绘图设置 QPixmap QImage QPicture

梦里梦外; 2021-11-22 06:04 234阅读 0赞

### 绘图设置： ###

QPixmap：针对屏幕进行优化了，和平台相关，不能对图片进行修改

QImage：和平台无关，可以对图片进行修改，在线程中绘图

QPicture：保存绘图的状态(二进制文件)

# QPixmap #

![2019072609182314.png][]

#include "mywidget.h"
    #include "ui_mywidget.h"
    #include <QPainter> //画家
    MyWidget::MyWidget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::MyWidget)
    {
        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("://C:/Users/Administrator/Desktop/Image/4.jpg"));
       //保存图片
       pixmap.save("../pixmap.jpg");
    
    }
    
    MyWidget::~MyWidget()
    {
        delete ui;
    }

# QImage #

![20190726092447352.png][]

#include "mywidget.h"
    #include "ui_mywidget.h"
    #include <QPainter>
    MyWidget::MyWidget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::MyWidget)
    {
        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("://C:/Users/Administrator/Desktop/Image/1.jpg"));
          //对绘图设备前50个点进行操作
        for(int i=0; i < 50; i++)
        {
            for(int j = 0; j < 50; j++)
            {
                image.setPixel(QPoint(i,j),qRgb(0,255,0));
            }
        }
        p.end();
    
        image.save("../QImage.jpg");
    }
    
    MyWidget::~MyWidget()
    {
        delete ui;
    }

# QPicture #

mywidget.h

#ifndef MYWIDGET_H
    #define MYWIDGET_H
    
    #include <QWidget>
    
    namespace Ui {
    class MyWidget;
    }
    
    class MyWidget : public QWidget
    {
        Q_OBJECT
    
    public:
        explicit MyWidget(QWidget *parent = 0);
        ~MyWidget();
    
    protected:
        void paintEvent(QPaintEvent *);
    
    private:
        Ui::MyWidget *ui;
    };
    
    #endif // MYWIDGET_H

### ![20190726092753457.png][] ###

#include "mywidget.h"
    #include "ui_mywidget.h"
    #include <QPainter>
    #include <QPicture>
    MyWidget::MyWidget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::MyWidget)
    {
        ui->setupUi(this);
    
        QPicture picture;
        QPainter p;
        p.begin(&picture);
    
        p.drawPixmap(0,0,80,80,QPixmap("://C:/Users/Administrator/Desktop/Image/2.jpg"));
        p.drawLine(100,100,150,100);
    
        p.end();
       //保存的是二进制文件
        picture.save("../QPicture.jpg");
    }
    
    MyWidget::~MyWidget()
    {
        delete ui;
    }
    
    
    void MyWidget::paintEvent(QPaintEvent *)
    {
        QPicture pic;
        //加载文件
        pic.load("../QPicture.jpg");
        QPainter p(this);
        p.drawPicture(0,0,pic);
    }

### 效果： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 1][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 2][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 3][]

[2019072609182314.png]: /images/20211122/fe79725c40194a3292411db1ce036306.png
[20190726092447352.png]: /images/20211122/78b893175e8c4a0c869fee8e661fc81a.png
[20190726092753457.png]: /images/20211122/8728c259687c44f086c9f85eed122ddc.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70]: /images/20211122/692e18cf69504566950bf34cce4d211d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 1]: /images/20211122/a397ca1e46884d2fb94677e26a5c0c80.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 2]: /images/20211122/7c41e50f738c41aabbbb5564730115ac.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 3]: /images/20211122/607b63ddd4344a388b6f1c25cd946dd7.png