c/c++语言开发共享Qt 小画板

菜单栏的功能都实现了，如果想添加工具栏可以用函数封装
代码放行使用

mainWindow.h

#ifndef MAINWINDOW_H #define MAINWINDOW_H  #include <QMainWindow> #include <QApplication> #include <QMenu> #include <QAction> #include <QMenuBar> #include <QDebug> #include <QMouseEvent> #include <QVector> #include <QPainter> #include <QPixmap> #include <QDialog> #include <QComboBox> #include <QFileDialog> class MainWindow : public QMainWindow {     Q_OBJECT  public:     MainWindow(QWidget *parent = nullptr);     ~MainWindow();      enum Number{         One = 1,         Two,         Three,         Four,         Five,         Six,         Seven,         Eight,         Nine,         Ten     };  protected:     void paintEvent(QPaintEvent *event)override;        // 重绘事件     void resizeEvent(QResizeEvent *size)override;       // 窗口大小变动事件     void mousePressEvent(QMouseEvent *event)override;   // 鼠标点击事件     void mouseMoveEvent(QMouseEvent *event)override;    // 鼠标移动事件     void mouseReleaseEvent(QMouseEvent *event)override; // 鼠标弹起事件 private:     QMenu *menu;     QAction *action1;     QAction *action2;     QAction *action3;     QAction *action4;     QAction *action5;     QAction *action6;     QAction *action7;     QAction *action8;     QAction *action9;     QAction *actioncolor;     QPixmap pixmap;     QPixmap pix;     QPixmap null;     QPen pen;     QComboBox *comboBox;     QVector<QLine>line;     // 直线     QVector<QLine>lines;    // 铅笔     QVector<QVector<QLine>>vecline;         // 记录铅笔移动的二维容器     QVector<QVector<QVector<QLine>>>myline; // 记录铅笔的三维容器     QVector<QRect>rect;     // 椭圆     QVector<QRect>elli;     // 矩形     QVector<int>vec;        // 记录绘画的笔数     bool isMouse;     Number num;     Number tool;      QApplication *t;     // 退出事件循环的对象指针 public slots:     void slotType(QAction *type);     void slotColor(int color); }; #endif // MAINWINDOW_H  

