子类 QGraphicsScene 出错

Posted 2023-02-17

【中文标题】子类 QGraphicsScene 出错

【英文标题】：Error With subclass QGraphicsScene

【发布时间】：2018-04-28 21:00:13

【问题描述】：

我正在尝试将省略号添加到 Qt 中的场景中，但出现此错误：

XXXXXX/mainwindow.cpp:20：错误：“类 mqlabel”没有名为“setScene”的成员 ui->imageLabel->setScene(场景);

还有这个：

XXXXXX/build-MyPic-Desktop_Qt_5_10_1_GCC_64bit-Debug/ui_mainwindow.h:136: 错误: 没有匹配函数调用‘QGridLayout::addWidget(mqlabel*&, int, int, int, int)’ gridLayout_2->addWidget(imageLabel, 0, 0, 3, 1); ^

重要的是，我将 imageLabel（我在 .ui 文件中的场景）提升为 mqlabel

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QWidget>
#include <QGraphicsScene>
#include <QGraphicsItem>
#include <QGraphicsSceneMouseEvent>
#include <QGraphicsView>

namespace Ui 
class MainWindow;

//class MainWindow : public QGraphicsView
class MainWindow : public QMainWindow

    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    //explicit MainWindow(QGraphicsView *parent = 0);
    ~MainWindow();

private slots:
    void on_actionOpen_triggered();

    void on_actionExit_triggered();

    void mouse_pressed();

    void mouse_pos();
private:
    Ui::MainWindow *ui;
    QImage image;
    QGraphicsScene* scene;
    QGraphicsItem* item;
    QGraphicsEllipseItem *ellipse;
    QGraphicsView *view = new QGraphicsView(this);


;

#endif // MAINWINDOW_H

MainWINdow.cpp

#include <QtWidgets>

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <iostream>
#include <QGraphicsView>
#include <QGraphicsScene>
#include "mqlabel.h"
using namespace std;

//MainWindow::MainWindow(QGraphicsView *parent) :
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)

    ui->setupUi(this);
    connect(ui->imageLabel, SIGNAL(mouse_pressed()),    this,SLOT(mouse_pressed()));
    connect(ui->imageLabel, SIGNAL(mouse_pos()), this,SLOT(mouse_pos()));
    scene = new QGraphicsScene();
    ui->imageLabel->setScene(scene);




MainWindow::~MainWindow()
    delete ui;
    delete scene;


void MainWindow::on_actionOpen_triggered()
    QFileDialog dialog(this, tr("Open File"));
    while (dialog.exec() == QDialog::Accepted &&     !loadFile(dialog.selectedFiles().first())) 


void MainWindow::on_actionExit_triggered()
   QCoreApplication::quit();


void MainWindow::mouse_pressed()

    QPen outlinePen(Qt::black);
    QBrush greenBrush(Qt::NoBrush);

    ui->pos_x->setText(QString("X: %1 ").arg(ui->imageLabel->x));
    ui->pos_y->setText(QString("Y: %1 ").arg(ui->imageLabel->y));
    ui->lblMouse_Current_Event->setText("Mouse Pressed");
    QGraphicsEllipseItem *ellipse = scene->addEllipse(pos().x(),pos().y(), 300, 60, outlinePen, greenBrush);


void MainWindow::mouse_pos()
    ui->lblMouse_Current_Event->setText("Mouse Moving");
    ui->pos_x->setText(QString("X: %1 ").arg(ui->imageLabel->x));
    ui->pos_y->setText(QString("Y: %1 ").arg(ui->imageLabel->y));

mqlabel.h

#ifndef MQLABEL_H
#define MQLABEL_H

#include <QWidget>
#include <QImage>
#include <QGraphicsView>
#include <QGraphicsScene>
#include <QGraphicsSceneMouseEvent>

class mqlabel : public QGraphicsScene
    Q_OBJECT

public:
    explicit mqlabel(QWidget *parent = 0);
    void mouseMoveEvent(QGraphicsSceneMouseEvent *move);
    void mousePressEvent(QGraphicsSceneMouseEvent *press);
    int x, y;

signals:
    void mouse_pressed();
    void mouse_pos();

public slots:

;

#endif // MQLABEL_H

mqlabel.cpp

#include "mqlabel.h"
#include <iostream>
#include <QGraphicsScene>
#include <QGraphicsSceneMouseEvent>
#include <QGraphicsView>
#include <QMouseEvent>
using namespace std;

mqlabel::mqlabel(QWidget *parent) : QGraphicsScene(parent)



void mqlabel::mouseMoveEvent(QGraphicsSceneMouseEvent *move) 
    QGraphicsScene::mouseMoveEvent(move);
    this->x = move->pos.x();
    this->y = move->pos.y();
    emit mouse_pos();


void mqlabel::mousePressEvent(QGraphicsSceneMouseEvent *press)
    QGraphicsScene::mousePressEvent(press);
    this->x = press->pos.x();
    this->y = press->pos.y();
    emit mouse_pressed();

【参考方案1】：

不完全确定您想通过为图形场景对象设置场景来实现什么。但是 QGraphicsScene 类实际上没有任何称为 setScene 的成员。 QGraphicsView 有那个方法。