我想通过在我使用QGraphicsSceneContextMenuEvent创建的上下文菜单中单击选项“info”来创建一个显示QGraphicsItem(宽度和高度)信息的程序。现在我只是试图用一个名为info的qDebug调用一个函数。
这是我的代码
dialog.h:
#ifndef DIALOG_H
#define DIALOG_H
#include <QDialog>
#include "QtCore"
#include "QtGui"
#include "mysquare.h"
namespace Ui {
class Dialog;
}
class Dialog : public QDialog
{
Q_OBJECT
public:
explicit Dialog(QWidget *parent = 0);
~Dialog();
private:
Ui::Dialog *ui;
QGraphicsScene *scene;
MySquare *square;
};
#endif // DIALOG_H
dialog.cpp
#include "dialog.h"
#include "ui_dialog.h"
#include <QWidget>
Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);
scene = new QGraphicsScene(this);
ui->graphicsView->setScene(scene);
square=new MySquare();
scene->addItem(square);
}
Dialog::~Dialog()
{
delete ui;
}
mysquare.h
#ifndef MYSQUARE_H
#define MYSQUARE_H
#include <QPainter>
#include <QGraphicsItem>
#include <QDebug>
#include <QMenu>
class MySquare: public QGraphicsItem
{
public:
MySquare();
QRectF boundingRect() const;
void paint (QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);
QMenu *menu;
QAction *heightAct;
QAction *widthAct;
QAction *color;
private slots:
void info();
protected:
void mousePressEvent(QGraphicsSceneMouseEvent *event);
void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);
void contextMenuEvent(QGraphicsSceneContextMenuEvent *event);
};
#endif // MYSQUARE_H
mysquare.cpp
#include "mysquare.h"
#include<QMenu>
#include <string>
using namespace std;
MySquare::MySquare()
{
}
QRectF MySquare::boundingRect() const
{
return QRectF(100,100,50,50);
}
void MySquare::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QRectF rec = boundingRect();
QBrush brushy(Qt::green);
painter->fillRect(rec,brushy);
painter->drawRect(rec);
}
void MySquare::info()
{
qDebug()<<"HERE'S MY INFO!!!";
}
void MySquare::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
{
QString height = "Height: "+QString::number(boundingRect().height());
QString width = "Width: "+QString::number(boundingRect().width());
menu = new QMenu();
heightAct = menu->addAction(height);
widthAct = menu->addAction(width);
color = menu->addAction("Change color");
menu->exec(QCursor::pos());
}
答案 0 :(得分:0)
要在点击菜单中的操作和插槽信息()之间建立“链接”,您需要使用信号/插槽机制。
您只需在QMenu初始化中添加QObject :: connect(...)。
void MySquare::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
{
QString height = "Height: "+QString::number(boundingRect().height());
QString width = "Width: "+QString::number(boundingRect().width());
menu = new QMenu();
heightAct = menu->addAction(height);
widthAct = menu->addAction(width);
color = menu->addAction("Change color");
QObject::connect(heightAct, SIGNAL(triggered()), this, SLOT(info()));
menu->exec(QCursor::pos());
}
但是,上面的代码不会编译,因为信号/槽机制只能用于QObject的子类,而QGraphicsItem则不能。所以你必须将它改为QGraphicsObject。 (不要忘记Q_OBJECT宏)
此外,还有一点超出主题:
使用
#include <QtCore>
而不是
#include "QtCore"
但我真的建议你只包括你需要的东西,而不是整个QtCore库。
此外,将您的包含在源文件而不是头文件中,除非它不可能。
不要混用标准C ++库,例如
#include <string>
除非绝对需要。在这种情况下,您必须包括
#include <QString>
只需删除
即可using namespace std;