Add command demos.

Author: davidbritch

WorkingWithGestures/DragAndDropGesture/DragAndDropGesture/CustomDataPackageCommandDemoPage.xaml

@@ -0,0 +1,61 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:local="clr-namespace:DragAndDropGesture"
+             x:Class="DragAndDropGesture.CustomDataPackageCommandDemoPage"
+             Title="Custom data package demo">
+    <ContentPage.BindingContext>
+        <local:CustomDataPackageViewModel />
+    </ContentPage.BindingContext>
+    <ContentPage.Resources>
+        <local:Square x:Key="bigSquare">
+            <x:Arguments>
+                <x:Double>200</x:Double>
+                <x:Double>200</x:Double>
+            </x:Arguments>
+        </local:Square>
+        <local:Square x:Key="smallSquare">
+            <x:Arguments>
+                <x:Double>150</x:Double>
+                <x:Double>150</x:Double>
+            </x:Arguments>
+        </local:Square>
+    </ContentPage.Resources>
+    <StackLayout Margin="20">
+        <Label Text="Drag the square with the largest area to the grey rectangle." />
+        <Rectangle Stroke="Red"
+                   Fill="DarkBlue"
+                   StrokeThickness="4"
+                   HeightRequest="200"
+                   WidthRequest="200"
+                   HorizontalOptions="Center">
+            <Rectangle.GestureRecognizers>
+                <DragGestureRecognizer CanDrag="True"
+                                       DragStartingCommand="{Binding DragStartingCommand}"
+                                       DragStartingCommandParameter="{StaticResource bigSquare}" />
+            </Rectangle.GestureRecognizers>
+        </Rectangle>
+        <Rectangle Stroke="DarkBlue"
+                    Fill="Red"                     
+                    StrokeThickness="4"
+                    HeightRequest="150"
+                    WidthRequest="150"
+                    HorizontalOptions="Center">
+            <Rectangle.GestureRecognizers>
+                <DragGestureRecognizer CanDrag="True"
+                                       DragStartingCommand="{Binding DragStartingCommand}"
+                                       DragStartingCommandParameter="{StaticResource smallSquare}" />
+            </Rectangle.GestureRecognizers>
+        </Rectangle>
+        <Frame CornerRadius="0"
+               HasShadow="False"
+               BackgroundColor="Silver"
+               HeightRequest="200">
+            <Frame.GestureRecognizers>
+                <DropGestureRecognizer AllowDrop="True"
+                                       DropCommand="{Binding DropCommand}"
+                                       DropCommandParameter="{StaticResource bigSquare}" />
+            </Frame.GestureRecognizers>
+        </Frame>
+    </StackLayout>
+</ContentPage>

WorkingWithGestures/DragAndDropGesture/DragAndDropGesture/CustomDataPackageCommandDemoPage.xaml.cs

@@ -0,0 +1,22 @@
+using Xamarin.Forms;
+
+namespace DragAndDropGesture
+{
+    public partial class CustomDataPackageCommandDemoPage : ContentPage
+    {
+        public CustomDataPackageCommandDemoPage()
+        {
+            InitializeComponent();
+
+            MessagingCenter.Subscribe<CustomDataPackageViewModel, string>(this, "Correct", async (s, e) =>
+            {
+                await DisplayAlert("Correct", e, "OK");
+            });
+
+            MessagingCenter.Subscribe<CustomDataPackageViewModel, string>(this, "Incorrect", async (s, e) =>
+            {
+                await DisplayAlert("Incorrect", e, "OK");
+            });
+        }
+    }
+}

WorkingWithGestures/DragAndDropGesture/DragAndDropGesture/CustomDataPackageViewModel.cs

@@ -0,0 +1,30 @@
+using System.Windows.Input;
+using Xamarin.Forms;
+
+namespace DragAndDropGesture
+{
+    public class CustomDataPackageViewModel
+    {
+        Square draggedSquare;
+
+        public ICommand DragStartingCommand => new Command<Square>(RegisterDragData);
+        public ICommand DropCommand => new Command<Square>(ProcessDrop);
+
+        void RegisterDragData(Square square)
+        {
+            draggedSquare = square;
+        }
+
+        void ProcessDrop(Square square)
+        {
+            if (square.Area.Equals(draggedSquare.Area))
+            {
+                MessagingCenter.Send<CustomDataPackageViewModel, string>(this, "Correct", "Congratulations!");
+            }
+            else
+            {
+                MessagingCenter.Send<CustomDataPackageViewModel, string>(this, "Incorrect", "Try again.");
+            }
+        }
+    }
+}

WorkingWithGestures/DragAndDropGesture/DragAndDropGesture/DataPackageCommandDemoPage.xaml