mainWindow.cpp

#include "mainwindow.h"  MainWindow::MainWindow(QWidget *parent)     : QMainWindow(parent) {     menu = menuBar()->addMenu(tr("绘图"));    // 添加一个菜单栏     action1 = menu->addAction(tr("打开"),nullptr,nullptr,QKeySequence("Ctrl+O")); // 添加一个菜单     action2 = menu->addAction(tr("保存"),nullptr,nullptr,QKeySequence("Ctrl+S"));     action3 = menu->addAction(tr("铅笔"),nullptr,nullptr,QKeySequence("Ctrl+1"));     action4 = menu->addAction(tr("直线"),nullptr,nullptr,QKeySequence("Ctrl+2"));     action5 = menu->addAction(tr("椭圆"),nullptr,nullptr,QKeySequence("Ctrl+3"));     action6 = menu->addAction(tr("矩形"),nullptr,nullptr,QKeySequence("Ctrl+4"));     actioncolor = menu->addAction(tr("颜色"));     action7 = menu->addAction(tr("撤回"),nullptr,nullptr,QKeySequence("Ctrl+Z"));     action8 = menu->addAction(tr("清除"),nullptr,nullptr,QKeySequence("Ctrl+D"));     action9 = menu->addAction(tr("退出"),nullptr,nullptr,QKeySequence("Esc"));      QActionGroup *actiongroup = new QActionGroup(this);     actiongroup->addAction(action1);    // 将动作存到Group中     actiongroup->addAction(action2);     actiongroup->addAction(action3);     actiongroup->addAction(action4);     actiongroup->addAction(action5);     actiongroup->addAction(action6);     actiongroup->addAction(actioncolor);     actiongroup->addAction(action7);     actiongroup->addAction(action8);     actiongroup->addAction(action9);      connect(actiongroup,SIGNAL(triggered(QAction *)),this,SLOT(slotType(QAction *)));      resize(this->width(),this->height());     pixmap = QPixmap(this->size());     pixmap.fill(Qt::white);     pix = QPixmap(this->size());     pix.fill(Qt::white);     null = QPixmap(this->size());     null.fill(Qt::white);     isMouse = false; }  MainWindow::~MainWindow() { }  void MainWindow::paintEvent(QPaintEvent *event) {     QPainter painter(this);     if(isMouse){         pix = pixmap;   // 得到上次绘画的东西         QPainter pain(&pix);         pain.setPen(pen);         if(num == Three){             pain.drawLine(lines.back());             lines.back().setP1(lines.back().p2()); // 更新首节点             pixmap = pix;   // 将每次绘画的初始点和末尾点赋给pixmap         }         else if(num == Four && isMouse){             pain.drawLine(line.back().p1(),line.back().p2());         }         else if(num == Five && isMouse){             pain.drawEllipse(elli.back());         }         else if(num == Six && isMouse){             pain.drawRect(rect.back());         }     }     if(!isMouse){         pixmap = pix;         QPainter pain(&pix);         pain.setPen(pen);         if(tool == Seven){             int linee=0,ellii=0,rectt=0;             for(int i=0;i<vec.length();i++){                 if(vec[i] == Three){                     for(int i=0;i<myline.length();i++){ // 进入外层 2                         for(int j=0;j<myline.at(i).length();j++){ // 进入 vecline 层                             for(int k=0;k<myline.at(i).at(j).length();k++){ // 进入lines 层                                 pain.drawLine(myline.at(i).at(j).at(k));                             }                         }                     }                 }                 else if(vec[i] == Four){                     pain.drawLine(line.at(linee).p1(),line.at(linee).p2());                     linee++;                 }                 else if(vec[i] == Five){                     pain.drawEllipse(elli.at(ellii));                     ellii++;                 }                 else if(vec[i] == Six){                     pain.drawRect(rect.at(rectt));                     rectt++;                 }             }             tool = Ten;         }     }     painter.drawPixmap(0,0,pix);     //    painter.drawPixmap(610,0,pixmap); }  void MainWindow::resizeEvent(QResizeEvent *size) // 当窗口大小变化更新画板 {     this->resize(size->size());     pixmap = QPixmap(size->size());     pixmap.fill(Qt::white);     pix = QPixmap(size->size());     pix.fill(Qt::white);     null = QPixmap(size->size());     null.fill(Qt::white); }  void MainWindow::mousePressEvent(QMouseEvent *event) {     if(event->button() == Qt::LeftButton){         if(num == Three){        // 铅笔模式             QLine Lines(event->pos(),QPoint(0,0));             lines.append(Lines); // 记录点击的第一笔             vec.append(Three);   // 添加那个模式点击的画笔             isMouse = true;      // 开启绘画锁         }         else if(num == Four){    // 直线模式             QLine Line(event->pos(),QPoint(0,0));             line.append(Line);             vec.append(Four);             isMouse = true;         }         else if(num == Five){    // 椭圆模式             QRect Elli(event->pos(),QPoint(0,0));             elli.append(Elli);             vec.append(Five);             isMouse = true;         }         else if(num == Six){     // 矩形模式             QRect Rect(event->pos(),QPoint(0,0));             