QT滚动数字 滚动选择器 滑动选择器

QT里没有找到数字滚动的控件，想实现数字滚动的效果只好自己实现。参考了http://blog.youkuaiyun.com/big_c_god/article/details/52452631

可以在代码中设定显示范围和刻度。为了美观还可以加上背景，这里没加。代码里有注释，方便理解。废话不说了，贴代码.

头文件

#ifndef VERTICALSCROLL_H
#define VERTICALSCROLL_H

#include <QWidget>
#include <QPropertyAnimation>
#include <QPainter>

namespace Ui {

class VerticalScroll;

}

class VerticalScroll : public QWidget

{

    Q_OBJECT

    Q_PROPERTY(int deviation READ readDeviation WRITE setDeviation )

public:

    explicit VerticalScroll(QWidget *parent = 0);

    ~VerticalScroll();
    //设置范围
    void setRange(double min, double max);
    //获取当前值
    double readValue();

protected:
    void mousePressEvent(QMouseEvent *);

    void mouseMoveEvent(QMouseEvent *);

    void mouseReleaseEvent(QMouseEvent *);

    void wheelEvent(QWheelEvent *);

    void paintEvent(QPaintEvent *);
    //描绘数字
    void paintNum(QPainter &painter, double num, int deviation);
    //使选中的数字回到屏幕中间
    void homing();
    //鼠标移动偏移量，默认为0
    int readDeviation();
    //设置偏移量
    void setDeviation(int n);

signals:

    void currentValueChanged(double value);

    void deviationChange(double deviation);

private:

    Ui::VerticalScroll *ui;

private:
    double m_minRange;      //最小值
    double m_maxRange;      //最大值
    double m_currentValue;  //当前选中的值
    bool isDragging;        //鼠标是否按下
    int m_deviation;        //偏移量,记录鼠标按下后移动的垂直距离
    int m_mouseSrcPos;
    int m_numSize;
    QPropertyAnimation *homingAni;
    const double interval;  //间隔大小
    const int devide;       //分隔数量
};

#endif // VERTICALSCROLL_H

源文件

#include "verticalscroll.h"
#include "ui_verticalscroll.h"
#include <QMouseEvent>
#include <QDebug>

VerticalScroll::VerticalScroll(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::VerticalScroll),
    m_minRange(0),      //最小值默认为0
    m_maxRange(100),    //最大值默认100
    m_currentValue(50), //当前值默认50
    isDragging(false),
    m_deviation(0),     //默认偏移量为0
    m_numSize(12),
    interval(0.5),      //间隔默认0.5
    devide(7)           //默认分成7格
{

    ui->setupUi(this);

    homingAni = new QPropertyAnimation(this, "deviation");
    homingAni->setDuration(300);
    homingAni->setEasingCurve(QEasingCurve::OutQuad);
}

VerticalScroll::~VerticalScroll()
{
    delete ui;
}
/*
 * 设置范围
 * double min 最小值
 * double max 最大值
*/
void VerticalScroll::setRange(double min, double max)
{
    m_minRange = min;
    m_maxRange = max;
    if (m_currentValue < min)
    {
        m_currentValue = min;
    }
    if (m_currentValue > max)
    {
        m_currentValue = max;
    }
    repaint();
}
//获取当前值
double VerticalScroll::readValue()
{
    return m_currentValue;
}

void VerticalScroll::mousePressEvent(QMouseEvent *e)
{
    qDebug()<<"mouse pressed on vertical scroll";

    homingAni->stop();
    isDragging = true;
    m_mouseSrcPos = e->pos().y();
    QWidget::mousePressEvent(e);
}

void VerticalScroll::mouseMoveEvent(QMouseEvent *e)
{
    if (isDragging)
    {
        if ((m_currentValue == m_minRange && e->pos().y() >= m_mouseSrcPos) ||
                ( m_currentValue == m_maxRange && e->pos().y() <= m_mouseSrcPos ))
        {
            return;
        }

