CentralizedControl/HandyControl/HandyControl_Shared/Tools/Helper/VisualHelper.cs

using System;
using System.Linq;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Media;
using HandyControl.Tools.Interop;

namespace HandyControl.Tools;

public static class VisualHelper
{
    internal static VisualStateGroup TryGetVisualStateGroup(DependencyObject d, string groupName)
    {
        var root = GetImplementationRoot(d);
        if (root == null) return null;

        return VisualStateManager
            .GetVisualStateGroups(root)?
            .OfType<VisualStateGroup>()
            .FirstOrDefault(group => string.CompareOrdinal(groupName, group.Name) == 0);
    }

    internal static FrameworkElement GetImplementationRoot(DependencyObject d) =>
        1 == VisualTreeHelper.GetChildrenCount(d)
            ? VisualTreeHelper.GetChild(d, 0) as FrameworkElement
            : null;

    public static T GetChild<T>(DependencyObject d) where T : DependencyObject
    {
        if (d == null) return default;
        if (d is T t) return t;

        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(d); i++)
        {
            var child = VisualTreeHelper.GetChild(d, i);

            var result = GetChild<T>(child);
            if (result != null) return result;
        }

        return default;
    }

    public static T GetParent<T>(DependencyObject d) where T : DependencyObject =>
        d switch
        {
            null => default,
            T t => t,
            Window _ => null,
            _ => GetParent<T>(VisualTreeHelper.GetParent(d))
        };

    public static IntPtr GetHandle(this Visual visual) => (PresentationSource.FromVisual(visual) as HwndSource)?.Handle ?? IntPtr.Zero;

    internal static void HitTestVisibleElements(Visual visual, HitTestResultCallback resultCallback, HitTestParameters parameters) =>
        VisualTreeHelper.HitTest(visual, ExcludeNonVisualElements, resultCallback, parameters);

    private static HitTestFilterBehavior ExcludeNonVisualElements(DependencyObject potentialHitTestTarget)
    {
        if (!(potentialHitTestTarget is Visual)) return HitTestFilterBehavior.ContinueSkipSelfAndChildren;

        if (!(potentialHitTestTarget is UIElement uIElement) || uIElement.IsVisible && uIElement.IsEnabled)
            return HitTestFilterBehavior.Continue;

        return HitTestFilterBehavior.ContinueSkipSelfAndChildren;
    }

    internal static bool ModifyStyle(IntPtr hWnd, int styleToRemove, int styleToAdd)
    {
        var windowLong = InteropMethods.GetWindowLong(hWnd, InteropValues.GWL.STYLE);
        var num = (windowLong & ~styleToRemove) | styleToAdd;
        if (num == windowLong) return false;
        InteropMethods.SetWindowLong(hWnd, InteropValues.GWL.STYLE, num);
        return true;
    }
}