QT-事件-绘图设备-QPixmap、QImage、QPicture

widget.h

#ifndef WIDGET_H
#define WIDGET_H
 
#include 
 
namespace Ui {
class Widget;
}
 
class Widget :  public QWidget
{
    Q_OBJECT
 
public :
    explicit Widget(QWidget *parent = 0);
    ~Widget();
 
    //绘图事件
    void paintEvent(QPaintEvent *);
 
private :
    Ui::Widget *ui;
};
 
#endif // WIDGET_H

　widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include 
#include 
#include 
#include 
Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui( new Ui::Widget)
{
    ui->setupUi( this );
 
//    //Pixmap绘图设备 专门为平台做了显示的优化
//    QPixmap pix(300,300);
 
//    //填充颜色
//    pix.fill(Qt::white);
 
//    //声明画家
//    QPainter painter(&pix);
//    painter.setPen(QPen(Qt::green));
//    painter.drawEllipse(QPoint(150,150) , 100,100);
//    //保存
//    pix.save("E:\\pix.png");
 
 
 
    //QImage 绘图设备  可以对像素进行访问
//    QImage img(300,300,QImage::Format_RGB32);
//    img.fill(Qt::white);
 
//    QPainter painter(&img);
//    painter.setPen(QPen(Qt::blue));
//    painter.drawEllipse(QPoint(150,150) , 100,100);
 
//    //保存
//    img.save("E:\\img.png");
 
 
    //QPicture 绘图设备  可以记录和重现 绘图指令
    QPicture pic;
    QPainter painter;
    painter.begin(&pic);   //开始往pic上画
    painter.setPen(QPen(Qt::cyan));
    painter.drawEllipse(QPoint(150,150) , 100,100);
    painter.end();  //结束画画
 
    //保存到磁盘
    pic.save( "E:\\pic.zt" );
 
}
 
//绘图事件
void Widget::paintEvent(QPaintEvent *)
{
 
//    QPainter painter(this);
 
//    //利用QImage 对像素进行修改
//    QImage img;
//    img.load(":/Image/Luffy.png");
 
//    //修改像素点
//    for(int i = 50 ;i < 100 ; i++)
//    {
//        for(int j = 50 ; j < 100;j++)
//        {
//            QRgb value = qRgb(255,0,0);
//            img.setPixel(i,j,value);
//        }
//    }
 
//    painter.drawImage(0,0,img);
 
 
    QPainter painter( this );
    //重现QPicture的绘图指令
    QPicture pic;
    pic.load( "E:\\pic.zt" );
    painter.drawPicture(0,0,pic);
 
}
 
 
Widget::~Widget()
{
    delete ui;
}