WPF Canvas做自动缩放时获取控件的实际高度

        WPF在 Canvas控件，因为要实现自动缩放，高度和款第都是设置为自动的。如果用ActualWidth和ActualHeight返回的值都是零。

解决方法：

我们Loaded方法等程序加载完成之后再获取实际高度和宽度。

   

Loaded：在元素已布局、已呈现且可用于交互时发生。

<Window x:Class="Smoke.Weather.Main"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Loaded="Window_Loaded"
        Title="Main" Height="300" Width="300">
    <Canvas x:Name="Carrier"  Background="Transparent"   >

    </Canvas>
</Window>

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.Shapes;

namespace Smoke.Weather
{
    /// <summary>
    /// Main.xaml 的交互逻辑
    /// </summary>
    public partial class Main : Window
    {
        public Main()
        {
            InitializeComponent();
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            Button  Spirit = new Button();
            Spirit.Width = Carrier.ActualWidth;
            Spirit.Height = Carrier.ActualHeight;
            Carrier.Children.Add(Spirit);
        }
    }
}