ShrlAlgoToolkit/Melskin/Extensions/VisualExtensions.cs

using System.Reflection;
using System.Windows.Controls.Primitives;
using System.Windows.Media.Media3D;

namespace Melskin.Extensions;

/// <summary>
///     VisualExtensions 类提供了对 WPF 视觉树和依赖属性操作的扩展方法。
///     该类中的方法主要用于在视觉树中查找特定元素、获取依赖属性值以及执行其他相关操作。
/// </summary>
public static class VisualExtensions
{
    /// <summary>
    ///     检查给定的依赖对象是否在其父级或子级中包含指定类型的元素。
    /// </summary>
    /// <typeparam name="T">要查找的类型，必须继承自DependencyObject。</typeparam>
    /// <param name="dp">当前的依赖对象，用于开始查找。</param>
    /// <returns>如果在父级或子级中找到指定类型的元素，则返回true；否则返回false。</returns>
    public static bool HitTest<T>(this DependencyObject dp) where T : DependencyObject
    {
        return dp.FindParent<T>() != null || dp.FindChild<T>() != null;
    }

    /// <summary>
    ///     如果指定的依赖属性值为默认值，则设置该属性的新值。
    /// </summary>
    /// <typeparam name="T">要设置的属性值的类型。</typeparam>
    /// <param name="o">要设置属性的DependencyObject。</param>
    /// <param name="property">要检查和设置的DependencyProperty。</param>
    /// <param name="value">要设置的新值。</param>
    /// <returns>如果属性被设置，则返回true；否则返回false。</returns>
    /// <exception cref="ArgumentNullException">当DependencyObject或DependencyProperty为null时抛出。</exception>
    /// <exception cref="ArgumentException">当提供的值类型与DependencyProperty的类型不匹配时抛出。</exception>
    public static bool SetIfDefault<T>(this DependencyObject o, DependencyProperty property, T value)
    {
        if (o == null)
            throw new ArgumentNullException(nameof(o), "DependencyObject cannot be null");
        if (property == null)
            throw new ArgumentNullException(nameof(property), "DependencyProperty cannot be null");

        if (!property.PropertyType.IsAssignableFrom(typeof(T)))
        {
            throw new ArgumentException(
                $"Expected {property.Name} to be of type {typeof(T).Name} but was {property.PropertyType}");
        }

        if (DependencyPropertyHelper.GetValueSource(o, property).BaseValueSource == BaseValueSource.Default)
        {
            o.SetValue(property, value);
            return true;
        }

        return false;
    }

    /// <summary>
    ///     WPF 的 VisualTreeHelper.GetParent 的增强版，支持内容元素
    /// </summary>
    public static DependencyObject? GetParentObject(this DependencyObject? child)
    {
        switch (child)
        {
            case null:
                return null;
            case ContentElement contentElement:
            {
                var parent = ContentOperations.GetParent(contentElement);
                if (parent != null) return parent;
                return contentElement is FrameworkContentElement fce ? fce.Parent : null;
            }
            case FrameworkElement frameworkElement:
            {
                var parent = frameworkElement.Parent;
                if (parent != null) return parent;
                break;
            }
        }

        return VisualTreeHelper.GetParent(child);
    }

    /// <summary>
    ///     获取依赖属性
    /// </summary>
    public static DependencyProperty? GetDependencyProperty(Type? type, string propertyName)
    {
        var fieldInfo = type?.GetField($"{propertyName}Property", BindingFlags.Static | BindingFlags.Public);
        return fieldInfo?.GetValue(null) as DependencyProperty;
    }

    /// <summary>
    ///     获取指定类型的依赖属性
    /// </summary>
    /// <param name="o"></param>
    /// <param name="propertyName">依赖属性的名称</param>
    /// <returns>返回找到的依赖属性，如果未找到则返回 null</returns>
    public static DependencyProperty? GetDependencyProperty(this DependencyObject? o, string propertyName)
    {
        return o != null ? GetDependencyProperty(o.GetType(), propertyName) : null;
    }

    /// <summary>
    /// 获取指定子元素的所有祖先元素。
    /// </summary>
    /// <param name="child"></param>
    /// <returns></returns>
    public static IEnumerable<DependencyObject> GetAncestors(this DependencyObject child)
    {
        var parent = VisualTreeHelper.GetParent(child);
        while (parent != null)
        {
            yield return parent;
            parent = VisualTreeHelper.GetParent(parent);
        }
    }

    /// <summary>
    ///     递归获取指定父元素的所有子元素。
    /// </summary>
    /// <param name="parent">要查找其子元素的父元素。</param>
    /// <param name="forceUsingTheVisualTreeHelper">如果为 true，则强制使用 VisualTreeHelper 获取子元素，否则优先使用逻辑树。</param>
    /// <returns>返回一个包含所有子元素的枚举集合。</returns>
    public static IEnumerable<DependencyObject> GetChildObjects(this DependencyObject? parent, bool forceUsingTheVisualTreeHelper = false)
    {
        if (parent == null) yield break;

        if (!forceUsingTheVisualTreeHelper && parent is ContentElement or FrameworkElement)
        {
            foreach (var obj in LogicalTreeHelper.GetChildren(parent))
            {
                if (obj is DependencyObject depObj)
                    yield return depObj;
            }
        }
        else if (parent is Visual or Visual3D)
        {
            var count = VisualTreeHelper.GetChildrenCount(parent);
            for (var i = 0; i < count; i++)
                yield return VisualTreeHelper.GetChild(parent, i);
        }
    }

