qt图表库qcustomplot使用心得记录四 （参考线）

qt图表库qcustomplot使用心得记录四 （参考线）

本系列讲述的是我使用qt图表库qcustomplot中的使用心得分享，借此记录我的学习内容，也希望可以给与初学者一些帮助。

本篇文章讲述的是实现标记线的功能，即使水平线和垂直线，标记线可以在图表内随意拖动。

实现原理

标记线功能的实现原理也不是很难，就是使用绘图在Widget内绘制一条水平/垂直线，在通过鼠标事件使其可以左后/上下拖动，以用来标记一个点。

代码实现：代码中只实现了垂直参考线，水平参考线实现原理同理在这里就不做重复解释了。

#ifndef CUSTONPLOTEX_H

#define CUSTONPLOTEX_H

#include

#include “QCustomPlot/qcustomplot.h”

#include

#include “stdio.h”

class CustomPlotEx : public QCustomPlot

{

Q_OBJECT

public:

CustomPlotEx();

CustomPlotEx(QWidget *widget);

~CustomPlotEx() Q_DECL_OVERRIDE;

//锁定，解锁

void lock();

void unLock();

/**********************************选点************************************************/

void showVLine();//显示垂直线 根据垂直线选点

void enableVScratchLine(bool enable);//使能标记线

void enableVScratchLine(bool enable,double key);//使能标记线 (使能标志，标记线位置)

bool vStcratchLineStatus(){return enableSLine;}

double keyFromVScratchLine();

protected:

//键盘按下事件

virtual void keyPressEvent(QKeyEvent *event) Q_DECL_OVERRIDE;

virtual void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;

virtual void mouseDoubleClickEvent(QMouseEvent *event) Q_DECL_OVERRIDE;

virtual void mouseMoveEvent(QMouseEvent *event) Q_DECL_OVERRIDE;

virtual void mouseReleaseEvent(QMouseEvent *event) Q_DECL_OVERRIDE;

virtual void wheelEvent(QWheelEvent *event) Q_DECL_OVERRIDE;

virtual void paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;

public slots:

//鼠标按下

void mousePress(QMouseEvent *event);

//鼠标移动

void mouseMove(QMouseEvent *event);

//鼠标释放

void mouseRelease(QMouseEvent *event);

//鼠标滑轮

void mouseWheel(QWheelEvent *event);

private:

void Init();

bool isLock = false;//锁定

bool enableSLine = false;//标记线使能标志

struct LINESEG{

bool bdraw;

bool bselLine;

QPoint startPoint;

QPoint endPoint;

};

QList lineSegList;

};

#endif // CUSTONPLOTEX_H

#include “customplotex.h”

CustomPlotEx::CustomPlotEx() : QCustomPlot(new QWidget())

{

Init();

}

CustomPlotEx::CustomPlotEx(QWidget *widget) : QCustomPlot(widget)

{

Init();

}

CustomPlotEx::~CustomPlotEx()

{

}

void CustomPlotEx::lock()

{

isLock = true;

}

void CustomPlotEx::unLock()

{

isLock = false;

}

void CustomPlotEx::showVLine()

{

// lineSegList[0].startPoint

lineSegList[0].startPoint.ry() = 0;

lineSegList[0].startPoint.rx() = this->width()/2;

lineSegList[0].endPoint.ry() = this->height();

lineSegList[0].endPoint.rx() = this->width()/2;

lineSegList[0].bdraw = true;

update();

}

void CustomPlotEx::enableVScratchLine(bool enable)

{

enableSLine = enable;

if(enableSLine)

{

lineSegList[0].startPoint.ry() = 0;

lineSegList[0].startPoint.rx() = this->width()/2;

lineSegList[0].endPoint.ry() = this->height();

lineSegList[0].endPoint.rx() = this->width()/2;

lineSegList[0].bdraw = true;

update();

}else{

lineSegList[0].bdraw = false;

update();

}

}

void CustomPlotEx::enableVScratchLine(bool enable, double key)

{

enableSLine = enable;

if(enableSLine)

{

lineSegList[0].startPoint.ry() = 0;

lineSegList[0].startPoint.rx() = static_cast(xAxis->coordToPixel(key));

lineSegList[0].endPoint.ry() = this->height();

lineSegList[0].endPoint.rx() = static_cast(xAxis->coordToPixel(key));

lineSegList[0].bdraw = true;

update();

}else{

lineSegList[0].bdraw = false;

update();

}

}

double CustomPlotEx::keyFromVScratchLine()

