Qt图形库——Qt画图板

完整代码：

//mainwindows.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QColorDialog>
#include <QInputDialog>
#include <QActionGroup>
#include <QFileDialog>
#include <QMainWindow>
#include <QKeyEvent>
#include <QToolBar>
#include <QMenuBar>
#include <QSlider>
#include <QAction>
#include <QColor>
#include <QMenu>
#include <QDial>
#include <QLabel>

#include "paint.h"
#include "type.h"

class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void keyPressEvent(QKeyEvent *);
    void keyReleaseEvent(QKeyEvent *);
signals:
    void select_shape(type);
    void color_change(QColor);
    void brush_change(QColor);
    void width_change(int);
    void alpha_change(int);
    void openFile_SIGNAL(QString);
    void saveFile_SIGNAL(QString);
    void change_straight(bool);
private slots:
    void color_SLOT();
    void brush_SLOT();
    void width_SLOT();
    void draw_rect();
    void draw_line();
    void draw_pen();
    void draw_polygon();
    void draw_ellipse();
    void change_widthLabel(int);
    void change_alphaLabel(int);
    void reset_dial();
private:
    QLabel *widthLabel;
    QDial *widthDial;
    QLabel *alphaLabel;
    QDial *alphaDial;
    virtual QSize sizeHint() const override;
};

#endif // MAINWINDOW_H

//mainWindow.cpp

#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    ///////形状选择框架///////
    QToolBar *shapeBar = this->addToolBar("Shape");
    QActionGroup *shapeGroup = new QActionGroup(shapeBar);

    QAction *act_rect = new QAction(QIcon(":res/Rect.ico"),"Draw a Rect", shapeBar);
    act_rect->setCheckable(true);
    act_rect->setChecked(true);
    shapeGroup->addAction(act_rect);
    shapeBar->addAction(act_rect);

    QAction *act_line = new QAction(QIcon(":res/Line.ico"),"Draw A Line", shapeBar);
    act_line->setCheckable(true);
    shapeGroup->addAction(act_line);
    shapeBar->addAction(act_line);

    QAction *act_pen = new QAction(QIcon(":res/pen.ico"), "Draw With Pen", shapeBar);
    act_pen->setCheckable(true);
    shapeGroup->addAction(act_pen);
    shapeBar->addAction(act_pen);

    QAction *act_ellipse = new QAction(QIcon(":res/Ellipse.ico"), "Draw A Ellipse", shapeBar);
    act_ellipse->setCheckable(true);
    shapeGroup->addAction(act_ellipse);
    shapeBar->addAction(act_ellipse);

    QAction *act_polygon = new QAction(QIcon(":res/Polygon.ico"), "Draw A Polygon", shapeBar);
    act_polygon->setCheckable(true);
    shapeGroup->addAction(act_polygon);
    shapeBar->addAction(act_polygon);

    ////////操作选择框架/////////////
    QToolBar *operatorBar = this->addToolBar("Operator");
    QActionGroup *operatorGroup = new QActionGroup(operatorBar);
    QAction *Undo = new QAction(QIcon(":/res/Undo.ico"), "Undo", operatorBar);
    Undo->setShortcut(tr("Ctrl+Z"));
    operatorGroup->addAction(Undo);
    operatorBar->addAction(Undo);

    QAction *Redo = new QAction(QIcon(":/res/Redo.ico"), "Redo", operatorBar);
    Redo->setShortcut(tr("Ctrl+Y"));
    operatorGroup->addAction(Redo);
    operatorBar->addAction(Redo);

    QAction *Reset = new QAction(QIcon(":/res/Reset.ico"), "Reset", operatorBar);
    Reset->setShortcut(tr("Ctrl+N"));
    operatorGroup->addAction(Reset);
    operatorBar->addAction(Reset);

    widthDial = new QDial(operatorBar);
    widthDial->setRange(1, 20);
    operatorBar->addWidget(widthDial);
    widthLabel = new QLabel("Size: 1", operatorBar);
    operatorBar->addWidget(widthLabel);

    alphaDial = new QDial(operatorBar);
    alphaDial->setRange(0, 100);
    alphaDial->setValue(100);
    operatorBar->addWidget(alphaDial);
    alphaLabel = new QLabel("Alpha: 100%", operatorBar);
    operatorBar->addWidget(alphaLabel);

