Qt学习（六） 软件启动界面 ，注册表使用 ，QT绘图， 视图和窗口绘图，Graphics View绘图框架：简易CAD

一 软件启动界面 注册表使用

• 知识点1：这样创建的界面是不可以拖动的，需要手动创建函数来进行拖动，以下的3个函数是从父类继承过来的函数

    virtual void mousePressEvent(QMouseEvent *event);virtual void mouseReleaseEvent(QMouseEvent *event);virtual void mouseMoveEvent(QMouseEvent *event);

步骤1：新建Qt设计师类，进行界面设计

• 添加背景图片，label标签，pixmap可以直接在标签所在位置插入图片
  
  
• 对于确认和取消按钮里面的图片，在如下所示地方插入即可
  

步骤2：main.cpp文件中，添加对话框

#include "mainwindow.h"
#include <QApplication>
#include "dialoglogin.h"
int main(int argc, char *argv[])
{QApplication a(argc, argv);DialogLogin *login = new DialogLogin();if(login->exec() != QDialog::Accepted){return 0;}MainWindow w;w.show();return a.exec();
}

步骤3：代码

• dialoglogin.h

#ifndef DIALOGLOGIN_H
#define DIALOGLOGIN_H
#include <QDialog>
namespace Ui {
class DialogLogin;
}
class DialogLogin : public QDialog
{Q_OBJECT
public:explicit DialogLogin(QWidget *parent = nullptr);~DialogLogin();
private slots:void on_pushButtonCancle_clicked();void on_pushButtonLog_clicked();
private:Ui::DialogLogin *ui;void loadSetting(); //读取本地的配置void saveSetting();QString m_user;QString m_pwd;int m_count = 0;QString Encrypt(const QString &str); //对密码加密bool m_moving= false;QPoint m_lastPosition;virtual void mousePressEvent(QMouseEvent *event);virtual void mouseReleaseEvent(QMouseEvent *event);virtual void mouseMoveEvent(QMouseEvent *event);
};#endif // DIALOGLOGIN_H

• dialoglogin.cpp

#include "dialoglogin.h"
#include "ui_dialoglogin.h"
#include <QSettings>
#include <QCryptographicHash>
#include <QMessageBox>
#include <QMouseEvent>DialogLogin::DialogLogin(QWidget *parent) :QDialog(parent),ui(new Ui::DialogLogin)
{ui->setupUi(this);//设置密码ui->lineEditNameCode->setEchoMode(QLineEdit::Password);this->setAttribute(Qt::WA_DeleteOnClose);//去掉登录窗口的左上角的标题this->setWindowFlags(Qt::FramelessWindowHint);  //任务栏中会显示标题//this->setWindowFlag(Qt::SplashScreen); //任务栏中也不会显示标题//读取本地电脑存储的用户名和密码，演示注册表的使用loadSetting();
}DialogLogin::~DialogLogin()
{delete ui;
}void DialogLogin::on_pushButtonCancle_clicked()
{this->reject();
}void DialogLogin::on_pushButtonLog_clicked()
{QString useName = ui->lineEditName->text().trimmed();  //trimmed去掉首位空格QString pwd = ui->lineEditNameCode->text().trimmed();if(useName == m_user && Encrypt(pwd) == m_pwd){//保存注册表saveSetting();this->accept();}else{m_count ++;if(m_count > 3){QMessageBox::critical(this,"错误","用户名和密码错误次数太多");this->reject();}else{QMessageBox::warning(this,"错误","用户名和密码错误");}}}void DialogLogin::loadSetting()
{QSettings setting("WD","IMAGE PROCESSING");  //公司名字 当前软件名字m_user = setting.value("user_name", "rook").toString();   //读默认值m_pwd = setting.value("pwd", Encrypt("123456")).toString();bool saved = setting.value("saved",false).toBool(); //默认保存if(saved){ui->lineEditName->setText(m_user);ui->checkBox->setChecked(saved);}
}void DialogLogin::saveSetting()
{QSettings setting("WD","IMAGE PROCESSING");setting.setValue("user_name", m_user);setting.setValue("pwd", m_pwd);setting.setValue("saved", ui->checkBox->isChecked());
}QString DialogLogin::Encrypt(const QString &str)
{//MD5加密QByteArray array;array.append(str);QCryptographicHash hash(QCryptographicHash::Md5); //设置加密算法hash.addData(array);QByteArray result = hash.result();QString md5 = result.toHex();return md5;
}void DialogLogin::mousePressEvent(QMouseEvent *event)
{if(event->button() ==Qt::LeftButton){m_moving = true;m_lastPosition = event->globalPos() - this->pos();}return QDialog::mousePressEvent(event);
}void DialogLogin::mouseReleaseEvent(QMouseEvent *event)
{m_moving = false;
}void DialogLogin::mouseMoveEvent(QMouseEvent *event)
{if(m_moving){move(event->globalPos() - m_lastPosition);m_lastPosition = event->globalPos()- this->pos();}return QDialog::mouseMoveEvent(event);
}

