使用了Thread.Sleep时不是WPF标签更新() [英] Wpf Label not being updated when using Thread.Sleep()
问题描述
我有一个标签,我想以后每一秒更新,3秒后我只看到最后一个字符串第三步......我在做什么错误,有另一种方式,如果实现这一目标的内容出于某种原因,我不能使用Thread.sleep()方法:
查看:
<窗口x:类=WpfApplication1.ScrollerView
的xmlns =http://schemas.microsoft.com/winfx/2006/xaml/presentation
的xmlns:X =http://schemas.microsoft.com/winfx/2006/xaml
标题=滚轮的DataContext ={StaticResource的scrollerVM}HEIGHT =150WIDTH =300> ;
<网格和GT;
< ListBox中的ItemsSource ={结合消息}WIDTH =200HEIGHT =50了borderThickness =0VerticalAlignment =顶部的HorizontalAlignment =左>
< ItemsControl.ItemTemplate>
<&DataTemplate的GT;
<标签内容={结合文字}/>
< / DataTemplate中>
< /ItemsControl.ItemTemplate>
< /列表框>
<按钮宽度=70HEIGHT =24CONTENT =添加新的命令={结合的AddNew}的HorizontalAlignment =左保证金=0,56,0,30/>
< /网格和GT;
< /窗GT;
查看模式:
使用System.Collections.ObjectModel;
使用System.ComponentModel;
使用的System.Threading;
命名空间WpfApplication1.Scroller
{
公共类消息
{
公共信息(字符串_text)
{
文本= _文本;
}
私人字符串文本;
公共字符串文本
{
{返回文本; }
组的{text =值;}
}
}
公共类ScrollerViewModel:INotifyPropertyChanged的
{
公共事件PropertyChangedEventHandler的PropertyChanged;
公共DelegateCommand的AddNew {搞定;保护套; }
&的ObservableCollection LT;消息> _messages =新的ObservableCollection<消息>();
公众的ObservableCollection<消息>消息
{
{返回_messages; }
组
{
_messages =价值;
OnPropertyChanged(信息);
}
}
公共ScrollerViewModel()
{
的AddNew =新DelegateCommand(添加);
}
私人无效添加(对象参数)
{
的UpdateProgress(第1步......);
的UpdateProgress(第2步......);
的UpdateProgress(第三步......);
}
私人无效的UpdateProgress(字符串步)
{
Messages.Clear();
Messages.Add(新消息(步骤));
Thread.sleep代码(1000);
}
保护无效OnPropertyChanged(字符串propertyName的)
{
如果(的PropertyChanged!= NULL)
{
的PropertyChanged(这一点,新PropertyChangedEventArgs(propertyName的));
}
}
}
}
这是因为你在UI线程睡觉。该UI将不会有机会更新,直到添加完成。您可以使用一个BackgroundWorker与ReportProgress达到你想要的东西。事情是这样的:
BackgroundWorker的工人=新的BackgroundWorker();
worker.WorkerReportsProgress = TRUE;
worker.DoWork + =委托(对象S,DoWorkEventArgs参数)
{
worker.ReportProgress(1,第一步);
Thread.sleep代码(1000);
worker.ReportProgress(2,步骤2);
Thread.sleep代码(1000);
worker.ReportProgress(3,第三步);
};
worker.ProgressChanged + =委托(对象S,ProgressChangedEventArgs参数)
{
串步=(字符串)args.UserState;
Messages.Clear();
Messages.Add(新消息(步骤));
};
worker.RunWorkerAsync();
UI线程不会,而的DoWork $ C $被占用C>被执行,但在
ProgressChanged
将在UI线程上执行。
I have a Label the Content of which I would like to update after each second,after 3 seconds I only see the last string "Step 3..." What am I doing wrong and is there another way to achieve this if for some reason I cannot use Thread.Sleep():
View:
<Window x:Class="WpfApplication1.ScrollerView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Scroller" DataContext="{StaticResource scrollerVM}" Height="150" Width="300">
<Grid>
<ListBox ItemsSource="{Binding Messages}" Width="200" Height="50" BorderThickness="0" VerticalAlignment="Top" HorizontalAlignment="Left">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Label Content="{Binding Text}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ListBox>
<Button Width="70" Height="24" Content="Add new" Command="{Binding AddNew}" HorizontalAlignment="Left" Margin="0,56,0,30" />
</Grid>
</Window>
View model:
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Threading;
namespace WpfApplication1.Scroller
{
public class Message
{
public Message(string _text)
{
text = _text;
}
private string text;
public string Text
{
get { return text; }
set {text = value;}
}
}
public class ScrollerViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public DelegateCommand AddNew { get; protected set; }
ObservableCollection<Message> _messages = new ObservableCollection<Message>();
public ObservableCollection<Message> Messages
{
get { return _messages; }
set
{
_messages = value;
OnPropertyChanged("Messages");
}
}
public ScrollerViewModel()
{
AddNew = new DelegateCommand(Add);
}
private void Add(object parameter)
{
UpdateProgress("Step 1...");
UpdateProgress("Step 2...");
UpdateProgress("Step 3...");
}
private void UpdateProgress(string step)
{
Messages.Clear();
Messages.Add(new Message(step));
Thread.Sleep(1000);
}
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
}
It is because you are sleeping in the UI thread. The UI won't have a chance to update until Add is finished. You can use a BackgroundWorker with ReportProgress to achieve what you want. Something like this:
BackgroundWorker worker = new BackgroundWorker();
worker.WorkerReportsProgress = true;
worker.DoWork += delegate(object s, DoWorkEventArgs args)
{
worker.ReportProgress(1, "Step1");
Thread.Sleep(1000);
worker.ReportProgress(2, "Step2");
Thread.Sleep(1000);
worker.ReportProgress(3, "Step3");
};
worker.ProgressChanged += delegate(object s, ProgressChangedEventArgs args)
{
string step = (string)args.UserState;
Messages.Clear();
Messages.Add(new Message(step));
};
worker.RunWorkerAsync();
The UI thread won't be occupied while DoWork
is executed, but the code in ProgressChanged
will be performed on the UI thread.
这篇关于使用了Thread.Sleep时不是WPF标签更新()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!