    ////////////菜单区域////////////////
    QMenu *file = menuBar()->addMenu(tr("&File"));
    QAction *newFile = new QAction(QIcon(":/res/New.ico"),tr("New"), file);
    newFile->setShortcut(tr("Ctrl+N"));
    file->addAction(newFile);
    QAction *openFile = new QAction(QIcon(":/res/open.ico"),tr("Open"), file);
    openFile->setShortcut(tr("Ctrl+O"));
    file->addAction(openFile);
    QAction *saveFile = new QAction(QIcon(":/res/Save.ico"),tr("Save"), file);
    saveFile->setShortcut(tr("Ctrl+S"));
    file->addAction(saveFile);
    QAction *quit = new QAction(QIcon(":/res/Quit.ico"),tr("Quit"), file);
    quit->setShortcut(tr("Ctrl+Q"));
    file->addAction(quit);

    QMenu *change = menuBar()->addMenu(tr("&Change"));
    QAction *changeColor = new QAction(QIcon(":/res/Color.ico"),tr("Color"), change);
    changeColor->setShortcut(tr("Ctrl+C"));
    change->addAction(changeColor);
    QAction *changeBrush = new QAction(QIcon(":/res/Brush.ico"),tr("Brush"), change);
    changeBrush->setShortcut(tr("Ctrl+B"));
    change->addAction(changeBrush);
    QAction *changeWidth = new QAction(QIcon(":/res/Width.ico"),tr("Width"), change);
    changeWidth->setShortcut(tr("Ctrl+W"));
    change->addAction(changeWidth);

    ////////////paint定义////////////
    Paint *paint = new Paint(this);
    setCentralWidget(paint);

    ////////工具栏信号槽//////////////////
    QObject::connect(act_rect, SIGNAL(triggered()), this, SLOT(draw_rect()));
    QObject::connect(act_line, SIGNAL(triggered()), this, SLOT(draw_line()));
    QObject::connect(act_pen, SIGNAL(triggered()), this, SLOT(draw_pen()));
    QObject::connect(act_polygon, SIGNAL(triggered()), this, SLOT(draw_polygon()));
    QObject::connect(act_ellipse, SIGNAL(triggered()), this, SLOT(draw_ellipse()));
    QObject::connect(Undo, SIGNAL(triggered()), paint, SLOT(Undo()));
    QObject::connect(Redo, SIGNAL(triggered()), paint, SLOT(Redo()));
    QObject::connect(Reset, SIGNAL(triggered()), paint, SLOT(Reset()));
    QObject::connect(Reset, SIGNAL(triggered()), this, SLOT(reset_dial()));
    QObject::connect(widthDial, SIGNAL(valueChanged(int)), paint, SLOT(set_width(int)));
    QObject::connect(widthDial, SIGNAL(valueChanged(int)), this, SLOT(change_widthLabel(int)));
    QObject::connect(alphaDial, SIGNAL(valueChanged(int)), paint, SLOT(set_alpha(int)));
    QObject::connect(alphaDial, SIGNAL(valueChanged(int)), this, SLOT(change_alphaLabel(int)));

    ////////菜单栏信号槽//////////////////
    QObject::connect(newFile, SIGNAL(triggered()), paint, SLOT(Reset()));
    QObject::connect(openFile, SIGNAL(triggered()), paint, SLOT(open_file()));
    QObject::connect(saveFile, SIGNAL(triggered()), paint, SLOT(save_file()));
    QObject::connect(quit, SIGNAL(triggered()),this, SLOT(close()));
    QObject::connect(changeColor, SIGNAL(triggered()), this, SLOT(color_SLOT()));
    QObject::connect(changeBrush, SIGNAL(triggered()), this, SLOT(brush_SLOT()));
    QObject::connect(changeWidth, SIGNAL(triggered()), this, SLOT(width_SLOT()));