    /// <summary>
    ///     递归查找所有指定类型的子元素
    /// </summary>
    public static IEnumerable<T> FindVisualChildren<T>(this DependencyObject parent)
        where T : DependencyObject
    {
        if (parent is Popup { Child: not null } popup)
        {
            if (popup.Child is T t)
                yield return t;
            foreach (var descendant in FindVisualChildren<T>(popup.Child))
                yield return descendant;
        }

        var childrenCount = VisualTreeHelper.GetChildrenCount(parent);
        for (var i = 0; i < childrenCount; i++)
        {
            var child = VisualTreeHelper.GetChild(parent, i);
            if (child is T t)
                yield return t;
            foreach (var descendant in FindVisualChildren<T>(child))
                yield return descendant;
        }
    }


    ///// <summary>
    /////     递归查找可视化树中指定类型的所有子元素
    ///// </summary>
    ///// <typeparam name="T">要查找的元素类型</typeparam>
    ///// <param name="depObj">起始依赖对象</param>
    ///// <returns>找到的所有匹配元素</returns>
    //public static IEnumerable<T> FindVisualChildren<T>(this DependencyObject? depObj) where T : DependencyObject
    //{
    //    if (depObj == null) yield break;

    //    for (var i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
    //    {
    //        var child = VisualTreeHelper.GetChild(depObj, i);
    //        if (child is T t)
    //            yield return t;

    //        // 递归查找子元素
    //        foreach (var descendant in FindVisualChildren<T>(child))
    //            yield return descendant;
    //    }
    //}

    /// <summary>
    ///     获取指定视觉对象的窗口句柄
    /// </summary>
    /// <param name="visual">要获取句柄的视觉对象</param>
    /// <returns>返回一个IntPtr类型的窗口句柄，如果未能找到句柄则返回IntPtr.Zero</returns>
    public static IntPtr GetHandle(this Visual visual)
    {
        return (PresentationSource.FromVisual(visual) as HwndSource)?.Handle ?? IntPtr.Zero;
    }

    /// <summary>
    ///     根据给定的属性路径从对象中获取属性值。
    /// </summary>
    /// <param name="obj">要从中获取属性值的对象。</param>
    /// <param name="path">属性的名称或路径。</param>
    /// <returns>如果找到并成功获取属性值，则返回该属性值；如果对象为空、属性不存在或获取失败，则返回空字符串。</returns>
    public static object GetPropertyValue(this object? obj, string path)
    {
        if (obj == null)
            return string.Empty;

        if (string.IsNullOrEmpty(path)) return obj;
        var property = obj.GetType().GetProperty(path);
        if (property == null) return obj;
        try
        {
            return property.GetValue(obj, null)!;
        }
        catch
        {
            try
            {
                var mInfo = obj.GetType().GetMethod($"get_{path}");
                if (mInfo != null)
                    return mInfo.Invoke(obj, null)!;
            }
            catch
            {
                // ignored
            }
        }

        return obj;
    }

    /// <summary>
    ///     递归查找第一个指定类型（可选名称）的子元素
    /// </summary>
    public static T? FindChild<T>(this DependencyObject? parent, string? childName = null)
        where T : DependencyObject
    {
        if (parent == null) return null;

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

            if (child is T t)
            {
                if (string.IsNullOrEmpty(childName))
                    return t;
                if (child is FrameworkElement fe && fe.Name == childName)
                    return t;
            }

            var foundChild = FindChild<T>(child, childName);
            if (foundChild != null)
                return foundChild;
        }

        return null;
    }

    /// <summary>
    ///     递归查找父元素，可指定类型和名称
    /// </summary>
    public static T? FindParent<T>(this DependencyObject? child, string? name = null)
        where T : DependencyObject
    {
        if (child == null) return null;
        var parent = GetParentObject(child);

        while (true)
        {
            if (parent is T t)
            {
                if (string.IsNullOrEmpty(name) || parent is FrameworkElement fe && fe.Name == name)
                    return t;
            }

            parent = GetParentObject(parent);
        }
    }

    /// <summary>
    /// </summary>
    /// <param name="parent"></param>
    /// <typeparam name="T"></typeparam>
    /// <returns></returns>
    public static T? FindVisualChild<T>(this DependencyObject? parent) where T : Visual
    {
        if (parent == null) return null;
        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        {
            var child = VisualTreeHelper.GetChild(parent, i);
            if (child is T correctlyTyped)
            {
                return correctlyTyped;
            }

            var descendent = FindVisualChild<T>(child);
            if (descendent != null)
            {
                return descendent;
            }
        }

        return null;
    }

    /// <summary>
    ///     从指定点尝试查找特定类型的元素。
    /// </summary>
    /// <typeparam name="T">要查找的元素类型。</typeparam>
    /// <param name="reference">参考UI元素，用于确定坐标系。</param>
    /// <param name="point">相对于参考元素的点。</param>
    /// <returns>如果找到则返回第一个匹配的元素，否则返回null。</returns>
    public static T? TryFindFromPoint<T>(UIElement reference, Point point)
        where T : DependencyObject
    {
        if (reference.InputHitTest(point) is not DependencyObject element) return null;
        if (element is T t) return t;
        return element.FindParent<T>();
    }
}