如何使用backgroundWorker填充SurfaceListBox [英] How to fill a SurfaceListBox with a backgroundWorker
问题描述
嘿那里，
Hey there,
我想在我的SurfaceListBox中填充XML结构的项目。这可以通过将ItemSourceProperty绑定到XPath过滤的文档来实现。有时需要一段时间才能装入所有物品。出于这个原因，我想调整加载过程。
i want to fill my SurfaceListBox with items of a XML-structure. This is possible by binding the ItemSourceProperty to the XPath filtered document. Sometimes it takes a while till all the items are loaded. For that reason i want to tweak the loading process.
我不认为可以通过使用itemsource绑定一个接一个地添加项目。因此，我有想法在backgroundWorker线程中加载新项目。如果物品尚未加载，我可以显示加载消息。
I don't think that the it is possible to add the items one after another by using the itemsource binding. Therefore i had the idea to load the new items in a backgroundWorker thread. If the items are not loaded yet i could display a loading-message.
private void Item_PreviewTouchUp(object sender, TouchEventArgs e)
{
loadingLibraryItems.Visibility = Visibility.Visible;
libraryListBox.Visibility = Visibility.Collapsed;
_Worker = new BackgroundWorker();
_Worker.DoWork += new DoWorkEventHandler(bgWorker_DoWork);
_Worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgWorker_WorkCompleted);
_Worker.RunWorkerAsync();
}
private void bgWorker_DoWork(object sender, DoWorkEventArgs e)
{
librarySourceBinding = new Binding();
librarySourceBinding.Source = libData.Document;
librarySourceBinding.XPath = "//Entry[@Category = "+catID+"]";
libraryListBox.SetBinding(SurfaceListBox.ItemsSourceProperty, librarySourceBinding);
}
private void bgWorker_WorkCompleted(object sender, RunWorkerCompletedEventArgs e)
{
loadingLibraryItems.Visibility = Visibility.Collapsed;
libraryListBox.Visibility = Visibility.Visible;
}
推荐答案
;
我做同样的事情，但在Mvvm
I'm doing the same thing but in Mvvm
例如：
你有一个属性ObservableCollectionEx< Image> MyImageCollection = new ObservableCollectionEx< Image>（）;
You have a property ObservableCollectionEx<Image> MyImageCollection = new ObservableCollectionEx<Image>();
您将该集合设置为列表框的itemsource。
you set that collection to be the itemsource of your listbox.
在loadingevent或任何你想要启动它的事件中（我不使用背景工作者，但它也是一个线程）
In the loadingevent or any event you want to start it (i don't use a backgroundworker but its also a thread)
&NBSP; ThreadPool.QueueUserWorkItem（o =>
ThreadPool.QueueUserWorkItem(o =>
{
{
; //加载图片或监视器的代码
//code to load image or wathever
MyImageCollection.add（新图片）;
MyImageCollection.add(the New Image);
; }）;
});
如果要在加载所有项目后设置某些内容的可见性，请计算在线程集之前需要多少项目
If you want to set the visibility of something after all items are loaded, you count how much items you need before the threadpool
Int NeededItems = 100;
Int NeededItems = 100;
Int CurrentItems = 0;
Int CurrentItems = 0;
添加内容后线程池中的内容在你的收藏中添加：
The in the threadpool after you added something to your collection you add:
Currentitems ++;
Currentitems++;
if（CurrentItems == NeededItems）设置可见性。
if(CurrentItems == NeededItems) set the visibility.
以下是Observa的代码bleCollectionEx类：
Here is the code of the ObservableCollectionEx class:
public class ObservableCollectionEx< T> ：ObservableCollection< T>
public class ObservableCollectionEx<T> : ObservableCollection<T>
&NBSP; {
{
&NBSP; &NBSP; &NBSP; //覆盖事件，以便该课程可以访问它
// Override the event so this class can access it
&NBSP; &NBSP; &NBSP;公共覆盖事件System.Collections.Specialized.NotifyCollectionChangedEventHandler CollectionChanged;
public override event System.Collections.Specialized.NotifyCollectionChangedEventHandler CollectionChanged;
&NBSP; &NBSP; &NBSP; protected override void OnCollectionChanged（System.Collections.Specialized.NotifyCollectionChangedEventArgs e）
protected override void OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
&NBSP; &NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; //很好 - 像MSDN一样使用BlockReentrancy
// Be nice - use BlockReentrancy like MSDN said
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP;使用（BlockReentrancy（））
using (BlockReentrancy())
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; System.Collections.Specialized.NotifyCollectionChangedEventHandler eventHandler = CollectionChanged;
System.Collections.Specialized.NotifyCollectionChangedEventHandler eventHandler = CollectionChanged;
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; if（eventHandler == null）
if (eventHandler == null)
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;返回;
return;
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;委托[]委托= eventHandler.GetInvocationList（）;
Delegate[] delegates = eventHandler.GetInvocationList();
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; //通过调用列表
// Walk thru invocation list
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; foreach（委托中的System.Collections.Specialized.NotifyCollectionChangedEventHandler处理程序）
foreach (System.Collections.Specialized.NotifyCollectionChangedEventHandler handler in delegates)
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; DispatcherObject dispatcherObject = handler.Target as DispatcherObject;
DispatcherObject dispatcherObject = handler.Target as DispatcherObject;
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; //如果订阅者是DispatcherObject且不同的帖子
// If the subscriber is a DispatcherObject and different thread
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; if（dispatcherObject！= null&& dispatcherObject.CheckAccess（）== false）
if (dispatcherObject != null && dispatcherObject.CheckAccess() == false)
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; //在目标调度员的线程中调用处理程序
// Invoke handler in the target dispatcher's thread
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; dispatcherObject.Dispatcher.Invoke（DispatcherPriority.DataBind，handler，this，e）;
dispatcherObject.Dispatcher.Invoke(DispatcherPriority.DataBind, handler, this, e);
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; }
}
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; else //按原样执行处理程序
else // Execute handler as is
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP;处理程序（this，e）;
handler(this, e);
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; }
}
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; }
}
&NBSP; &NBSP; &NBSP; }
}
&NBSP; }
}
这篇关于如何使用backgroundWorker填充SurfaceListBox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！