    /////////Paint交互信号槽///////////////////
    QObject::connect(this, SIGNAL(select_shape(type)), paint, SLOT(set_shape(type)));
    QObject::connect(this, SIGNAL(color_change(QColor)), paint, SLOT(set_color(QColor)));
    QObject::connect(this, SIGNAL(brush_change(QColor)), paint, SLOT(set_brush(QColor)));
    QObject::connect(this, SIGNAL(width_change(int)), paint, SLOT(set_width(int)));
    QObject::connect(this, SIGNAL(change_straight(bool)), paint, SLOT(set_straight(bool)));
}

///////信息发射///////////////
void MainWindow::keyPressEvent(QKeyEvent *k)
{
    if (k->modifiers() == Qt::ShiftModifier)
    {
        emit change_straight(true);
    }
}

void MainWindow::keyReleaseEvent(QKeyEvent *k)
{
    if (k->modifiers() == Qt::ShiftModifier)
    {
        emit change_straight(false);
    }
}

void MainWindow::color_SLOT()
{
    QColor c = QColorDialog::getColor(Qt::black);
    emit color_change(c);
}

void MainWindow::brush_SLOT()
{
    QColor c = QColorDialog::getColor(Qt::transparent);
    emit brush_change(c);
}

void MainWindow::width_SLOT()
{
    int c = QInputDialog::getInt(this, tr("Width Set"), tr("Enter the Width"), true, 1, 20, 1);
    emit width_change(c);
}

void MainWindow::draw_rect()
{
    emit select_shape(type_Rect);
}
void MainWindow::draw_line()
{
    emit select_shape(type_Line);
}
void MainWindow::draw_pen()
{
    emit select_shape(type_Pen);
}
void MainWindow::draw_polygon()
{
    emit select_shape(type_Polygon);
}
void MainWindow::draw_ellipse()
{
    emit select_shape(type_Ellipse);
}
///////////////////槽函数////////////////
void MainWindow::change_widthLabel(int w)
{
    widthLabel->setText("Size: " + QString::number(w));
}

void MainWindow::change_alphaLabel(int w)
{
    alphaLabel->setText("Alpha: " + QString::number(w) + "%");
}

void MainWindow::reset_dial()
{
    widthDial->setValue(1);
    alphaDial->setValue(100);
    widthLabel->setText("Size: 1");
    alphaLabel->setText("Alpha: 100%");
}

//////////其他//////////
MainWindow::~MainWindow()
{

}

QSize MainWindow::sizeHint() const
{
    return QSize(1024, 768);
}

//paint.h

#ifndef PAINT_H
#define PAINT_H

#include <QTextStream>
#include <QFileDialog>
#include <QMessageBox>
#include <QMouseEvent>
#include <QKeyEvent>
#include <QWidget>
#include <QBrush>
#include <QStack>
#include <QFile>
#include <QPen>

#include "ellipse.h"
#include "polygon.h"
#include "shape.h"
#include "type.h"
#include "line.h"
#include "rect.h"
#include "pen.h"

class Paint : public QWidget
{
    Q_OBJECT
public:
    explicit Paint(QWidget *parent = 0);
protected:
    void paintEvent(QPaintEvent *);
    void mouseMoveEvent(QMouseEvent *);
    void mousePressEvent(QMouseEvent *);
    void mouseReleaseEvent(QMouseEvent *);
public slots:
    void set_shape(type);
    void set_color(QColor);
    void set_brush(QColor);
    void set_width(int);
    void set_alpha(int);
    void set_straight(bool);
    void open_file();
    void save_file();
    void Undo();
    void Redo();
    void Reset();
private:
    type shapeType;
    QStack<Shape *>stack;
    QStack<Shape *>redoStack;  //撤销恢复用
    Shape *shape;
    QColor currentColor;
    QColor currentBrush;
    QString currentPath;
    int currentWidth;

    bool stop_polygon;
    bool is_straight;
};

#endif // PAINT_H

//paint.cpp

#include "paint.h"

