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简短：在我调用 myModel.InvalidatePlot(true/false) 更新我的模型后，OxyPlot 鼠标事件处理程序（例如 mySeries.MouseDown）没有被捕获一瞬间。

详细：我以一种非常规的方式使用 OxyPlot 库。我通过快速更新占据整个图形的图像注释来模仿在后台播放视频。这允许我使用鼠标事件在图像上绘图。我的问题是视频/图像注释播放和鼠标事件是分开工作的，但是当鼠标事件在“帧更新”期间发生时，其中一些会被遗漏。我的信念是，当情节失效 myModel.InvalidatePlot(true/false) 时，鼠标事件在模型更新之前不会被拾取。

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2 回答 2

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我发现 InvalidatePlot 导致了鼠标按钮事件（例如 OnMouseDown(MouseButtonEventArgs e)）从未被 PlotView 捕获的问题。为了解决这个问题，我使用了另一个 WPF 对象来捕获鼠标事件并强制调用我的 PlotView 的鼠标处理方法：

1）我在另一个 ZIndex 级别上添加了一个 WPF 网格。并将函数附加到鼠标事件（MouseDown、MouseWheel 等）：

<Grid x:Name="Grid_MouseCatcher"
        HorizontalAlignment="Stretch"
        VerticalAlignment="Stretch"
        Panel.ZIndex="2"
        MouseDown="Grid_MouseCatcher_MouseDown"
        MouseEnter="Grid_MouseCatcher_MouseEnter"
        MouseLeave="Grid_MouseCatcher_MouseLeave"
        MouseMove="Grid_MouseCatcher_MouseMove"
        MouseUp="Grid_MouseCatcher_MouseUp"
        MouseWheel="Grid_MouseCatcher_MouseWheel"
        Opacity="0.0"
        PreviewMouseMove="SetFocusToOxyPlot" />
<oxy:PlotView x:Name="PlotView"
        HorizontalContentAlignment="Stretch"
        VerticalContentAlignment="Stretch"
        Panel.ZIndex="1"
        Model="{Binding PlotModel}" />

2) 网格处理的每个事件都会调用我在 OxyPlot 源代码中创建的公共方法：

 /// <summary>
 /// Sends mouse events from the overlaying grid to the PlotView. Forcing an Action.
 /// This was included due to an OxyPlot bug where the OnMouse... methods were not being called 
 /// when the plot was invalidated via InvalidatePlot(...)
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void Grid_MouseCatcher_MouseDown(object sender, MouseButtonEventArgs e)
 {
     Debug.WriteLine("MouseCatcher - Down: " + e.GetPosition(Grid_MouseCatcher).X + " " + e.GetPosition(Grid_MouseCatcher).Y);
     PlotView.ForceMouseDown(e);
 }

3) 在源代码文件OxyPlot.Wpf\PlotBase.Events.cs 中，我创建了明确调用受保护鼠标事件 (OnMouseDown(MouseButtonEventArgs e)) 的函数（例如 ForceMouseDown(MouseButtonEventArgs e)）

/// <summary>
/// Forces a call to Mouse handler. 
/// This was needed because the events were getting lost when the model was updating
/// </summary>
/// <param name="e"></param>
/// <returns></returns>
public void ForceMouseDown(MouseButtonEventArgs e){
    this.OnMouseDown(e);
}


/// <summary>
/// Invoked when an unhandled MouseDown attached event reaches an element in its route that is derived from this class. 
/// Implement this method to add class handling for this event.
/// </summary>
/// <param name="e">The <see cref="T:System.Windows.Input.MouseButtonEventArgs" /> that contains the event data. 
/// This event data reports details about the mouse button that was pressed and the handled state.</param>
protected override void OnMouseDown(MouseButtonEventArgs e)
{
    base.OnMouseDown(e);
    if (e.Handled)
    {
        return;
    }

    this.Focus();
    this.CaptureMouse();

    // store the mouse down point, check it when mouse button is released to determine if the context menu should be shown
    this.mouseDownPoint = e.GetPosition(this).ToScreenPoint();

    e.Handled = this.ActualController.HandleMouseDown(this, e.ToMouseDownEventArgs(this));
}

通过以这种方式解决问题，我仍然可以按照 OxyPlot 推荐的方式将鼠标事件处理程序添加到我的 Plotview 中，因为它们的 OnMouse#### 事件仍在被调用，它们现在刚刚被覆盖网格显式调用。

于 2015-05-11T18:14:10.330 回答
0

基于 CodyF 的修复，我找到了一个更简单的修复。将以下行添加到 OxyPlot.Wpf.PlotBase 中 OnApplyTemplate() 的末尾：

var mouseGrid = new Grid();
mouseGrid.Background = Brushes.Transparent; // background must be set for hit test to work
this.grid.Children.Add(mouseGrid);

但是，此更改当前会阻止工具提示。另请参阅 OxyPlot 的 github 页面上的此拉取请求。

于 2017-01-19T14:50:30.887 回答