WPF线程和Dispather.Invoke [英] WPF Threading and Dispather.Invoke

问题描述

我在(*)行收到此错误:

I get this error at line (*):

PresentationCore.dll中发生了类型为'System.ArgumentException'的未处理的异常其他信息:已访问此API 带有来自错误上下文的参数.

An unhandled exception of type 'System.ArgumentException' occurred in PresentationCore.dll Additional information: This API was accessed with arguments from the wrong context.

奇怪的是，它经过了上面的行. 我的城市元素像一个图像一样被加载到MainWindow.xaml中.

The curious thing is that it passes the line above this. My City element is loaded in MainWindow.xaml like an Image for examle.

有人有想法吗?

public class City : FrameworkElement
{
    VisualCollection _buildingsList;

    public City()
    {
        Thread t = new Thread(new ThreadStart(Draw));
        t.start();
    }

    private void Draw() 
    {
        DrawingVisual building = new DrawingVisual();

        // [...]

        Dispatcher.Invoke(DispatcherPriority.Normal, new Action(() =>
        {
            _buildingsList.Clear();
            _buildingsList.Add(building); // (*)
        }));
    }

    protected override Visual GetVisualChild(int index)
    {
        return _buildingsList[index];
    }

    protected override int VisualChildrenCount
    {
        get { return _buildingsList.Count; }
    }
}

推荐答案

应仅在UI线程上添加和创建所有UI对象.

在您的情况下，您正在在后台线程上创建DrawingVisual并将其添加到UI线程的VisualCollection中.您还应该在UI线程上创建DrawingVisual.

In your case you are creating DrawingVisual on background thread and adding it in VisualCollection on UI thread. You should create DrawingVisual also on UI thread.

Dispatcher.Invoke(DispatcherPriority.Normal, new Action(() =>
{
   DrawingVisual building = new DrawingVisual(); <-- Create on UI thread.
   _buildingsList.Clear();
   _buildingsList.Add(building);
}));

这篇关于WPF线程和Dispather.Invoke的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！