WPF - 无法更改OnChanged方法内的GUI属性(从FileSystemWatcher触发)

Question

我想在OnChanged方法中更改GUI属性...(实际上我试图设置图像源..但为了简单起见,这里使用了一个按钮).每次filesystemwatcher检测到文件中的更改时都会调用它.它会转到"顶部"输出..但在尝试设置按钮宽度时会捕获异常.

但如果我把相同的代码放在一个按钮..它的工作正常.我真诚地不明白为什么..能有人帮助我吗？

private void OnChanged(object source, FileSystemEventArgs e)
        {
            //prevents a double firing, known bug for filesystemwatcher
            try
            {
                _jsonWatcher.EnableRaisingEvents = false;
                FileInfo objFileInfo = new FileInfo(e.FullPath);
                if (!objFileInfo.Exists) return;   // ignore the file open, wait for complete write

                //do stuff here                    
                Console.WriteLine("top");
                Test_Button.Width = 500;
                Console.WriteLine("bottom");
            }
            catch (Exception)
            {
                //do nothing
            }
            finally
            {
                _jsonWatcher.EnableRaisingEvents = true;
            }
        }

我真的想做什么,而不是改变按钮宽度:

BlueBan1_Image.Source = GUI.GetChampImageSource(JSONFile.Get("blue ban 1"), "avatar");

Answer 1

问题是此事件是在后台线程上引发的.您需要将回调编组回UI线程:

// do stuff here                    
Console.WriteLine("top");
this.Dispatcher.BeginInvoke(new Action( () =>
{
    // This runs on the UI thread
    BlueBan1_Image.Source = GUI.GetChampImageSource(JSONFile.Get("blue ban 1"), "avatar");
    Test_Button.Width = 500;
}));
Console.WriteLine("bottom");