• mainwindow.cpp和mainwindow.h文件没有任何改变和代码添加

二 QT绘图

2.1 矩形

• 知识点：需要重写父类的virtual void paintEvent(QPaintEvent *event);

• widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();private:Ui::Widget *ui;virtual void paintEvent(QPaintEvent *event);
};
#endif // WIDGET_H

• widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include <QPainter>Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget)
{ui->setupUi(this);
}Widget::~Widget()
{delete ui;
}void Widget::paintEvent(QPaintEvent *event)
{QPainter painter(this);QPen pen;pen.setWidth(4);  //线宽pen.setColor(Qt::red);painter.setPen(pen);//使用刷子进行填充QBrush brush;brush.setColor(Qt::green);brush.setStyle(Qt::SolidPattern);painter.setBrush(brush);QRect rect(50,50,200,200);  //左上角坐标（x，y,宽度，高度)painter.drawRect(rect);}

2.1.1

• 圆角矩形：将2.1 函数void Widget::paintEvent(QPaintEvent *event)中 painter.drawRect(rect);代码修改为 painter.drawRoundedRect(rect,20,20);
• 椭圆：painter.drawEllipse(rect);
• 圆弧： //绘制圆弧 绘制0~90度 painter.drawArc(rect,0,90*16);，Qt最小度单位不是1度，是1/16度
• 弦长：painter.drawChord(rect, 0,*16,90*16)
• 多边形：

QPainter painter(this);
QPen
pen;
pen.setWidth(4); //线宽
pen.setColor(Qt::red); //划线颜色
painter.setPen(pen);
//注意，点的顺序，就是绘制的顺序
QPoint points[5] = {
{50, 100},
{100, 50},
{500, 160},
{200, 200},
{110, 400}};
painter.drawPolygon(
points,
5); //表示有几个点

• 图片

void Widget::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
QRect rect(10, 10, 400, 300);
//QImage image(":image/bg.png");
QPixmap pixmap(":image/bg.png");
//会自动在 rect 区域进行缩放
//painter.drawImage(rect, image);
painter.drawPixmap(rect, pixmap);
}

• 直线

void Widget::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
QPen
pen;
pen.setWidth(4); //线宽
pen.setColor(Qt::red); //划线颜色
painter.setPen(pen);
QLine line(50, 50, 400, 400);
painter.drawLine(line);
}

• 多条直线

void Widget::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
QPen
pen;
pen.setWidth(4); //线宽
pen.setColor(Qt::red); //划线颜色
painter.setPen(pen);
QRect rect(50, 50, 400, 300);
QVector<QLine>lines;
lines.append(QLine(rect.topLeft(), rect.bottomRight()));
lines.append(QLine(rect.bottomLeft(), rect.topRight()));
lines.append(QLine(rect.topLeft(), rect.bottomLeft()));
painter.drawLines(lines);
}

• 绘制多条连接的直线

void Widget::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
QPen
pen;
pen.setWidth(4); //线宽
pen.setColor(Qt::red); //划线颜色
painter.setPen(pen);
//注意，点的顺序，就是绘制的顺序
QPoint points[5] = {
{50, 100},
{100, 50},
{500, 160},
{200, 200},
{110, 400}};
painter.drawPolyline(points, 5);
}

• 绘制线路径

void Widget::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
QPen
pen;
pen.setWidth(4); //线宽
pen.setColor(Qt::red); //划线颜色
painter.setPen(pen);
QRect rect(50, 50, 400, 300);
//绘制由 QPaintPath 对象定义的路线
QPainterPath path;
path.addEllipse(rect); //在 rect 内的内接椭圆
path.addRect(rect);
painter.drawPath(path);
}

• 绘制扇形
  
• 画点
  
• 绘制文本
  
• 擦除指定区域
• 
• 填充指定位置
  

三 坐标变换

3.1 平移

• 知识点：依然是需要继承父类的void Widget::paintEvent(QPaintEvent *event)函数，在改函数内进行相应的实现

3.2 旋转

3.3 扭转

3.4 放大缩小

void Widget::paintEvent(QPaintEvent *event)
{QPainter painter(this);QImage img(":/images/bg.png");QRect rect(0,0,200,150);painter.drawImage(rect,img);QRect rect2(200,200,200,150);painter.scale(2.0,1.0);painter.drawImage(rect2,img);}