rect.append(Rect);             vec.append(Six);             isMouse = true;         }     }     else if(event->button() == Qt::RightButton){    // 右击菜单栏         menu->exec(cursor().pos());     } }  void MainWindow::mouseMoveEvent(QMouseEvent *event) {     if(!isMouse)         return;     if(event->buttons() == Qt::LeftButton){         if(num == Three){       // 铅笔移动模式             lines.back().setP2(event->pos()); // 设置点p2 的坐标为移动的坐标             vecline.append(lines);  // 记录移动的两点 坐标             update();         }         else if(num == Four){   // 直线移动模式             line.back().setP2(event->pos());             update();         }         else if(num == Five){   // 椭圆移动模式             elli.back().setBottomRight(event->pos());             update();         }         else if(num == Six){    // 矩形移动模式             rect.back().setBottomRight(event->pos());             update();         }     } }  void MainWindow::mouseReleaseEvent(QMouseEvent *event) {     if(!isMouse)         return;     if(event->button() == Qt::LeftButton){         if(num == Three){       // 弹起铅笔模式             lines.back().setP2(event->pos()); // 更新一次释放点的坐标             myline.append(vecline);     // 将上面移动的记录存到 三维容器中             QVector<QVector<QLine>>vecnullptr;             vecline = vecnullptr;   // 清空上一次 的vecline 记录的移动项             update();         }         else if(num == Four){   // 弹起直线模式             line.back().setP2(event->pos());             update();         }         else if(num == Five){   // 弹起椭圆模式             elli.back().setBottomRight(event->pos());             update();         }         else if(num == Six){    // 弹起矩形模式             rect.back().setBottomRight(event->pos());             update();         }         isMouse = false; // 关闭绘画锁     } }  void MainWindow::slotType(QAction *type)    // 触发点击的哪一个动作的槽函数 如果添加工具栏的话可以用函数封装下就行 {     if(type == action1){        // 打开         QString filename = QFileDialog::getOpenFileName(this,tr("打开文件"),"/","Image(*.png);;Image(*.jpg)");         if(filename.isEmpty())             return;         QPixmap pixopen(filename);         QPainter p(&pix);         p.drawPixmap(0,0,pixopen);         update();     }     else if(type == action2){   // 保存         QString filename = QFileDialog::getSaveFileName(this,tr("保存文件"),"image.png","Image(*.png);;Image(*.jpg)");         if(filename.isEmpty())             return;         pix.save(filename);     }     else if(type == action3){   // 铅笔         num = Three;     }     else if(type == action4){   //  直线         num = Four;     }     else if(type == action5){   // 椭圆         num = Five;     }     else if(type == action6){   // 矩形         num = Six;     }     else if(type == actioncolor){         QDialog w;         comboBox = new QComboBox(&w);         QPixmap compix(16,16);         QPainter painter(&compix);         painter.fillRect(0,0,16,16,Qt::black);         comboBox->addItem(QIcon(compix),tr("黑色"));         painter.fillRect(0,0,16,16,Qt::white);         comboBox->addItem(QIcon(compix),tr("白色"));         painter.fillRect(0,0,16,16,Qt::red);         comboBox->addItem(QIcon(compix),tr("红色"));         painter.fillRect(0,0,16,16,Qt::blue);         comboBox->addItem(QIcon(compix),tr("蓝色"));         painter.fillRect(0,0,16,16,Qt::green);         comboBox->addItem(QIcon(compix),tr("绿色"));         painter.fillRect(0,0,16,16,Qt::yellow);         comboBox->addItem(QIcon(compix),tr("黄色"));         connect(comboBox,SIGNAL(currentIndexChanged(int)),this,SLOT(slotColor(int)));         w.exec();     }     else if(type == action7){   // 撤回         if(vec.isEmpty())             return;         if(vec.back() == Three){             myline.pop_back();         }         else if(vec.back() == Four){             line.pop_back();         }         else if(vec.back() == Five){             elli.pop_back();         }         else if(vec.back() == Six){             rect.pop_back();         }         vec.pop_back();         pix = null;         pixmap = null;         tool = Seven;         update();     }     else if(type == action8){   // 清除         pix = null;         pixmap = null;         tool = Eight;         update();     }     else if(type == action9){   // 退出         t->quit();     } }  void MainWindow::slotColor(int color) {     switch (color) {     case 0:pen.setColor(Qt::black); break;     case 1:pen.setColor(Qt::white); break;     case 2:pen.setColor(Qt::red);   break;     case 3:pen.setColor(Qt::blue);  break;     case 4:pen.setColor(Qt::green); break;     case 5:pen.setColor(Qt::yellow);break;     } }   

main.cpp

#include "mainwindow.h"  int main(int argc, char *argv[]) {     QApplication a(argc, argv);     MainWindow w;     w.show();     return a.exec(); }  

c/c++开发分享Qt 小画板地址：https://blog.csdn.net/qq_44698445/article/details/107347256