c# - ItemsControl - 可绑定(bind)集合 - 通过计时器事件更新 Ui

Question

我正在为现场的几个传感器设备创建一个仪表板类型的用户界面。基于计时器的事件从数据库中获取最后一条记录并更新仪表板 UI。我想动态创建位于 BindableCollection 上的“传感器”，然后与包含嵌套 ItemsControl 的 XAML 上的 ItemsControl 相关联。使用 MVVM 架构和 Caliburn Micro 进行绑定(bind)。

已使用完整属性并确保在更新 BindableColleciton 后调用 NotifyOfPropertyChange

编辑:在其他线程之后，我更改了 DispatcherTimer() 的 System.Timer，以便更新在 UI 线程上运行。 DispatcherTimer vs a regular Timer in WPF app for a task scheduler

此外，因为我的 BindableCollection 成员总是相同的，所以我确保每次都重新创建集合，因为我有这样的想法“ObservableCollection 将在添加或删除记录时通知 UI，但在编辑记录时不会. 由已更改的对象通知它已更改。”

属性:

  private int _offlineSensors;
    public int OfflineSensors
    {
        get { return _offlineSensors; }
        set
        {
            _offlineSensors = value;
            NotifyOfPropertyChange(() => OfflineSensors);

        }
    }

    private int _latchedAlarms;
    public int LatchedAlarms
    {
        get { return _latchedAlarms; }
        set
        {
            _latchedAlarms = value;
            NotifyOfPropertyChange(() => LatchedAlarms);
        }
    }

    private int _activeAlarms;
    public int ActiveAlarms
    {
        get { return _activeAlarms; }
        set
        {
            _activeAlarms = value; 
            NotifyOfPropertyChange(() => ActiveAlarms);

        }
    }

    private Caliburn.Micro.BindableCollection<SensorStatusTable> _sensorStatusFilteredDash;
    public Caliburn.Micro.BindableCollection<SensorStatusTable> SensorStatusFilteredDash
    {
        get { return _sensorStatusFilteredDash; }
        set
        {
            _sensorStatusFilteredDash = value;
            NotifyOfPropertyChange(() => SensorStatusFilteredDash);
        }
    }

XAML:

<ItemsControl Foreground="Black" Background="Black" ItemsSource="{Binding Path=SensorStatusFilteredDash, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <WrapPanel Orientation="Horizontal"></WrapPanel>
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <Border BorderBrush="RoyalBlue" BorderThickness="2" Margin="2" Padding="5">
                        <StackPanel Orientation="Vertical">
                            <TextBlock Text="{Binding Name}" Foreground="White" VerticalAlignment="Center" HorizontalAlignment="Center" FontWeight="Bold" FontSize="20" />
                            <Image MaxWidth="60" MaxHeight="60" Source="{Binding CardStatusImage, Converter={StaticResource ResourceKey = ImageConverter}, UpdateSourceTrigger=PropertyChanged}" Stretch="Uniform"></Image>
                                <ItemsControl Foreground="Black" Background="Black" ItemsSource="{Binding Path=SensorTypes, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
                                    <ItemsControl.ItemsPanel>
                                        <ItemsPanelTemplate>
                                            <WrapPanel Orientation="Horizontal"></WrapPanel>
                                        </ItemsPanelTemplate>
                                    </ItemsControl.ItemsPanel>
                                    <ItemsControl.ItemTemplate>
                                        <DataTemplate>
                                            <TextBlock Text="{Binding }" TextWrapping="WrapWithOverflow" FontWeight="Bold" FontSize="12" TextAlignment="Center" VerticalAlignment="Center" HorizontalAlignment="Center" Foreground="White" Margin="25.5,1,18,1"></TextBlock>
                                        </DataTemplate>
                                    </ItemsControl.ItemTemplate>
                                </ItemsControl>
                                <ItemsControl Foreground="Black" Background="Black" ItemsSource="{Binding Path=InternalSensorStatusImages, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
                                    <ItemsControl.ItemsPanel>
                                        <ItemsPanelTemplate>
                                            <WrapPanel Orientation="Horizontal"></WrapPanel>
                                        </ItemsPanelTemplate>
                                    </ItemsControl.ItemsPanel>
                                    <ItemsControl.ItemTemplate>
                                        <DataTemplate>
                                            <Image Margin="11.5,1" MaxWidth="40" HorizontalAlignment="Center" VerticalAlignment="Center" MaxHeight="40" Source="{Binding  Converter={StaticResource ResourceKey = ImageConverter}}" Stretch="Uniform"></Image>
                                        </DataTemplate>
                                    </ItemsControl.ItemTemplate>
                                </ItemsControl>
                                <ItemsControl Foreground="Black" Background="Black" ItemsSource="{Binding Path=InternalSensorStatusDescription, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
                                    <ItemsControl.ItemsPanel>
                                        <ItemsPanelTemplate>
                                            <WrapPanel Orientation="Horizontal"></WrapPanel>
                                        </ItemsPanelTemplate>
                                    </ItemsControl.ItemsPanel>
                                    <ItemsControl.ItemTemplate>
                                        <DataTemplate>
                                            <TextBlock Text="{Binding}" TextWrapping="WrapWithOverflow" FontWeight="Bold" FontSize="12" TextAlignment="Center" VerticalAlignment="Center" HorizontalAlignment="Center" Foreground="White" Margin="10,1,10,1"></TextBlock>
                                        </DataTemplate>
                                    </ItemsControl.ItemTemplate>
                                </ItemsControl>

                            </StackPanel>
                    </Border>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>

事件(已编辑):

 var conn = GlobalConfig.Connections.FirstOrDefault(c => c.GetType() == typeof(SQLConnector));
        if (conn == null) return;
        try
        {
            ActiveAlarms = conn.GetNumberActiveAlarms(0);
            LatchedAlarms = conn.GetNumberActiveAlarms(2);
            GasSensors = new Caliburn.Micro.BindableCollection<GasSensor>(conn.GetGasSensors());
            SensorStatusDash = new Caliburn.Micro.BindableCollection<SensorStatusTable>(conn.SensorStatusDashboard());
            _sensorStatusFilteredDash.Clear();
            _sensorStatusFilteredDash = new Caliburn.Micro.BindableCollection<SensorStatusTable>(StatusImageConverter());
            NotifyOfPropertyChange(() => SensorStatusFilteredDash);
            NotifyOfPropertyChange(() => OfflineSensors);
            NotifyOfPropertyChange(() => ActiveAlarms);
            NotifyOfPropertyChange(() => LatchedAlarms);
        }
        catch (Exception ex)
        {
            _logger.Error(ex, "Error - Refreshing Dashboard Status");
        }

这是我的应用程序的第一个 View / View 模型，上面的 UI 刷新事件一直有效，直到我聚焦另一个 View 并返回到它。计时器仍然被触发并将正确的状态置于 BindableCollection 上。此外，即使是简单 Int 的属性也不会更新。在属性 setter 上放置一个断点，我可以看到它永远不会触发它，就像 NotifyOfPropertyChange 事件不会被触发一样。有什么想法吗？

Answer 1

感谢大家的提示和帮助。

我已经成功了，有几件事导致 UI 没有刷新。

1. 如上所述，我使用的是 System.Timer 中的计时器。我已将其替换为 DispatcherTimer，以确保事件将在与 UI 相同的线程上引发。
2. 每个周期都重新创建可绑定(bind)集合以确保触发 PropertyChanged 事件，因为成员是常量并且只有属性被修改。
3. 确保在切换 View 时取消订阅调度程序定时器事件，并在返回时重新订阅。

它是以上所有 3 点的组合。