Qt绘制曲线图（基于qt画图QPainter）

admin 管理员组

文章数量: 1087649

Qt绘制曲线图（基于qt画图QPainter）

在没有QCharst模块时，可以使用QPainter自定义绘制曲线折线图

下面提供完整代码供参考：
直接在qt创建一个QMainWindow类的app的工程,不自动生成ui文件，然后把下面代码复制到mainwindow.cpp编译运行即可。
mainwindow.cpp:

#include "mainwindow.h"#include <QPainter>
#include <QLabel>
#include <QImage>
#include <QPixmap>//使用QPainter将数据到曲线画在图片中
QImage imageCurve(const QVector<int> &data1, const QVector<int> &data2);MainWindow::MainWindow(QWidget *parent): QMainWindow(parent)
{resize(800,600);int n=10;//n为数据个数QVector<int> data1;QVector<int> data2;for(int i=0;i<n;i++)//随机产生两个数据集data1.append(rand()%20+10);for(int i=0;i<n;i++)data2.append(rand()%30+10);QLabel *label = new QLabel(this);label->setGeometry(50,50,600,500);//将画出来到曲线显示到label上面label->setPixmap(QPixmap::fromImage(imageCurve(data1,data2)));label->show();
}MainWindow::~MainWindow()
{}QImage imageCurve(const QVector<int> &data1, const QVector<int> &data2)
{QString x_title = "x_title";//x坐标名称QString y_title = "y_title";//y坐标名称QString title = "xx title charst";//曲线图xx名称QString overView = "charst: test,csdn: boonion";//图内容说明QString data1_name = "first";//第一条曲线名称QString data2_name = "second";QImage mimage = QImage(600,500,QImage::Format_RGB32);  //画布的初始化大小设为600*500，使用32位颜色QColor backColor = qRgb(255,255,255);    //画布初始化背景色使用白色mimage.fill(backColor);//对画布进行填充QPainter painter(&mimage);painter.setRenderHint(QPainter::Antialiasing, true);//设置反锯齿模式，好看一点int pointx=30,pointy=420;//确定坐标轴起点坐标，这里定义(35,280)int width=560-pointx,height=280;//确定坐标轴宽度跟高度painter.drawLine(pointx,pointy,width+pointx,pointy);//坐标轴x宽度为widthpainter.drawLine(pointx,pointy-height,pointx,pointy);//坐标轴y高度为heightint n=data1.size();//n为第一个数据集个数int m = data2.size();int max=0;//数组里的最大值for(int i = 0 ; i < n; i++){if(data1[i] > max){max = data1[i];}}for(int i = 0 ; i < m; i++){if(data2[i] > max){max = data2[i];}}double kx=(double)width/(n-1); //x轴的系数double ky=(double)height/max;//y方向的比例系数//设置两条的画笔QPen pen,penPoint;pen.setColor(Qt::green);pen.setWidth(2);penPoint.setColor(Qt::blue);penPoint.setWidth(5);QPen penOther,penPointOther;penOther.setColor(Qt::yellow);penOther.setWidth(2);penPointOther.setColor(Qt::red);penPointOther.setWidth(5);for(int i=0;i<n-1;i++)//画第一条线{if(i+1 > n-1)break;//由于y轴是倒着的，所以y轴坐标要pointy-a[i]*ky 其中ky为比例系数painter.setPen(pen);//用于连线painter.drawLine(pointx+kx*i,pointy-data1[i]*ky,pointx+kx*(i+1),pointy-data1[i+1]*ky);painter.setPen(penPoint);//蓝色的笔，用于标记各个点painter.drawPoint(pointx+kx*i,pointy-data1[i]*ky);painter.drawText(pointx+kx*i,pointy-data1[i]*ky-4,QString::number(data1[i]));}if(!data1.isEmpty())painter.drawPoint(pointx+kx*(n-1),pointy-data1[n-1]*ky);//绘制最后一个点//画线图示painter.setPen(pen);painter.drawLine(pointx+width-50,pointy-height-50,pointx+width-25,pointy-height-50);painter.setPen(penPoint);painter.drawPoint(pointx+width-25,pointy-height-50);painter.setPen(pen);painter.drawLine(pointx+width-20,pointy-height-50,pointx+width,pointy-height-50);painter.setPen(Qt::black);painter.drawText(pointx+width-40,pointy-height-30,QString("%1").arg(data1_name));for(int i=0;i<m-1;i++){if(i+1 > m-1)break;painter.setPen(penOther);painter.drawLine(pointx+kx*i,pointy-data2[i]*ky,pointx+kx*(i+1),pointy-data2[i+1]*ky);painter.setPen(penPointOther);painter.drawPoint(pointx+kx*i,pointy-data2[i]*ky);painter.drawText(pointx+kx*i,pointy-data2[i]*ky-5,QString::number(data2[i]));}if(!data2.isEmpty())painter.drawPoint(pointx+kx*(m-1),pointy-data2[m-1]*ky);//绘制最后一个点//画线图示painter.setPen(penOther);painter.drawLine(pointx+width-50,pointy-height-100,pointx+width-25,pointy-height-100);painter.setPen(penPointOther);painter.drawPoint(pointx+width-25,pointy-height-100);painter.setPen(penOther);painter.drawLine(pointx+width-20,pointy-height-100,pointx+width,pointy-height-100);painter.setPen(Qt::black);painter.drawText(pointx+width-40,pointy-height-80,QString("%1").arg(data2_name));//绘制刻度线int tmp = n > m ? n : m; //取刻度最大的分度值int xn = tmp > 16 ? 16 : tmp;int yn = max > 20 ? 20 : max;QPen penDegree;penDegree.setColor(Qt::black);penDegree.setWidth(2);painter.setPen(penDegree);//画上x轴刻度线for(int i=0;i<xn;i++)//分成dn份{//选取合适的坐标，绘制一段长度为4的直线，用于表示刻度painter.drawLine(pointx+(i+1)*width/xn,pointy,pointx+(i+1)*width/xn,pointy+4);painter.drawText(pointx+(i)*width/xn,pointy+15,QString::number((int)((i)*((double)tmp/xn))));}//画xy刻度名称painter.setPen(Qt::black);painter.drawText(pointx+width-40,pointy+30,QString("%1").arg(x_title));painter.setPen(Qt::black);painter.drawText(pointx-10,pointy-height-30,QString("%1").arg(y_title));//y轴刻度线double _maStep=(double)max/yn;//y轴刻度间隔需根据最大值来表示for(int i=0;i<yn;i++){//主要就是确定一个位置，然后画一条短短的直线表示刻度。painter.drawLine(pointx,pointy-(i+1)*height/yn,pointx-4,pointy-(i+1)*height/yn);painter.drawText(pointx-20,pointy-(i+0.85)*height/yn,QString::number((int)(_maStep*(i+1))));}//画图内容说明QStringList strlist = overView.split(',');//分割字符串painter.setPen(Qt::gray);int t_h = 100;foreach(QString str,strlist){painter.drawText(pointx+40,pointy-height-t_h,QString("%1").arg(str));t_h -= 20;}//画标题painter.setPen(Qt::black);QFont font;font.setPixelSize(20);painter.setFont(font);painter.drawText(pointx+width/2-80,pointy-height-60,QString("%1").arg(title));return mimage;
}
//博客：booinon
//=1011.2415.3001.5343

//博客：booinon
//=1011.2415.3001.5343

本文标签： Qt绘制曲线图（基于qt画图QPainter）