QT_QCustomPlot学习

Posted 2021-10-12 Leslie X徐

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QCustomPlot学习

QCustomPlot默认提供了6个层，如下代码所示，分别是：背景层、网格层、主层、坐标轴层、图例层和矩形选择区域层。

1.在一张视图中表现两个线

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    demo();
}

Widget::~Widget()
{
    delete ui;
}

void Widget::demo()
{
    QVector<double> x,y,z;
    for (double i=0;i<10 ;i+=0.1 ) {
        x.append(i);
        y.append(i);
        z.append(i*i);
    }
    ui->cw->addGraph();
    ui->cw->graph()->setData(x,y);

    ui->cw->addGraph();
    ui->cw->graph()->setData(x,z);
    ui->cw->graph()->setPen(QPen(QColor(Qt::green)));
    
    ui->cw->graph()->setLineStyle(QCPGraph::LineStyle::lsNone);//设置连线的样式
    ui->cw->graph()->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssCross, 10));//设置散点的样式，ssCross为十字样式
    ui->cw->graph()->setSelectable(QCP::SelectionType::stMultipleDataRanges);//设置图形中可选的元素，这里配合选择框使用多点选择，可以通过选取框选择多个点，也可以按住ctrl多选

    ui->cw->setInteractions(QCP::iRangeDrag|QCP::iRangeZoom|QCP::iSelectPlottables|QCP::iMultiSelect);

    ui->cw->replot();
}

//可以把矩形框设置放在外面
void Widget::on_checkBox_2_clicked(bool checked)
{
    if(checked){
        ui->cw->setSelectionRectMode(QCP::SelectionRectMode::srmSelect);//添加鼠标选取矩形框，并设置为选择操作，此时鼠标的拖拽功能失效。按住ctrl可以多选
    }else{
        ui->cw->setSelectionRectMode(QCP::SelectionRectMode::srmNone);//取消矩形框选取，鼠标拖拽功能返回
        ui->cw->deselectAll();
        ui->cw->replot();
    }
}

2.一张视图中多个图表:使用QCPLayoutGrid

void Widget::demo2()
{
    //一张视图中多个图表

    //创建QCPAxisRect
    QCPAxisRect* a = new QCPAxisRect (ui->cw);
    QCPAxisRect* b = new QCPAxisRect (ui->cw);

    //添加到QCPLayoutGrid
    ui->cw->plotLayout()->clear();
    QCPLayoutGrid* lay = ui->cw->plotLayout() ;
    lay->addElement(0,0,a);
    lay->addElement(1,0,b);


    //创建数据
    QVector<QCPGraphData> d1,d2;
    for (double i=0;i<10 ;i+=0.1 ) {
        d1.append(QCPGraphData(i,i));
        d2.append(QCPGraphData(i,i*i));
    }

    //创建数据，添加到QCPGraph
    QCPGraph* ga = ui->cw->addGraph(a->axis(QCPAxis::atBottom),a->axis(QCPAxis::atLeft));
    ga->data()->set(d1);
    ga->rescaleAxes();

    QCPGraph* gb = ui->cw->addGraph(b->axis(QCPAxis::atBottom),b->axis(QCPAxis::atLeft));
    gb->data()->set(d2);
    gb->rescaleAxes();

    //同时改变X轴大小，可以用来进行对比
    ui->cw->setInteractions(QCP::iRangeDrag|QCP::iRangeZoom|QCP::iSelectPlottables);
    
    connect(ga->keyAxis(),SIGNAL(rangeChanged(QCPRange)),gb->keyAxis(),SLOT(setRange(QCPRange)));
    connect(gb->keyAxis(),SIGNAL(rangeChanged(QCPRange)),ga->keyAxis(),SLOT(setRange(QCPRange)));
    
    ui->cw->axisRect(0)->setRangeZoom(Qt::Horizontal);
    ui->cw->axisRect(1)->setRangeZoom(Qt::Horizontal);
}

同步X轴大小：

{  
//同时改变X轴大小，可以用来进行对比
    ui->cw->setInteractions(QCP::iRangeDrag|QCP::iRangeZoom|QCP::iSelectPlottables);

    for(int i=0 ; i < ui->cw->graphCount(); ++i){
         connect(ui->cw->graph(i)->keyAxis(),SIGNAL(rangeChanged(QCPRange)),this,SLOT(setXRange(QCPRange)));
        ui->cw->axisRect(i)->setRangeZoom(Qt::Horizontal);
    }
}

void Widget::setXRange(QCPRange range)
{
    for(int i=0 ; i < ui->cw->graphCount(); ++i){
        ui->cw->graph(i)->keyAxis()->setRange(range);
    }
}

添加checkbox是否同步：

void Widget::on_checkBox_clicked(bool checked)
{
    if(checked){
        for(int i=0 ; i < ui->cw->graphCount(); ++i){
             connect(ui->cw->graph(i)->keyAxis(),SIGNAL(rangeChanged(QCPRange)),this,SLOT(setXRange(QCPRange)));
             ui->cw->axisRect(i)->setRangeZoom(Qt::Horizontal);
             ui->cw->axisRect(i)->setRangeDrag(Qt::Horizontal);
             ui->cw->graph(i)->rescaleAxes();
        }
    }else{
        for(int i=0 ; i < ui->cw->graphCount(); ++i){
             disconnect(ui->cw->graph(i)->keyAxis(),SIGNAL(rangeChanged(QCPRange)),this,SLOT(setXRange(QCPRange)));
             ui->cw->axisRect(i)->setRangeZoom(Qt::Horizontal|Qt::Vertical);
             ui->cw->axisRect(i)->setRangeDrag(Qt::Horizontal|Qt::Vertical);
        }
    }
}

