qt跟随鼠标动态绘制_采用Qt绘制多条曲线，跟随鼠标动态显示线上点的值（基于Qt的开源绘图控件QCustomPlot进行二次开发）...

采用Qt绘制多条曲线，跟随鼠标动态显示线上点的值(基于Qt的开源绘图控件QCustomPlot进行二次开发)

QCustomPlot是一个开源的基于Qt的第三方绘图库，能够绘制漂亮的2D图形。

QCustomPlot的官方网址：https://www.qcustomplot.com/

从官网下载QCustomPlot的源文件，包括qcustomplot.h和qcustomplot.cpp。

1. 自定义鼠标显示跟随类XxwTracer和XxwTraceLine：

XxwTracer用于在图表中显示鼠标所在位置的x,y值

XxwTraceLine用于在图中显示水平或垂直的虚线

头文件XxwTracer.h

#ifndef MYTRACER_H

#define MYTRACER_H

#include

#include "qcustomplot.h"

///

/// brief The XxwTracer class:在图表中显示鼠标所在位置的x,y值的追踪显示器

///

class XxwTracer : public QObject

{

Q_OBJECT

public:

enum TracerType

{

XAxisTracer,//依附在x轴上显示x值

YAxisTracer,//依附在y轴上显示y值

DataTracer//在图中显示x,y值

};

explicit XxwTracer(QCustomPlot *_plot, TracerType _type, QObject *parent = Q_NULLPTR);

~XxwTracer();

void setPen(const QPen &pen);

void setBrush(const QBrush &brush);

void setText(const QString &text);

void setLabelPen(const QPen &pen);

void updatePosition(double xValue, double yValue);

void setVisible(bool m_visible);

protected:

bool m_visible;//是否可见

TracerType m_type;//类型

QCustomPlot *m_plot;//图表

QCPItemTracer *m_tracer;//跟踪的点

QCPItemText *m_label;//显示的数值

QCPItemLine *m_arrow;//箭头

};

///

/// brief The XxwCrossLine class:用于显示鼠标移动过程中的鼠标位置的直线

///

class XxwTraceLine : public QObject

{

public:

enum LineType

{

VerticalLine,//垂直线

HorizonLine, //水平线

Both//同时显示水平和垂直线

};

explicit XxwTraceLine(QCustomPlot *_plot, LineType _type = VerticalLine, QObject *parent = Q_NULLPTR);

~XxwTraceLine();

void initLine();

void updatePosition(double xValue, double yValue);

void setVisible(bool vis)

{

if(m_lineV)

m_lineV->setVisible(vis);

if(m_lineH)

m_lineH->setVisible(vis);

}

protected:

bool m_visible;//是否可见

LineType m_type;//类型

QCustomPlot *m_plot;//图表

QCPItemStraightLine *m_lineV; //垂直线

QCPItemStraightLine *m_lineH; //水平线

};

#endif // MYTRACER_H

源文件MyTracer.cpp

#include "MyTracer.h"

XxwTracer::XxwTracer(QCustomPlot *_plot, TracerType _type, QObject *parent)

: QObject(parent),

m_plot(_plot),

m_type(_type)

{

m_visible = true;

m_tracer = Q_NULLPTR;// 跟踪的点

m_label = Q_NULLPTR;// 显示的数值

m_arrow = Q_NULLPTR;// 箭头

if (m_plot)

{

QColor clrDefault(Qt::red);

QBrush brushDefault(Qt::NoBrush);

QPen penDefault(clrDefault);

// penDefault.setBrush(brushDefault);

penDefault.setWidthF(0.5);

m_tracer = new QCPItemTracer(m_plot);

m_tracer->setStyle(QCPItemTracer::tsCircle);

m_tracer->setPen(penDefault);

m_tracer->setBrush(brushDefault);

m_label = new QCPItemText(m_plot);

m_label->setLayer("overlay");

m_label->setClipToAxisRect(false);

m_label->setPadding(QMargins(5, 5, 5, 5));

m_label->setBrush(brushDefault);

m_label->setPen(penDefault);

m_label->position->setParentAnchor(m_tracer->position);

// m_label->setFont(QFont("宋体", 8));

m_label->setFont(QFont("Arial", 8));

m_label->setColor(clrDefault);

m_label->setText("");

m_arrow = new QCPItemLine(m_plot);

