feat(dragdrop): Implement basic UI

src/Uno.UI/UI/Xaml/DragRoot.cs

@@ -0,0 +1,73 @@
+#nullable enable
+
+using System;
+using System.Linq;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Input;
+using Windows.UI.Xaml.Media;
+
+namespace Windows.UI.Xaml
+{
+	internal class DragRoot : Canvas
+	{
+		private readonly DragDropManager _manager;
+
+		public DragRoot(DragDropManager manager)
+		{
+			_manager = manager;
+
+			VerticalAlignment = VerticalAlignment.Stretch;
+			HorizontalAlignment = HorizontalAlignment.Stretch;
+			Background = new SolidColorBrush(Colors.Transparent);
+
+			//PointerEntered += OnPointerEntered;
+			//PointerExited += OnPointerExited;
+			//PointerMoved += OnPointerMoved;
+			//PointerReleased += OnPointerReleased;
+			//PointerCanceled += OnPointerCanceled;
+		}
+
+		public int PendingDragCount => Children.Count;
+
+		public void Show(DragView view)
+		{
+			view.IsHitTestVisible = false;
+			Children.Add(view);
+		}
+
+		public void Hide(DragView view)
+		{
+			Children.Remove(view);
+		}
+
+		private static void OnPointerEntered(object snd, PointerRoutedEventArgs e)
+		{
+			((DragRoot)snd)._manager.ProcessPointerEnteredWindow(e);
+			e.Handled = true;
+		}
+
+		private static void OnPointerExited(object snd, PointerRoutedEventArgs e)
+		{
+			((DragRoot)snd)._manager.ProcessPointerExitedWindow(e);
+			e.Handled = true;
+		}
+
+		private static void OnPointerMoved(object snd, PointerRoutedEventArgs e)
+		{
+			((DragRoot)snd)._manager.ProcessPointerMovedOverWindow(e);
+			e.Handled = true;
+		}
+
+		private static void OnPointerReleased(object snd, PointerRoutedEventArgs e)
+		{
+			((DragRoot)snd)._manager.ProcessPointerReleased(e);
+			e.Handled = true;
+		}
+
+		private static void OnPointerCanceled(object snd, PointerRoutedEventArgs e)
+		{
+			((DragRoot)snd)._manager.ProcessPointerCanceled(e);
+			e.Handled = true;
+		}
+	}
+}

src/Uno.UI/UI/Xaml/DragView.cs

@@ -1,35 +1,192 @@
-#nullable enable
+#nullable enable
 
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using Windows.ApplicationModel.DataTransfer;
+using Windows.ApplicationModel.DataTransfer.DragDrop.Core;
 using Windows.Foundation;
 using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Media;
 
 namespace Windows.UI.Xaml
 {
 	internal class DragView : Control
 	{
-		private readonly Stack<DragUIOverride> _overrides = new Stack<DragUIOverride>();
+		#region Glyph
+		public static readonly DependencyProperty GlyphProperty = DependencyProperty.Register(
+			"Glyph", typeof(string), typeof(DragView), new PropertyMetadata(default(string)));
+
+		public string Glyph
+		{
+			get { return (string)GetValue(GlyphProperty); }
+			set { SetValue(GlyphProperty, value); }
+		} 
+		#endregion
+
+		#region GlyphVisibility
+		public static readonly DependencyProperty GlyphVisibilityProperty = DependencyProperty.Register(
+			"GlyphVisibility", typeof(Visibility), typeof(DragView), new PropertyMetadata(default(Visibility)));
+
+		public Visibility GlyphVisibility
+		{
+			get => (Visibility)GetValue(GlyphVisibilityProperty);
+			private set => SetValue(GlyphVisibilityProperty, value);
+		}
+		#endregion
+
+		#region Caption
+		public static readonly DependencyProperty CaptionProperty = DependencyProperty.Register(
+			"Caption", typeof(string), typeof(DragView), new PropertyMetadata(default(string)));
+
+		public string Caption
+		{
+			get => (string)GetValue(CaptionProperty);
+			set => SetValue(CaptionProperty, value);
+		}
+		#endregion
+
+		#region CaptionVisibility
+		public static readonly DependencyProperty CaptionVisibilityProperty = DependencyProperty.Register(
+			"CaptionVisibility", typeof(Visibility), typeof(DragView), new PropertyMetadata(default(Visibility)));
+
+		public Visibility CaptionVisibility
+		{
+			get => (Visibility)GetValue(CaptionVisibilityProperty);
+			private set => SetValue(CaptionVisibilityProperty, value);
+		}
+		#endregion
+
+		#region Content
+		public static readonly DependencyProperty ContentProperty = DependencyProperty.Register(
+			"Content", typeof(ImageSource), typeof(DragView), new PropertyMetadata(default(ImageSource)));
+
+		public ImageSource? Content
+		{
+			get => (ImageSource?)GetValue(ContentProperty);
+			private set => SetValue(ContentProperty, value);
+		}
+		#endregion
+
+		#region ContentVisibility
+		public static readonly DependencyProperty ContentVisibilityProperty = DependencyProperty.Register(
+			"ContentVisibility", typeof(Visibility), typeof(DragView), new PropertyMetadata(default(Visibility)));
+
+		public Visibility ContentVisibility
+		{
+			get => (Visibility)GetValue(ContentVisibilityProperty);
+			private set => SetValue(ContentVisibilityProperty, value);
+		}
+		#endregion
+
+		#region TooltipVisibility
+		public static readonly DependencyProperty TooltipVisibilityProperty = DependencyProperty.Register(
+			"TooltipVisibility", typeof(Visibility), typeof(DragView), new PropertyMetadata(default(Visibility)));
+
+		public Visibility TooltipVisibility
+		{
+			get => (Visibility)GetValue(TooltipVisibilityProperty);
+			set => SetValue(TooltipVisibilityProperty, value);
+		} 
+		#endregion
+
+		private readonly DragUI? _ui;
+		private readonly TranslateTransform _transform;
+
+		private Point _location;
 
 		public DragView(DragUI? ui)
 		{
-
+			_ui = ui;
+			DefaultStyleKey = typeof(DragView);
+			RenderTransform = _transform = new TranslateTransform();
+
+			Content = ui?.Content;
 		}
 
 		public void SetLocation(Point location)
 		{
+			// TODO: Make sure to not move the element out of the bounds of the window
+			_location = location;
 
