WPF中获取动态添加控件的ActualHeight和相对坐标

      在WPF中有时会用到获取控件的ActualHeight，从而进行相关运算，我是需要在一个UniformGrid中动态的添加Button，然后获取 Button的ActualHeight和相对于UniformGrid的坐标。测试项目代码如下（VS2010）：
    XAML部分：

<Window x:Class="WpfApplication2.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="450" Width="525"> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition/> </Grid.ColumnDefinitions> <Grid.RowDefinitions> <RowDefinition Height="*"/> <RowDefinition Height="5*"/> </Grid.RowDefinitions> <Button Name="btnTest" Grid.Column="0" Grid.Row="0" Height="50" Click="btnTest_Click">TestHeight</Button> <UniformGrid Name="ufg" Height="300" Grid.Row="1" Margin="0,21"> </UniformGrid> </Grid></Window> 

     C#部分：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Windows;using System.Windows.Controls;using System.Windows.Data;using System.Windows.Documents;using System.Windows.Input;using System.Windows.Media;using System.Windows.Media.Imaging;using System.Windows.Navigation;using System.Windows.Shapes;namespace WpfApplication2{ /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void btnTest_Click(object sender, RoutedEventArgs e) { this.ufg.Children.Clear(); for (int i = 0; i < 20; i++) { Button btn = new Button(); btn.Content = i.ToString(); btn.Click += new RoutedEventHandler(btn_Click); this.ufg.Children.Add(btn); } Button b; GeneralTransform transform; Point thePoint; b = ufg.Children[10] as Button;//b的实际高度是60 MessageBox.Show("Before UpdateUniformGrid Children[10].ActualHeight:{0}", b.ActualHeight.ToString()); transform = b.TransformToAncestor(ufg); thePoint = transform.Transform(new Point(0, 0)); MessageBox.Show("Before UpdateUniformGrid the Point.Y relative to UniformGrid of Children[10](TransformToAncestor): {0}", thePoint.Y.ToString()); MessageBox.Show("Before UpdateUniformGrid the Point.Y relative to UniformGrid of Children[10](TranslatePoint):{0}", b.TranslatePoint(new Point(0, 0), ufg).Y.ToString()); ufg.UpdateLayout();//更新UniformGrid的界面，为获取ActualHeight很重要，但是获取相对坐标倒是可以没有 MessageBox.Show("After UpdateUniformGrid Children[10].ActualHeight:{0}", b.ActualHeight.ToString()); transform = b.TransformToAncestor(ufg); thePoint = transform.Transform(new Point(0, 0)); MessageBox.Show("After UpdateUniformGrid, the Point.Y relative to UniformGrid of Children[10](TransformToAncestor):{0}" , thePoint.Y.ToString()); MessageBox.Show("After UpdateUniformGrid, the Point.Y relative to UniformGrid of Children[10](TranslatePoint):{0}", b.TranslatePoint(new Point(0, 0), ufg).Y.ToString()); } //UniformGrid中Button单击事件 private void btn_Click(object sender, EventArgs e) { MessageBox.Show((sender as Button).ActualHeight.ToString()); Button b = sender as Button; MessageBox.Show("the Point.Y relative to UniformGrid:{0}", b.TranslatePoint(new Point(0, 0), ufg).Y.ToString()); } }}

       运行一下测试项目就会发现在UpdataLayout之前是得不到ActualHeight 的，但是可以得到相对坐标，而在UpdataLayout之后就可以得到ActualHeight和相对坐标。网上说WPF控件需要在Render之后才能得到ActualHeight，而UpdataLayout应该就有这个功能吧，初接触WPF，所以具体的原理还不太清楚。

      另外一个是在获取相对坐标的时，在for循环外的btnTest_Click事件中和在UniformGrid中的按钮单击事件中，使用TransformToAncestor，或TranslatePoint的方法才能得到，其实获取控件的相对坐标还有其他方法，在此不一一列出，需要的朋友可以Google一下。

附件下载（2010项目）