3.5 案例展示

void Widget::paintEvent(QPaintEvent *event)
{QPainter painter(this);painter.setRenderHint(QPainter::Antialiasing); //使得图行没有锯齿QPen  pen;pen.setWidth(4);pen.setColor(Qt::red);painter.setPen(pen);QFont font;font.setPointSize(20);painter.setFont(font);qreal r = 200;  //qreal其实就是doubleqreal unit = 72*3.141596/180;QPoint points[5] = {QPoint(r,0),QPoint(r*cos(unit),r*sin(unit)),QPoint(r*cos(2*unit),r*sin(2*unit)),QPoint(r*cos(3*unit),r*sin(3*unit)),QPoint(r*cos(4*unit),r*sin(4*unit))};QPainterPath path;path.moveTo(points[0]);  //把画笔移动到该位置path.lineTo(points[2]);path.lineTo(points[4]);path.lineTo(points[1]);path.lineTo(points[3]);path.closeSubpath();path.addText(points[0],font,"0");path.addText(points[1],font,"1");path.addText(points[2],font,"2");path.addText(points[3],font,"3");path.addText(points[4],font,"4");//保存此时坐标painter.save();painter.translate(250,210);painter.rotate(-18);painter.drawPath(path);painter.restore();}

四 视图和窗口绘图

• 功能，能使得建立的图片，随着窗口的大小变化而变化
• 知识点：需要重写void paintEvent( QPaintEvent *event);
• 知识点：也就是说，painter.setWindow是重定义视口的原点的逻辑大小

案例1：

void Widget::paintEvent(QPaintEvent *event)
{Q_UNUSED(event);//设计一个视口，也即是绘图窗口QPainter painter(this);painter.drawRect(QRect(200,0,200,200));painter.setViewport(200,0,    //视口区域的左上角坐标，实际大小200,200); //视口区域的左上角宽度和高度，实际大小//设置视口后，一定要设置对应的窗口坐标//否则会使用默认的窗口坐标，导致绘制效果不是预期的//如下代码表示在当前的视口区域内，设置一个窗口坐标，//在这个窗口坐标下，视口的左上角坐标是（-50， -50），//视口的宽度是 100 个逻辑大小，视口的高度是 100 个逻辑大小painter.setWindow(-50,-50,  //在这个窗口坐标系下，视口左上角的坐标100, //在这个窗口坐标系下，视图区域的宽度大小，逻辑大小，不是实际大小100);//在这个窗口坐标系下，视图区域的高度大小，逻辑大小，不是实际大小QPen pen;pen.setColor(Qt::red);painter.setPen(pen);painter.drawRect(QRect(0,0,50,50));
}

案例2：

void Widget::paintEvent(QPaintEvent *event)
{Q_UNUSED(event);//设计一个视口，也即是绘图窗口QPainter painter(this);painter.setRenderHint(QPainter::Antialiasing);int w= qMin(this->width(), this->height());QRect rect((this->width() - w)/2,(this->height() - w)/2,w,w);painter.drawRect(rect);//设置视口区域painter.setViewport(rect);//设置视口的窗口坐标系painter.setWindow(-100,-100,200,200);QPen pen;pen.setColor(Qt::red);pen.setWidth(1);pen.setStyle(Qt::SolidLine);painter.setPen(pen);int count = 10;for(int i =0; i< count ;i ++){painter.drawEllipse(QPoint(50,0),50,50);painter.rotate(360/count);}
}

五 Graphics View绘图框架

5.1 案例1 视图，场景，图形项之间的关系

• 知识点1： scene->addItem(item3);默认父节点是场景，如果要设置其他的图形项是当前图i图形项目的父节点，需要使用函数`item->setParentItem(item2)
• 知识点2：设置item可拖动

    item2->setFlags(QGraphicsItem::ItemIsSelectable |QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable);

MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);//创建场景，当前的原点创建在了场景的中心scene =  new QGraphicsScene(-200,-100,   //场景区域的左上角在场景坐标下的坐标，也就是原点被设置成矩形框的正中心400,200);  //场景的宽度，场景的高度ui->graphicsView->setScene(scene);//图形项 当前创建了和场景一样大小的图形项QGraphicsRectItem *item = new QGraphicsRectItem(-200,-100,  //矩形图形项的左上角在图像项内部的坐标系下的坐标400,200);//设置图形项的原点，在场景坐标系下的位置item->setPos(0,0);//设置图形项的画笔QPen pen;pen.setColor(Qt::blue);pen.setWidth(2);item->setPen(pen);scene->addItem(item);//图形项2 当前创建了和场景一样大小的图形项QGraphicsRectItem *item2 = new QGraphicsRectItem(0,0,  //矩形图形项的左上角在图像项内部的坐标系下的坐标，也就是原点被设置成左上角200,100);//设置图形项的原点，在场景坐标系下的位置item2->setPos(-200,-100);item2->setBrush(QBrush(Qt::red));scene->addItem(item2);//图形项2 当前创建了和场景一样大小的图形项QGraphicsRectItem *item3 = new QGraphicsRectItem(-100,-50,  //矩形图形项的左上角在图像项内部的坐标系下的坐标，也就是原点被设置图形项的正中心200,100);//设置图形项的原点，在场景坐标系下的位置,item3->setPos(0,0);item3->setBrush(QBrush(Qt::yellow));scene->addItem(item3);默认父节点是场景
}

