利用QT中Qpainter画点，直线，弧线等简单图形

MyImgTest.h:

#ifndef MYIMGTEST_H

#define MYIMGTEST_H

 

#include <QWidget>

class MyImgTest : public QWidget

{

    //Q_OBJECT

public:

    MyImgTest(QWidget* parent = 0);

    ~MyImgTest();

    void paintEvent(QPaintEvent *);

};

#endif

MyImgTest.cpp:

#include "MyImgTest.h"

#include <QPainter>

//#include <QRect>

//#include <QPointF>

//#include <QLineF>

MyImgTest::MyImgTest(QWidget* parent) : QWidget(parent)

{

    setFixedSize(360,360); //固定大小

    setWindowTitle("Hello DevDiv!");

}

MyImgTest::~MyImgTest()

{

   

}

void MyImgTest::paintEvent(QPaintEvent *)

{

    // 画一条直线

    QPainter painter(this);             // 创建QPainter一个对象

    QPen pen;

   

    //pen.setStyle(Qt::DashLine);        

    pen.setColor(Qt::red);           // 设置画笔为黄色

    painter.setPen(pen);                // 设置画笔

    painter.drawLine(rect().topLeft(), rect().bottomRight());

   // 画一个空心矩形

    pen.setColor(Qt::darkRed);

    painter.setPen(pen);

    painter.drawRect(1, 1, 100, 100);     //painter.drawRect(QRect(1, 1, 100, 100));

   

    // 画一个实心矩形

    QBrush bruch(Qt::FDiagPattern);     // 画刷

    painter.setBrush(bruch);            // 设置画刷

    painter.drawRect(QRect(105, 1, 100, 100));

   

   // 画一个多点线

    pen.setColor(Qt::black);

    painter.setPen(pen);

    bruch.setStyle(Qt::NoBrush);        // 将画刷设置成null//fow what

    painter.setBrush(bruch);

    static const QPointF points[4] = {QPointF(210.0, 1), QPointF(220.0, 50.3), QPointF(300, 100.4), QPointF(260.4, 120.0)};

    painter.drawPolyline(points, 4);

   

    // 画多个点

    QPointF pointf[10];

    for (int i=0; i<10; ++i)

    {

        pointf[i].setX(2.0+i*10.0);

        pointf[i].setY(130.0);

    }

    painter.drawPoints(pointf, 10);

   

     // 画多条线

    QLineF linef[5];

    for (int j=0; j<5; ++j)

    {

        linef[j].setP1(QPointF(110.9+j*10, 120.0));

        linef[j].setP2(QPointF(120.8+j*12, 200.0));

    }

    painter.drawLines(linef, 5);

   

    // 画一个多边形

    QPolygonF polygon;

    polygon << QPointF(200.0, 120.0) << QPointF(230.0, 130.0) << QPointF(260.0, 180.0) << QPointF(200.0, 200.0);

    bruch.setStyle(Qt::CrossPattern);

    painter.setBrush(bruch);

    painter.drawPolygon(polygon, Qt::WindingFill);

   

    // 画一个圆角矩形

    QRectF rectangle(290.0, 110.0, 50, 50);

    bruch.setStyle(Qt::SolidPattern);

    painter.setBrush(bruch);

    painter.drawRoundedRect(rectangle, 20.0, 15.0);

   

   // 画一个QString

    painter.drawText(50, 300, "Hello DevDiv!");

 

}
main.cpp：

#include <QApplication>

#include "MyImgTest.h"

int main(int argc,char *argv[])

{

QApplication app(argc,argv);

MyImgTest* widget = new MyImgTest();

    widget->show();

return app.exec();

}

操作步骤：

1.qmake-qt4 -project

2.qmake-qt4

3.make