如何从按钮按下 Qt 运行命令 - 可能是 C++

Question

当我试图完成一个程序并且我想要一个图形界面时，我正在尝试非常快速地重建一个 QT 应用程序作为 QT Creator 提供的示例。以下是我希望相关的部分：

arrowpad.h:

#ifndef ARROWPAD_H
#define ARROWPAD_H

#include <QWidget>

QT_BEGIN_NAMESPACE
class QPushButton;
QT_END_NAMESPACE

//! [0]
class ArrowPad : public QWidget
//! [0] //! [1]
{
//! [1] //! [2]
    Q_OBJECT
//! [2]

public:
    ArrowPad(QWidget *parent = 0);

private:
    QPushButton *upButton;
    QPushButton *downButton;
    QPushButton *leftButton;
    QPushButton *rightButton;
};

#endif

arrowpad.cpp:

#include <QtGui>

#include "arrowpad.h"

ArrowPad::ArrowPad(QWidget *parent)
    : QWidget(parent)
{
//! [0]
    upButton = new QPushButton(tr("&Up"));
//! [0] //! [1]
    downButton = new QPushButton(tr("&Down"));
//! [1] //! [2]
    leftButton = new QPushButton(tr("&Left"));
//! [2] //! [3]
    rightButton = new QPushButton(tr("&Right"));
//! [3]

    QGridLayout *mainLayout = new QGridLayout;
    mainLayout->addWidget(upButton, 0, 1);
    mainLayout->addWidget(leftButton, 1, 0);
    mainLayout->addWidget(rightButton, 1, 2);
    mainLayout->addWidget(downButton, 2, 1);
    setLayout(mainLayout);
}

当我按下按钮时，如何让它运行命令？我找到了this，但我不知道如何与 qpushbutton 集成，否则它只是认为它是一串文本...... 任何命令都必须在 LINUX - FEDORA 19 中工作，因为那是我正在运行它。

这是当前的结果——顺便说一下，在上面的.cpp 脚本中，我不认为按钮名称被指定为(tr("&Up"));。

Answer 1

Apartidge 是对的，但要添加到这一点并将多个按钮连接到相同的功能，您只需连接正确的信号和插槽。

你的例子：

connect(upButton, SIGNAL(clicked()), this, SLOT(onButtonPressed()));
connect(downButton, SIGNAL(clicked()), this, SLOT(onButtonPressed()));
connect(leftButton, SIGNAL(clicked()), this, SLOT(onSomeOtherButtonPressed()));
connect(rightButton, SIGNAL(clicked()), this, SLOT(onYetAnotherButtonPressed()));

将它放在你的构造函数中会将 upButton 和 downButton 连接到同一个插槽 onButtonPressed()。 leftButton 会触发 onSomeOtherButtonPressed()，rightButton 会触发 onYetAnotherButtonPressed()。

Answer 2

按钮在被点击时会发出pressed 信号。您必须做的是将此信号连接到一个插槽，然后在该插槽中执行您的操作。

例如，

ArrowPad::ArrowPad(QWidget *parent)
    : QWidget(parent)
{

    upButton = new QPushButton(tr("&Up"));
    connect(upButton, SIGNAL(clicked()), this, SLOT(onButtonPressed()));
    // And so on for the other buttons
}

void ArrowPad::onButtonPressed()
{
    // Button is pressed, do actions
}

Answer 3

在 qt 中，大多数事情都是通过信号/插槽机制工作的。 因此，您定义了一些插槽并简单地将信号连接到它们。

arrowpad.h

#ifndef ARROWPAD_H
#define ARROWPAD_H

#include <QWidget>

QT_BEGIN_NAMESPACE
class QPushButton;
QT_END_NAMESPACE

//! [0]
class ArrowPad : public QWidget
//! [0] //! [1]
{
//! [1] //! [2]
    Q_OBJECT
//! [2]

public:
    ArrowPad(QWidget *parent = 0);

private:
    QPushButton *upButton;
    QPushButton *downButton;
    QPushButton *leftButton;
    QPushButton *rightButton;



// 1- Here you declare the slots
private slots:
 void onUpButtonClick();
 void onDownButtonClick();
 void onLeftButtonClick();
 void onRightButtonClick();
};

#endif

现在在 arrowpad.cpp 中

#include <QtGui>

#include "arrowpad.h"

ArrowPad::ArrowPad(QWidget *parent)
    : QWidget(parent)
{
//! [0]
    upButton = new QPushButton(tr("&Up"));
//! [0] //! [1]
    downButton = new QPushButton(tr("&Down"));
//! [1] //! [2]
    leftButton = new QPushButton(tr("&Left"));
//! [2] //! [3]
    rightButton = new QPushButton(tr("&Right"));
//! [3]

// 2- Connect signals to slots
  QObject::connect(upButton, signal(clicked()), this, slot(onUpButtonClick()));

  QObject::connect(downButton, signal(clicked()), this, slot(onDownButtonClick()));

  QObject::connect(rightButton, signal(clicked()), this, slot(onRightButtonClick()));

  QObject::connect(leftButton, signal(clicked()), this, slot(onLeftButtonClick()));


    QGridLayout *mainLayout = new QGridLayout;
    mainLayout->addWidget(upButton, 0, 1);
    mainLayout->addWidget(leftButton, 1, 0);
    mainLayout->addWidget(rightButton, 1, 2);
    mainLayout->addWidget(downButton, 2, 1);
    setLayout(mainLayout);
}

// 3- Define the slots
 void ArrowPad::onUpButtonClick()
{
   qDebug() << "onUpButtonClick clicked";
}
 void ArrowPad::onDownButtonClick()
{
   qDebug() << "onDownButtonClick clicked";
}
 void ArrowPad::onLeftButtonClick()
{
   qDebug() << "onLeftButtonClick clicked";
}
 void ArrowPad::onRightButtonClick()
{
   qDebug() << "onRightButtonClick clicked";
}

Answer 4

您是否尝试过了解 SIGNAL 和 SLOT 机制？

http://doc.qt.io/qt-4.8/signalsandslots.html