5.1 案例2： 拖动鼠标或者图形项，显示鼠标当前所在位置的，对应的视图，场景以及图形项中的坐标

• 也是图形项发出信号

• mainwindow

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include <QGraphicsScene>
#include "mygraphicview.h"QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();private:Ui::MainWindow *ui;QGraphicsScene *scene;private slots:void on_graphicsView_mousePress(QPoint point);void on_graphicsView_mouseMove(QPoint point);
};
#endif // MAINWINDOW_H#######################################################################################
#######################################################################################
#######################################################################################
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGraphicsRectItem>MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);//创建场景，当前的原点创建在了场景的中心scene =  new QGraphicsScene(-200,-100,   //场景区域的左上角在场景坐标下的坐标，也就是原点被设置成矩形框的正中心400,200);  //场景的宽度，场景的高度ui->graphicsView->setScene(scene);//图形项 当前创建了和场景一样大小的图形项QGraphicsRectItem *item = new QGraphicsRectItem(-200,-100,  //矩形图形项的左上角在图像项内部的坐标系下的坐标400,200);//设置图形项的原点，在场景坐标系下的位置item->setPos(0,0);//设置图形项的画笔QPen pen;pen.setColor(Qt::blue);pen.setWidth(2);item->setPen(pen);scene->addItem(item);//图形项2 当前创建了和场景一样大小的图形项QGraphicsRectItem *item2 = new QGraphicsRectItem(0,0,  //矩形图形项的左上角在图像项内部的坐标系下的坐标，也就是原点被设置成左上角200,100);//设置图形项的原点，在场景坐标系下的位置item2->setPos(-200,-100);item2->setBrush(QBrush(Qt::red));scene->addItem(item2);item2->setFlags(QGraphicsItem::ItemIsSelectable |QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable);//图形项2 当前创建了和场景一样大小的图形项QGraphicsRectItem *item3 = new QGraphicsRectItem(-100,-50,  //矩形图形项的左上角在图像项内部的坐标系下的坐标，也就是原点被设置图形项的正中心200,100);//设置图形项的原点，在场景坐标系下的位置,item3->setPos(0,0);item3->setBrush(QBrush(Qt::yellow));scene->addItem(item3);}MainWindow::~MainWindow()
{delete ui;
}void MainWindow::on_graphicsView_mousePress(QPoint point)
{//把视图坐标转换成场景坐标QPointF pointSence =ui->graphicsView->mapToScene(point);//判断当前按下了哪个图形项QGraphicsItem *item = scene->itemAt(pointSence,ui->graphicsView->transform());if(item){//把场景坐标，进一步转换成对应的图形项的坐标QPointF pointItem = item->mapFromScene(pointSence);ui->labelGraph->setText(QString::asprintf("item坐标：%.0f, %.0f",pointItem.x(),pointItem.y() ));}
}void MainWindow::on_graphicsView_mouseMove(QPoint point)
{ui->labelView->setText(QString::asprintf("视图坐标：%d, %d",point.x(),point.y() ));QPointF pointSence =ui->graphicsView->mapToScene(point);ui->labelSence->setText(QString::asprintf("场景坐标：%.0f, %.0f",pointSence.x(),pointSence.y() ));
}

• MyGraphicView

#ifndef MYGRAPHICVIEW_H
#define MYGRAPHICVIEW_H#include <QObject>
#include <QGraphicsView>class MyGraphicView : public QGraphicsView
{Q_OBJECT
public:explicit MyGraphicView(QObject *parent = nullptr);signals://这里是自己定义的，不是查的void mousePress(QPoint point);void mouseMove(QPoint point);
private://重载父类QGraphicsView鼠标事件void mousePressEvent(QMouseEvent *event) override;void mouseMoveEvent(QMouseEvent *event) override;
};#endif // MYGRAPHICVIEW_H#######################################################################################
#######################################################################################
#######################################################################################
#include "mygraphicview.h"
#include <QMouseEvent>
MyGraphicView::MyGraphicView(QObject *parent)
{setMouseTracking(true); //直接拖动鼠标，也能显示坐标的改变
}void MyGraphicView::mousePressEvent(QMouseEvent *event)
{if(event->button() == Qt::LeftButton){QPoint point = event->pos();emit mousePress(point);}QGraphicsView::mousePressEvent(event); //调用父类的mousePressEvent
}void MyGraphicView::mouseMoveEvent(QMouseEvent *event)
{QPoint point = event->pos();emit mouseMove(point);QGraphicsView::mouseMoveEvent(event); //调用父类的mouseMoveEvent
}