Paint::Paint(QWidget *parent)
    :QWidget(parent), shape(nullptr), shapeType(type_Rect)
{
    currentBrush = Qt::transparent;
    currentColor = Qt::black;
    currentWidth = 1;
    stop_polygon = true;
    is_straight = false;
    setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
}

void Paint::paintEvent(QPaintEvent *)
{
    QPainter paint(this);
    paint.setBrush(Qt::white);
    paint.setPen(Qt::white);
    paint.drawRect(0, 0, size().width(), size().height());
    foreach(Shape *shape, stack)
    {
        shape->paint(paint);
    }
}

void Paint::mousePressEvent(QMouseEvent *e)
{
    ////////////Polygon特殊处理/////////////////
    while(!redoStack.empty())
    {
        Shape *tmp = redoStack.top();
        redoStack.pop();
        delete tmp;
    }
    if(e->button() == Qt::RightButton)
    {
        stop_polygon = true;
        return;
    }
    if (shapeType == type_Polygon)
    {
        if(stop_polygon == true || stack.isEmpty())
        {
            shape = new Polygon;
            Polygon *tmp = dynamic_cast<Polygon *>(shape);
            QPoint *p = new QPoint(e->pos());
            tmp->push(p);
            QPoint *p2 = new QPoint(e->pos() + QPoint(0, 1));
            tmp->push(p2);
            stack.push(shape);
            shape->set(currentColor, currentBrush, currentWidth);
            stop_polygon = false;
        }
        else
        {
            if (typeid(*stack.top()) != typeid(Polygon))
            {
                stop_polygon = true;
                return;
            }
            Polygon *tmp = dynamic_cast<Polygon *>(shape);
            QPoint *p = new QPoint(e->pos());
            tmp->push(p);
        }
        update();
        return;
    }
    stop_polygon = true;
    switch(shapeType)
    {
    case type_Line:
        shape = new Line;
        break;
    case type_Rect:
        shape = new Rect;
        break;
    case type_Pen:
        shape = new Pen;
        break;
    case type_Ellipse:
        shape = new Ellipse;
        break;
    }
    if(shape != NULL)
    {
        if (shapeType == type_Pen)
        {
            Shape *zero = new Pen;
            zero->set_start(QPoint(0, 0));
            zero->set_end(QPoint(0, 0));
            stack.push(zero);

        }//制造间隔点
        shape->set(currentColor, currentBrush, currentWidth);
        stack.push(shape);
        //shape->set_start(e->pos());
        //shape->set_end(e->pos() + QPoint(0, 1)); //避免出现同一起点终点
        shape->set_pos(e->pos(), e->pos() + QPoint(0, 1), is_straight);
    }
    update();
}

void Paint::mouseMoveEvent(QMouseEvent *e)
{
    if (shapeType == type_Polygon)
    {
        Polygon *tmp = dynamic_cast<Polygon *>(stack.top());
        QPoint *p = tmp->top();
        p->setX(e->x());
        p->setY(e->y());
        update();
        return;
    }
    shape->set_pos(shape->get_start(), e->pos(), is_straight);

    if (shapeType == type_Pen)
    {
        shape = new Line;
        shape->set(currentColor, currentBrush, currentWidth);
        stack.push(shape);
        shape->set_start(e->pos());
        shape->set_end(e->pos());
    }
    update();
}


void Paint::mouseReleaseEvent(QMouseEvent *)
{
    if (shapeType== type_Pen)
    {
        Shape *zero = new Pen;
        zero->set_start(QPoint(0, 0));
        zero->set_end(QPoint(0, 0));
        stack.push(zero);
    }//制造间隔点
}

void Paint::set_straight(bool c)
{
    qDebug("%d", c);
    is_straight = c;
}

///////////////////SLOT/////////////
void Paint::set_color(QColor c)
{
    currentColor = c;
}
void Paint::set_brush(QColor c)
{
    currentBrush = c;
}

