Qt 简易画板

制作简单画板

该画板功能包括，书写，画直线，矩形，椭圆。并可进行保存，清空，其它功能自行添加

效果

代码如下

DrawWidget.h

#ifndef DRAWWIDGET_H
#define DRAWWIDGET_H
#include <QWidget>
#include <QPen>
#include <QPainter>
#include <QVector>
#include "Shapes.h"

class DrawWidget :public QWidget
{
     Q_OBJECT
public:
    DrawWidget(QWidget *parent = nullptr);
    Shape::shapes post;
public slots:
    void cleanall();
private:
    QVector<Shape*> shapelists;
    QPoint start_point;
    QPoint end_point;
    QSize size;
    QPainter paint;
    Shape *shape;
    bool isDraw;
    QPen pen;
protected:
    void paintEvent(QPaintEvent *e) override;
    void mouseMoveEvent(QMouseEvent *e) override;
    void mousePressEvent(QMouseEvent *e) override;
    void mouseReleaseEvent(QMouseEvent *e) override;
private:
    void init_connect();
    void drawing();
    void initDrawing();
private slots:
    void startDraw(QPoint);
    void endDraw(QPoint);
    void save();
};

#endif // DRAWWIDGET_H

everyShapest.h

#ifndef EVERYSHAPES_H
#define EVERYSHAPES_H
#include "Shapes.h"
#include <QDebug>

class def :public Shape
{
public:
    def(shapes shap):Shape(shap)
    {
        qDebug()<<"default start draw"<<"\n";
        post = shap;
    }
    void draw(QPainter &painter)
    {
        qDebug()<<"default draw"<<"\n";
        painter.drawLine(start, end);
    }
};

class line :public Shape
{
public:
    line(shapes shap):Shape(shap)
    {
        post = shap;
    }
    void draw(QPainter &painter)
    {
        painter.drawLine(start, end);
    }
};

class cricle :public Shape
{
public:
    cricle(shapes shap):Shape(shap)
    {
        post = shap;
    }
    void draw(QPainter &painter)
    {
        painter.drawEllipse(start.x(), start.y(),end.x() - start.x(), end.y() - start.y());
    }
};

class rectp :public Shape
{
public:
    rectp(shapes shap):Shape(shap)
    {
        post = shap;
    }
    void draw(QPainter &painter)
    {
        painter.drawRect(start.x(), start.y(),end.x() - start.x(), end.y() - start.y());
    }
};
#endif // EVERYSHAPES_H

mainwindowt.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include "drawwidget.h"
#include "Shapes.h"
#include <QString>
#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
signals:
    void formChange(Shape::shapes);
private:
    Ui::MainWindow *ui;
    DrawWidget *widget;
    QString message;
    void initconnect();
    bool isout;
private slots:
    void on_save_clicked();
    void on_clean_clicked();
    void on_write_clicked();
    void on_line_clicked();
    void on_cricle_clicked();
    void on_rect_clicked();
    void on_out_clicked();
};
#endif // MAINWINDOW_H

Shapes.h

#ifndef SHAPES_H
#define SHAPES_H

#include <QPoint>
#include <QRect>
#include <vector>
#include <QPainter>

class Shape{
public:
    enum shapes{
      def=0,line,cricle,rect
    };
    Shape(shapes shap)
    { post = shap;}
    virtual void draw(QPainter&) = 0;
    void addlist(QPoint p)
    {
        start = end;
        end = p;
        pointList.push_back(p);
    }
    std::vector<QPoint> pointList;
    void setStart(QPoint p){  start = p;}
    void setEnd(QPoint p) { end = p;}
    shapes post;
    QPoint start;
    QPoint end;
   // shapes post;
};
#endif // SHAPES_H

