Question

我的UWP应用程序中有DispatcherTimer用于从Web服务更新数据库。

public DispatcherTimer SessionTimer { get; set; }

在此计时器的tick事件中更新数据库之前，我会折叠主网格并显示更新消息，更新完成后我会反转。

private void SessionTimer_Tick(object sender, object e)
{
    rpWait.Visibility = Visibility.Visible; 
    LayoutRoot.Visibility = Visibility.Collapsed;
    Update();
    rpWait.Visibility = Visibility.Collapsed;
    LayoutRoot.Visibility = Visibility.Visible;
}

我的XAML代码：

<Grid x:Name="LayoutRoot" Style="{StaticResource backGrid}">
<RelativePanel Style="{StaticResource rpTop}">
 ...
</RelativePanel>
<Frame x:Name="frameBody" Loaded="frameBody_Loaded" Margin="0,100,0,0"/>
</Grid>

<RelativePanel x:Name="rpWait" Visibility="Collapsed">
    <StackPanel  RelativePanel.AlignHorizontalCenterWithPanel="True" RelativePanel.AlignVerticalCenterWithPanel="True">
         <TextBlock x:Name="lbMessage" FontSize="30"  HorizontalAlignment="Center">Updating</TextBlock>
         <TextBlock x:Name="lbWaiting" FontSize="30" Margin="0 50 0 0">Please Wait</TextBlock>
    </StackPanel>
</RelativePanel>

但是计时器没有显示任何内容（DB正确更新）。

请帮帮我？

Answer 1

我相信你的问题是你不运行Update（）Asynchronous并等待更新。另外，如果您更好地进行UI更新，则可以在UI线程中执行它们。

DispatcherTimer ds = new DispatcherTimer();

// In Constuctor of the page

ds.Interval = new TimeSpan(0, 1, 0);
ds.Tick += ds_Tick;
ds.Start();

void ds_Tick(object sender, object e)
        {
            ShowHide(true);
            await Update();
            ShowHide(false);
        }

private async void ShowHide(bool state)
{
    await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
    {
        if(state)
        {
             rpWait.Visibility = Visibility.Visible; 
             LayoutRoot.Visibility = Visibility.Collapsed;
        }
        else
        {
            rpWait.Visibility = Visibility.Collapsed;
            LayoutRoot.Visibility = Visibility.Visible;
        }
    });
}

private Task Update()
{
    //run your update
    //if your update doesnt have await use
    //return Task.Run(() => {
    //            //doto
    //        });
    //If it does just write your code
}

DispatcherTimer不会在tick事件中显示UI操作 - UWP

1 个答案: