当我明确要求控件重绘时，为什么没有捕获绘制异常？

Question

我有一个 GUI 应用程序，它使用 Windows::Forms::DataVisualization::Charting::Chart 显示数据，大多数情况下工作正常。只是偶尔我们会得到一些图表控件不喜欢的虚假数据，从而引发异常。为了尝试捕获导致这些问题的原因，我将重新绘制请求包装在 try/catch 中：

try
{
    m_chart->Invalidate();
    m_chart->Update();
}
catch(System::Exception^ e)
{
    // If something goes wrong during the drawing, we probably want to try 
    // and record some more information then re-throw it so we can capture 
    // it properly.
    String^ detailString = String::Format("Exception caught while trying to draw raw data. {0}", "Add more debug info here");
    throw gcnew System::Exception(detailString, e);
}

...不过出于某种原因，异常不会在那里抛出（我有一个断点和一些日志记录永远不会被击中） - 它发生在其他某个时刻：

Exception:
    Value was either too large or too small for a Decimal.
Exception type:
    System.OverflowException
Source:
    mscorlib
Stack trace:
   at System.Decimal..ctor(Double value)
   at System.Windows.Forms.DataVisualization.Charting.Axis.RoundedValues(Double inter, Boolean shouldStartFromZero, Boolean autoMax, Boolean autoMin, Double& min, Double& max)
   at System.Windows.Forms.DataVisualization.Charting.Axis.EstimateNumberAxis(Double& minimumValue, Double& maximumValue, Boolean shouldStartFromZero, Int32 preferredNumberOfIntervals, Boolean autoMaximum, Boolean autoMinimum)
   at System.Windows.Forms.DataVisualization.Charting.Axis.EstimateAxis(Double& minimumValue, Double& maximumValue, Boolean autoMaximum, Boolean autoMinimum)
   at System.Windows.Forms.DataVisualization.Charting.Axis.EstimateAxis()
   at System.Windows.Forms.DataVisualization.Charting.ChartArea.SetDefaultAxesValues()
   at System.Windows.Forms.DataVisualization.Charting.ChartArea.SetData(Boolean initializeAxes, Boolean checkIndexedAligned)
   at System.Windows.Forms.DataVisualization.Charting.ChartArea.ReCalcInternal()
   at System.Windows.Forms.DataVisualization.Charting.ChartPicture.Paint(Graphics graph, Boolean paintTopLevelElementOnly)
   at System.Windows.Forms.DataVisualization.Charting.Chart.OnPaint(PaintEventArgs e)
   at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer, Boolean disposeEventArgs)
   at System.Windows.Forms.Control.WmPaint(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
Installed .net Versions:
    v2.0.50727.5420
    v3.0.30729.5420
    v3.5.30729.5420
    v4.0.30319

我在这里错过了什么吗？无效/更新是否不会触发与 Windows 消息泵的其他部分相同的重新绘制？

Answer 1

大多数 UI 框架都遵循这种模式。 Invalidate等只需更新窗口状态中的标志，以便稍后重新绘制。

如果您无法捕获绘制代码中的错误，则必须处理 ThreadException。捕获绘制（或数据绑定）代码中的错误是首选解决方案，但如果您只是临时添加一个处理程序来查看数据是什么，ThreadException 应该可以正常工作。