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:local="clr-namespace:DragAndDropGesture"
+             x:Class="DragAndDropGesture.DataPackageCommandDemoPage"
+             Title="Data package demo">
+    <ContentPage.BindingContext>
+        <local:DataPackageViewModel />
+    </ContentPage.BindingContext>
+    <StackLayout Margin="20">
+        <Label Text="Drag the cat to the grey rectangle." />
+        <Image Source="monkeyface.png"
+               HorizontalOptions="Center">
+            <Image.GestureRecognizers>
+                <DragGestureRecognizer CanDrag="True"
+                                       DragStartingCommand="{Binding DragCommand}"
+                                       DragStartingCommandParameter="Monkey" />
+            </Image.GestureRecognizers>
+        </Image>
+        <Path Stroke="Black"
+              StrokeThickness="4"
+              RenderTransform="0.5 0 0 0.5 0 0"
+              HorizontalOptions="Center">
+            <Path.GestureRecognizers>
+                <DragGestureRecognizer CanDrag="True"
+                                       DragStartingCommand="{Binding DragCommand}"
+                                       DragStartingCommandParameter="Cat" />
+            </Path.GestureRecognizers>
+            <Path.Data>
+                <PathGeometry Figures="M 160 140 L 150 50 220 103
+                                       M 320 140 L 330 50 260 103
+                                       M 215 230 L 40 200
+                                       M 215 240 L 40 240
+                                       M 215 250 L 40 280
+                                       M 265 230 L 440 200
+                                       M 265 240 L 440 240
+                                       M 265 250 L 440 280
+                                       M 240 100
+                                       A 100 100 0 0 1 240 300
+                                       A 100 100 0 0 1 240 100 
+                                       M 180 170
+                                       A 40 40 0 0 1 220 170
+                                       A 40 40 0 0 1 180 170
+                                       M 300 170
+                                       A 40 40 0 0 1 260 170
+                                       A 40 40 0 0 1 300 170" />
+            </Path.Data>
+        </Path>
+        <Frame CornerRadius="0"
+               HasShadow="False"
+               BackgroundColor="Silver"
+               HeightRequest="200">
+            <Frame.GestureRecognizers>
+                <DropGestureRecognizer AllowDrop="True"
+                                       DropCommand="{Binding DropCommand}" />
+            </Frame.GestureRecognizers>
+        </Frame>
+    </StackLayout>
+</ContentPage>

WorkingWithGestures/DragAndDropGesture/DragAndDropGesture/DataPackageCommandDemoPage.xaml.cs

@@ -0,0 +1,22 @@
+using Xamarin.Forms;
+
+namespace DragAndDropGesture
+{
+    public partial class DataPackageCommandDemoPage : ContentPage
+    {
+        public DataPackageCommandDemoPage()
+        {
+            InitializeComponent();
+
+            MessagingCenter.Subscribe<DataPackageViewModel, string>(this, "Correct", async (s, e) =>
+            {
+                await DisplayAlert("Correct", e, "OK");
+            });
+
+            MessagingCenter.Subscribe<DataPackageViewModel, string>(this, "Incorrect", async (s, e) =>
+            {
+                await DisplayAlert("Incorrect", e, "OK");
+            });
+        }
+    }
+}

WorkingWithGestures/DragAndDropGesture/DragAndDropGesture/DataPackageDemoPage.xaml.cs

@@ -1,5 +1,4 @@
-
-using Xamarin.Forms;
+using Xamarin.Forms;
 
 namespace DragAndDropGesture
 {

WorkingWithGestures/DragAndDropGesture/DragAndDropGesture/DataPackageViewModel.cs

@@ -0,0 +1,30 @@
+using System.Windows.Input;
+using Xamarin.Forms;
+
+namespace DragAndDropGesture
+{
+    public class DataPackageViewModel
+    {
+        string dragData;
+
+        public ICommand DragCommand => new Command<string>(RegisterDragData);
+        public ICommand DropCommand => new Command(ProcessDrop);
+
+        void RegisterDragData(string data)
+        {
+            dragData = data;
+        }
+
+        void ProcessDrop()
+        {
+            if (dragData.Equals("Cat"))
+            {
+                MessagingCenter.Send<DataPackageViewModel, string>(this, "Correct", "Congratulations!");
+            }
+            else if (dragData.Equals("Monkey"))
+            {
+                MessagingCenter.Send<DataPackageViewModel, string>(this, "Incorrect", "Try again.");
+            }
+        }
+    }
+}

WorkingWithGestures/DragAndDropGesture/DragAndDropGesture/MainPage.xaml

@@ -8,17 +8,29 @@
         <TableRoot>
             <TableSection Title="Drag and drop">
                 <TextCell Text="Text drag demo"
+                          Detail="Events"
                           Command="{Binding NavigateCommand}"
                           CommandParameter="{x:Type local:TextDragDemoPage}" />
                 <TextCell Text="Image drag demo"
+                          Detail="Events"
                           Command="{Binding NavigateCommand}"
                           CommandParameter="{x:Type local:ImageDragDemoPage}" />
                 <TextCell Text="Data package drag demo"
+                          Detail="Events"
                           Command="{Binding NavigateCommand}"
                           CommandParameter="{x:Type local:DataPackageDemoPage}" />
+                <TextCell Text="Data package drag demo"
+                          Detail="Commands"
+                          Command="{Binding NavigateCommand}"
+                          CommandParameter="{x:Type local:DataPackageCommandDemoPage}" />
                 <TextCell Text="Custom data package drag demo"
+                          Detail="Events"
                           Command="{Binding NavigateCommand}"
                           CommandParameter="{x:Type local:CustomDataPackageDemoPage}" />
+                <TextCell Text="Custom data package drag demo"
+                          Detail="Commands"
+                          Command="{Binding NavigateCommand}"
+                          CommandParameter="{x:Type local:CustomDataPackageCommandDemoPage}" />
             </TableSection>
         </TableRoot>
     </TableView>