刷新 OxyPlot 图表

Question

我正在开发 WPF 应用程序。此应用程序使用 OxyPlot chart control。我让用户执行计算。用户可以以网格和图表形式查看结果。为了做到这一点，我有以下内容：

home.xaml

<DataGrid x:Name="resultDataGrid" ItemsSource="{Binding Items}">
  <DataGrid.Columns>
    <DataGridTextColumn Header="#" Binding="{Binding Number}" />
    <DataGridTextColumn Header="Description" Binding="{Binding Description}" />
  </DataGrid.Columns>
</DataGrid>

<oxy:Plot x:Name="resultGraph" Background="Transparent" Height="400" HorizontalContentAlignment="Stretch" VerticalAlignment="Stretch" Visibility="Collapsed">
  <oxy:Plot.Series>
    <oxy:LineSeries ItemsSource="{Binding Points}" MarkerType="Circle"  Title="Result" />
  </oxy:Plot.Series>
</oxy:Plot>

<StackPanel Orientation="Horizontal">
  <Button x:Name="executeButton" Click="executeButton_Click" />
  <Button x:Name="viewData" Click="viewData_Click" />
  <Button x:Name="viewChart" Click="viewChart_Click" />
</StackPanel>

home.xaml.cs

public partial class Home: Page
{
  private MyViewModel viewModel = null;
  public Home()
  {
    InitializeComponent();

    viewModel = new MyViewModel();
    this.DataContext = viewModel;
  }

  private void executeButton_Click(object sender, RoutedEventArgs e) {
    viewModel.Execute();
  }

  private void viewData_Click(object sender, RoutedEventArgs e) 
  {
    resultDataGrid.Visibility = System.Windows.Visibility.Visible;
    resultGraph.Visibility = System.Windows.Visibility.Collapsed;
  }

  private void viewChart_Click(object sender, RoutedEventArgs e)
  {
    resultDataGrid.Visibility = System.Windows.Visibility.Collapsed;
    resultGraph.Visibility = System.Windows.Visibility.Visible;
  }
}

MyViewModel.cs

public class MyViewModel : INotifyPropertyChanged
{
  public Dictionary<int, string> Items{ get; set; }
  public IList<DataPoint> Points{ get; set; }

  public void Execute() 
  {
    this.Items = new Dictionary<int, string>();
    this.Points = new List<DataPoint>();

    var randomNumber = GetRandomNumber();
    for (var i=0; i<10; i++) 
    {
      this.Items.Add((i+1), "Item #" + i);

      var dataPoint = new DataPoint(i, (randomNumber*i));
      this.Points.Add(dataPoint);
    }

    NotifyPropertyChanged("Items");
    NotifyPropertyChanged("Points");
  }
}

我的问题是，当用户单击 "Execute" 按钮时，DataGrid 中的数据会刷新，这正是我所期望的。但是，图表只有在图表首次可见时才会刷新。换句话说，如果我在 DataGrid 可见时单击 "execute"，图表中的绘图点将变得陈旧。但是，如果 resultGraph 可见并单击 "Execute"，则点会按预期刷新。我不明白我做错了什么。感谢任何帮助。

Answer 1

其实我找到了答案here:

OxyPlot is not observing property or collection changes. This means that the client application is responsible for refreshing the plot when the content has changed.

更改后必须使绘图无效。有几个possibilities.

最简单的可能是 dirty MVVM：在视图订阅 viewmodel PropertyChanged 事件中，检查此事件是否由 Points 改变并使情节无效。

Answer 2

在您的 ViewModel 中创建

private int _invalidateFlag = 0;
public int InvalidateFlag
{
   get {return _invalidateFlag;}
   set
   {
      _invalidateFlag = value;
      NotifyPropertyChanged();
   }
}

//and to the end of Execute() add

InvalidateFlag++;

也不要忘记绑定 InvalidateFlag

<oxy:Plot x:Name="resultGraph" InvalidateFlag="{Binding InvalidateFlag}" Background="Transparent" Height="400" HorizontalContentAlignment="Stretch" VerticalAlignment="Stretch" Visibility="Collapsed">

这应该可以解决问题

Answer 3

通常 OxyPlot 提供 PlotModel.InvalidatePlot(true) 方法来使用新的输入数据刷新图表。编辑：哦，我看到你的 ViewModel 中没有 PlotModel 属性。我的答案需要这样一个属性也可以绑定到 xaml。

刷新 OxyPlot 图表

Refreshing OxyPlot Chart

wpf

xaml

oxyplot