SinglePage

唔，那两个按钮在外部改变位置和样式等

#ifndef SINGLEPAGE_H
#define SINGLEPAGE_H

#include <QWidget>

class QPushButton;

class SinglePage : public QWidget
{
    Q_OBJECT
public:
    explicit SinglePage(QWidget *parent = 0);
    void setSpeed(int speed);
    QPushButton *getPreviousButton();
    QPushButton *getNextButton();

signals:
    void previousPage();
    void nextPage();

public slots:
    void setPixmap(const QPixmap &pixmap);

protected:
    void mousePressEvent(QMouseEvent *event);
    void mouseMoveEvent(QMouseEvent *event);
    void keyPressEvent(QKeyEvent *event);
    void paintEvent(QPaintEvent *event);
    void wheelEvent(QWheelEvent *event);

private:
    int m_Speed;
    QPoint m_PixmapPos;
    QPoint m_MousePos;
    QPixmap m_Pixmap;
    QPushButton *m_PreviousButton;
    QPushButton *m_NextButton;
};

#endif // SINGLEPAGE_H

#include "singlepage.h"
#include <QPainter>
#include <QMouseEvent>
#include <QDebug>
#include <QApplication>
#include <QKeyEvent>
#include <QPushButton>

SinglePage::SinglePage(QWidget *parent) : QWidget(parent)
{
    m_Speed = 20;
    m_PixmapPos = QPoint(0,0);
    m_PreviousButton = new QPushButton(this);
    m_NextButton = new QPushButton(this);

    connect(m_PreviousButton, &QPushButton::clicked,this, &SinglePage::previousPage);
    connect(m_NextButton, &QPushButton::clicked,this, &SinglePage::nextPage);
}

void SinglePage::setSpeed(int speed)
{
    m_Speed = speed;
}

QPushButton *SinglePage::getPreviousButton()
{
    return m_PreviousButton;
}

QPushButton *SinglePage::getNextButton()
{
    return m_NextButton;
}

void SinglePage::setPixmap(const QPixmap &pixmap)
{
    m_Pixmap = pixmap;
    m_PixmapPos = QPoint((width()-pixmap.width())/2,
                         (height()-pixmap.height())/2);
}

void SinglePage::mousePressEvent(QMouseEvent *event)
{
    if(event->button() == Qt::LeftButton){
        m_MousePos = event->globalPos();
    }else if(event->button() == Qt::RightButton){
        emit nextPage();
    }
}

void SinglePage::mouseMoveEvent(QMouseEvent *event)
{
    if( event->buttons().testFlag(Qt::LeftButton) )
    {
        m_PixmapPos += (this->pos()+ (event->globalPos() - m_MousePos));
        m_MousePos = event->globalPos();
    }
    this->update();
}

void SinglePage::keyPressEvent(QKeyEvent *event)
{
    if(event->key() == Qt::Key_Backspace){
        emit previousPage();
    }
}

void SinglePage::paintEvent(QPaintEvent *)
{
    if(m_Pixmap.isNull())
        return;

    QPainter *p = new QPainter(this);
    p->drawPixmap(m_PixmapPos,m_Pixmap);
    p->end();
}

void SinglePage::wheelEvent(QWheelEvent *event)
{
    if (event->delta() > 0){
        m_PixmapPos.setY(m_PixmapPos.y()+m_Speed);
    }
    else
        m_PixmapPos.setY(m_PixmapPos.y()-m_Speed);
    this->update();
}