如何刷新MVVM WPF中的UI

Question

我的项目基于MVVM模式.

我已经构建了一个显示我的文件系统的树视图.每个文件夹都有一个用于选择当前文件夹的复选框 选择过程需要一些时间,因此在操作运行时,有一个禁用的按钮,在操作结束时我启用按钮.

我的问题是,当按钮被"禁用"时,我会立即看到它.但是,当按钮返回启用模式时,我必须执行一些操作(如鼠标单击)以查看启用的按钮.

如何确保在启用按钮后立即更新UI？

这些是我的按钮:

<Button Content="&lt;- Back" Margin="5,0,5,0" Width="80" Height="25"
        IsEnabled="{Binding CanMoveToPreviousPage, UpdateSourceTrigger=PropertyChanged}" 
        Command="{Binding Path=NavigateBackCommand, IsAsync=True}" />

<Button Content="{Binding ButtonNextCaption}" Margin="5,0,5,0" Width="80" Height="25"
        IsEnabled="{Binding CanMoveToNextPage, UpdateSourceTrigger=PropertyChanged}" 
        Command="{Binding Path=NavigateNextCommand, IsAsync=True}" />

在我的ViewModel中,我添加了以下代码:

public bool CanMoveToNextPage
{
    get
    {
        return this.CurrentPage != null && this.CurrentPage.CanMoveNext;
    }
    set
    {
        if (CurrentPage != null)
        {
            this.CurrentPage.CanMoveNext = value;
            OnPropertyChanged("CanMoveToNextPage");
        }
    }
}

public bool CanMoveToPreviousPage
{
    get { return 0 < this.CurrentPageIndex && CurrentPage.CanMoveBack; }
    set
    {
        if (CurrentPage != null)
        {
            this.CurrentPage.CanMoveBack = value;
            OnPropertyChanged("CanMoveToPreviousPage");
        }
    }
}

UI更新发生在我执行鼠标单击或任何击键后.

这是禁用和启用按钮的操作代码:

void bg_RunWorkerCompleted(object sender, System.ComponentModel.RunWorkerCompletedEventArgs e)
{
    DecrementDoneCounter();
    if (ThreadSafeCouner == 0)//means all bg workers are done
    {
        UIlimitation(true);
    }
}

private int ThreadSafeCouner; // check how many bgworkers run
public void IncrementDoneCounter() { Interlocked.Increment(ref ThreadSafeCouner); }
public void DecrementDoneCounter() { Interlocked.Decrement(ref ThreadSafeCouner); }


void bg_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
{
    IncrementDoneCounter();
    UIlimitation(false);
    ((bgArguments)e.Argument).SelectedDirectory.CanSelected = false;
    MarkItems(((bgArguments)e.Argument).SelectedDirectory, ((bgArguments)e.Argument).IsSelect);
    ((bgArguments)e.Argument).FreeWorkerAllocation();
    ((bgArguments)e.Argument).SelectedDirectory.CanSelected = true;
}

//this is the enabling action which execute the propeties setters at the upper part of this post
private static void UIlimitation(bool limit)
{
    MainWindowViewModel.Instance.CanMoveToNextPage = limit;
    MainWindowViewModel.Instance.CanMoveToPreviousPage = limit;
}

我能做什么？

Answer 1

您可以调整控件 Binding mode TwoWay并进行定义triggers with PropertyChanged

{Binding ElementName=.., Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}