5.Qt自定义Button按钮的实现

#define
MYBUTTON_H

#include
<QWidget>

/**

*
@brief
The
MyButton
class

*
如果想重写button，需要继承QWidget

*/

class
MyButton
:
public
QWidget

{

Q_OBJECT

public:

explicit
MyButton(QWidget
*parent
= 0);

//重写MyButton的构造函数

MyButton(const
QString&
text,
QWidget*
parent =
0);

//表示一个矩形

QRect
_rect;

//表示按钮中的文字

QString
_text;

//用来表示是否按下了的布尔值

bool
_pressed;

//表示鼠标按下的事件

void
mousePressEvent(QMouseEvent
*);

//表示鼠标释放的事件

void
mouseReleaseEvent(QMouseEvent
*);

void
paintEvent(QPaintEvent
*);

signals:

//信号，点击的信号

void
clicked();

public
slots:

};

#endif
//
MYBUTTON_H

#include "MyButton.h"

#include <QPainter>

#include <QMouseEvent>

MyButton::MyButton(QWidget *parent) :

    QWidget(parent), _rect(0, 0, 100, 30), _text(QString())

{

    //通过这个标记按钮是否被按下了

    _pressed = false;

    this->setGeometry(_rect);

}

MyButton::MyButton(const QString &text, QWidget *parent):

    QWidget(parent),_text(text),_rect(0,0,100,30)

{

    _pressed = false;

    this->setGeometry(_rect);

}

void MyButton::mousePressEvent(QMouseEvent *ev)

{

    _pressed = true;

    update();

}

void MyButton::mouseReleaseEvent(QMouseEvent *ev)

{

    _pressed = false;

    update();

    if(_rect.contains(ev->pos()))

        emit clicked();

    // callback handler

}

void MyButton::paintEvent(QPaintEvent *)

{

    QPainter p(this);

    if(_pressed)

        //如果是按下的，则显示的是黄色的

        p.setBrush(Qt::yellow);

    else

        //如果没有被按下了，回复称灰色的

        p.setBrush(Qt::darkGray);

    p.drawRect(_rect);

    p.drawText(_rect,_text,QTextOption(Qt::AlignCenter));

}

#ifndef MYWIDGET_H

#define MYWIDGET_H

#include <QWidget>

#include "MyButton.h"

class MyWidget : public QWidget

{

    Q_OBJECT

public:

    explicit MyWidget(QWidget *parent = 0);

    MyButton* button;

    void paintEvent(QPaintEvent *);

    void mousePressEvent(QMouseEvent *);

    void mouseReleaseEvent(QMouseEvent *);

    void mouseMoveEvent(QMouseEvent *);

    QVector< QVector<QPoint> > _lines;

signals:

public slots:

    void slotButtonClicked();

};

#endif // MYWIDGET_H

#include "MyWidget.h"

#include <QPainter>

#include <QPixmap>

#include <QMouseEvent>

#include <QDebug>

#include <QApplication>

MyWidget::MyWidget(QWidget *parent) :

    QWidget(parent)

{

    button = new MyButton("MyButton", this);

    connect(button, SIGNAL(clicked()), this, SLOT(slotButtonClicked()));

    button->setGeometry(30, 30, 100, 30);

}

//槽函数

void MyWidget::slotButtonClicked()

{

    qDebug() << "button is clicked";

}

void MyWidget::paintEvent(QPaintEvent *)

{

    QPainter p(this);

    //通过下面的方式实现画多条线

    for(int i = 0; i < _lines.size();++i)

    {

        const QVector<QPoint> & line = _lines.at(i);

        for(int j = 0; j < line.size() - 1;++j)

        {

            p.drawLine(line.at(j),line.at(j + 1));

        }

    }

}

/**

 * @brief MyWidget::mouseMoveEvent 鼠标移动的事件

 * @param ev

 */

void MyWidget::mouseMoveEvent(QMouseEvent *ev)

{

    if(_lines.size() == 0)

    {

        QVector<QPoint> line;

        _lines.append(line);

    }

    QVector<QPoint>& lastLine = _lines.last();

    lastLine.append(ev->pos());

    update();

}

void MyWidget::mousePressEvent(QMouseEvent *ev)

{

    QVector<QPoint> line;

    _lines.append(line);

    QVector<QPoint>& lastLine = _lines.last();

    lastLine.append(ev->pos());

}

void MyWidget::mouseReleaseEvent(QMouseEvent *ev)

{

    QVector<QPoint>& lastLine = _lines.last();

    lastLine.append(ev->pos());

}

int main(int argc,char** argv)

{

    QApplication app(argc,argv);

    MyWidget w;

    w.show();

    return app.exec();

}

鼠标离开的运行效果：