+			_transform.X = location.X - (ActualWidth / 2);
+			_transform.Y = location.Y - 40; // The caption is above the pointer
 		}
 
-		public void Stack(DragUIOverride @override)
+		public void Update(DataPackageOperation acceptedOperation, CoreDragUIOverride viewOverride)
+		{
+			// UWP does not allow new lines (trim to the first line, even if blank) and trims the text.
+			var caption = viewOverride
+				.Caption
+				?.Split(new[] {'\r', '\n'}, StringSplitOptions.None)
+				.FirstOrDefault()
+				?.Trim();
+
+			if (string.IsNullOrEmpty(caption))
+			{
+				caption = ToCaption(acceptedOperation);
+			}
+
+			Glyph = ToGlyph(acceptedOperation);
+			GlyphVisibility = ToVisibility(viewOverride.IsGlyphVisible);
+			Caption = caption!;
+			CaptionVisibility = ToVisibility(viewOverride.IsCaptionVisible);
+			Content = viewOverride.Content as ImageSource ?? _ui?.Content;
+			ContentVisibility = ToVisibility(viewOverride.IsContentVisible);
+			TooltipVisibility = ToVisibility(viewOverride.IsGlyphVisible || viewOverride.IsCaptionVisible);
+			Visibility = Visibility.Visible;
+		}
+
+		public void Hide()
+		{
+			Visibility = Visibility.Collapsed;
+		}
+
+		private static Visibility ToVisibility(bool isVisible)
+			=> isVisible ? Visibility.Visible : Visibility.Collapsed;
+
+		private static string ToGlyph(DataPackageOperation result)
 		{
-			_overrides.Push(@override);
+			// If multiple flags set (which should not!), the UWP precedence is Link > Copy > Move
+			// TODO: Real glyph
+			if (result.HasFlag(DataPackageOperation.Link))
+			{
+				return "🔗";
+			}
+			else if (result.HasFlag(DataPackageOperation.Copy))
+			{
+				return "⎘";
+			}
+			else if (result.HasFlag(DataPackageOperation.Move))
+			{
+				return "🡕";
+			}
+			else // None
+			{
+				return "🚫";
+			}
 		}
 
-		public void Pop()
+		private static string ToCaption(DataPackageOperation result)
 		{
-			_overrides.Pop();
+			// If multiple flags set (which should not!), the UWP precedence is Link > Copy > Move
+			// TODO: Localize
+			if (result.HasFlag(DataPackageOperation.Link))
+			{
+				return "Link";
+			}
+			else if (result.HasFlag(DataPackageOperation.Copy))
+			{
+				return "Copy";
+			}
+			else if (result.HasFlag(DataPackageOperation.Move))
+			{
+				return "Move";
+			}
+			else // None
+			{
+				return string.Empty;
+			}
 		}
 	}
 }

src/Uno.UI/UI/Xaml/DragView.xaml

@@ -0,0 +1,45 @@
+<ResourceDictionary
+	xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+	xmlns:win="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+	xmlns:u="using:Uno.UI.Controls"
+	xmlns:ios="http://uno.ui/ios"
+	xmlns:android="http://uno.ui/android"
+	xmlns:wasm="http://uno.ui/wasm"
+	xmlns:netstdref="http://uno.ui/netstdref"
+	xmlns:skia="http://uno.ui/skia"
+	xmlns:macos="http://uno.ui/macos"
+	xmlns:uBehaviors="using:Uno.UI.Behaviors"
+	mc:Ignorable="d ios android wasm netstdref macos skia">
+
+	<!-- Default style for Windows.UI.Xaml.Controls.ScrollViewer -->
+	<Style TargetType="DragView">
+		<Setter Property="IsTabStop" Value="False" />
+		<Setter Property="IsHitTestVisible" Value="False" />
+		<Setter Property="HorizontalAlignment" Value="Left" />
+		<Setter Property="VerticalAlignment" Value="Top" />
+		<Setter Property="Padding" Value="0" />
+		<Setter Property="BorderThickness" Value="0" />
+		<Setter Property="Template">
+			<Setter.Value>
+				<ControlTemplate TargetType="DragView">
+					<Grid>
+						<Image Visibility="{TemplateBinding CaptionVisiblity}" Source="{TemplateBinding Content}" Opacity=".8" />
+						<StackPanel
+							Orientation="Horizontal"
+							BorderThickness="1"
+							BorderBrush="{StaticResource SystemControlForegroundChromeHighBrush}"
+							Background="{StaticResource SystemControlBackgroundChromeMediumLowBrush}"
+							Padding="2,5"
+							Visibility="{TemplateBinding TooltipVisibility}">
+							<TextBlock Visibility="{TemplateBinding GlyphVisiblity}" Text="{TemplateBinding Glyph}" Margin="3,0" />
+							<TextBlock Visibility="{TemplateBinding CaptionVisiblity}" Text="{TemplateBinding Caption}" Margin="3,0" />
+						</StackPanel>
+					</Grid>
+				</ControlTemplate>
+			</Setter.Value>
+		</Setter>
+	</Style>
+</ResourceDictionary>