DrawWidget.cpp

#include "drawwidget.h"
#include "everyShapes.h"
#include <QMouseEvent>
#include <QDebug>
DrawWidget::DrawWidget(QWidget *parent)
{
  post = Shape::def;
  pen.setWidth(2);
  pen.setBrush(Qt::SolidPattern);
  isDraw = false;
}
void DrawWidget::initDrawing()
{
    switch(post)
        {
            case Shape::def:
            {
                shape =  new def(post);
                break;
            }
            case Shape::line:
            {
                shape =  new line(post);
                break;
            }
            case Shape::cricle:
            {
                shape =  new cricle(post);
                break;
            }
            case Shape::rect:
            {
                shape =  new rectp(post);
                break;
             }}}
void DrawWidget::startDraw(QPoint p)
{
    initDrawing();
    start_point = p;
    end_point = p;
    shape->setEnd(end_point);
    shape->setStart(start_point);
    isDraw = true;
    drawing();
}
void DrawWidget::drawing()
{
   if(isDraw)
    {
       switch(post){
        case Shape::def:
       {
           shape->addlist(end_point);
           //this->update();
       }
       default:
       {
           shape->setEnd(end_point);
           this->update();
       }}
    }
}
void DrawWidget::endDraw(QPoint p)
{
    isDraw = false;
    switch(post){
     case Shape::def:
    {
        shape->addlist(end_point);
    }
    default:
    {
        shape->setEnd(end_point);
    }}
    shapelists.append(shape);
}
void DrawWidget::paintEvent(QPaintEvent *e)
{
    QPainter paint(this);
    paint.setPen(pen);
    if(!shapelists.isEmpty())
    {
        foreach (Shape *shape, shapelists) {
            switch (shape->post) {
            case Shape::def:
            {
                QPoint start;
                QPoint end = shape->pointList[0];
                foreach(QPoint p,shape->pointList)
                {
                    start = end;
                    end = p;
                    paint.drawLine(start,end);
                }break;
            }
            default:
            {
                shape->draw(paint);
                break;
            }}}}
    if(isDraw)
    {
        if(!shape->pointList.empty())
        {
            QPoint start;
            QPoint end = shape->pointList[0];
            foreach(QPoint p,shape->pointList)
            {
                start = end;
                end = p;
                paint.drawLine(start,end);
            } }
        shape->draw(paint);
    }}
void DrawWidget::mouseMoveEvent(QMouseEvent *e)
{
    qDebug()<<"move"<<"\n";
    end_point = e->pos();
    drawing();
}
void DrawWidget::mousePressEvent(QMouseEvent *e)
{
    qDebug()<<"clicked"<<"\n";
    startDraw(e->pos());
}
void DrawWidget::mouseReleaseEvent(QMouseEvent *e)
{
    endDraw(e->pos());
}
void DrawWidget::save()
{
}
void DrawWidget::cleanall()
{
   shapelists.clear();
   this->update();
}

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include <QDateTime>
#include <QScreen>
#include <QPixmap>
#include <QThread>
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->widget->hide();
    isout = false;//是否弹出
}
MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::initconnect()
{
}
void MainWindow::on_save_clicked()
{
    on_out_clicked();
    QRect rect = ui->centralwidget->geometry();
    qDebug()<<rect<<"\n";
    QScreen* screen = QApplication::primaryScreen();
    QPixmap p = screen->grabWindow(ui->centralwidget->winId(),rect.x(),rect.y(),rect.width(),rect.height());
    QString filePathName = "F:/widget/";
    filePathName += QDateTime::currentDateTime().toString("MM-dd-hh-mm-ss-zz");
    filePathName += ".png";
    message = filePathName;
    if(!p.save(filePathName,"PNG"))
    {
     message = "save widget screen failed!!";
    }
    qDebug()<<message<<"\n";
    this->setWindowTitle(this->message);
    QThread::sleep(3);
    this->setWindowTitle("drawing");
}
void MainWindow::on_clean_clicked()
{
    ui->centralwidget->cleanall();
}
void MainWindow::on_line_clicked()
{
    ui->centralwidget->post = Shape::line;
}
void MainWindow::on_write_clicked()
{
    ui->centralwidget->post = Shape::def;
}
void MainWindow::on_cricle_clicked()
{
    ui->centralwidget->post = Shape::cricle;
}
void MainWindow::on_rect_clicked()
{
    ui->centralwidget->post = Shape::rect;
}
void MainWindow::on_out_clicked()
{
    if(isout) {ui->widget->hide(); isout = false;}
    else {ui->widget->show(); isout = true;}
}