Qt 画图

素颜马尾好姑娘i 2021-11-23 04:18 365阅读 0赞

![20190725202533861.png][]

#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();
     /*
      * 重写绘图事件，虚函数
      * 如果在窗口绘图，必须放在绘图事件里实现
      * 绘图事件内部自动调用，窗口需要重绘的时候(状态改变)
      */
    protected:
        void paintEvent(QPaintEvent *);
    
    private slots:
        //手动更新窗口
        void on_pushButton_clicked();
    
    private:
        Ui::MyWidget *ui;
    
        int x;
    };
    
    #endif // MYWIDGET_H

![20190725203039896.png][]

#include "mywidget.h"
    #include "ui_mywidget.h"
    #include <QPainter>
    #include <QPen> //画笔
    #include <QBrush> //填充颜色
    MyWidget::MyWidget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::MyWidget)
    {
        ui->setupUi(this);
    
        x=0;
    }
    
    MyWidget::~MyWidget()
    {
        delete ui;
    }
    
    void MyWidget::paintEvent(QPaintEvent *)
    {
        //QPainter p(this);
    
        QPainter p; //创建画家对象
        p.begin(this);//指定当前窗口为绘图设备
    
        //p.drawxxx();//绘图操作
        //1)画背景图
         //p.drawPixmap(0,0,width(),height(),QPixmap("://C:/Users/Administrator/Desktop/1.jpg"));
         // p.drawPixmap(rect(),QPixmap("://C:/Users/Administrator/Desktop/1.jpg"));
    
        //2) 画直线
            //定义画笔
            QPen pen;
            pen.setWidth(5); //设置线宽
            //pen.setColor(Qt::red);//设置颜色
            pen.setColor(QColor(14,9,234));//rgb设置颜色
            pen.setStyle(Qt::DotLine); //设置风格
            //将画笔交给画家
            p.setPen(pen);
    
           p.drawLine(50,50,150,50); //起点坐标  终点坐标
           p.drawLine(50,50,50,150);
    
           //创建画刷对象
           QBrush brush;
           brush.setColor(Qt::red);//设置颜色
           brush.setStyle(Qt::Dense1Pattern);//设置样式
           //将画刷交给画家
           p.setBrush(brush);
    
         //3)画矩形  X  Y  长  宽
           p.drawRect(200,200,100,50);
    
         //4）画圆  圆心坐标  水平半径  垂直半径
           p.drawEllipse(QPoint(150,150),50,25);
    
    
          //5)画笑脸  起点坐标 宽 高
          p.drawPixmap(x,200,80,80,QPixmap("://C:/Users/Administrator/Desktop/4.jpg"));
    
           p.end();
    }
    
    void MyWidget::on_pushButton_clicked()
    {
       x += 20;
       if(x > width())
       {
           x=0;
       }
       //刷新窗口，让窗口重绘,整个窗口都刷新
       update(); //间接调用paintEvent()
    }

![20190725203135601.png][]

###     选中按钮（点击右键）----> 转到槽 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70][]

### 效果： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 1][]

### QBitmap和QPixmap的区别： ###

1）QBitmap继承于QPixmap

2）QPixmap主要是画彩色图片，QBitmap是画黑白图片

![20190725222446339.png][]

#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:
        //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::MyWidget *ui;
    };
    
    #endif // MYWIDGET_H

![20190725222522242.png][]

#include "mywidget.h"
    #include "ui_mywidget.h"
    #include <QPainter>
    #include <QBitmap>
    MyWidget::MyWidget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::MyWidget)
    {
        ui->setupUi(this);
    }
    
    MyWidget::~MyWidget()
    {
        delete ui;
    }
    
    void MyWidget::paintEvent(QPaintEvent *)
    {
        QPainter p(this);
        //QPixmap
        p.drawPixmap(0,0,QPixmap("://C:/Users/Administrator/Desktop/6.PNG"));
        //QBitmap
        p.drawPixmap(200,0,QBitmap("://C:/Users/Administrator/Desktop/6.PNG"));
    
       //QPixmap 图片背景白色
        QPixmap pixmap;
        pixmap.load("://C:/Users/Administrator/Desktop/6.PNG");
        p.drawPixmap(0,200,pixmap);
    
        //QBitmap  图片背景白色
        QBitmap bitmap;
        bitmap.load("://C:/Users/Administrator/Desktop/6.PNG");
        p.drawPixmap(200,200,bitmap);
    
    }

### 效果： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 2][]

[20190725202533861.png]: /images/20211122/925706e4fb8b40af9458b6f6f7c33815.png
[20190725203039896.png]: /images/20211122/8886260820c54e3bbdcc21f3aa139128.png
[20190725203135601.png]: /images/20211122/ae3cbbf4fcc947e09e5d77cfe4c7f87d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70]: /images/20211122/32c72e0a531d4199afa050c7e19313fa.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 1]: /images/20211122/a5ce63e41c0d4f5fb4191ab401de2c78.png
[20190725222446339.png]: /images/20211122/f978063c9a434f8fb97f689294ba80d8.png
[20190725222522242.png]: /images/20211122/ea631eaea8ad436e84cbc576702d263d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pzMTM0MjA4NDc3Ng_size_16_color_FFFFFF_t_70 2]: /images/20211122/3fe7d648ae874554be07ab7799630108.png