Implement PointerGestureRecognizer

[rachelkang]

PointerGestureRecognizer

Description

Implementation of PointerGestureRecognizer with PointerEntered, PointerExited, and PointerMoved events.

Windows implementation complete!
Mac implementation TBD

Implements part of #9139

API Changes

Maui.Controls

namespace Microsoft.Maui.Controls
{
  /// <summary>
  /// Provides pointer gesture recognition and events.
  /// </summary>
  public sealed class PointerGestureRecognizer : GestureRecognizer
  {
      public static readonly BindableProperty PointerEnteredCommandProperty = BindableProperty.Create(nameof(PointerEnteredCommand), typeof(ICommand), typeof(PointerGestureRecognizer), null);
      
      public static readonly BindableProperty PointerEnteredCommandParameterProperty = BindableProperty.Create(nameof(PointerEnteredCommandParameter), typeof(object), typeof(PointerGestureRecognizer), null);
      
      public static readonly BindableProperty PointerExitedCommandProperty = BindableProperty.Create(nameof(PointerExitedCommand), typeof(ICommand), typeof(PointerGestureRecognizer), null);
      
      public static readonly BindableProperty PointerExitedCommandParameterProperty = BindableProperty.Create(nameof(PointerExitedCommandParameter), typeof(object), typeof(PointerGestureRecognizer), null);
      
      public static readonly BindableProperty PointerMovedCommandProperty = BindableProperty.Create(nameof(PointerMovedCommand), typeof(ICommand), typeof(PointerGestureRecognizer), null);
      
      public static readonly BindableProperty PointerMovedCommandParameterProperty = BindableProperty.Create(nameof(PointerMovedCommandParameter), typeof(object), typeof(PointerGestureRecognizer), null);

      public event EventHandler<PointerEventArgs>? PointerEntered;
      public event EventHandler<PointerEventArgs>? PointerExited;
      public event EventHandler<PointerEventArgs>? PointerMoved;

namespace Microsoft.Maui.Controls
{
    /// <summary>
    /// Arguments for PointerGestureRecognizer events.
    /// </summary>
    public class PointerEventArgs : EventArgs
    {
        public virtual Point? GetPosition(Element? relativeTo);
    }
}

Scenario

<Label 
  x:Name="hoverLabel"
  FontSize="24"
  Text="Hover me!">
  <Label.GestureRecognizers>
      <PointerGestureRecognizer PointerEntered="HoverBegan" PointerExited="HoverEnded" PointerMoved="HoverMoved" />
  </Label.GestureRecognizers>
</Label>
<Label x:Name="positionLabel" Text="Hover above label to reveal pointer position"/>

private void HoverBegan(object sender, PointerEventArgs e)
{
    hoverLabel.Text = "Thanks for hovering me!";
}

private void HoverEnded(object sender, PointerEventArgs e)
{
    hoverLabel.Text = "Hover me again!";
    positionLabel.Text = "Hover above label to reveal pointer position again";
}

private void HoverMoved(object sender, PointerEventArgs e)
{
    positionLabel.Text = $"Pointer position is at: {e.GetPosition((View)sender)}";
}

Screenshots

aka quick home video since my screen record isn't working at the moment :p

IMG_5070.MOV

[jfversluis]

Some minor code things mainly :)

[rmarinho]

API seems fine and it works. just little comments on code style but shouldn't block the merge.

• Needs public api file changes
• Maybe add some xml doc comments

Good stuff Rachel

[rmarinho]

just little thing we don't use the "private" keyword because it's the default

[rmarinho]

Is there a reason why there wouldn't be a Position?

[rachelkang]

We're using Point from Maui.Graphics - to my knowledge, there's no Position there

ccing @PureWeen who implemented GetPosition in his other PR

[PureWeen]

If the user passes an invalid element
The other option here would be to throw an exception

[rmarinho]

Suggested change

	if (cmd != null && cmd.CanExecute(PointerMovedCommandParameter))
	if (cmd?.CanExecute(PointerMovedCommandParameter))

[rachelkang]

Intellisense tells me this won't work since it can't implicitly convert type bool? to bool, so I'll leave this one as is for now.
Alternatively, I can cast it as a bool, but I prefer to leave it as is. Let me know what you think!

[PureWeen]

you can do it like this

cmd?.CanExecute(PointerMovedCommandParameter) == true

[rachelkang]

ahh of course, fixed!

[rmarinho]

i don't think you need this check since your are doing handler?. bellow