遗憾的是，现在QCPLayoutGrid这个方法还没找到有QSplitter这样可以分割的部件实现调整窗口的大小。

3.一张视图中多个图表:使用QSplitter

使用两个QCustomPlot窗口，加上一个QSplitter实现调整大小

void Widget::demo3()
{
    ui->cw->plotLayout()->clear();
    //创建数据
    QVector<QCPGraphData> d1,d2,d3;
    for (double i=0;i<10 ;i+=0.1 ) {
        d1.append(QCPGraphData(i,i));
        d2.append(QCPGraphData(i,i*i));
        d3.append(QCPGraphData(i,qSqrt(i)));
    }

    QCustomPlot* qcp1 = new QCustomPlot();
    QCustomPlot* qcp2 = new QCustomPlot();
    QCustomPlot* qcp3 = new QCustomPlot();

    qcp1->addGraph()->data()->set(d1);
    qcp2->addGraph()->data()->set(d2);
    qcp3->addGraph()->data()->set(d3);

    qcp1->setInteractions(QCP::iRangeDrag|QCP::iRangeZoom|QCP::iSelectPlottables);
    qcp2->setInteractions(QCP::iRangeDrag|QCP::iRangeZoom|QCP::iSelectPlottables);
    qcp3->setInteractions(QCP::iRangeDrag|QCP::iRangeZoom|QCP::iSelectPlottables);

    /*QSplitter**/ pSplitter = new QSplitter(Qt::Vertical,this);
    pSplitter->addWidget(qcp1);
    pSplitter->addWidget(qcp2);
    pSplitter->addWidget(qcp3);
    ui->show->addWidget(pSplitter); //注意这里的 ui->show为 QGridLayout类型

    QCustomPlot* q = nullptr;
    for(int i=0;i < pSplitter->count();++i){
        q = static_cast<QCustomPlot*>(pSplitter->widget(i));
        connect(q->graph()->keyAxis(),SIGNAL(rangeChanged(QCPRange)),this,SLOT(set3Range(QCPRange)));
    }

}

void Widget::set3Range(QCPRange range)
{
    QCustomPlot* q = nullptr;
    for(int i=0;i < pSplitter->count();++i){
        q = static_cast<QCustomPlot*>(pSplitter->widget(i));
        q->graph()->keyAxis()->setRange(range);
        q->replot();
    }
}

4.时间轴

double now = QDateTime::currentDateTime().toSecsSinceEpoch();
QSharedPointer<QCPAxisTickerDateTime> dateTicker(new QCPAxisTickerDateTime);
dateTicker->setDateTimeFormat("d MMMM\\n yyyy");
ui->cw->xAxis2->setTicker(dateTicker);
ui->cw->xAxis2->setRange(now,now+24*3600*10);
ui->cw->xAxis2->setVisible(true);

5.实现鼠标左键选框，中键平移，右键菜单

以下鼠标键都在qcustomplot.cpp中修改，注意不要搞错成员函数所在的类名

左键选框：

把官方的框选功能限制在左键上，在函数void QCustomPlot::mousePressEvent(QMouseEvent *event)中修改如下：

void QCustomPlot::mousePressEvent(QMouseEvent *event)
{
  emit mousePress(event);
  // save some state to tell in releaseEvent whether it was a click:
  mMouseHasMoved = false;
  mMousePressPos = event->pos();
  //添加 event->button() == Qt::LeftButton ，将选取框按键绑定在左键
  if (event->button() == Qt::LeftButton && mSelectionRect && mSelectionRectMode != QCP::srmNone)
  {
    if (mSelectionRectMode != QCP::srmZoom || qobject_cast<QCPAxisRect*>(axisRectAt(mMousePressPos))) // in zoom mode only activate selection rect if on an axis rect
      mSelectionRect->startSelection(event);
  } else if(event->button() != Qt::LeftButton)//添加if
  {//...
  }
}

中键平移：

官方默认左键是平移曲线，我们把平移功能改到中键上去，以便右键菜单。直接在函数
void QCPAxisRect::mousePressEvent(QMouseEvent *event, const QVariant &details)改，把Qt::LeftButton改成Qt::RightButton即可。

void QCPAxisRect::mousePressEvent(QMouseEvent *event, const QVariant &details)
{
  Q_UNUSED(details)
  if (event->buttons() & Qt::midButton)//将Qt::LeftButton改成你要绑定的拖拽的按键
  {
      //...
  }
}

右键菜单：

void demo(){
    ui->cw->setContextMenuPolicy(Qt::CustomContextMenu);
    connect(ui->cw,&QCustomPlot::customContextMenuRequested,this,&Widget::MenuRequested);
}

void Widget::MenuRequested(QPoint p)
{
    QMenu *menu = new QMenu(this);
    menu->setAttribute(Qt::WA_DeleteOnClose);
    menu->addAction("resize",this,[=](){
        ui->cw->rescaleAxes();
        ui->cw->replot();
    });
    menu->addAction("zoom",this,[=](){
        ui->cw->setSelectionRectMode(QCP::SelectionRectMode::srmZoom);
    });
    menu->addAction("select",this,[=](){
        ui->cw->setSelectionRectMode(QCP::SelectionRectMode::srmSelect);
    });
    menu->addAction("None",this,[=](){
        ui->cw->setSelectionRectMode(QCP::SelectionRectMode::srmNone);
    });
    menu->popup(ui->cw->mapToGlobal(p));//必须要，否则不显示菜单
}

写进新的类：plotView

//hpp
#include "../../plotLib/qcustomplot.h"
class plotView : public QCustomPlot
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