5.1.1 创建项目的步骤

-Graphics View组件对应的类对象是QGraphicsView，是标准类对象，无法进行修改，需要自定义一个视图，去重载该类的鼠标事件

步骤1：自定义视图类

• add new->c++ class->QObject
  选项里面并没有我们要继承的QGraphicsView类，所以可以随便选一个要继承的类，在代码里进行修改即可
  

步骤2：修改自定义视图类，使其继承QGraphicsView，在QGraphicsView中寻找到鼠标相关时事件，在自定义视图类中重写。由于本身本没有信号，但是要实现鼠标移动或单击时发送信号，因此要MyGraphicView中定义信号，在mianwindow中定义槽函数

`MyGraphicView`signals://这里是自己定义的，不是查的void mousePress(QPoint point);void mouseMove(QPoint point);
private://重载父类QGraphicsView鼠标事件void mousePressEvent(QMouseEvent *event) override;void mouseMoveEvent(QMouseEvent *event) override;

mainwindowprivate slots:void on_graphicsView_mousePress(QPoint point);void on_graphicsView_mouseMove(QPoint point);

步骤3：选中graphics View组件，右键单击，选择提升为，

6 案例2 简易版CAD项目

• 知识点：如何添加侧面的toolbox
  

6.1 创建界面

1. 定义界面

2.自定义mygraphicsview.h``,Add new->c++->c++ class ->父类选择Qobject, 步骤同5中的创建步骤，新定义的继承QObject类的来要修改成继承QGraphicsView`

6.2 代码

• mainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include <QGraphicsScene>
#include <QLabel>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();private:Ui::MainWindow *ui;QGraphicsScene *sence;int itemZvalue = 0;  //图形堆叠的顺序，数字越大，叠放越上面int itemID =0;static const int ITEM_ID = 1; //图形项的编号static const int ITEM_DISCRIPTION = 2;  //图形项的描述信息//手动代码添加标签QLabel *labelViewCoord;  //视图坐标QLabel *labelFigureCoord;   //图形项坐标QLabel *labelSenceCoord;   //场景坐标QLabel *itemName;
private slots:void on_graphicsView_keyPress(QKeyEvent *event);void on_graphicsView_mouseDouble(QPoint point);void on_graphicsView_mousePress(QPoint point);void on_graphicsView_mouseMove(QPoint point);void on_actionRectangle_triggered();void on_actionElipse_triggered();void on_actionCilcle_triggered();void on_actionTriangle_triggered();void on_actionLine_triggered();void on_actionTixing_triggered();void on_actionText_triggered();void on_actionZoom_triggered();void on_actionSmall_triggered();void on_actionRestore_triggered();void on_actionLeft_triggered();void on_actionRight_triggered();void on_actionTop_triggered();void on_actionBottom_triggered();void on_actionCombine_triggered();void on_actionDepart_triggered();void on_actionDel_triggered();void on_actionExit_triggered();
};
#endif // MAINWINDOW_H

• mygraphicsview.h

#ifndef MYGRAPHICSVIEW_H
#define MYGRAPHICSVIEW_H#include <QObject>
#include <QGraphicsView>class MyGraphicsView : public QGraphicsView
{Q_OBJECT
public:explicit MyGraphicsView(QWidget *parent = nullptr);signals:void keyPress(QKeyEvent *event);void mouseDouble(QPoint point);void mousePress(QPoint point);void mouseMove(QPoint point);
protected://override重载关键字void keyPressEvent(QKeyEvent *event) override;  //按键按下void mouseDoubleClickEvent(QMouseEvent *event) override;void mousePressEvent(QMouseEvent *event) override;void mouseMoveEvent(QMouseEvent *event) override;
};#endif // MYGRAPHICSVIEW_H

• mainWindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGraphicsRectItem>
#include <QTime>
#include <QPoint>
#include <QInputDialog>
#include <QDebug>
#include <QColorDialog>
#include <QColor>
#include <QFontDialog>
#include <QKeyEvent>
//设置填充色
template <class T>
void setItemBrushColor(T *item){QColor color = item->brush().color();color = QColorDialog::getColor(color, NULL, "选择填充颜色");if(color.isValid()){item->setBrush(color);}
}//设置画笔色
template <class T>
void setItemPenColor(T *item){QPen pen = item->pen();QColor color = pen.color();color = QColorDialog::getColor(color, NULL, "选择填充颜色");if(color.isValid()){pen.setColor(color);item->setPen(pen);}
}MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);ui->graphicsView->setCursor(Qt::CrossCursor); //设置鼠标样式是十字//设置鼠标跟踪ui->graphicsView->setMouseTracking(true);//设置视图的拖动模式ui->graphicsView->setDragMode(QGraphicsView::RubberBandDrag);//创建场景sence = new QGraphicsScene(-300,-100,600,200);ui->graphicsView->setScene(sence);//设置随机种子qsrand(QTime::currentTime().second());labelViewCoord = new QLabel("视图坐标:");labelViewCoord->setMinimumWidth(150);ui->statusbar->addWidget(labelViewCoord);labelSenceCoord = new QLabel("场景坐标:");labelSenceCoord->setMinimumWidth(150);ui->statusbar->addWidget(labelSenceCoord);labelFigureCoord = new QLabel("图形项坐标:");labelFigureCoord->setMinimumWidth(150);ui->statusbar->addWidget(labelFigureCoord);itemName = new QLabel("图形项信息:");itemName->setMinimumWidth(150);ui->statusbar->addWidget(itemName);}MainWindow::~MainWindow()
{delete ui;
}//按键控制旋转平移操作
void MainWindow::on_graphicsView_keyPress(QKeyEvent *event)
{//只管选一个的情况if(sence->selectedItems().count() != 1){return;}auto item = sence->selectedItems().at(0);if(event->key() == Qt::Key_Delete){sence->removeItem(item);}else if(event->key() == Qt::Key_Space){item->setRotation(item->rotation() + 10);}else if(event->key() == Qt::Key_PageUp){item->setScale(item->scale() +0.1);}else if(event->key() == Qt::Key_PageDown){item->setScale(item->scale() -0.1);}else if(event->key() == Qt::Key_Left){item->setX(item->x() -1);}else if(event->key() == Qt::Key_Right){item->setX(item->x() +1);}else if(event->key() == Qt::Key_Up){item->setY(item->y() -1);}else if(event->key() == Qt::Key_Down){item->setY(item->y() +1);}}void MainWindow::on_graphicsView_mouseDouble(QPoint point)
{//双击图形项，自动弹出颜色编辑器//QGraphicsRectItem : public QAbstractGraphicsShapeItem// QGraphicsEllipseItem : public QAbstractGraphicsShapeItem//QGraphicsPolygonItem : public QAbstractGraphicsShapeItem 三角形//QGraphicsPolygonItem : public QAbstractGraphicsShapeItem 梯形qDebug() << "in in --------------";//由于不同图形继承的类不同QPointF pointSence = ui->graphicsView->mapToScene(point);  //获取场景坐标QGraphicsItem *item = sence->itemAt(pointSence, ui->graphicsView->transform()); //计算改场景坐标对应是哪个图形if(!item){return;}switch (item->type()) {case QGraphicsRectItem::Type:{//矩形auto item2 =qgraphicsitem_cast<QGraphicsRectItem*>(item);setItemBrushColor(item2);break;}case QGraphicsEllipseItem::Type:{//椭圆/园auto item2 =qgraphicsitem_cast<QGraphicsEllipseItem*>(item);setItemBrushColor(item2);break;}case QGraphicsPolygonItem::Type:{//多边形auto item2 =qgraphicsitem_cast<QGraphicsPolygonItem*>(item);setItemBrushColor(item2);break;}case QGraphicsLineItem::Type:{//直线auto item2 =qgraphicsitem_cast<QGraphicsLineItem*>(item);setItemPenColor(item2);break;}case QGraphicsTextItem::Type:{//多边形auto item2 =qgraphicsitem_cast<QGraphicsTextItem*>(item);QFont font = item2->font();bool ok = false;font = QFontDialog::getFont(&ok,font, this,"设置字体");if(ok){item2->setFont(font);}break;}}
}//图形项目坐标需要单击选中图形项 
void MainWindow::on_graphicsView_mousePress(QPoint point)
{QPointF pointScene = ui->graphicsView->mapToScene(point);  //视图坐标转场景坐标QGraphicsItem *item = sence->itemAt(pointScene,ui->graphicsView->transform());//图形项坐标if(item){QPointF pointItem = item->mapFromScene(pointScene);  //获取点的图形项坐标labelFigureCoord->setText(QString::asprintf("图形项坐标：%.0f %.0f",pointItem.x(),pointItem.y()));itemName->setText(item->data(ITEM_DISCRIPTION).toString());}}void MainWindow::on_graphicsView_mouseMove(QPoint point)
