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在之前的问题中,我问过如何访问回调线程中的UI元素。我得到了很多很好的答案,其中之一就是实现一个包装类,如这样的:UI线程/调度问题(BeginInvoke)
public static class UIThread
{
private static readonly Dispatcher Dispatcher;
static UIThread()
{
Dispatcher = Deployment.Current.Dispatcher;
}
public static void Invoke(Action action)
{
if (Dispatcher.CheckAccess())
{
action.Invoke();
}
else
{
Dispatcher.BeginInvoke(action);
}
}
}
而且你可以通过调用称这个为使用
UIThread.Invoke(() => TwitterPost.Text = "hello there");
但是我试图延长这一以下在我的回调函数
UIThread.Invoke(() => loadUserController(jsonObject));
以下方法:
private void loadUserController(JObject jsonObject)
{
string profile_image_url = (string)jsonObject["profile_image_url"];
string screen_name = (string)jsonObject["screen_name"];
string name = (string)jsonObject["name"];
string location = (string)jsonObject["location"];
int statuses_count = (int)jsonObject["statuses_count"];
if (!string.IsNullOrEmpty(profile_image_url))
{
ProfileImage.Source = new BitmapImage(new Uri("blahblahbalhb.jpg", UriKind.Absolute));
}
// Set the screen name and display name if it differs
if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(screen_name))
{
ScreenName.Text = screen_name;
if (!screen_name.Equals(name))
{
_Name.Text = name;
}
}
if (!string.IsNullOrEmpty(location))
{
Location.Text = location;
}
Tweets.Text = statuses_count.ToString() + " Tweets";
}
然后,图像将不会呈现,直到另一个动作强制重绘(单击按钮),但文本控件将被更新。如果在我的回调函数中,我将调用setImageFile(string imageFile),其实现为:
private void setImageFile(string imageFile)
{
if (this.Dispatcher.CheckAccess())
{
ProfileImage.Source = new BitmapImage(new Uri("fdsfdfdsf.jpg", UriKind.Absolute));
}
else
{
this.Dispatcher.BeginInvoke(new Action<string>(setImageFile), imageFile);
}
}
然后图像将立即呈现。这是为什么发生?调度员的哪些属性我不完全理解?