ScrollArea支持鼠标拖动

来源：互联网发布：中国m2月度数据编辑：程序博客网时间：2024/06/06 02:57

创建自定义类，实现在滚动区域内拖动鼠标显示滚动条，否则不显示滚动条。

头文件

#ifndef MYSCROLLAREA_H#define MYSCROLLAREA_H#include <QObject>#include <QScrollArea>#include <QPoint>class MyScrollArea : public QScrollArea{    Q_OBJECTpublic:    MyScrollArea(QWidget* parent = NULL);    ~MyScrollArea();protected:    bool eventFilter(QObject *obj,QEvent *evt);private:    bool mMoveStart;    bool mContinuousMove;    QPoint mMousePoint;};#endif // MYSCROLLAREA_H

源文件

#include "myscrollarea.h"#include <QMouseEvent>#include <QScrollBar>MyScrollArea::MyScrollArea(QWidget *parent)    :QScrollArea(parent)     //基类    ,mMoveStart(false)    ,mContinuousMove(false)    ,mMousePoint(QPoint(0,0)){    installEventFilter(this);}MyScrollArea::~MyScrollArea(){}bool MyScrollArea::eventFilter(QObject *obj, QEvent *evt){    if(evt->type() == QEvent::MouseMove)    {        QMouseEvent *me = (QMouseEvent*) evt;        if(me->buttons() & Qt::LeftButton)        {            if(!mMoveStart)            {//                if(me->pos().y() < (horizontalScrollBar()->pos().y() + horizontalScrollBar()->height())//                        || me->pos().x() < (verticalScrollBar()->pos().x() + verticalScrollBar()->width()) )//                    return false;                mMoveStart = true;                mContinuousMove = false;                mMousePoint = me->globalPos();            }            else            {                setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);//开启滚动条                setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);                QScrollBar *scrollBarx = horizontalScrollBar();                QScrollBar *scrollBary = verticalScrollBar();                QPoint p = me->globalPos();                int offsetx = p.x() - mMousePoint.x();                int offsety = p.y() - mMousePoint.y();                if(!mContinuousMove && (offsetx > -10 && offsetx < 10) && (offsety > -10 && offsety < 10))                    return false;                mContinuousMove = true;                scrollBarx->setValue(scrollBarx->value() - offsetx);                scrollBary->setValue(scrollBary->value() - offsety);                mMousePoint = p;            }            return true;        }    }    else if(evt->type() == QEvent::MouseButtonRelease)    {        mMoveStart = false;        setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);//关闭滚动条        setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);    }    return QObject::eventFilter(obj,evt);}

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