void Paint::set_shape(type new_shape)
{
    shapeType = new_shape;
}

void Paint::set_width(int w)
{
    currentWidth = w;
}

void Paint::set_alpha(int a)
{
    currentBrush.setAlpha((100 - a) * 255 / 100);
}

void Paint::Undo()
{
    if (!stack.empty())
    {
        if(typeid(*stack.top()) == typeid(Pen))//运行期类型识别
        {

            redoStack.push(stack.top());
            stack.pop();

            while(1) //寻找临界点
            {
                if (stack.top()->get_start() == QPoint(0, 0) && stack.top()->get_end() == QPoint(0, 0))
                    break;
                redoStack.push(stack.top());
                stack.pop();
            }
            redoStack.push(stack.top());    //加入临界点
            stack.pop();

        }
        else
        {
            Shape *tmp = stack.top();
            stack.pop();
            redoStack.push(tmp);
        }
    }
    update();
}

void Paint::Redo()
{
    if (!redoStack.empty())
    {
        if(typeid(*redoStack.top()) == typeid(Pen))//运行期类型识别
        {

            stack.push(redoStack.top());
            redoStack.pop();

            while(1) //寻找临界点
            {
                if (redoStack.top()->get_start() == QPoint(0, 0) && redoStack.top()->get_end() == QPoint(0, 0))
                    break;
                stack.push(redoStack.top());
                redoStack.pop();
            }
            stack.push(redoStack.top());    //加入临界点
            redoStack.pop();

        }
        else
        {
            Shape *tmp = redoStack.top();
            redoStack.pop();
            stack.push(tmp);
        }
    }
    update();
}

void Paint::Reset()
{
    currentBrush = Qt::transparent;
    currentColor = Qt::black;
    currentWidth = 1;
    stack.clear();
    redoStack.clear();
    stop_polygon = true;
    update();
}

void Paint::open_file()
{
    QString s = QFileDialog::getOpenFileName(this, "Select A File", "/", "Paint File(*.paint)");
    if (s.isEmpty())
    {
        QMessageBox::information(this, tr("INformation"), tr("Open failed!"));
        return;
    }
    int st = 0;
    int x1, y1, x2, y2;
    int r1, r2, g1, g2, b1, b2, a1, a2;
    int width;
    Reset();
    currentPath = s;
    QFile file(currentPath);
    if (file.open(QFile::ReadOnly))
    {
        QTextStream cin(&file);
        while(!cin.atEnd())
        {
            st = 0;
            cin >>st;
            Shape *tmp;
            if (st == 0)
                break;  //每次都会莫名其妙多读一行，，What A Fhuack
            if (st == 5)
            {
                tmp = new Polygon;

                int size;
                cin >> size;

                for(int i = 0; i < size; ++i)
                {
                    cin >> x1 >> y1;
                    QPoint *p = new QPoint(x1, y1);
                    dynamic_cast<Polygon*>(tmp)->push(p);
                }
                cin >> r1>>g1>>b1>>a1>>r2>>g2>>b2>>a2>>width;
                tmp->set(QColor(r1, g1, b1, a1), QColor(r2, g2, b2, a2), width);
                stack.push(tmp);

                continue;
            }
            else
                cin >>x1>>y1>>x2>>y2>>r1>>g1>>b1>>a1>>r2>>g2>>b2>>a2>>width;

            switch(st)
            {
            case 1:
             tmp = new Rect;
                break;
            case 2:
                tmp = new Line;
                break;
            case 3:
                tmp = new Pen;
                break;
            case 4:
                tmp = new Ellipse;
            }
            tmp->set_start(QPoint(x1, y1));
            tmp->set_end(QPoint(x2, y2));
            tmp->set(QColor(r1, g1, b1, a1), QColor(r2, g2, b2, a2), width);

            stack.push(tmp);
        }
    }
    file.close();
    update();

