC.TapGestureRecognizer { NumberOfTapsRequired = 2 };
+                NativeControl.GestureRecognizers.Add(tapGestureRecognizer);
+            }
+
+            tapGestureRecognizer.Tapped -= GestureRecognizerTapped;
+            tapGestureRecognizer.Tapped += GestureRecognizerTapped;
+        }
+
+        private void HandleSwipe()
+        {
+            void GestureRecognizerSwiped(object sender, SwipedEventArgs e) => OnSwipe.InvokeAsync(e);
+
+            var swipeGestureRecognizer = NativeControl.GestureRecognizers
+                .OfType<MC.SwipeGestureRecognizer>()
+                .FirstOrDefault();
+
+            if (swipeGestureRecognizer is null)
+            {
+                swipeGestureRecognizer = new MC.SwipeGestureRecognizer();
+                NativeControl.GestureRecognizers.Add(swipeGestureRecognizer);
+            }
+
+            swipeGestureRecognizer.Swiped -= GestureRecognizerSwiped;
+            swipeGestureRecognizer.Swiped += GestureRecognizerSwiped;
+        }
+
+        private void HandlePinch()
+        {
+            void GestureRecognizerPinchUpdated(object sender, PinchGestureUpdatedEventArgs e) => OnPinchUpdate.InvokeAsync(e);
+
+            var pinchGestureRecognizer = NativeControl.GestureRecognizers
+                .OfType<MC.PinchGestureRecognizer>()
+                .FirstOrDefault();
+
+            if (pinchGestureRecognizer is null)
+            {
+                pinchGestureRecognizer = new MC.PinchGestureRecognizer();
+                NativeControl.GestureRecognizers.Add(pinchGestureRecognizer);
+            }
+
+            pinchGestureRecognizer.PinchUpdated -= GestureRecognizerPinchUpdated;
+            pinchGestureRecognizer.PinchUpdated += GestureRecognizerPinchUpdated;
+        }
+
+        private void HandlePan()
+        {
+            void GestureRecognizerPanUpdated(object sender, PanUpdatedEventArgs e) => OnPanUpdate.InvokeAsync(e);
+
+            var pinchGestureRecognizer = NativeControl.GestureRecognizers
+                .OfType<MC.PanGestureRecognizer>()
+                .FirstOrDefault();
+
+            if (pinchGestureRecognizer is null)
+            {
+                pinchGestureRecognizer = new MC.PanGestureRecognizer();
+                NativeControl.GestureRecognizers.Add(pinchGestureRecognizer);
+            }
+
+            pinchGestureRecognizer.PanUpdated -= GestureRecognizerPanUpdated;
+            pinchGestureRecognizer.PanUpdated += GestureRecognizerPanUpdated;
+        }
+    }
+}