c# - 标签 MVVM 中显示的 WPF 百分比状态

Question

我在 WCF 的 GridView 中显示下载百分比时遇到了一些问题。我使用了 MVVM 模式。

这是我在应用程序启动时的后台 worker :

public partial class MainWindow : Window
   {
       public MainWindow()
       {
           Overall.EverythingOk = "Nothing";

           InitializeComponent();
           //IRepo repo = new Repo();
           ViewModel.MainWindowsViewModel viewModel = new ViewModel.MainWindowsViewModel();
           this.DataContext = viewModel;     
           BackGroundThread bgT = new BackGroundThread();
           bgT.bgWrk.RunWorkerAsync();
       }}

这是BackGroundTHread类中的DoWork函数

 public void bw_DoWork(object sender, DoWorkEventArgs e)
   {
       if (!Overall.stopStatus)
       {
           for (int i=0; i < 10000; i++)
           {
               Overall.PercentageDwnd = i;
               Overall.caseRefId = "999999";
               if (i == 9998)
               {
                   i = 1;
               }
           }
       }
   }

Overall.PercentageDwnd 和 Overall.caseRefId 是静态变量(您可以从应用程序的任何地方调用)并且始终更新直到后台工作人员完成。我得到了另一个名为 TestViewModel 的 ViewModel，就在这里。

public class TestViewModel:BindableBase
    {        
        private String _UpdatePer=Overall.PercentageDwnd.ToString();
        public String UpdatePercentage
        {
            get { return _UpdatePer; }
            set { SetProperty(ref _UpdatePer, value); }
        }

        private ObservableCollection _ViewAKA = new ObservableCollection();
        private tblTransaction model;

        public TestViewModel(tblTransaction model)
        {
            // TODO: Complete member initialization

        }
        public ObservableCollection ViewAKA
        {
            get { return _ViewAKA; }
            set { SetProperty(ref _ViewAKA, value); }
        }
    }

我绑定(bind)了 TestView.xaml 文件

    <Window x:Class="EmployeeManager.View.TestView"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="TestView" Height="359.774" Width="542.481">
    <Grid Margin="0,0,2,0">
        <Label Content="{Binding UpdatePercentage,UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Background="Red" Foreground="White" Margin="130,86,0,0" VerticalAlignment="Top" Width="132" Height="39">            
        </Label> 
    </Grid>
</Window>

Label 没有实时更新，即使我将 UpdatePercentage 绑定(bind)到它。如何实时更新标签？

Answer 1

问题在于您正在更新未绑定(bind)任何内容的静态属性。您需要为绑定(bind)到标签控件的属性更新和引发属性更改通知，即 UpdatePercentage

能否将 TestViewModel 实例传递到 RunWorkerAsync 调用中？

bgT.bgWrk.RunWorkerAsync(testViewModel);

然后在DoWork事件处理器中访问:

public void bw_DoWork(object sender, DoWorkEventArgs e)
{
   if (!Overall.stopStatus)
   {
       var viewModel = e.Argument as TestViewModel;
       for (int i=0; i < 10000; i++)
       {
           Overall.PercentageDwnd = i;
           viewModel.UpdatePercentage = i;
           Overall.caseRefId = "999999";
           if (i == 9998)
           {
               i = 1;
           }
        }
    }
}