{labelViewCoord->setText(QString::asprintf("视图坐标：%d %d",point.x(),point.y()));QPointF pointScene = ui->graphicsView->mapToScene(point);labelSenceCoord->setText(QString::asprintf("场景坐标：%.0f %.0f",pointScene.x(),pointScene.y()));
}void MainWindow::on_actionRectangle_triggered()
{QGraphicsRectItem *item = new QGraphicsRectItem(-100,-50,200,100);item->setFlags(QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable |QGraphicsItem:: ItemIsSelectable);item->setBrush(QBrush(Qt::lightGray));  //填充颜色item->setZValue(itemZvalue++);//设置图形项位置，在视图的中心位置附近设计随机变量 0~100 -50item->setPos(qrand()%100-50,qrand()%100-50);//设置图形项的自定义数据item->setData(ITEM_ID,itemID++);item->setData(ITEM_DISCRIPTION,"矩形");sence->addItem(item);sence->clearSelection();item->setSelected(true); //选中当前新生成的图形
}void MainWindow::on_actionElipse_triggered()
{QGraphicsEllipseItem *item = new QGraphicsEllipseItem(-100,-50,200,100);item->setFlags(QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable |QGraphicsItem:: ItemIsSelectable);item->setBrush(QBrush(Qt::blue));  //填充颜色item->setZValue(itemZvalue++);//设置图形项位置，在视图的中心位置附近设计随机变量 0~100 -50item->setPos(qrand()%100-50,qrand()%100-50);//设置图形项的自定义数据item->setData(ITEM_ID,itemID++);item->setData(ITEM_DISCRIPTION,"椭圆");sence->addItem(item);sence->clearSelection();item->setSelected(true); //选中当前新生成的图形
}void MainWindow::on_actionCilcle_triggered()
{QGraphicsEllipseItem *item = new QGraphicsEllipseItem(-100,-100,200,200);item->setFlags(QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable |QGraphicsItem:: ItemIsSelectable);item->setBrush(QBrush(Qt::yellow));  //填充颜色item->setZValue(itemZvalue++);//设置图形项位置，在视图的中心位置附近设计随机变量 0~100 -50item->setPos(qrand()%100-50,qrand()%100-50);//设置图形项的自定义数据item->setData(ITEM_ID,itemID++);item->setData(ITEM_DISCRIPTION,"圆");sence->addItem(item);sence->clearSelection();item->setSelected(true); //选中当前新生成的图形
}void MainWindow::on_actionTriangle_triggered()
{QGraphicsPolygonItem *item = new QGraphicsPolygonItem;QPolygonF points;points.append(QPointF(0,-80));points.append(QPointF(-50,0));points.append(QPointF(0,50));item->setPolygon(points);item->setFlags(QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable |QGraphicsItem:: ItemIsSelectable);item->setBrush(QBrush(Qt::red));  //填充颜色item->setZValue(itemZvalue++);//设置图形项位置，在视图的中心位置附近设计随机变量 0~100 -50item->setPos(qrand()%100-50,qrand()%100-50);//设置图形项的自定义数据item->setData(ITEM_ID,itemID++);item->setData(ITEM_DISCRIPTION,"三角形");sence->addItem(item);sence->clearSelection();item->setSelected(true); //选中当前新生成的图形
}void MainWindow::on_actionLine_triggered()
{QGraphicsLineItem *item = new QGraphicsLineItem(50, 50, 200, 200);item->setFlags(QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable |QGraphicsItem:: ItemIsSelectable);item->setZValue(itemZvalue++);//设置图形项位置，在视图的中心位置附近设计随机变量 0~100 -50item->setPos(qrand()%100-50,qrand()%100-50);//设置图形项的自定义数据item->setData(ITEM_ID,itemID++);item->setData(ITEM_DISCRIPTION,"直线");sence->addItem(item);sence->clearSelection();item->setSelected(true); //选中当前新生成的图形
}void MainWindow::on_actionTixing_triggered()
{QGraphicsPolygonItem *item = new QGraphicsPolygonItem;QPolygonF points;points.append(QPointF(-50,-50));points.append(QPointF(-100,50));points.append(QPointF(100,50));points.append(QPointF(50,-50));item->setPolygon(points);item->setFlags(QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable |QGraphicsItem:: ItemIsSelectable);item->setBrush(QBrush(Qt::black));  //填充颜色item->setZValue(itemZvalue++);//设置图形项位置，在视图的中心位置附近设计随机变量 0~100 -50item->setPos(qrand()%100-50,qrand()%100-50);//设置图形项的自定义数据item->setData(ITEM_ID,itemID++);item->setData(ITEM_DISCRIPTION,"梯形");sence->addItem(item);sence->clearSelection();item->setSelected(true); //选中当前新生成的图形
}void MainWindow::on_actionText_triggered()
{//弹出文本提示框，输入文本QString str = QInputDialog::getText(this,"输入文本","请输入文本");if(str.isEmpty()){return;}QGraphicsTextItem *item = new QGraphicsTextItem(str);item->setFlags(QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable |QGraphicsItem:: ItemIsSelectable);QFont font;font.setFamily("微软雅黑");font.setPointSize(20);font.setBold(true);item->setFont(font);item->setZValue(itemZvalue++);//设置图形项位置，在视图的中心位置附近设计随机变量 0~100 -50item->setPos(qrand()%100-50,qrand()%100-50);//设置图形项的自定义数据item->setData(ITEM_ID,itemID++);item->setData(ITEM_DISCRIPTION,"文本");sence->addItem(item);sence->clearSelection();item->setSelected(true); //选中当前新生成的图形
}void MainWindow::on_actionZoom_triggered()
{//如果当前选择了一个图元，那么对这个图元进行放大//如果选择了多个图，对多个放大int count = sence->selectedItems().count();if(count ==1){QGraphicsItem *item= sence->selectedItems().at(0); //取出图形item->setScale(item->scale()+0.1);}else if(count >1){for(int i =0 ; i < count; i++){QGraphicsItem *item= sence->selectedItems().at(i); //取出图形item->setScale(item->scale()+0.1);}}
}void MainWindow::on_actionSmall_triggered()
{int count = sence->selectedItems().count();if(count ==1){QGraphicsItem *item= sence->selectedItems().at(0); //取出图形item->setScale(item->scale()-0.1);}else if(count >1){for(int i =0 ; i < count; i++){QGraphicsItem *item= sence->selectedItems().at(i); //取出图形item->setScale(item->scale()-0.1);}}
}void MainWindow::on_actionRestore_triggered()
{int count = sence->selectedItems().count();for(int i =0 ; i < count; i++){QGraphicsItem *item= sence->selectedItems().at(i); //取出图形item->setScale(1);item->setRotation(0);}
}void MainWindow::on_actionLeft_triggered()
{int count = sence->selectedItems().count();if(count ==1){QGraphicsItem *item= sence->selectedItems().at(0); //取出图形item->setRotation(item->rotation()-30);}else if(count >1){for(int i =0 ; i < count; i++){QGraphicsItem *item= sence->selectedItems().at(i); //取出图形item->setRotation(item->rotation()-30);}}
}void MainWindow::on_actionRight_triggered()
{int count = sence->selectedItems().count();if(count ==1){QGraphicsItem *item= sence->selectedItems().at(0); //取出图形item->setRotation(item->rotation()+30);}else if(count >1){for(int i =0 ; i < count; i++){QGraphicsItem *item= sence->selectedItems().at(i); //取出图形item->setRotation(item->rotation()+30);}}
}void MainWindow::on_actionTop_triggered()
{int count = sence->selectedItems().count();if(count >0){QGraphicsItem *item= sence->selectedItems().at(0);item->setZValue(item->zValue()+1);}
}void MainWindow::on_actionBottom_triggered()
{int count = sence->selectedItems().count();if(count >0){QGraphicsItem *item= sence->selectedItems().at(0);item->setZValue(item->zValue()-1);}
}void MainWindow::on_actionCombine_triggered()
{int count = sence->selectedItems().count();qDebug() <<"count = " << count;if(count >=2){QGraphicsItemGroup *group = new QGraphicsItemGroup;sence->addItem(group);for(int i =0 ; i < count; i++){auto item = sence->selectedItems().at(0);  //获取每次循环的第一个itemitem->setSelected(false);item->clearFocus();group->addToGroup(item);}group->setFlags(QGraphicsItem::ItemIsMovable |QGraphicsItem::ItemIsFocusable |QGraphicsItem:: ItemIsSelectable);group->setZValue(itemZvalue++);sence->clearSelection();group->setSelected(true);}
}void MainWindow::on_actionDepart_triggered()
{int count = sence->selectedItems().count();if(count ==1){auto group = (QGraphicsItemGroup *)sence->selectedItems().at(0);sence->destroyItemGroup(group);}
}void MainWindow::on_actionDel_triggered()
{int count = sence->selectedItems().count();if(count > 0){auto item = sence->selectedItems().at(0);sence->removeItem(item);}
}void MainWindow::on_actionExit_triggered()
{close();
}

• mygraphicsview.cpp

#include "mygraphicsview.h"
#include <QMouseEvent>
#include <QDebug>
MyGraphicsView::MyGraphicsView(QWidget *parent):QGraphicsView(parent)
{}void MyGraphicsView::keyPressEvent(QKeyEvent *event)
{emit keyPress(event);QGraphicsView::keyPressEvent(event);
}void MyGraphicsView::mouseDoubleClickEvent(QMouseEvent *event)
{//qDebug() << "mouseDoubleClickEvent ";if(event->button() == Qt::LeftButton){//获取视图坐标QPoint point = event->pos();emit mouseDouble(point);}QGraphicsView::mouseDoubleClickEvent(event);
}void MyGraphicsView::mousePressEvent(QMouseEvent *event)
{if(event->button() == Qt::LeftButton){//获取视图坐标QPoint point = event->pos();emit mousePress(point);}QGraphicsView::mousePressEvent(event);
}void MyGraphicsView::mouseMoveEvent(QMouseEvent *event)
{QPoint point = event->pos();emit mouseMove(point);QGraphicsView::mouseMoveEvent(event);
}