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322 lines
12 KiB
C#
322 lines
12 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Windows;
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using System.Windows.Media;
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namespace MediaBrowser.UI.Controls
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{
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/// <summary>
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/// Helper methods for UI-related tasks.
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/// </summary>
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public static class TreeHelper
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{
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/// <summary>
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/// Gets the window.
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/// </summary>
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/// <param name="element">The element.</param>
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/// <returns>Window.</returns>
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/// <value>The window.</value>
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public static Window GetWindow(this FrameworkElement element)
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{
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return element.ParentOfType<Window>();
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}
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/// <summary>
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/// Gets the parent.
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/// </summary>
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/// <param name="element">The element.</param>
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/// <returns>DependencyObject.</returns>
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private static DependencyObject GetParent(this DependencyObject element)
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{
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DependencyObject parent = VisualTreeHelper.GetParent(element);
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if (parent == null)
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{
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FrameworkElement frameworkElement = element as FrameworkElement;
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if (frameworkElement != null)
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{
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parent = frameworkElement.Parent;
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}
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}
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return parent;
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}
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/// <summary>
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/// Gets the parents.
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/// </summary>
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/// <param name="element">The element.</param>
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/// <returns>IEnumerable{DependencyObject}.</returns>
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/// <exception cref="System.ArgumentNullException">element</exception>
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public static IEnumerable<DependencyObject> GetParents(this DependencyObject element)
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{
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if (element == null)
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{
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throw new ArgumentNullException("element");
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}
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while ((element = element.GetParent()) != null)
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{
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yield return element;
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}
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yield break;
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}
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/// <summary>
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/// Parents the type of the of.
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="element">The element.</param>
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/// <returns>``0.</returns>
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public static T ParentOfType<T>(this DependencyObject element) where T : DependencyObject
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{
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if (element == null)
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{
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return default(T);
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}
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return element.GetParents().OfType<T>().FirstOrDefault<T>();
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}
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/// <summary>
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/// Finds a Child of a given item in the visual tree.
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/// </summary>
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/// <typeparam name="T">The type of the queried item.</typeparam>
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/// <param name="parent">A direct parent of the queried item.</param>
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/// <param name="childName">x:Name or Name of child.</param>
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/// <returns>The first parent item that matches the submitted type parameter.
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/// If not matching item can be found,
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/// a null parent is being returned.</returns>
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public static T FindChild<T>(DependencyObject parent, string childName)
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where T : DependencyObject
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{
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// Confirm parent and childName are valid.
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if (parent == null) return null;
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T foundChild = null;
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int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
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for (int i = 0; i < childrenCount; i++)
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{
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var child = VisualTreeHelper.GetChild(parent, i);
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// If the child is not of the request child type child
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T childType = child as T;
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if (childType == null)
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{
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// recursively drill down the tree
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foundChild = FindChild<T>(child, childName);
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// If the child is found, break so we do not overwrite the found child.
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if (foundChild != null) break;
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}
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else if (!string.IsNullOrEmpty(childName))
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{
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var frameworkElement = child as FrameworkElement;
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// If the child's name is set for search
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if (frameworkElement != null && frameworkElement.Name == childName)
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{
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// if the child's name is of the request name
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foundChild = (T)child;
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break;
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}
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}
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else
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{
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// child element found.
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foundChild = (T)child;
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break;
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}
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}
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return foundChild;
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}
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/// <summary>
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/// Gets the visual child.
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="referenceVisual">The reference visual.</param>
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/// <returns>``0.</returns>
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public static T GetVisualChild<T>(this Visual referenceVisual) where T : Visual
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{
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Visual child = null;
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for (Int32 i = 0; i < VisualTreeHelper.GetChildrenCount(referenceVisual); i++)
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{
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child = VisualTreeHelper.GetChild(referenceVisual, i) as Visual;
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if (child != null && (child.GetType() == typeof(T)))
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{
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break;
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}
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else if (child != null)
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{
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child = GetVisualChild<T>(child);
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if (child != null && (child.GetType() == typeof(T)))
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{
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break;
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}
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}
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}
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return child as T;
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}
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#region find parent
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/// <summary>
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/// Finds a parent of a given item on the visual tree.