QPen arrowPen(clrDefault, 1);

m_arrow->setPen(penDefault);

m_arrow->setLayer("overlay");

m_arrow->setClipToAxisRect(false);

m_arrow->setHead(QCPLineEnding::esSpikeArrow);//设置头部为箭头形状

switch (m_type)

{

case XAxisTracer:

{

m_tracer->position->setTypeX(QCPItemPosition::ptPlotCoords);

m_tracer->position->setTypeY(QCPItemPosition::ptAxisRectRatio);

m_tracer->setSize(7);

m_label->setPositionAlignment(Qt::AlignTop | Qt::AlignHCenter);

m_arrow->end->setParentAnchor(m_tracer->position);

m_arrow->start->setParentAnchor(m_arrow->end);

m_arrow->start->setCoords(0, 20);//偏移量

break;

}

case YAxisTracer:

{

m_tracer->position->setTypeX(QCPItemPosition::ptAxisRectRatio);

m_tracer->position->setTypeY(QCPItemPosition::ptPlotCoords);

m_tracer->setSize(7);

m_label->setPositionAlignment(Qt::AlignRight | Qt::AlignHCenter);

m_arrow->end->setParentAnchor(m_tracer->position);

m_arrow->start->setParentAnchor(m_label->position);

m_arrow->start->setCoords(-20, 0);//偏移量

break;

}

case DataTracer:

{

m_tracer->position->setTypeX(QCPItemPosition::ptPlotCoords);

m_tracer->position->setTypeY(QCPItemPosition::ptPlotCoords);

m_tracer->setSize(5);

m_label->setPositionAlignment(Qt::AlignLeft | Qt::AlignVCenter);

m_arrow->end->setParentAnchor(m_tracer->position);

m_arrow->start->setParentAnchor(m_arrow->end);

m_arrow->start->setCoords(20, 0);

break;

}

default:

break;

}

setVisible(false);

}

}

XxwTracer::~XxwTracer()

{

if(m_plot)

{

if (m_tracer)

m_plot->removeItem(m_tracer);

if (m_label)

m_plot->removeItem(m_label);

if (m_arrow)

m_plot->removeItem(m_arrow);

}

}

void XxwTracer::setPen(const QPen &pen)

{

if(m_tracer)

m_tracer->setPen(pen);

if(m_arrow)

m_arrow->setPen(pen);

}

void XxwTracer::setBrush(const QBrush &brush)

{

if(m_tracer)

m_tracer->setBrush(brush);

}

void XxwTracer::setLabelPen(const QPen &pen)

{

if(m_label)

{

m_label->setPen(pen);

m_label->setBrush(Qt::NoBrush);

m_label->setColor(pen.color());

}

}

void XxwTracer::setText(const QString &text)

{

if(m_label)

m_label->setText(text);

}

void XxwTracer::setVisible(bool vis)

{

m_visible = vis;

if(m_tracer)

m_tracer->setVisible(m_visible);

if(m_label)

m_label->setVisible(m_visible);

if(m_arrow)

m_arrow->setVisible(m_visible);

}

void XxwTracer::updatePosition(double xValue, double yValue)

{

if (!m_visible)

{

setVisible(true);

m_visible = true;

}

if (yValue > m_plot->yAxis->range().upper)

yValue = m_plot->yAxis->range().upper;

switch (m_type)

{

case XAxisTracer:

{

m_tracer->position->setCoords(xValue, 1);

m_label->position->setCoords(0, 15);

m_arrow->start->setCoords(0, 15);

m_arrow->end->setCoords(0, 0);

setText(QString::number(xValue));

break;

}

case YAxisTracer:

{

m_tracer->position->setCoords(0, yValue);

m_label->position->setCoords(-20, 0);

// m_arrow->start->setCoords(20, 0);

// m_arrow->end->setCoords(0, 0);

setText(QString::number(yValue));

break;

}

case DataTracer:

{

m_tracer->position->setCoords(xValue, yValue);

m_label->position->setCoords(20, 0);

setText(QString("x:%1,y:%2").arg(xValue).arg(yValue));

break;

}

default:

break;

}

}

XxwTraceLine::XxwTraceLine(QCustomPlot *_plot, LineType _type, QObject *parent)

: QObject(parent),

m_type(_type),

m_plot(_plot)

{

m_lineV = Q_NULLPTR;

m_lineH = Q_NULLPTR;

initLine();

}

XxwTraceLine::~XxwTraceLine()

