qt5之QImage,QBitmap,QPixmap

野性酷女 2022-01-21 10:47 262阅读 0赞

绘图（打开jpg,bmp文件显示）

1，QBitmap和QPixmap的使用

widgt.cpp

#include "widget.h"
    #include "ui_widget.h"
    #include <QPainter>
    #include <QBitmap>
    
    Widget::Widget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::Widget)
    {
        ui->setupUi(this);
    }
    
    Widget::~Widget()
    {
        delete ui;
    }
    
    void Widget::paintEvent(QPaintEvent *)
    {
        QPainter p(this);
        //QPixmap 图片背景透明
        p.drawPixmap(0, 0, QPixmap("../Image/butterfly.png"));
        //QBitmap 图片背景透明
        p.drawPixmap(200, 0, QBitmap("../Image/butterfly.png"));
    
         //QPixmap 图片背景白色
        QPixmap pixmap;
        pixmap.load("../Image/butterfly1.png");
        p.drawPixmap(0, 200, pixmap);
    
        //QBitmap 图片背景白色
        QBitmap bitmap;
        bitmap.load("../Image/butterfly1.png");
        p.drawPixmap(200, 200, bitmap);
    
    }

widgt.h

#ifndef WIDGET_H
    #define WIDGET_H
    
    #include <QWidget>
    
    namespace Ui {
    class Widget;
    }
    
    class Widget : public QWidget
    {
        Q_OBJECT
    
    public:
        explicit Widget(QWidget *parent = 0);
        ~Widget();
    
    protected:
        //重写绘图事件
        //如果给窗口绘图，一定要在paintEvent()绘图
        void paintEvent(QPaintEvent *);
    
    private:
        Ui::Widget *ui;
    };
    
    #endif // WIDGET_H

2，背景填充：

#include "widget.h"
    #include "ui_widget.h"
    #include <QPainter>
    
    Widget::Widget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::Widget)
    {
        ui->setupUi(this);
    
        //绘图设备， 400*300
        QPixmap pixmap(400, 300);
    
        QPainter p(&pixmap);
        //填充白色背景色
        //p.fillRect(0, 0, 400, 300, QBrush(Qt::white));
    
        pixmap.fill(Qt::white);
    
        p.drawPixmap(0, 0, 80, 80, QPixmap("../Image/face.png"));
    
        //保存图片
        pixmap.save("../pixmap.jpg");
    
    
    
    }
    
    Widget::~Widget()
    {
        delete ui;
    }

3，setpixel 函数功能：该函数将指定坐标处的像素设为指定的颜色。

#include "widget.h"
    #include "ui_widget.h"
    #include <QPainter>
    
    Widget::Widget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::Widget)
    {
        ui->setupUi(this);
    
        //创建一个绘图设备，QImage::Format_ARGB32背景是透明
        QImage image(400, 300, QImage::Format_ARGB32);
        QPainter p;
        p.begin(&image);
    
        //绘图
        p.drawImage(0, 0, QImage("../Image/face.png"));
    
        //对绘图设备前50个像素点进行操作
        for(int i = 0; i < 50; i++)
        {
            for(int j = 0; j < 50; j++)
            {
                image.setPixel(QPoint(i, j), qRgb(0, 255, 0));
                //image.pixel(QPoint(i, j));
            }
        }
    
        p.end();
    
        image.save("../image.png");
    
    }
    
    Widget::~Widget()
    {
        delete ui;
    }

4,QPicture的使用：

#include "widget.h"
    #include "ui_widget.h"
    #include <QPainter>
    #include <QPicture>
    #include <QImage>
    #include <QPixmap>
    
    Widget::Widget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::Widget)
    {
        ui->setupUi(this);
    
        QPicture picture;
        QPainter p;
        p.begin(&picture);
    
        p.drawPixmap(0, 0, 80, 80, QPixmap("../Image/face.png"));
        p.drawLine(50, 50, 150, 50);
    
        p.end();
    
        //保存的是二进制文件
        picture.save("../picture.png");
    }
    
    Widget::~Widget()
    {
        delete ui;
    }
    
    void Widget::paintEvent(QPaintEvent *)
    {
    
    #if 0
        QPicture pic;
        pic.load("../picture.png"); //加载文件
    
        QPainter p(this);
        p.drawPicture(0, 0, pic);
    
    #endif
    
        QPainter p(this);
        QPixmap pixmap;
        pixmap.load("../Image/face.png");
    
        //QPixmap -> QImage
        QImage tempImage = pixmap.toImage();
        p.drawImage(0, 0, tempImage);
    
    
        QImage image;
        image.load("../Image/face.png");
    
        //QImage -> QPixmap
        QPixmap tempPixmap = QPixmap::fromImage(image);
        p.drawPixmap(100, 0, tempPixmap);
    
    }