本文介绍了'QwtLog10ScaleEngine' 之前的预期类型说明符?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
版本:qwt 6.0.1我尝试为 Spectrum 开发对数缩放.我使用简单的线来启用缩放 plotspectrum->setAxisScaleEngine(QwtPlot::yLeft, new QwtLog10ScaleEngine);
Version: qwt 6.0.1I've tried to develop logarithmic scaling for Spectrum.I've used simple line to enable scaling plotspectrum->setAxisScaleEngine(QwtPlot::yLeft, new QwtLog10ScaleEngine);
问题:数据没有绘制，所以绘图为空，编译器返回以下错误:预期类型说明符在'QwtLog10ScaleEngine'之前"任何帮助将不胜感激这是我的代码:
Problems: the data are not drawn, so the plot is empty and the compiler returns following error:"expected type-specifier before 'QwtLog10ScaleEngine'"Any help woulb be appreciatedHere is my code:
class SpectrumPlot : public QWidget
{
Q_OBJECT
public:
PlotSpektrum();
private:
QHBoxLayout* m_SpectrumLayout;
QwtPlot* m_SpectrumPlot;
QwtPlotCurve* m_SpectrumCurve;
QwtPlotMarker* m_Marker;
};
SpectrumPlot::SpectrumPlot()
{
m_SpectrumLayout = new QHBoxLayout();
m_SpectrumPlot = new QwtPlot();
m_SpectrumCurve = new QwtPlotCurve();
QwPlotGrid* pGrid = new QwtPlotGrid();
QPen GridPen;
GridPen.setColor(Qt::green);
GridPen.setWidthF(0.7);
GridPen.setStyle(Qt::DashLine);
QPen SpectrumPen;
SpectrumPen.setColor(Qt::white);
pGrid->setRenderHint(QwtPlotItem::RenderAntialiased);
pGrid->setPen(GridPen);
pGrid->enableXMin(true);
pGrid->attach(m_SpectrumPlot);
m_SpectrumPlot->setTitle("Spectrum");
m_SpectrumPlot->setCanvasBackground(QBrush(Qt::black));
m_SpectrumPlot->setAutoDelete(true);
m_SpectrumPlot->setAxisTitle(QwtPlot::xBottom, "Frequency Hz");
m_SpectrumPlot->setAxisScale(QwtPlot::xBottom, 100, nNyquistFrequency);
m_SpectrumPlot->setAxisScale(QwtPlot::yLeft, 0, 150);
m_SpectrumPlot->setAxisScaleEngine(QwtPlot::xBottom, new QwtLog10ScaleEngine());
m_SpectrumLayout->addWidget(m_SpectrumPlot);
this->setLayout(m_SpectrumLayout);
}
推荐答案
我认为你应该使用:
new QwtLogScaleEngine(10)
QwtScaleEngine 的手册没有显示任何称为QwtLog10ScaleEngine.
这篇关于'QwtLog10ScaleEngine' 之前的预期类型说明符?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！