{

if(m_plot)

{

if (m_lineV)

m_plot->removeItem(m_lineV);

if (m_lineH)

m_plot->removeItem(m_lineH);

}

}

void XxwTraceLine::initLine()

{

if(m_plot)

{

QPen linesPen(Qt::red, 1, Qt::DashLine);

if(VerticalLine == m_type || Both == m_type)

{

m_lineV = new QCPItemStraightLine(m_plot);//垂直线

m_lineV->setLayer("overlay");

m_lineV->setPen(linesPen);

m_lineV->setClipToAxisRect(true);

m_lineV->point1->setCoords(0, 0);

m_lineV->point2->setCoords(0, 0);

}

if(HorizonLine == m_type || Both == m_type)

{

m_lineH = new QCPItemStraightLine(m_plot);//水平线

m_lineH->setLayer("overlay");

m_lineH->setPen(linesPen);

m_lineH->setClipToAxisRect(true);

m_lineH->point1->setCoords(0, 0);

m_lineH->point2->setCoords(0, 0);

}

}

}

void XxwTraceLine::updatePosition(double xValue, double yValue)

{

if(VerticalLine == m_type || Both == m_type)

{

if(m_lineV)

{

m_lineV->point1->setCoords(xValue, m_plot->yAxis->range().lower);

m_lineV->point2->setCoords(xValue, m_plot->yAxis->range().upper);

}

}

if(HorizonLine == m_type || Both == m_type)

{

if(m_lineH)

{

m_lineH->point1->setCoords(m_plot->xAxis->range().lower, yValue);

m_lineH->point2->setCoords(m_plot->xAxis->range().upper, yValue);

}

}

}

2. 自定义的图表类XCustomPlot

XCustomPlot是基于QCustomPlot二次开发的图表类，在鼠标移动过程中动态显示曲线上点的值。

头文件XCustomPlot.h

#ifndef XCUSTOMPLOT_H

#define XCUSTOMPLOT_H

#include "XxwTracer.h"

#include "qcustomplot.h"

#include

#include

class XxwCustomPlot:public QCustomPlot

{

Q_OBJECT

public:

XxwCustomPlot(QWidget *parent = 0);

protected:

virtual void mouseMoveEvent(QMouseEvent *event);

public:

///

/// brief 设置是否显示鼠标追踪器

/// param show:是否显示

///

void showTracer(bool show)

{

m_isShowTracer = show;

if(m_xTracer)

m_xTracer->setVisible(m_isShowTracer);

foreach (XxwTracer *tracer, m_dataTracers)

{

if(tracer)

tracer->setVisible(m_isShowTracer);

}

if(m_lineTracer)

m_lineTracer->setVisible(m_isShowTracer);

}

///

/// brief 是否显示鼠标追踪器

/// return

///

bool isShowTracer(){return m_isShowTracer;};

private:

bool m_isShowTracer;//是否显示追踪器(鼠标在图中移动，显示对应的值)

XxwTracer *m_xTracer;//x轴

XxwTracer *m_yTracer;//y轴

QList m_dataTracers;//

XxwTraceLine *m_lineTracer;//直线

};

#endif // XCUSTOMPLOT_H

源文件XCustomPlot.h

#include "XxwCustomPlot.h"

XxwCustomPlot::XxwCustomPlot(QWidget *parent)

:QCustomPlot(parent)

,m_isShowTracer(false)

,m_xTracer(Q_NULLPTR)

,m_yTracer(Q_NULLPTR)

,m_dataTracers(QList())

,m_lineTracer(Q_NULLPTR)

{

}

void XxwCustomPlot::mouseMoveEvent(QMouseEvent *event)

{

QCustomPlot::mouseMoveEvent(event);

if(m_isShowTracer)

{

//当前鼠标位置(像素坐标)

int x_pos = event->pos().x();

int y_pos = event->pos().y();

//像素坐标转成实际的x,y轴的坐标

float x_val = this->xAxis->pixelToCoord(x_pos);

float y_val = this->yAxis->pixelToCoord(y_pos);

if(Q_NULLPTR == m_xTracer)

m_xTracer = new XxwTracer(this, XxwTracer::XAxisTracer);//x轴

m_xTracer->updatePosition(x_val, y_val);

if(Q_NULLPTR == m_yTracer)

m_yTracer = new XxwTracer(this, XxwTracer::YAxisTracer);//y轴

m_yTracer->updatePosition(x_val, y_val);

int nTracerCount = m_dataTracers.count();

int nGraphCount = graphCount();

if(nTracerCount < nGraphCount)

