《Qt开发》基于QWT的曲线图绘制

Qwt绘制曲线图

该示例包含以下功能:

1.使用qwt绘制曲线图

2.通过鼠标实现绘图的缩放，只缩放x轴或只缩放y轴或同时缩放

3.设置绘图区域和绘图区域外的背景颜色

4.通过点击图例实现曲线的显示和隐藏

QwtPlot绘图部件

头文件	#include <qwt_plot.h>
枚举类型	enum Axis {yLeft, yRight, xBottom, xTop,axisCnt}	坐标轴
	enum LegendPosition { LeftLegend, RightLegend, BottomLegend, TopLegend }	图例位置
常用函数	QwtPlot (QWidget ∗=NULL)	QwtPlot *plot=newQwtPlot()
	QwtPlot (const QwtText &title, QWidget ∗=NULL)	QwtPlot *plot=new QwtPlot(QwtText("plot demo"));
	void setAutoReplot (bool=true)	设置自动绘图
	void setTitle (const QString &)	plot->setTitle(“plot demo”);
	void setTitle (const QwtText &t)	plot->setTitle(QwtText(“plot demo”));
	void setCanvasBackground (const QBrush &)	plot->setCanvasBackground(Qt::white);
	void setAxisAutoScale (int axisId, bool on=true)	plot->setAxisAutoScale(QwtPlot::xBottom, true);
	void enableAxis (int axisId, bool tf=true)	plot->setAxisAutoScale(QwtPlot::xBottom, false);
	void setAxisFont (int axisId, const QFont &f)	plot->setAxisFont(QwtPlot::xBottom,QFont("宋体"));
	void setAxisScale (int axisId, double min, double max, double step=0)	plot->setAxisScale(QwtPlot::xBottom,0,50,5);
	void setAxisLabelAlignment (int axisId, Qt::Alignment)	plot->setAxisLabelAlignment(QwtPlot::xBottom, Qt::AlignBaseline | Qt::AlignVCenter);
	void setAxisLabelRotation (int axisId, double rotation)	plot->setAxisLabelRotation(QwtPlot::xBottom,30);
	void setAxisTitle (int axisId, const QString &)	plot->setAxisTitle(QwtPlot::yLeft,"yLabel");
	void setAxisTitle (int axisId, const QwtText &)	plot->setAxisTitle(QwtPlot::yLeft,QwtText("yLabel"));
	void setAxisMaxMinor (int axisId, int maxMinor)	plot->setAxisMaxMinor(QwtPlot::xBottom, 5); 设置每个大格刻度分为几个小格刻度
	void setAxisMaxMajor (int axisId, int maxMajor)	plot->setAxisMaxMajor(QwtPlot::xBottom, 5); 设置xBottom轴有多少个大格
	void insertLegend (QwtAbstractLegend ∗, LegendPosition=QwtPlot::RightLegend, double ratio=-1.0)	QwtLegend *legend = new QwtLegend; legend->setDefaultItemMode(QwtLegendData::Checkable); plot->insertLegend(legend,QwtPlot::RightLegend);

QwtPlotCurve绘图曲线

头文件	#include <qwt_plot_curve.h>
枚举类型	enum CurveStyle {NoCurve = -1, Lines, Sticks, Steps,Dots, UserCurve = 100 }
	enum CurveAttribute { Inverted = 0x01, Fitted = 0x02 }
	enum LegendAttribute { LegendNoAttribute = 0x00, LegendShowLine = 0x01, LegendShowSymbol = 0x02, LegendShowBrush = 0x04 }
	enum PaintAttribute { ClipPolygons = 0x01, FilterPoints = 0x02, MinimizeMemory = 0x04, ImageBuffer = 0x08}
常用函数	QwtPlotCurve (const QString &title=QString::null) QwtPlotCurve (const QwtText &title)
	void setRawSamples (const double ∗xData, const double ∗yData, int size)
	void setSamples (const double ∗xData, const double ∗yData, int size)
	void setSamples (const QVector< double > &xData, const QVector< double > &yData)
	void setSamples (const QVector< QPointF > &)
	void setSamples (QwtSeriesData< QPointF > ∗)
	double minXValue () const
	double maxXValue () const
	double minYValue () const
	double maxYValue () const
	void setPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
	void setPen (const QPen &)
	void setBrush (const QBrush &)
	void setSymbol (QwtSymbol ∗)
	void setStyle (CurveStyle style)