        m_deviation = e->pos().y() - m_mouseSrcPos;
        //若移动速度过快，则进行限制
        if (m_deviation > (height() - 1) / devide)
        {
            m_deviation = (height() - 1) / devide;
        }
        else if (m_deviation < -(height() - 1) / devide)
        {
            m_deviation = -( height() - 1) / devide;
        }

        emit deviationChange((double)m_deviation / ((height() - 1) / devide));
        repaint();
    }
}

void VerticalScroll::mouseReleaseEvent(QMouseEvent *)
{
    if (isDragging)
    {
        isDragging = false;
        homing();
    }
}

void VerticalScroll::wheelEvent(QWheelEvent *e)
{
    if (e->delta() > 0)
    {
        m_deviation = (this->height() - 1) / devide;
    }
    else
    {
        m_deviation = -(this->height() - 1) / devide;
    }
    homing();
    repaint();
}

void VerticalScroll::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing, true);
    int Height = height() - 1;

    if ( m_deviation >= Height / devide && m_currentValue > m_minRange )
    {
        m_mouseSrcPos += Height / devide;
        m_deviation -= Height / devide;
        m_currentValue -= interval;
    }

    if ( m_deviation <= -Height / devide && m_currentValue < m_maxRange )
    {
        m_mouseSrcPos -= Height / devide;
        m_deviation += Height / devide;
        m_currentValue += interval;
    }

    //middle number
    paintNum(painter, m_currentValue, m_deviation);

    //两侧数字1
    if (m_currentValue != m_minRange)
    {
        paintNum(painter, m_currentValue - interval, m_deviation - Height / devide);
    }

    if (m_currentValue != m_maxRange)
    {
        paintNum(painter, m_currentValue + interval, m_deviation + Height / devide);
    }

    for (int i=2; i <= devide/2; ++i)
    {
        if (m_currentValue - interval * i >= m_minRange)
        {
            paintNum(painter, m_currentValue - interval * i, m_deviation - Height / devide * i);
        }

        if (m_currentValue + interval * i <= m_maxRange)
        {
            paintNum(painter, m_currentValue + interval * i, m_deviation + Height / devide * i);
        }
    }
}
/*
 * 根据偏移量描绘数字
 * double num 需要显示的数字
 * int deviation 数字相对中间的偏移量
*/
void VerticalScroll::paintNum(QPainter &painter, double num, int deviation)
{
    int Width = width() - 1;
    int Height = height() - 1;
    int size = (Height - qAbs(deviation)) / m_numSize; //偏移量越大，数字越小
    int transparency = 255 - 255 * qAbs(deviation) / Height;
    int height = Height / devide;
    int y = Height / 2 + deviation - height / 2;

    QFont font;
    font.setPixelSize(size);
    painter.setFont(font);
    painter.setPen(QColor(255, 2,2,transparency));

    if ( y >= 0 && y + height < Height)
    {
        painter.drawRect(0, y, Width, height);
        painter.drawText(QRectF(0, y, Width-20, height),
                         Qt::AlignCenter,
                         QString::number(num, 'f', 1));
    }
}

/*
 * 使选中的数字回到屏幕中间
*/
void VerticalScroll::homing()
{
    if ( m_deviation > height() / 10)
    {
        homingAni->setStartValue( ( height() - 1 ) / 8 - m_deviation);
        homingAni->setEndValue(0);
        m_currentValue -= interval;
    }
    else if ( m_deviation > -height() / 10 )
    {
        homingAni->setStartValue(m_deviation);
        homingAni->setEndValue(0);
    }
    else if ( m_deviation < -height() / 10 )
    {
        homingAni->setStartValue(-(height() - 1) / 8 - m_deviation);
        homingAni->setEndValue(0);
        m_currentValue += interval;
    }

    emit currentValueChanged(m_currentValue);
    homingAni->start();
}

int VerticalScroll::readDeviation()
{
    return m_deviation;
}

void VerticalScroll::setDeviation(int n)
{
    m_deviation = n;
    repaint();
}

效果如下图：

通过滚动鼠标，数字会随着上下移动。如果觉得有帮助，欢迎留言或点赞。