Fix Windows Popup Position and Size

[cat0363]

This PR fixes the following:

1. The content of the Popup will not be displayed beyond the size specified in the Size property of the Popup.
2. If Center is specified for VerticalOptions of Popup, the Popup will be displayed in the center of the Window where the Popup is displayed.
3. If End is specified for VerticalOptions of Popup, the Popup will be displayed so that it fits at the bottom of the Window where the Popup is displayed.
4. The position of the Popup will be updated according to the resizing of the Window that displays the Popup.

Description of Change

Modified as follows to update the position of the Popup following the resizing of the Window that displays the Popup.

[src\CommunityToolkit.Maui.Core\Handlers\Popup\PopUpHandler.windows.cs]

protected override void ConnectHandler(Popup platformView)
{
    platformView.Closed += OnClosed;
    platformView.ConfigureControl(VirtualView, MauiContext);
    if (MauiContext is not null)
    {
        MauiContext.GetPlatformWindow().SizeChanged += OnSizeChanged;
    }
    base.ConnectHandler(platformView);
}

protected override void DisconnectHandler(Popup platformView)
{
    ArgumentNullException.ThrowIfNull(VirtualView.Parent);
    ArgumentNullException.ThrowIfNull(VirtualView.Handler?.MauiContext);
    var parent = VirtualView.Parent.ToPlatform(VirtualView.Handler.MauiContext);
    parent.IsHitTestVisible = true;
    platformView.IsOpen = false;
    platformView.Closed -= OnClosed;
    if (MauiContext is not null)
    {
        MauiContext.GetPlatformWindow().SizeChanged -= OnSizeChanged;
    }
}

void OnSizeChanged(object? sender, WindowSizeChangedEventArgs e)
{
    if (VirtualView is not null)
    {
        PopupExtensions.SetSize(PlatformView, VirtualView);
        PopupExtensions.SetLayout(PlatformView, VirtualView, MauiContext);
    }
}

Caught Window's SizeChanged event and called SetSize and SetLayout methods.
As a result, the position of the Popup is updated according to the resizing of the Window that displays the Popup.

Next, I added the following code to limit the Content Size to the Size specified in the Popup's Size property.

[src\CommunityToolkit.Maui.Core\Views\Popup\PopupExtensions.windows.cs]

public static void SetSize(this Popup mauiPopup, IPopup popup)
{
    omit ... 

    if (popup.Parent is IView popupParent)
    {
        currentSize.Width = Math.Min(currentSize.Width, popupParent.Frame.Width);
        currentSize.Height = Math.Min(currentSize.Height, popupParent.Frame.Height);
    }
	
    mauiPopup.Width = currentSize.Width;
    mauiPopup.Height = currentSize.Height;
    mauiPopup.MinWidth = mauiPopup.MaxWidth = currentSize.Width + (defaultBorderThickness * 2);
    mauiPopup.MinHeight = mauiPopup.MaxHeight = currentSize.Height + (defaultBorderThickness * 2);

    if (mauiPopup.Child is FrameworkElement control)
    {
        control.Width = mauiPopup.Width;
        control.Height = mauiPopup.Height;
    }
}

By explicitly specifying the size of the Popup's Child, the size of the Popup is now limited.

Next, I changed the code as follows so that it is displayed at the intended position when Center or End is specified for VerticalOptions of Popup.

static Rect? GetTitleBarRectangle(IMauiContext? mauiContext)
{
    if (!AppWindowTitleBar.IsCustomizationSupported())
    {
        return null;
    }

    if (mauiContext?.GetNavigationRootManager()?.RootView is WindowRootView rootView &&
        rootView.AppTitleBarContainer is FrameworkElement element)
    {
        return new Rect((int)element.Margin.Left, 0, (int)element.ActualWidth, (int)element.ActualHeight);
    }

    return null;
}

public static void SetLayout(this Popup mauiPopup, IPopup popup, IMauiContext? mauiContext)
{
    ArgumentNullException.ThrowIfNull(mauiContext);
    var popupParent = popup.Parent as IView;
    popup.Content?.Measure(double.PositiveInfinity, double.PositiveInfinity);
    var contentSize = popup.Content?.ToPlatform(mauiContext).DesiredSize ?? Windows.Foundation.Size.Empty;
    var popupParentFrame = popupParent?.Frame ?? new Rect(0, 0, contentSize.Width, contentSize.Height);

    Rect? titleBarRect = GetTitleBarRectangle(mauiContext);

    var verticalOptions = popup.VerticalOptions;
    var horizontalOptions = popup.HorizontalOptions;
    if (IsTopLeft(verticalOptions, horizontalOptions))
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.TopEdgeAlignedLeft;
        mauiPopup.HorizontalOffset = 0;
        mauiPopup.VerticalOffset = 0;
    }
    else if (IsTop(verticalOptions, horizontalOptions))
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.Top;
        mauiPopup.HorizontalOffset = (popupParentFrame.Width - contentSize.Width) / 2;
        mauiPopup.VerticalOffset = 0;
    }
    else if (IsTopRight(verticalOptions, horizontalOptions))
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.TopEdgeAlignedRight;
        mauiPopup.HorizontalOffset = (popupParentFrame.Width - contentSize.Width);
        mauiPopup.VerticalOffset = 0;
    }
    else if (IsRight(verticalOptions, horizontalOptions))
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.Right;
        mauiPopup.HorizontalOffset = (popupParentFrame.Width - contentSize.Width);
        mauiPopup.VerticalOffset = (popupParentFrame.Height - contentSize.Height / 2 + titleBarRect?.Height ?? 0) / 2;
    }
    else if (IsBottomRight(verticalOptions, horizontalOptions))
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.BottomEdgeAlignedRight;
        mauiPopup.HorizontalOffset = (popupParentFrame.Width - contentSize.Width);
        mauiPopup.VerticalOffset = popupParentFrame.Height - contentSize.Height / 2 + titleBarRect?.Height ?? 0;
    }
    else if (IsBottom(verticalOptions, horizontalOptions))
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.Bottom;
        mauiPopup.HorizontalOffset = (popupParentFrame.Width - contentSize.Width) / 2;
        mauiPopup.VerticalOffset = popupParentFrame.Height - contentSize.Height / 2 + titleBarRect?.Height ?? 0;
    }
    else if (IsBottomLeft(verticalOptions, horizontalOptions))
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.BottomEdgeAlignedLeft;
        mauiPopup.HorizontalOffset = 0;
        mauiPopup.VerticalOffset = popupParentFrame.Height - contentSize.Height / 2 + titleBarRect?.Height ?? 0;
    }
    else if (IsLeft(verticalOptions, horizontalOptions))
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.Left;
        mauiPopup.HorizontalOffset = 0;
        mauiPopup.VerticalOffset = (popupParentFrame.Height - contentSize.Height / 2 + titleBarRect?.Height ?? 0) / 2;
    }
    else if (popup.Anchor is null)
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.Auto;
        mauiPopup.HorizontalOffset = (popupParentFrame.Width - contentSize.Width) / 2;
        mauiPopup.VerticalOffset = (popupParentFrame.Height - contentSize.Height / 2 + titleBarRect?.Height ?? 0) / 2;
    }
    else
    {
        mauiPopup.DesiredPlacement = PopupPlacementMode.Top;
    }
    
    omit ...
}

I had to get the height of the Window's title bar because it wasn't taking into account the height of the Window's title bar.
The GetTitleBarRectangle method that acquires the Rectangle of the title bar added this time was implemented with reference to the following source code of .NET MAUI.

[src\Platform\Windows\WindowExtensions.cs]

internal static Rect[]? GetDefaultTitleBarDragRectangles(this UI.Xaml.Window platformWindow, IMauiContext mauiContext)
{
    if (!AppWindowTitleBar.IsCustomizationSupported())
        return null;

    if (mauiContext?.GetNavigationRootManager()?.RootView is WindowRootView rootView &&
        rootView.AppTitleBarContainer is FrameworkElement element)
    {
        return new[]
        {
            new Rect((int)element.Margin.Left, 0, (int)element.ActualWidth, (int)element.ActualHeight),
        };
    }

    return null;
}

With this fix, when Center or End is specified for VerticalOptions of Popup, it is now displayed at the intended position.

Linked Issues

• Fixes [BUG] Incorrect Position and Size of Popup on Windows #1349

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: https://github.com/MicrosoftDocs/CommunityToolkit/pull/XYZ

Additional information

The following is the verification result when the Content Size exceeds the Size specified in the Popup Size property.

Size = "100, 100" HorizontalOptions = "Start" VerticalOptions = "Center"

You can see that the Popup's Content Size is limited by the Size specified in the Popup's Size property.

Next is the verification result when Center is specified for VerticalOptions of Popup.

Size = "100, 100" HorizontalOptions = "Start" VerticalOptions = "Center"

Size = "100, 100" HorizontalOptions = "Center" VerticalOptions = "Center"

Size = "100, 100" HorizontalOptions = "End" VerticalOptions = "Center"

The red line in the execution result is the horizontal and vertical center.
You can see that the Popup is displayed in the center of the Window from which the Popup is displayed when Center is specified for the VerticalOptions of the Popup.

Next is the verification result when End is specified for VerticalOptions of Popup.

Size = "100, 100" HorizontalOptions = "Start" VerticalOptions = "End"

Size = "100, 100" HorizontalOptions = "Center" VerticalOptions = "End"

Size = "100, 100" HorizontalOptions = "End" VerticalOptions = "End"

You can see that when the Popup's VerticalOptions is set to End, the Popup is displayed so that it fits at the bottom of the Window from which the Popup is displayed.

Next is the verification result when resizing the Window that is the display source of the Popup.

Size = "100, 100" HorizontalOptions = "Start" VerticalOptions = "End" CanBeDismissedByTappingOutsideOfPopup = "False"

[Before Resize]	[After Resize]

You can see that the position of the Popup is updated according to the resizing of the Window that displays the Popup.

Concerns:
I can't verify it because I don't have a verification environment for Windows 10 at hand.

[cat0363]

Additional Information:
Below is information about the support status of the AppWindowTitleBar.IsCustomizationSupported method.
https://learn.microsoft.com/en-us/windows/apps/develop/title-bar?tabs=wasdk

[cat0363]

The PR I uploaded today does not support maximizing/minimizing the window that displays the Popup, so we will fix it.
Please wait a moment now.

[cat0363]

In order to support maximizing/minimizing the window, the acquisition of the window
from which the Popup is displayed has been changed as follows.

var popupParent = mauiContext.GetPlatformWindow();

This removed the need to get the title bar height.

In addition, the calculation formulas for horizontal position and vertical position have been changed.
In addition, added behavior when Fill is specified for VerticalOptions and HorizontalOptions of Popup.

[VladislavAntonyuk]

Could you please resolve conflicts?

[cat0363]

@VladislavAntonyuk , I resolved the conflict.