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/// </summary>
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/// <typeparam name="T">The type of the queried item.</typeparam>
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/// <param name="child">A direct or indirect child of the
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/// queried item.</param>
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/// <returns>The first parent item that matches the submitted
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/// type parameter. If not matching item can be found, a null
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/// reference is being returned.</returns>
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public static T TryFindParent<T>(this DependencyObject child)
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where T : DependencyObject
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{
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//get parent item
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DependencyObject parentObject = GetParentObject(child);
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//we've reached the end of the tree
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if (parentObject == null) return null;
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//check if the parent matches the type we're looking for
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T parent = parentObject as T;
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if (parent != null)
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{
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return parent;
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}
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//use recursion to proceed with next level
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return TryFindParent<T>(parentObject);
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}
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/// <summary>
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/// This method is an alternative to WPF's
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/// <see cref="VisualTreeHelper.GetParent" /> method, which also
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/// supports content elements. Keep in mind that for content element,
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/// this method falls back to the logical tree of the element!
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/// </summary>
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/// <param name="child">The item to be processed.</param>
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/// <returns>The submitted item's parent, if available. Otherwise
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/// null.</returns>
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public static DependencyObject GetParentObject(this DependencyObject child)
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{
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if (child == null) return null;
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//handle content elements separately
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ContentElement contentElement = child as ContentElement;
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if (contentElement != null)
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{
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DependencyObject parent = ContentOperations.GetParent(contentElement);
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if (parent != null) return parent;
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FrameworkContentElement fce = contentElement as FrameworkContentElement;
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return fce != null ? fce.Parent : null;
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}
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//also try searching for parent in framework elements (such as DockPanel, etc)
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FrameworkElement frameworkElement = child as FrameworkElement;
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if (frameworkElement != null)
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{
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DependencyObject parent = frameworkElement.Parent;
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if (parent != null) return parent;
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}
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//if it's not a ContentElement/FrameworkElement, rely on VisualTreeHelper
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return VisualTreeHelper.GetParent(child);
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}
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#endregion
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#region find children
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/// <summary>
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/// Analyzes both visual and logical tree in order to find all elements of a given
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/// type that are descendants of the <paramref name="source" /> item.
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/// </summary>
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/// <typeparam name="T">The type of the queried items.</typeparam>
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/// <param name="source">The root element that marks the source of the search. If the
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/// source is already of the requested type, it will not be included in the result.</param>
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/// <returns>All descendants of <paramref name="source" /> that match the requested type.</returns>
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public static IEnumerable<T> FindChildren<T>(this DependencyObject source) where T : DependencyObject
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{
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if (source != null)
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{
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var childs = GetChildObjects(source);
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foreach (DependencyObject child in childs)
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{
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//analyze if children match the requested type
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if (child is T)
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{
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yield return (T)child;
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}
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//recurse tree
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foreach (T descendant in FindChildren<T>(child))
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{
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yield return descendant;
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}
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}
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}
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}
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/// <summary>
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/// This method is an alternative to WPF's
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/// <see cref="VisualTreeHelper.GetChild" /> method, which also
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/// supports content elements. Keep in mind that for content elements,
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/// this method falls back to the logical tree of the element.
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/// </summary>
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/// <param name="parent">The item to be processed.</param>
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/// <returns>The submitted item's child elements, if available.</returns>
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public static IEnumerable<DependencyObject> GetChildObjects(this DependencyObject parent)
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{
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if (parent == null) yield break;
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if (parent is ContentElement || parent is FrameworkElement)
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{
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//use the logical tree for content / framework elements
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foreach (object obj in LogicalTreeHelper.GetChildren(parent))
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{
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var depObj = obj as DependencyObject;
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if (depObj != null) yield return (DependencyObject)obj;
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}
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}
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else
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{
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//use the visual tree per default
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int count = VisualTreeHelper.GetChildrenCount(parent);
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for (int i = 0; i < count; i++)
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{
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yield return VisualTreeHelper.GetChild(parent, i);
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}
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}
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}
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#endregion
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#region find from point
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/// <summary>
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/// Tries to locate a given item within the visual tree,
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/// starting with the dependency object at a given position.
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/// </summary>
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/// <typeparam name="T">The type of the element to be found
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/// on the visual tree of the element at the given location.</typeparam>
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/// <param name="reference">The main element which is used to perform
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/// hit testing.</param>
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/// <param name="point">The position to be evaluated on the origin.</param>
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/// <returns>``0.</returns>
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public static T TryFindFromPoint<T>(UIElement reference, Point point)
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where T : DependencyObject
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{
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DependencyObject element = reference.InputHitTest(point) as DependencyObject;
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if (element == null) return null;
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if (element is T) return (T)element;
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return TryFindParent<T>(element);
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}
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#endregion
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}
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}
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