分享一个颜色栏

QList<QColor> colorList;
colorList << "#EC7063"
          << "#1ABC9C"
          << "#2ECC71"
          << "#F1C40F"
          << "#34495E";
/* 传入颜色列表 */
ColorBar colorBar(colorList);
colorBar.setWindowTitle(QString::fromLocal8Bit("颜色栏 By Qt君"));
colorBar.resize(580, 140);
/* 捕获按钮事件(Qt5风格信号槽) */
QObject::connect(&colorBar, qOverload<QAbstractButton *>(&ColorBar::clicked),
                 [](QAbstractButton *btn) {
                     ColorButton *colorBtn = static_cast<ColorButton*>(btn);
                     qDebug() << colorBtn->color();
                });
colorBar.show();

ColorBar::ColorBar(QList<QColor> colorList, QWidget *parent) :
    QWidget(parent)
{
    /* 添加一个按钮组 */
    m_buttonGroup = new QButtonGroup(this);
    QHBoxLayout *hLayout = new QHBoxLayout(this);
    /* 设置按钮之间的分隔距离 */
    hLayout->setSpacing(12);
    /* 设置边距距离 */
    hLayout->setContentsMargins(25, 3, 25, 3);

    foreach (const QColor each, colorList) {
        ColorButton *btn = new ColorButton(each, this);
        /* 跟随布局管理器自动调整大小 */
        btn->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
        /* 开启按下不回弹事件 */
        btn->setCheckable(true);
        hLayout->addWidget(btn);
        m_buttonGroup->addButton(btn);
    }

    this->setLayout(hLayout);

    connect(m_buttonGroup, SIGNAL(buttonClicked(int)), this, SIGNAL(clicked(int)));
    connect(m_buttonGroup, SIGNAL(buttonClicked(QAbstractButton*)), this, SIGNAL(clicked(QAbstractButton*)));
}

void ColorBar::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    /* 开启抗锯齿 */
    painter.setRenderHint(QPainter::Antialiasing);

    /* 画背景边框 */
    painter.setPen(QPen(QColor("black"), 2));
    painter.drawRect(QRectF(rect()));
}

ColorButton::ColorButton(QColor color, QWidget *parent) :
    m_color(color),
    m_isEntered(false),
    QPushButton(parent)
{
}

void ColorButton::setColor(const QString &color)
{
    m_color = color;
    update();
}

QColor ColorButton::color() const
{
    return m_color;
}

void ColorButton::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    /* 开启抗锯齿功能 */
    painter.setRenderHint(QPainter::Antialiasing);
    painter.setPen(QColor("#00000000"));

    float w = width();
    float h = height();
    float scale = 0.75;
    float size = w > h ? h : w;
    size = size * scale;

    /* 鼠标进入控件画背景颜色 */
    if (m_isEntered) {
        painter.fillRect(QRect(0, 0, w, h), QColor("#90DEDEDE"));
    }

    if (this->isChecked()) {
        /* 画外圈 */
        {
            float x = (w - size)/2;
            float y = (h - size)/2;
            painter.setBrush(QBrush(m_color));
            painter.drawEllipse(QRectF(x, y, size, size));
        }

        /* 画空白圈 */
        {
            float x1 = (w - size * 0.9)/2;
            float y1 = (h - size * 0.9)/2;
            painter.setBrush(QBrush("white"));
            painter.drawEllipse(QRectF(x1, y1, size * 0.9, size * 0.9));
        }
    }

    /* 画内圈 */
    float x2 = (w - size * 0.8)/2;
    float y2 = (h - size * 0.8)/2;
    painter.setBrush(QBrush(m_color));
    /* 画圆形 */
    painter.drawEllipse(QRectF(x2, y2, size * 0.8, size * 0.8));
}

void ColorButton::enterEvent(QEvent *)
{
    m_isEntered = true;
    update();
}

void ColorButton::leaveEvent(QEvent *)
{
    m_isEntered = false;
    update();
}