doubleSlider.cpp

[詳解]

#include "doubleSlider.h"
#include <QtWidgets/QStyleOptionSlider>
 
DoubleSlider::DoubleSlider(Qt::Orientation orientation, QWidget *parent)
    : QSlider(orientation, parent), m_lowerValue(0), m_upperValue(maximum()) {}
 
int DoubleSlider::lowerValue() const {
    return m_lowerValue;
}
 
int DoubleSlider::upperValue() const {
    return m_upperValue;
}
 
void DoubleSlider::setLowerValue(int value) {
    if (value < minimum()) value = minimum();
    if (value > m_upperValue) value = m_upperValue;
    m_lowerValue = value;
    update();
}
 
void DoubleSlider::setUpperValue(int value) {
    if (value > maximum()) value = maximum();
    if (value < m_lowerValue) value = m_lowerValue;
    m_upperValue = value;
    update();
}
 
void DoubleSlider::paintEvent(QPaintEvent *event) {
    QSlider::paintEvent(event);
    QPainter painter(this);
 
    QStyleOptionSlider opt;
    initStyleOption(&opt);
 
    QRect groove = style()->subControlRect(QStyle::CC_Slider, &opt, QStyle::SC_SliderGroove, this);
    QRect handleLower = style()->subControlRect(QStyle::CC_Slider, &opt, QStyle::SC_SliderHandle, this);
    QRect handleUpper = style()->subControlRect(QStyle::CC_Slider, &opt, QStyle::SC_SliderHandle, this);
 
    handleLower.moveLeft(lowerValueToPos());
    handleUpper.moveLeft(upperValueToPos());
 
    painter.fillRect(groove, Qt::gray);
    painter.fillRect(handleLower, Qt::blue);
    painter.fillRect(handleUpper, Qt::blue);
}
 
int DoubleSlider::lowerValueToPos() const {
    return static_cast<int>((m_lowerValue - minimum()) / static_cast<double>(maximum() - minimum()) * width());
}
 
int DoubleSlider::upperValueToPos() const {
    return static_cast<int>((m_upperValue - minimum()) / static_cast<double>(maximum() - minimum()) * width());
}