ShrlAlgoToolkit/WPFluent/Controls/Primitives/CustomPopupPlacementHelper.cs

using System;
using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Media;

namespace WPFluent.Controls.Primitives;

internal static class CustomPopupPlacementHelper
{
    public static readonly DependencyProperty PlacementProperty =
        DependencyProperty.RegisterAttached("Placement", typeof(CustomPlacementMode), typeof(CustomPopupPlacementHelper), new PropertyMetadata(CustomPlacementMode.Top));

    public static CustomPlacementMode GetPlacement(DependencyObject element)
    {
        return (CustomPlacementMode)element.GetValue(PlacementProperty);
    }

    public static void SetPlacement(DependencyObject element, CustomPlacementMode value)
    {
        element.SetValue(PlacementProperty, value);
    }

    internal static CustomPopupPlacement[] PositionPopup(
        CustomPlacementMode placement,
        Size popupSize,
        Size targetSize,
        Point offset,
        FrameworkElement child = null!)
    {
        Matrix transformToDevice = default;
        if (child != null)
        {
            Helper.TryGetTransformToDevice(child, out transformToDevice);
        }

        var preferredPlacement = CalculatePopupPlacement(placement, popupSize, targetSize, offset, child!, transformToDevice);

        CustomPopupPlacement? alternativePlacement = null;
        var alternativePlacementMode = GetAlternativePlacementMode(placement);
        if (alternativePlacementMode.HasValue)
        {
            alternativePlacement = CalculatePopupPlacement(alternativePlacementMode.Value, popupSize, targetSize, offset, child!, transformToDevice);
        }

        if (alternativePlacement.HasValue)
        {
            return [preferredPlacement, alternativePlacement.Value];
        }
        else
        {
            return [preferredPlacement];
        }
    }

    private static CustomPopupPlacement CalculatePopupPlacement(
        CustomPlacementMode placement,
        Size popupSize,
        Size targetSize,
        Point offset,
        FrameworkElement child = null!,
        Matrix transformToDevice = default)
    {
        Point point;
        PopupPrimaryAxis primaryAxis;

        switch (placement)
        {
            case CustomPlacementMode.Top:
                point = new Point((targetSize.Width - popupSize.Width) / 2, -popupSize.Height);
                primaryAxis = PopupPrimaryAxis.Horizontal;
                break;

            case CustomPlacementMode.Bottom:
                point = new Point((targetSize.Width - popupSize.Width) / 2, targetSize.Height);
                primaryAxis = PopupPrimaryAxis.Horizontal;
                break;

            case CustomPlacementMode.Left:
                point = new Point(-popupSize.Width, (targetSize.Height - popupSize.Height) / 2);
                primaryAxis = PopupPrimaryAxis.Vertical;
                break;

            case CustomPlacementMode.Right:
                point = new Point(targetSize.Width, (targetSize.Height - popupSize.Height) / 2);
                primaryAxis = PopupPrimaryAxis.Vertical;
                break;

            case CustomPlacementMode.Full:
                point = new Point((targetSize.Width - popupSize.Width) / 2, (targetSize.Height - popupSize.Height) / 2);
                primaryAxis = PopupPrimaryAxis.None;
                break;

            case CustomPlacementMode.TopEdgeAlignedLeft:
                point = new Point(0, -popupSize.Height);
                primaryAxis = PopupPrimaryAxis.Horizontal;
                break;

            case CustomPlacementMode.TopEdgeAlignedRight:
                point = new Point(targetSize.Width - popupSize.Width, -popupSize.Height);
                primaryAxis = PopupPrimaryAxis.Horizontal;
                break;

            case CustomPlacementMode.BottomEdgeAlignedLeft:
                point = new Point(0, targetSize.Height);
                primaryAxis = PopupPrimaryAxis.Horizontal;
                break;

            case CustomPlacementMode.BottomEdgeAlignedRight:
                point = new Point(targetSize.Width - popupSize.Width, targetSize.Height);
                primaryAxis = PopupPrimaryAxis.Horizontal;
                break;

