WPF TreeView tools

在WPF的TreeView使用方式和WinForm下有很大不同，那些展开某节点、获取父节点，判断某节点是否被选中等常用的操作在WinForm下都有相关函数，而在WPF中却不能轻易实现。

一种常规的方式是通过MVVM模式来将TreeViewItem节点中的IsSelect，IsExpanded等属性来双向绑定到要显示的节点数据中，然后直接通过节点数据的属性来实现相关操作。

但是，有的时候，当我们没有ViewModel层，但又想像WinFrom那样直接简单的获取或设置这些属性的时候，该如何办呢。其实WPF还是提供了类似WinForm中的这些设置的，只不过形式不一样了而已，但是却没WinFrom的那么直观和方便。CodeProject上就有人将常用函数总结了一下，写成了扩展函数，主要提供如下功能：

public static void SelectObject(this TreeView treeView, object obj)
public static void SelectObject(this TreeView treeView, object obj, bool selected)
public static bool IsObjectSelected(this TreeView treeView, object obj)
public static bool IsObjectFocused(this TreeView treeView, object obj)
public static void ExpandObject(this TreeView treeView, object obj)
public static void ExpandObject(this TreeView treeView, object obj, bool expanded)
public static bool IsObjectExpanded(this TreeView treeView, object obj)
public static TreeViewItem GetParentItem(this TreeViewItem item)

文章地址如下：WPF TreeView tools

但是，这里面有一个小bug：当TreeView节点中使用延迟绑定的时候，根据数据节点获取TreeItem会失败。这里我把它修正了一下，感兴趣的朋友可以直接使用我修改后的函数。  

代码

     public   static   class  TreeViewTools
    {
         ///   <summary>
         ///  Returns the TreeViewItem of a data bound object.
         ///   </summary>
         ///   <param name="treeView"> TreeView </param>
         ///   <param name="obj"> Data bound object </param>
         ///   <returns> The TreeViewItem of the data bound object or null. </returns>
         public   static  TreeViewItem GetItemFromObject( this  TreeView treeView,  object  obj)
        {
             try
            {
                DependencyObject dObject  =  GetContainerFormObject(treeView, obj);
                TreeViewItem tvi  =  dObject  as  TreeViewItem;
                 while  (tvi  ==   null )
                {
                    dObject  =  VisualTreeHelper.GetParent(dObject);
                    tvi  =  dObject  as  TreeViewItem;
                }
                 return  tvi;
            }
             catch  { }
             return   null ;
        }

         private   static  DependencyObject GetContainerFormObject(ItemsControl item,  object  obj)
        {
             if  (item  ==   null )
                 return   null ;

            DependencyObject dObject  =   null ;
            dObject  =  item.ItemContainerGenerator.ContainerFromItem(obj);

             if  (dObject  !=   null )
                 return  dObject;

            var query  =  from childItem  in  item.Items.Cast < object > ()
                        let childControl  =  item.ItemContainerGenerator.ContainerFromItem(childItem)  as  ItemsControl
                        select GetContainerFormObject(childControl, obj);

             return  query.FirstOrDefault(i  =>  i  !=   null );
        }

         ///   <summary>
         ///  Selects a data bound object of a TreeView.
         ///   </summary>
         ///   <param name="treeView"> TreeView </param>
         ///   <param name="obj"> Data bound object </param>
         public   static   void  SelectObject( this  TreeView treeView,  object  obj)
        {
            treeView.SelectObject(obj,  true );
        }

         ///   <summary>
         ///  Selects or deselects a data bound object of a TreeView.
         ///   </summary>
         ///   <param name="treeView"> TreeView </param>
         ///   <param name="obj"> Data bound object </param>
         ///   <param name="selected"> select or deselect </param>
         public   static   void  SelectObject( this  TreeView treeView,  object  obj,  bool  selected)
        {
            var tvi  =  treeView.GetItemFromObject(obj);
             if  (tvi  !=   null )
            {
                tvi.IsSelected  =  selected;
            }
        }

         ///   <summary>
         ///  Returns if a data bound object of a TreeView is selected.
         ///   </summary>
         ///   <param name="treeView"> TreeView </param>
         ///   <param name="obj"> Data bound object </param>
         ///   <returns> Returns true if the object is selected, and false if it is not selected or obj is not in the tree. </returns>
         public   static   bool  IsObjectSelected( this  TreeView treeView,  object  obj)
        {
            var tvi  =  treeView.GetItemFromObject(obj);
             if  (tvi  !=   null )
            {
                 return  tvi.IsSelected;
            }
             return   false ;
        }

         ///   <summary>
         ///  Returns if a data bound object of a TreeView is focused.
         ///   </summary>
         ///   <param name="treeView"> TreeView </param>
         ///   <param name="obj"> Data bound object </param>
         ///   <returns> Returns true if the object is focused, and false if it is not focused or obj is not in the tree. </returns>
         public   static   bool  IsObjectFocused( this  TreeView treeView,  object  obj)
        {
            var tvi  =  treeView.GetItemFromObject(obj);
             if  (tvi  !=   null )
            {
                 return  tvi.IsFocused;
            }
             return   false ;
        }

         ///   <summary>
         ///  Expands a data bound object of a TreeView.
         ///   </summary>
         ///   <param name="treeView"> TreeView </param>
         ///   <param name="obj"> Data bound object </param>
         public   static   void  ExpandObject( this  TreeView treeView,  object  obj)
        {
            treeView.ExpandObject(obj,  true );
        }

         ///   <summary>
         ///  Expands or collapses a data bound object of a TreeView.
         ///   </summary>
         ///   <param name="treeView"> TreeView </param>
         ///   <param name="obj"> Data bound object </param>
         ///   <param name="expanded"> expand or collapse </param>
         public   static   void  ExpandObject( this  TreeView treeView,  object  obj,  bool  expanded)
        {
            var tvi  =  treeView.GetItemFromObject(obj);
             if  (tvi  !=   null )
            {
                tvi.IsExpanded  =  expanded;
                 if  (expanded)
                {
                     //  update layout, so that following calls to f.e. SelectObject on child nodes will 
                     //  find theire TreeViewNodes
                    treeView.UpdateLayout();
                }
            }
        }

         ///   <summary>
         ///  Returns if a douta bound object of a TreeView is expanded.
         ///   </summary>
         ///   <param name="treeView"> TreeView </param>
         ///   <param name="obj"> Data bound object </param>
         ///   <returns> Returns true if the object is expanded, and false if it is collapsed or obj is not in the tree. </returns>
         public   static   bool  IsObjectExpanded( this  TreeView treeView,  object  obj)
        {
            var tvi  =  treeView.GetItemFromObject(obj);
             if  (tvi  !=   null )
            {
                 return  tvi.IsExpanded;
            }
             return   false ;
        }

         ///   <summary>
         ///  Retuns the parent TreeViewItem.
         ///   </summary>
         ///   <param name="item"> TreeViewItem </param>
         ///   <returns> Parent TreeViewItem </returns>
         public   static  TreeViewItem GetParentItem( this  TreeViewItem item)
        {
            var dObject  =  VisualTreeHelper.GetParent(item);
            TreeViewItem tvi  =  dObject  as  TreeViewItem;
             while  (tvi  ==   null )
            {
                dObject  =  VisualTreeHelper.GetParent(dObject);
                tvi  =  dObject  as  TreeViewItem;
            }
             return  tvi;
        }
    }

 

 

 

转载于:https://www.cnblogs.com/TianFang/archive/2010/02/06/1665162.html