C# wpf实现控件刷新的示例代码

//创建
var da = new DoubleAnimation(1, 0, new Duration(TimeSpan.FromMilliseconds(1)), FillBehavior.Stop);
da.Completed += (S, E) {
//动画完成，此处表明控件已刷新
};
//启动动画触发绘制
elememt.BeginAnimation(Control.OpacityProperty, da);

 var tcs = new TaskCompletionSource();
 da.Completed += (S, E) => tcs.SetResult();
 await tcs.Task;

public static class ElementExtensions
{
    /// <summary>
    /// 等待控件真实刷新后
    /// </summary>
    internal static Task WaitForPaint(this UIElement elememt)
    {
        var tcs = new TaskCompletionSource();
        //通过动画来获取这个时机
        var da = new DoubleAnimation(1, 0, new Duration(TimeSpan.FromMilliseconds(1)), FillBehavior.Stop);
        da.Completed += (S, E) => tcs.SetResult();
        //启动动画触发绘制
        elememt.BeginAnimation(Control.OpacityProperty, da);
        return tcs.Task;
    }
}

private async void Button_Click(object sender, RoutedEventArgs e)
{   
    //隐藏工具条
    toolBar.Visibility= Visibility.Collapsed;
    //等待界面上真正隐藏
    await toolBar.WaitForPaint();
    //截屏
    略
    //显示工具条
    toolBar.Visibility= Visibility.Visible;
}

private async void Button_Click(object sender, RoutedEventArgs e)
{
    var button = sender as Button;
    Console.WriteLine("ActualWidth=" + button.ActualWidth + "   ActualHeight=" + button.ActualHeight);
    button.Width = 100;
    button.Height = 100;
    Console.WriteLine("ActualWidth=" + button.ActualWidth + "   ActualHeight=" + button.ActualHeight);
    await button.WaitForPaint();
    Console.WriteLine("ActualWidth=" + button.ActualWidth + "   ActualHeight=" + button.ActualHeight);
}