QwtPlotGrid绘图网格

头文件	#include <qwt_plot_grid.h>
常用函数	void enableX (bool tf)
	void enableY (bool tf)
	void enableXMin (bool tf)
	void enableYMin (bool tf)
	void setPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
	void setPen (const QPen &)
	void setMajorPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
	void setMajorPen (const QPen &)
	void setMinorPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
	void setMinorPen (const QPen &p)

QwtSymbol绘图标识符

头文件	#include <qwt_symbol.h>
枚举类型	enum Style {NoSymbol = -1, Ellipse, Rect, Diamond,Triangle, DTriangle, UTriangle, LTriangle,RTriangle, Cross, XCross, HLine,VLine, Star1, Star2, Hexagon,Path, Pixmap, Graphic, SvgDocument,UserStyle = 1000 }
	enum CachePolicy { NoCache, Cache, AutoCache }
常用函数	QwtSymbol (Style=NoSymbol)
	QwtSymbol (Style, const QBrush &, const QPen &, const QSize &)
	QwtSymbol (const QPainterPath &, const QBrush &, const QPen &)
	void setSize (const QSize &)
	void setSize (int width, int height=-1)
	virtual void setColor (const QColor &)
	void setBrush (const QBrush &b)
	void setPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
	void setPen (const QPen &)
	void setStyle (Style)

QwtPlotPicker绘图拾取器，获取坐标信息

QwtPlotPicker能够获取Plot中的以原点为起点的坐标并通过跟随鼠标的Label显示，

头文件	#include <qwt_plot_picker.h>
常用函数	QwtPlotPicker (int xAxis, int yAxis, QWidget ∗)
	QwtPlotPicker (int xAxis, int yAxis, RubberBand rubberBand, DisplayMode trackerMode, QWidget ∗)

QwtPicker

头文件	#include <qwt_picker.h>
枚举类型	enum RubberBand { NoRubberBand = 0, HLineRubberBand, VLineRubberBand, CrossRubberBand, RectRubberBand, EllipseRubberBand, PolygonRubberBand, UserRubberBand = 100 }
	enum DisplayMode { AlwaysOff, AlwaysOn, ActiveOnly }
	enum ResizeMode { Stretch, KeepSize }
常用函数	QwtPicker (QWidget ∗parent)
	QwtPicker (RubberBand rubberBand, DisplayMode trackerMode, QWidget ∗)
	void setStateMachine (QwtPickerMachine ∗)
	void setRubberBand (RubberBand)
	void setTrackerMode (DisplayMode)
	void setRubberBandPen (const QPen &)
	void setTrackerPen (const QPen &)
	void setTrackerFont (const QFont &)

更多详情查看用户手册。

示例程序

头文件内容如下：

#ifndef QWTLINEEG_H

#define QWTLINEEG_H

#include

#include "ui_qwtlineeg.h"

#include "QWT\qwt_plot.h"

#include "QWT\qwt_plot_grid.h"

#include "QWT\qwt_plot_curve.h"

#include "QWT\qwt_plot_picker.h"

#include "QWT\qwt_picker_machine.h"

#include "qmath.h"

#include "QWT\qwt_symbol.h"

#include "QWT\qwt_plot_magnifier.h"

#include "QWT\qwt_plot_panner.h"

#include "QWT\qwt_legend.h"

#include "QWT\qwt_plot_zoomer.h"

#include "QWT\qwt_text.h"

class QwtLineEg : public QWidget

{

    Q_OBJECT

public:

    QwtLineEg(QWidget *parent = 0);

    ~QwtLineEg();

private:

    Ui::QwtLineEgClass ui;

   

    QwtPlot *plot;

    void DrawLine();  //绘制曲线

    void ZoomInOut(); //缩放

    public slots:

    void showItem(const QVariant &itemInfo, bool on);

};

#endif // QWTLINEEG_H

源文件内容如下：

#include "qwtlineeg.h"

QwtLineEg::QwtLineEg(QWidget *parent)

    : QWidget(parent)

{

    ui.setupUi(this);

    DrawLine();

    ZoomInOut();

}

QwtLineEg::~QwtLineEg()

{

}

void QwtLineEg::DrawLine()

{

    //设置绘图对象

    plot = new QwtPlot(QwtText("plot demo"));

    //plot->setTitle("plot demo");

    plot->setCanvasBackground(QColor(255,255,255));  //设置绘图区域的颜色

    plot->setAutoReplot(true);

    QPalette pal = palette();

    pal.setBrush(QPalette::Window, QColor(255, 231, 147));  //设置整个界面的颜色

    setPalette(pal);

   

    //设置坐标轴

    plot->setAxisTitle(QwtPlot::yLeft,"yLabel");

    plot->setAxisTitle(QwtPlot::xBottom,"xBottom");

    plot->setAxisFont(QwtPlot::xBottom,QFont("宋体"));

    plot->setAxisScale(QwtPlot::xBottom,0,50,5);

   

    plot->setAxisLabelAlignment(QwtPlot::xBottom, Qt::AlignBaseline | Qt::AlignVCenter);

    plot->setAxisLabelRotation(QwtPlot::xBottom,30);

    //设置绘图区域网格

    QwtPlotGrid *grid = new QwtPlotGrid();

    grid->setMajorPen(Qt::darkGreen, 0, Qt::DotLine);

    grid->attach(plot);

    //设置图例

    QwtLegend *legend = new QwtLegend;

    legend->setDefaultItemMode(QwtLegendData::Checkable);

    plot->insertLegend(legend,QwtPlot::RightLegend);

    connect(legend, SIGNAL(checked(const QVariant &,bool,int)), SLOT(showItem(const QVariant &,bool)));

    //设置曲线对象

    QwtPlotCurve *curve = new QwtPlotCurve();

    curve->setTitle("--sin--");

    curve->setPen(Qt::green, 2);

    curve->setRenderHint(QwtPlotItem::RenderAntialiased, true);

   

    QwtPlotCurve *curve2 = new QwtPlotCurve();

    curve2->setTitle("--cos--");

    curve2->setPen(Qt::blue, 2);

    curve2->setRenderHint(QwtPlotItem::RenderAntialiased, true);

   

    //准备符号对象

    QwtSymbol *symbol = new QwtSymbol(QwtSymbol::Star2);

    symbol->setPen(Qt::red);

    symbol->setSize(7);

    curve->setSymbol(symbol);

    QwtSymbol *symbol2 = new QwtSymbol(QwtSymbol::XCross);

    symbol2->setPen(Qt::cyan);

    symbol2->setSize(7);

    curve2->setSymbol(symbol2);

    //生成数据点并添加到曲线

    QPolygonF points,points2;

    for (int i = 0; i < 50; i++)

    {

        double y = sin(i * 2 * M_PI / 50);

        points.append(QPointF(i,y));

        y = cos(i * 2 * M_PI / 50);

        points2.append(QPointF(i, y));

    }

    curve->setSamples(points);

    curve->attach(plot);  //将曲线添加到绘图对象

    curve2->setSamples(points2);

    curve2->attach(plot);  //将曲线添加到绘图对象

    //显示鼠标位置

    QwtPlotPicker *picker = new QwtPlotPicker(QwtPlot::xBottom, QwtPlot::yLeft,

        QwtPlotPicker::CrossRubberBand, QwtPicker::AlwaysOn, plot->canvas());

    picker->setStateMachine(new QwtPickerDragPointMachine());

    picker->setRubberBandPen(QColor(Qt::green));

    picker->setTrackerPen(QColor(Qt::red));

    //设置绘图区域布局

    QHBoxLayout *hLayout = new QHBoxLayout(ui.widget);

    hLayout->setContentsMargins(QMargins(0, 0, 0, 0));

    hLayout->setMargin(0);

    hLayout->addWidget(plot);

}

void QwtLineEg::ZoomInOut()

{

    //鼠标控制平移和缩放

    QwtPlotMagnifier *magnifier = new QwtPlotMagnifier(plot->canvas()); //使用滚轮缩放

    QwtPanner *panner = new QwtPlotPanner(plot->canvas());  //使用鼠标左键平移

    //Shift+滚轮，X轴缩放

    QwtPlotMagnifier *zoomX = new QwtPlotMagnifier(plot->canvas());

    QwtPlotMagnifier *zoomY = new QwtPlotMagnifier(plot->canvas());

    zoomX->setWheelModifiers(Qt::ShiftModifier);

    zoomX->setAxisEnabled(QwtPlot::xBottom, true);

    zoomX->setAxisEnabled(QwtPlot::yLeft, false);

    //Ctrl+滚轮，Y轴缩放

    zoomY->setWheelModifiers(Qt::ControlModifier);

    zoomY->setAxisEnabled(QwtPlot::xBottom, false);

    zoomY->setAxisEnabled(QwtPlot::yLeft, true);

}

void QwtLineEg::showItem(const QVariant &itemInfo, bool on)

{

    //获取曲线

    QwtPlotItem *plotItem = plot->infoToItem(itemInfo);

    //根据曲线选择状态，设置曲线隐藏和显示,选中隐藏

    if (plotItem)

        plotItem->setVisible(!on);

    plot->replot();

}

运行结果如下，鼠标点击图例可以实现曲线显示和隐藏的切换