{

return xAxis->pixelToCoord(lineSegList.at(0).startPoint.x());

}

void CustomPlotEx::keyPressEvent(QKeyEvent *event)

{

if(isLock)

return;

}

void CustomPlotEx::mousePressEvent(QMouseEvent *event)

{

if(isLock)

return;

if(enableSLine)

{

if(lineSegList[0].bdraw || lineSegList[1].bdraw)

{

lineSegList[0].startPoint.rx() = event->pos().x();

lineSegList[0].endPoint.rx() = event->pos().x();

lineSegList[0].bselLine = true;

return;

}

}

QCustomPlot::mousePressEvent(event);

}

void CustomPlotEx::mouseDoubleClickEvent(QMouseEvent *event)

{

if(isLock)

return;

QCustomPlot::mouseDoubleClickEvent(event);

}

void CustomPlotEx::mouseMoveEvent(QMouseEvent *event)

{

if(isLock)

return;

QCustomPlot::mouseMoveEvent(event);

}

void CustomPlotEx::mouseReleaseEvent(QMouseEvent *event)

{

if(isLock)

return;

QCustomPlot::mouseReleaseEvent(event);

}

void CustomPlotEx::wheelEvent(QWheelEvent *event)

{

if(isLock)

return;

QCustomPlot::wheelEvent(event);

}

void CustomPlotEx::paintEvent(QPaintEvent *event)

{

QCustomPlot::paintEvent(event);

QPainter p(this);

QPen pen;

pen.setColor(QColor(87,152,252));

pen.setWidth(2);

p.setPen(pen);

foreach(auto i,lineSegList)

{

if(i.bdraw)

p.drawLine(i.startPoint,i.endPoint);

}

}

void CustomPlotEx::mousePress(QMouseEvent *event)

{

Q_UNUSED(event);

}

void CustomPlotEx::mouseMove(QMouseEvent *event)

{

if(enableSLine){

if(lineSegList[0].bdraw || lineSegList[1].bdraw)

{

if(lineSegList[0].bselLine)

{

lineSegList[0].startPoint.rx() = event->pos().x();

lineSegList[0].endPoint.rx() = event->pos().x();

update();

return;

}else{

if(event->pos().x() == lineSegList[0].startPoint.x())

{

setCursor(Qt::PointingHandCursor);

return;

}

}

}

}

QList candidates = layerableListAt(event->pos(), false);

if(candidates.contains(this->xAxis))

{

setCursor(Qt::SizeHorCursor);

}else if(candidates.contains(this->yAxis))

{

setCursor(Qt::SizeVerCursor);

}else{

setCursor(Qt::ArrowCursor);

}

}

void CustomPlotEx::mouseRelease(QMouseEvent *event)

{

if(lineSegList[0].bselLine)

lineSegList[0].bselLine = false;

}

void CustomPlotEx::mouseWheel(QWheelEvent *event)

{

Q_UNUSED(event);

}

void CustomPlotEx::Init()

{

// setAntialiasedElement(QCP::aeAll);//抗锯齿

setInteractions(QCP::iRangeDrag | QCP::iRangeZoom | QCP::iSelectAxes |

QCP::iSelectLegend | QCP::iSelectPlottables);

setPlottingHints(QCP::phFastPolylines | QCP::phImmediateRefresh | QCP::phCacheLabels);

this->setOpenGl(true);

setNoAntialiasingOnDrag(true);

LINESEG vLine;

vLine.bdraw = false;

vLine.bselLine = false;

vLine.startPoint.ry() = 0;

vLine.startPoint.rx() = this->width()/2;

vLine.endPoint.ry() = this->height();

vLine.endPoint.rx() = this->width()/2;

LINESEG hLine;

hLine.bdraw = false;

hLine.bselLine = false;

hLine.startPoint.ry() = 0;

hLine.startPoint.rx() = this->width()/2;

hLine.endPoint.ry() = this->height();

hLine.endPoint.rx() = this->width()/2;

lineSegList.append(vLine);

lineSegList.append(hLine);

connect(this, SIGNAL(mousePress(QMouseEvent*)), this, SLOT(mousePress(QMouseEvent*)));

connect(this, SIGNAL(mouseMove(QMouseEvent*)), this, SLOT(mouseMove(QMouseEvent*)));

connect(this, SIGNAL(mouseRelease(QMouseEvent*)), this, SLOT(mouseRelease(QMouseEvent*)));

connect(this, SIGNAL(mouseWheel(QWheelEvent*)), this, SLOT(mouseWheel(QWheelEvent*)));

}