Question

我正在尝试使用zedgraph创建滚动图。我使用了网站上给出的代码 http://zedgraph.dariowiz.com/index3061.html。它运作正常。样本中的图形已使用curveitem实现，如下所示：

if ( zedGraphControl2->GraphPane->CurveList->Count <= 0 )
    return;

// Get the first CurveItem in the graph
LineItem ^curve = dynamic_cast<LineItem ^>(zedGraphControl2->GraphPane->CurveList[0]);

if(curve == nullptr)
    return;


// Get the PointPairList
IPointListEdit ^list = dynamic_cast <IPointListEdit^>(curve->Points);

// If this is null, it means the reference at curve.Points does not
// support IPointListEdit, so we won't be able to modify it
if ( list == nullptr)
   return;

// Time is measured in seconds
double time = (Environment::TickCount - tickStart);

Output_data = CreateVariable(0);// User defined function


list->Add(time, Output_data);

我尝试通过附加以下代码创建第二条曲线：

LineItem ^curve1 = dynamic_cast<LineItem ^>(zedGraphControl2->GraphPane->CurveList[1]);

if(curve1 == nullptr)
    return;

// Get the PointPairList
IPointListEdit ^list1 = dynamic_cast <IPointListEdit^>(curve1->Points);

// If this is null, it means the reference at curve.Points does not
// support IPointListEdit, so we won't be able to modify it
if ( list1 == nullptr)
    return;

// Time is measured in seconds
double time = (Environment::TickCount - tickStart);

Output_data = CreateVariable(0);// User defined function    

list1->Add(time, Output_data); }

现在的问题是如何创建第二个LineItem？

如果我输入： LineItem ^ curve1 = dynamic_cast（zedGraphControl2-＆gt; GraphPane-＆gt; CurveList [1]）; 它在调试期间显示错误，表示CurveList [1]不存在。

Answer 1

在您访问zedGraphControl2-＆gt; GraphPane-＆gt; CurveList [1]（因为它尚不存在）之前，您需要首先使用GraphPane对象上的AddCurve（）方法添加它。

http://zedgraph.sourceforge.net/documentation/html/M_ZedGraph_GraphPane_AddCurve_3.htm

这也将返回新创建的曲线，您可以将其指定给curve1。

如何为滚动图创建一个新的curveitem？

我尝试通过附加以下代码创建第二条曲线：

1 个答案: