Qt第十七天

快来打我* 2022-04-04 09:18 290阅读 0赞

## QGraphicsView程序基本结构和功能实现 ##

mainwindow.h

#ifndef MAINWINDOW_H
    #define MAINWINDOW_H
    
    
    #include <QMainWindow>
    #include <QLabel>
    #include<QGraphicsScene>
    #include<QGraphicsItem>
    #include"qwgraphicsview.h"
    
    
    namespace Ui {
    class MainWindow;
    }
    
    
    class MainWindow : public QMainWindow
    {
    Q_OBJECT
    private:
        QGraphicsScene  *scene;
        QLabel  *labViewCord;
        QLabel  *labSceneCord;
        QLabel  *labItemCord;
        void iniGraphicsSystem(); //创建Graphics View的各项
    
    
    protected:
        void resizeEvent(QResizeEvent *event);//重定义了resizeEvent（）事件
    
    
    private slots:
        void on_mouseMovePoint(QPoint point);
    
    
        void on_mouseClicked(QPoint point);
    
    
    public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
    
    
    private:
    Ui::MainWindow *ui;
    };
    
    
    #endif // MAINWINDOW_H

qwgraphicsview.h

#ifndef QWGRAPHICSVIEW_H
    #define QWGRAPHICSVIEW_H
    #include<QGraphicsView>
    #include <QObject>
    #include<qwgraphicsview.h>
    #include"mainwindow.h"
    
    
    /**
     * 从QGraphicsView类继承一个类
     * 实现mouseMoveEvent和mousePressEvent事件
     * 把鼠标事件转换为信号，在主程序中设计槽函数响应这些鼠标事件
     **/
    class QWGraphicsView : public QGraphicsView
    {
        Q_OBJECT
    protected:
        void mouseMoveEvent(QMouseEvent *event);
        void mousePressEvent(QMouseEvent *event);
    public:
        QWGraphicsView(QWidget *parent=nullptr);
    
    
    signals:
        void mouseMovePoint(QPoint point);
        void mouseClicked(QPoint point);
    
    
    };
    
    
    #endif // QWGRAPHICSVIEW_H

mainwindow.cpp

#include "mainwindow.h"
    #include "ui_mainwindow.h"
    #include"qwgraphicsview.h"
    #include<QFlags>
    #include<QPen>
    #include<QGraphicsEllipseItem>
    #include<QBrush>
    
    
    MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
    {
    ui->setupUi(this);
    labViewCord=new QLabel("View 坐标：");
    labViewCord->setMinimumWidth(150);
    ui->statusBar->addWidget(labViewCord);
    labSceneCord=new QLabel("Sence 坐标:");
    labSceneCord->setMinimumWidth(150);
    ui->statusBar->addWidget(labSceneCord);
    labItemCord=new QLabel("Item 坐标：");
    labItemCord->setMinimumWidth(150);
    ui->statusBar->addWidget(labItemCord);
    ui->View->setCursor(Qt::CrossCursor);//指针
    ui->View->setMouseTracking(true);//该属性用来设置某个控件是否被跟踪轨迹。
    ui->View->setDragMode(QGraphicsView::RubberBandDrag);
    QObject::connect(ui->View,SIGNAL(mouseMovePoint(QPoint)),this,SLOT(on_mouseMovePoint(QPoint)));
    QObject::connect(ui->View,SIGNAL(mouseClicked(QPoint)),this,SLOT(on_mouseClicked(QPoint)));
    iniGraphicsSystem();
    }
    
    
    MainWindow::~MainWindow()
    {
    delete ui;
    }
    /**
     * @brief MainWindow::on_mouseClicked
     * @param point
     */
    void MainWindow::on_mouseClicked(QPoint point)//鼠标点击事件
    {
        QPointF pointScene=ui->View->mapToScene(point);//转换到Scene坐标
        QGraphicsItem *item=nullptr;
        item=scene->itemAt(pointScene,ui->View->transform());//获取光标下的图形项
        if(item!=nullptr)//判断是否有图形项
        {
            QPointF pointItem=item->mapFromScene(pointScene);//图形项的局部坐标
            labItemCord->setText(QString::asprintf("Item坐标：%。0f，%。0f",pointItem.x(),pointItem.y()));
        }
    }
    /**
     * @brief MainWindow::on_mouseMovePoint
     * @param point
     */
    void MainWindow::on_mouseMovePoint(QPoint point)
    /*
     * 鼠标移动事件
     * point是GraphicsView的坐标
     * 是物理坐标
     */
    {
        labViewCord->setText(QString::asprintf("View坐标：%d,%d",point.x(),point.y()));
        QPointF pointScene=ui->View->mapToScene(point);//转换到Scene坐标
        labSceneCord->setText(QString::asprintf("Sence坐标：%.0f,%.0f",pointScene.x(),pointScene.y()));
    }
    /**
     * @brief MainWindow::resizeEvent
     * @param event
     */
    void MainWindow::resizeEvent(QResizeEvent *event)//窗口变化时事件
    {
        Q_UNUSED(event);
        ui->label->setText(QString::asprintf("Graphics View坐标，左上角总是（0,0），宽度=%d，高度=%d",ui->View->width(),ui->View->height()));
        QRectF rectF=ui->View->sceneRect();//
        ui->label_2->setText(QString::asprintf("GraphcsView::sceneRect=(Left,Top,Width,Height)=%.0f,%.0f,%.0f,%.0f",
                                               rectF.left(),rectF.top(),rectF.width(),rectF.height()));
    }
    void MainWindow::iniGraphicsSystem()//构造Graphics View中的各项
    {
        QRectF   rect(-200,-100,400,200);//左上角的坐标，宽度，高度
        scene=new QGraphicsScene(rect);//scene逻辑坐标系定义
        ui->View->setScene(scene);
        //画一个矩形，大小等于scene
        QGraphicsRectItem *item=new QGraphicsRectItem(rect);
        item->setFlags(QGraphicsItem::ItemIsSelectable|//设置flags
                       //QGraphicsItem::ItemIsMovable|
                       QGraphicsItem::ItemIsFocusable);
        QPen pen;
        pen.setWidth(2);
        item->setPen(pen);
        scene->addItem(item);
        //画一个位于scene中心的椭圆
        QGraphicsEllipseItem *item2=new QGraphicsEllipseItem(-100,-50,200,100);
        item2->setPos(0,0);
        item2->setBrush(QBrush(Qt::blue));
        item2->setFlags(QGraphicsItem::ItemIsSelectable|
                        QGraphicsItem::ItemIsMovable|
                        QGraphicsItem::ItemIsFocusable);
        scene->addItem(item2);
        //画一个圆，中心位于scene的边缘
        QGraphicsEllipseItem *item3=new QGraphicsEllipseItem(-50,-50,100,100);
        item3->setPos(rect.right(),rect.bottom());
        item3->setBrush(QBrush(Qt::red));
        item3->setFlags(QGraphicsItem::ItemIsSelectable|
                        QGraphicsItem::ItemIsMovable|
                        QGraphicsItem::ItemIsFocusable);
        scene->addItem(item3);
        scene->clearSelection();
    }

qwgraphicsview.cpp

#include "qwgraphicsview.h"
    #include<QPoint>
    #include<QMouseEvent>
    /**
     * @brief QWGraphicsView::QWGraphicsView
     * @param parent
     */
    QWGraphicsView::QWGraphicsView(QWidget *parent):QGraphicsView(parent)
    {
    
    
    }
    /**
     * @brief QWGraphicsView::mouseMoveEvent
     * @param event
     */
    void QWGraphicsView::mouseMoveEvent(QMouseEvent *event)//鼠标移动事件
    {
        QPoint point=event->pos();//QGraphicsView的坐标
        emit mouseMovePoint(point);//发射信号
        QGraphicsView::mouseMoveEvent(event);
    }
    /**
     * @brief QWGraphicsView::mousePressEvent
     * @param event
     */
    void QWGraphicsView::mousePressEvent(QMouseEvent *event)
    {
        if(event->button()==Qt::LeftButton)//判断按下鼠标左键
        {
            QPoint point=event->pos();//获取坐标
            emit mouseClicked(point);//发射信号
        }
        QGraphicsView::mousePressEvent(event);
    }

运行结果  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RoZVJvb2tpZTE_size_16_color_FFFFFF_t_70]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RoZVJvb2tpZTE_size_16_color_FFFFFF_t_70]: /images/20220404/740612d7b15b450caeacebd74dfd4a3f.png