c# - DispatcherTimer 不触发

Question

我刚刚开始开发 Windows 应用商店应用程序，我只想要一个非常简单的应用程序:几乎是一个从左到右填满的进度条，但即使是这个任务对我来说显然也无法完成。

我有以下代码:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238

namespace TimeLoader
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        private DispatcherTimer refreshTimer;

        public MainPage()
        {
            this.InitializeComponent();
        }

        void refreshTimer_Tick(object sender, object e)
        {
            TimePassedBar.Value += 5;
        }

        private void Page_Loaded(object sender, RoutedEventArgs e)
        {
            TimePassedBar.Value = 50;
            new DispatcherTimer();
            this.refreshTimer = new DispatcherTimer();
            this.refreshTimer.Interval = new TimeSpan(0, 0, 0, 100);
            this.refreshTimer.Tick += refreshTimer_Tick;
            this.refreshTimer.Start();
        }
    }
}

<Page
    x:Class="TimeLoader.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:TimeLoader"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d" Loaded="Page_Loaded">

    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <Grid.RowDefinitions>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition></ColumnDefinition>
        </Grid.ColumnDefinitions>
        <ProgressBar Grid.Row="0" Grid.Column="0" Height="150" Value="75" VerticalAlignment="Center" Name="TimePassedBar"/>
    </Grid>
</Page>

现在，当我在 WPF 中执行相同的设置时，它工作得很好，但是当我启 Action 为 Windows 商店应用程序构建的代码时，Tick 事件永远不会触发。构建 Windows 应用商店应用程序时有什么特别需要注意的吗？我四处寻找，遗憾的是在这件事上一无所获。

Answer 1

您的代码运行良好。你只是没有等足够长的时间来注意到。 :)

private void Page_Loaded(object sender, RoutedEventArgs e)
{
    TimePassedBar.Value = 50;
    this.refreshTimer = new DispatcherTimer();
    this.refreshTimer.Interval = TimeSpan.FromMilliseconds(100);
    this.refreshTimer.Tick += refreshTimer_Tick;
    this.refreshTimer.Start();
}

您正在设置 TimeSpan as 100 seconds .您需要使用五参数重载来获取毫秒数。但恕我直言，仅使用 FromMilliseconds() 方法(如上所述)更容易且更易读。

另外，您不需要两次创建 DispatcherTimer 对象，尤其是当您要完全忽略第一个对象时。 :)