            case CustomPlacementMode.LeftEdgeAlignedTop:
                point = new Point(-popupSize.Width, 0);
                primaryAxis = PopupPrimaryAxis.Vertical;
                break;

            case CustomPlacementMode.LeftEdgeAlignedBottom:
                point = new Point(-popupSize.Width, targetSize.Height - popupSize.Height);
                primaryAxis = PopupPrimaryAxis.Vertical;
                break;

            case CustomPlacementMode.RightEdgeAlignedTop:
                point = new Point(targetSize.Width, 0);
                primaryAxis = PopupPrimaryAxis.Vertical;
                break;

            case CustomPlacementMode.RightEdgeAlignedBottom:
                point = new Point(targetSize.Width, targetSize.Height - popupSize.Height);
                primaryAxis = PopupPrimaryAxis.Vertical;
                break;
            //case CustomPopupPlacementMode.Auto:
            default:
                throw new ArgumentOutOfRangeException(nameof(placement));
        }

        if (child != null)
        {
            var childOffset = VisualTreeHelper.GetOffset(child);
            if (transformToDevice != default)
            {
                childOffset = transformToDevice.Transform(childOffset);
            }
            point -= childOffset;
        }

        return new CustomPopupPlacement(point, primaryAxis);
    }

    private static CustomPlacementMode? GetAlternativePlacementMode(CustomPlacementMode placement)
    {
        switch (placement)
        {
            case CustomPlacementMode.Top:
                return CustomPlacementMode.Bottom;

            case CustomPlacementMode.Bottom:
                return CustomPlacementMode.Top;

            case CustomPlacementMode.Left:
                return CustomPlacementMode.Right;

            case CustomPlacementMode.Right:
                return CustomPlacementMode.Left;

            case CustomPlacementMode.Full:
                return null;

            case CustomPlacementMode.TopEdgeAlignedLeft:
                return CustomPlacementMode.BottomEdgeAlignedLeft;

            case CustomPlacementMode.TopEdgeAlignedRight:
                return CustomPlacementMode.BottomEdgeAlignedRight;

            case CustomPlacementMode.BottomEdgeAlignedLeft:
                return CustomPlacementMode.TopEdgeAlignedLeft;

            case CustomPlacementMode.BottomEdgeAlignedRight:
                return CustomPlacementMode.TopEdgeAlignedRight;

            case CustomPlacementMode.LeftEdgeAlignedTop:
                return CustomPlacementMode.RightEdgeAlignedTop;

            case CustomPlacementMode.LeftEdgeAlignedBottom:
                return CustomPlacementMode.RightEdgeAlignedBottom;

            case CustomPlacementMode.RightEdgeAlignedTop:
                return CustomPlacementMode.RightEdgeAlignedTop;

            case CustomPlacementMode.RightEdgeAlignedBottom:
                return CustomPlacementMode.LeftEdgeAlignedBottom;
            //case CustomPopupPlacementMode.Auto:
            default:
                return null;
        }
    }
}

internal enum CustomPlacementMode
{
    Top = 0,
    Bottom = 1,
    Left = 2,
    Right = 3,
    Full = 4,
    TopEdgeAlignedLeft = 5,
    TopEdgeAlignedRight = 6,
    BottomEdgeAlignedLeft = 7,
    BottomEdgeAlignedRight = 8,
    LeftEdgeAlignedTop = 9,
    LeftEdgeAlignedBottom = 10,
    RightEdgeAlignedTop = 11,
    RightEdgeAlignedBottom = 12,
    //Auto = 13
}

file static class Helper
{
    public static bool TryGetTransformToDevice(Visual visual, out Matrix value)
    {
        var presentationSource = PresentationSource.FromVisual(visual);
        if (presentationSource != null)
        {
            value = presentationSource.CompositionTarget.TransformToDevice;
            return true;
        }

        value = default;
        return false;
    }
}