    Polygon *p = dynamic_cast<Polygon*>(stack.top());
    for(int i = 0; i < p->get_size(); ++i)
        qDebug("%d %d", p->index(i)->rx(), p->index(i)->ry());
}

void Paint::save_file()
{
    if (stack.empty())
    {
        QMessageBox::information(this, tr("Information"), tr("Nothing To Be Save!"));
        return;
    }
    if (currentPath.isEmpty())
    {
        QString s = QFileDialog::getSaveFileName(this, "Select A File", "/", "Paint File(*.paint)");
        currentPath = s;
    }
    else
    {
        QMessageBox::information(this, tr("Information"), tr("Save Successful!"));
    }

    int r1, r2, g1, g2, b1, b2, a1, a2;
    QFile file(currentPath);
    if (file.open(QFile::WriteOnly))
    {
        QTextStream cout(&file);
        foreach(Shape *shape, stack)
        {
            if (shape->get_typeid() == 5)
            {
                cout << "5 ";
                Polygon *p = dynamic_cast<Polygon*>(shape);
                cout << p->get_size() << " ";
                for(int i = 0; i < p->get_size(); ++i)
                    cout << p->index(i)->rx() << " " << p->index(i)->ry() << " ";
            }
            else
            {
                cout << shape->get_typeid() << " "
                 << shape->get_start().rx() << " " << shape->get_start().ry() << " "
                 << shape->get_end().rx() << " " << shape->get_end().ry() << " ";
             }

                 shape->get_color().getRgb(&r1, &g1, &b1, &a1);
                 shape->get_brush().getRgb(&r2, &g2, &b2, &a2);

            cout <<r1<<" "<<g1<<" "<<b1<<" "<<a1<<" "
                 <<r2<<" "<<g2<<" "<<b2<<" "<<a2<<" "
                 << shape->get_width() << endl;
        }
    }
    file.close();
}

//shape.h

#ifndef SHAPE_H
#define SHAPE_H
#include <QPoint>
#include <QPainter>
#include <QColor>

class Shape
{
public:
    Shape();
    void set_start(QPoint p);
    void set_end(QPoint p);
    void set_pos(QPoint, QPoint, bool);
    void set(QColor, QColor, int);

    QPoint get_start();
    QPoint get_end();
    QColor get_color();
    QColor get_brush();
    int get_width();
    virtual void paint(QPainter& painter) = 0;
    virtual int get_typeid() = 0;
protected:
    QPoint start;
    QPoint end;
    QColor color;
    QColor brush;
    int width;
};

#endif // SHAPE_H

//shape.cpp

#include "shape.h"

Shape::Shape()
    :start(QPoint(0, 0)), end(QPoint(0, 0))
{
    ;
}

void Shape::set_end(QPoint p)
{
    end = p;
}

void Shape::set_start(QPoint p)
{
    start = p;
}

void Shape::set_pos(QPoint p1, QPoint p2, bool is_straight)
{
    start = p1;
    if (is_straight)
    {
        if (abs(p1.rx() - p2.rx()) <= abs(p1.ry() - p2.ry()))
        {
            p2.setX(p1.rx() - p1.rx() + p2.rx());
            p2.setY(p1.ry() - p1.rx() + p2.rx());
        }
        else
        {
            p2.setX(p1.rx() - p1.ry() + p2.ry());
            p2.setY(p1.ry() - p1.ry() + p2.ry());
        }
    }
    end = p2;
}

QPoint Shape::get_end()
{
    return end;
}

QPoint Shape::get_start()
{
    return start;
}

QColor Shape::get_color()
{
    return color;
}

QColor Shape::get_brush()
{
    return  brush;
}

int Shape::get_width()
{
    return width;
}

void Shape::set(QColor c1, QColor c2, int w)
{
    color = c1;
    brush = c2;
    width = w;
}

//rect.h

#ifndef RECT_H
#define RECT_H

#include "shape.h"
#include <QPainter>

class Rect : public Shape
{
public:
    Rect();
private:
    virtual void paint(QPainter& paint) override;
    virtual int get_typeid() override;
};

#endif // RECT_H

//rect.cpp

#include "rect.h"

