使用代码中的样式自定义Qt滑块时，手柄会脱离凹槽

在大多数示例中，自定义Qt滑块的操作如下（使用样式表）：

mySlider = new QSlider(centralWidget);
mySlider->setObjectName(QStringLiteral("mySlider"));
mySlider->setGeometry(QRect(645, 678, 110, 21));
mySlider->setOrientation(Qt::Horizontal);
mySlider->setStyleSheet("QSlider::groove:horizontal {background-image:url(:/main/graphics/mySliderBackround.png);}"
               "QSlider::handle:horizontal {background-image:url(:/main/graphics/mySliderHandle.png); height:21px; width: 21px;}");

这对我也很好。

我遇到一种情况，需要使用动态创建的像素图以编程方式设置背景。使用下面的代码，这就是我完成它的方式。问题是当我使用Fedora Linux时，此滑块可以正常工作。当我在OSX或Windows上时，滑块手柄会松动。

这是OSX上的样子。注意手柄如何脱离凹槽。左侧使用样式表自定义，右侧使用下面的Style对象自定义。

创建滑块并指定样式：

mySlider = new QSlider(centralWidget);
mySlider->setObjectName(QStringLiteral("mySlider"));
mySlider->setGeometry(QRect(645, 678, 110, 21));
mySlider->setOrientation(Qt::Horizontal);
mySlider->setStyle(new MySliderStyle(mySlider->style()));

自定义滑块样式代码：

标头

#ifndef MYSTYLE_H
#define MYSTYLE_H

#include <QObject>
#include <QWidget>
#include <QProxyStyle>
#include <QPainter>
#include <QStyleOption>
#include <QtWidgets/QCommonStyle>

class MySliderStyle : public QProxyStyle
{
      private:
    QPixmap groovePixmap;
    QPixmap handlePixmap;

      public:
    LightingSliderStyle(QStyle *style)
        : QProxyStyle(style)
    {
        setColor(QColor::fromRgba(0));

        this->handlePixmap = <snip initialize the pixmap>;
        this->grooveMaskPixmap = <snip initialize the pixmap>;
    }

    void drawComplexControl(QStyle::ComplexControl control, const QStyleOptionComplex *option, QPainter *painter, const QWidget *widget) const;

    QRect subControlRect(ComplexControl cc, const QStyleOptionComplex *opt, SubControl sc, const QWidget *widget) const;

    void setColor(QColor color);
};

#endif // MYSTYLE_H

实施*

#include "MySliderStyle.h"

QRect MySliderStyle::subControlRect(ComplexControl control,
                      const QStyleOptionComplex *option,
                      SubControl subControl,
                      const QWidget *widget) const
{
    QRect rect;

    rect = QCommonStyle::subControlRect(control, option, subControl, widget);

    if (control == CC_Slider && subControl == SC_SliderHandle)
    {
        // this is the exact pixel dimensions of the handle png files
        rect.setWidth(21);
        rect.setHeight(21);
    }
    else if (control == CC_Slider && subControl == SC_SliderGroove)
    {
        // this is the exact pixel dimensions of the slider png files
        rect.setWidth(widget->width());
        rect.setHeight(widget->height());
    }

    return rect;
}

void MySliderStyle::drawComplexControl(QStyle::ComplexControl control,
                         const QStyleOptionComplex *option,
                         QPainter *painter,
                         const QWidget *widget) const
{
    if (control == CC_Slider)
    {
        if (const QStyleOptionSlider *slider = qstyleoption_cast<const QStyleOptionSlider *>(option))
        {
            QRect groove = subControlRect(CC_Slider, slider, SC_SliderGroove, widget);
            QRect handle = subControlRect(CC_Slider, slider, SC_SliderHandle, widget);

            if ((slider->subControls & SC_SliderGroove) && groove.isValid())
            {
                Qt::BGMode oldMode = painter->backgroundMode();
                painter->setBackgroundMode(Qt::TransparentMode);
                painter->drawPixmap(groove, groovePixmap);
                painter->setBackgroundMode(oldMode);
            }

            if ((slider->subControls & SC_SliderHandle) && handle.isValid())
            {
                Qt::BGMode oldMode = painter->backgroundMode();
                painter->setBackgroundMode(Qt::TransparentMode);
                painter->drawPixmap(handle, handlePixmap);
                painter->setBackgroundMode(oldMode);
            }
        }
    }
    else
    {
        QProxyStyle::drawComplexControl(control, option, painter, widget);
    }
}

void MySliderStyle::setColor(QColor color)
{
  QImage myGrooveImage;

  // <snip>
  // Code to create the custom pixmap
  // <snip>

    groovePixmap = QPixmap::fromImage(myGrooveImage);
}

更新此项目的代码是开源的，可在此处获得