{

for(int i = nTracerCount; i < nGraphCount; ++i)

{

XxwTracer *tracer = new XxwTracer(this, XxwTracer::DataTracer);

m_dataTracers.append(tracer);

}

}

else if(nTracerCount > nGraphCount)

{

for(int i = nGraphCount; i < nTracerCount; ++i)

{

XxwTracer *tracer = m_dataTracers[i];

if(tracer)

{

tracer->setVisible(false);

}

}

}

for (int i = 0; i < nGraphCount; ++i)

{

XxwTracer *tracer = m_dataTracers[i];

if(!tracer)

tracer = new XxwTracer(this, XxwTracer::DataTracer);

tracer->setVisible(true);

tracer->setPen(this->graph(i)->pen());

tracer->setBrush(Qt::NoBrush);

tracer->setLabelPen(this->graph(i)->pen());

auto iter = this->graph(i)->data()->findBegin(x_val);

double value = iter->mainValue();

// double value = this->graph(i)->data()->findBegin(x_val)->value;

tracer->updatePosition(x_val, value);

}

if(Q_NULLPTR == m_lineTracer)

m_lineTracer = new XxwTraceLine(this,XxwTraceLine::Both);//直线

m_lineTracer->updatePosition(x_val, y_val);

this->replot();//曲线重绘

}

}

3. 使用自定义图表类XCustomPlot

在需要绘图的地方使用，代码如下：

m_customPlot = new XxwCustomPlot();

m_customPlot->showTracer(true);

// add title layout element:

m_customPlot->plotLayout()->insertRow(0);

m_customPlot->plotLayout()->addElement(0, 0, new QCPTextElement(m_customPlot, "标题", QFont("黑体", 12, QFont::Bold)));

m_customPlot->legend->setVisible(true);

QFont legendFont = font(); // start out with MainWindow's font..

legendFont.setPointSize(9); // and make a bit smaller for legend

m_customPlot->legend->setFont(legendFont);

m_customPlot->legend->setBrush(QBrush(QColor(255,255,255,230)));

// by default, the legend is in the inset layout of the main axis rect. So this is how we access it to change legend placement:

m_customPlot->axisRect()->insetLayout()->setInsetAlignment(0, Qt::AlignTop|Qt::AlignCenter);

// make left and bottom axes always transfer their ranges to right and top axes:

connect(m_customPlot->xAxis, SIGNAL(rangeChanged(QCPRange)), m_customPlot->xAxis2, SLOT(setRange(QCPRange)));

connect(m_customPlot->yAxis, SIGNAL(rangeChanged(QCPRange)), m_customPlot->yAxis2, SLOT(setRange(QCPRange)));

// Allow user to drag axis ranges with mouse, zoom with mouse wheel and select graphs by clicking:

m_customPlot->setInteractions(QCP::iRangeDrag | QCP::iRangeZoom | QCP::iSelectPlottables);

// generate some data:

int nCount = 100;

QVector x(nCount), y0(nCount), y1(nCount); // initialize with entries 0..100

for (int i = 0; i < nCount; ++i)

{

x[i] = i; // x goes from -1 to 1

y0[i] = qSin(i * 10.0f / nCount); //sin

y1[i] = qCos(i * 10.0f / nCount); //cos

}

// create graph and assign data to it:

QPen pen;

int i = 1;

QCPGraph *pGraph = m_customPlot->addGraph();

// m_customPlot->graph(0)->setData(x, y0);

pGraph->setName("sin曲线");

pGraph->setData(x,y0);

pGraph->setPen(QPen(Qt::blue));

pGraph = m_customPlot->addGraph();

// m_customPlot->graph(0)->setData(x, y0);

pGraph->setName("cos曲线");

pGraph->setData(x,y1);

pGraph->setPen(QPen(Qt::darkYellow));

// give the axes some labels:

m_customPlot->xAxis->setLabel("x");

m_customPlot->yAxis->setLabel("y");

// set axes ranges, so we see all data:

// m_customPlot->xAxis->setRange(-1, 1);

// m_customPlot->yAxis->setRange(0, 1);

m_customPlot->rescaleAxes(true);

m_customPlot->replot();

4. 效果图

效果图