Rect::Rect()
{

}

void Rect::paint(QPainter &paint)
{
    paint.setPen(QPen(color, width));
    paint.setBrush(brush);
    paint.drawRect(start.x(), start.y(),end.x() - start.x(), end.y() - start.y());
}

int Rect::get_typeid()
{
    return 1;
}

//line.h

#ifndef LINE_H
#define LINE_H

#include <QPainter>
#include "shape.h"
class Line : public Shape
{
public:
    Line();
private:
    virtual void paint(QPainter& paint) override;
    virtual int get_typeid() override;
};

#endif // LINE_H

//line.cpp

#include "line.h"

Line::Line()
{

}

void Line::paint(QPainter &paint)
{
    paint.setPen(QPen(color, width));
    paint.setBrush(brush);
    paint.drawLine(start, end);
}

int Line::get_typeid()
{
    return 2;
}

//pen.h

#ifndef PEN_H
#define PEN_H
#include "shape.h"
#include <QPainter>
class Pen : public Shape
{
public:
    Pen();
    virtual void paint(QPainter& paint) override;
    virtual int get_typeid() override;
};

#endif // PEN_H

//pen.cpp

#include "pen.h"

Pen::Pen()
{
   ;
}

void Pen::paint(QPainter &paint)
{
    paint.setPen(QPen(color, width));
    paint.setBrush(brush);
    paint.drawLine(start, end);
}

int Pen::get_typeid()
{
    return 3;
}

//ellipse.h

#ifndef CIRCLE_H
#define CIRCLE_H

#include "shape.h"
class Ellipse : public Shape
{
public:
    Ellipse();<pre name="code" class="cpp">#ifndef POLYGON_H
#define POLYGON_H

#include "shape.h"
#include <QPolygon>
#include <QPoint>
#include <QVector>

class Polygon : public Shape
{
public:
    Polygon();
    ~Polygon();
    virtual void paint(QPainter&);
    virtual int get_typeid();
    void push(QPoint *);
    QPoint *top();
    int get_size();
    QPoint *index(int pos);
private:
    QVector<QPoint *>polygonStack;

};

#endif // POLYGON_H

//ellipse.cpp

#include "ellipse.h"

Ellipse::Ellipse()
{

}

void Ellipse::paint(QPainter &paint)
{
    paint.setPen(QPen(color, width));
    paint.setBrush(brush);
    paint.drawEllipse(start, end.rx() - start.rx(), end.ry() - start.ry());
}

int Ellipse::get_typeid()
{
    return 4;
}

//polygon.h

#ifndef POLYGON_H
#define POLYGON_H

#include "shape.h"
#include <QPolygon>
#include <QPoint>
#include <QVector>

class Polygon : public Shape
{
public:
    Polygon();
    ~Polygon();
    virtual void paint(QPainter&);
    virtual int get_typeid();
    void push(QPoint *);
    QPoint *top();
    int get_size();
    QPoint *index(int pos);
private:
    QVector<QPoint *>polygonStack;

};

#endif // POLYGON_H

//polygon.cpp

#include "polygon.h"

Polygon::Polygon()
{

}

void Polygon::paint(QPainter &paint)
{
    paint.setPen(QPen(color, width));
    paint.setBrush(brush);
    QPolygon polygon(polygonStack.size());
    for(int i = 0; i < polygonStack.size(); ++i)
    {
        polygon.setPoint(i, *polygonStack[i]);
    }
    paint.drawPolygon(polygon);
}

int Polygon::get_typeid()
{
    return 5;
}

void Polygon::push(QPoint *p)
{
    polygonStack.push_back(p);
}

QPoint *Polygon::top()
{
    return polygonStack[polygonStack.size() - 1];
}

Polygon::~Polygon()
{
    foreach(QPoint *p, polygonStack)
    {
        delete p;
    }
}

int Polygon::get_size()
{
    return polygonStack.size();
}

QPoint* Polygon::index(int pos)
{
    return polygonStack[pos];
}

//type.h

#ifndef TYPE_H
#define TYPE_H

enum type{type_Rect, type_Line, type_Pen, type_Ellipse, type_Polygon};

#endif // TYPE_H

代码还有很多冗余  还在更新中！！！！！！！

程序截图：