在 WPF 中使用数据绑定时 OxyPlot 不刷新 [英] OxyPlot not refreshing when using data binding in WPF

问题描述

我正在异步获取数据并尝试通过 LineSeries 填充绘图，但在更新绑定集合 (ObservableCollection) 时绘图不会刷新.注意:当绑定集合更改时，我有一个 XAML 行为来调用 InvalidatePlot(true).

I'm asynchonrously getting data and attempting to populate a plot via the LineSeries, except the plot does not refresh when the bound collection (ObservableCollection) is updated. Note: I have a XAML behavior to call InvalidatePlot(true) when the bound collection changes.

谁能解释为什么情节没有按预期更新?

WPF.Net 4.0OxyPlot 2014.1.293.1

WPF .Net 4.0 OxyPlot 2014.1.293.1

我有以下 XAML 数据模板，您可以看到 LineSeries ItemsSource 绑定到 ViewModel 中的属性 (PlotData):

I have the following XAML datatemplate, as you can see the LineSeries ItemsSource is bound to a property (PlotData) in the ViewModel:

<DataTemplate DataType="{x:Type md:DataViewModel}">

    <Grid>

        <oxy:Plot x:Name="MarketDatePlot"
                    Margin="10">
            <oxy:Plot.Axes>
                <oxy:DateTimeAxis Position="Bottom"
                                    StringFormat="dd/MM/yy"
                                    MajorGridlineStyle="Solid"
                                    MinorGridlineStyle="Dot"
                                    IntervalType="Days"
                                    IntervalLength="80" />
                <oxy:LinearAxis Position="Left"
                                MajorGridlineStyle="Solid"
                                MinorGridlineStyle="Dot"
                                IntervalLength="100" />
            </oxy:Plot.Axes>
            <oxy:LineSeries ItemsSource="{Binding Path=PlotData, Mode=OneWay}" />
            <i:Interaction.Behaviors>
                <behaviors:OxyPlotBehavior ItemsSource="{Binding Path=PlotData, Mode=OneWay}" />
            </i:Interaction.Behaviors>
        </oxy:Plot>
    </Grid>

</DataTemplate>

正如我所说，ViewModel 异步请求并填充绑定集合(绑定集合的实际填充发生在 UI 线程上):

As I said the ViewModel requests and populates the bound collection asynchronously (the actual population of bound collection happens on the UI thread):

public sealed class DataViewModel : BaseViewModel, IDataViewModel
{
    private readonly CompositeDisposable _disposable;
    private readonly CancellationTokenSource _cancellationTokenSource;
    private readonly RangeObservableCollection<DataPoint> _plotData;

    public DataViewModel(DateTime fromDate, DateTime toDate, IMarketDataService marketDataService, ISchedulerService schedulerService)
    {
        _plotData = new RangeObservableCollection<DataPoint>();
        _disposable = new CompositeDisposable();

        if (fromDate == toDate)
        {
            // nothing to do...
            return;
        }

        _cancellationTokenSource = new CancellationTokenSource();

        _disposable.Add(Disposable.Create(() =>
        {
            if (!_cancellationTokenSource.IsCancellationRequested)
            {
                _cancellationTokenSource.Cancel();
            }
        }));

        marketDataService.GetDataAsync(fromDate, toDate)
            .ContinueWith(t =>
            {
                if (t.IsFaulted)
                {
                    throw new Exception("Failed to get market data!", TaskHelper.GetFirstException(t));
                }

                return t.Result.Select(x => new DataPoint(DateTimeAxis.ToDouble(x.Time), x.Value));
            }, schedulerService.Task.Default)
            .SafeContinueWith(t => _plotData.AddRange(t.Result), schedulerService.Task.CurrentSynchronizationContext);
    }

    public void Dispose()
    {
        _disposable.Dispose();
    }

    public IEnumerable<DataPoint> PlotData
    {
        get { return _plotData; }
    }
}

XAML 行为如下所示:

And the XAML behavior looks like this:

(我似乎不能再粘贴代码了，所以保存时总是抛出错误)

(I can't seem to paste in anymore code, SO keeps throwing an error on save)

推荐答案

添加数据时，OxyPlot 不会自动更新.

OxyPlot does not automatically update when you add data.

你必须调用 plotname.InvalidatePlot(true);

You must call plotname.InvalidatePlot(true);

并且它必须运行在 UI 调度程序线程上，即

and it must run on the UI dispatcher thread, ie

Dispatcher.InvokeAsync(() => 
{
    plotname.InvalidatePlot(true);
}

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