#include "SlideWidget.h"
#include <QScrollBar>
#include <QMouseEvent>
#include <QApplication>
#include <qdebug.h>


SlideWidget::SlideWidget(QWidget* parent):
QWidget(parent)
, mIsDragging(false)
, mOriginPosY(-1)
, mOriginScrollBarV(0)
{
}

SlideWidget::~SlideWidget()
{
}

void SlideWidget::setVerticalScrollBar(QScrollBar* bar)
{
    if (!bar) return;
    mVerticalScrollBar = bar;
}

void SlideWidget::mousePressEvent(QMouseEvent* ev)
{
    mIsDragging = true;
    mOriginPosY = ev->globalPos().y();
    mOriginScrollBarV = this->verticalScrollBar()->value();
    QWidget::mousePressEvent(ev);
}

void SlideWidget::mouseMoveEvent(QMouseEvent* ev)
{
    if (!mIsDragging) {
        QWidget::mouseMoveEvent(ev);
        return;
    }
    if (this->verticalScrollBar()->isVisible()) {
        int offset = mOriginPosY - ev->globalPos().y();
        int nv = offset+mOriginScrollBarV;
        int max = this->verticalScrollBar()->maximum();
        int min = this->verticalScrollBar()->minimum();
        nv = nv > max ? max : (nv < min ? min : nv);

        this->verticalScrollBar()->setValue(nv);
    }
    QWidget::mouseMoveEvent(ev);
}

void SlideWidget::mouseReleaseEvent(QMouseEvent* ev)
{
    if (!mIsDragging)mIsDragging = false;
    QWidget::mouseReleaseEvent(ev);
}

QScrollBar* SlideWidget::verticalScrollBar()
{
    return mVerticalScrollBar;
}