int QStyle::pixelMetric(PixelMetric metric,
                        const QStyleOption *option = nullptr,
                        const QWidget *widget = nullptr) const;

// 示例：在自定义 style 中精细控制按钮 margin
int MyStyle::pixelMetric(PixelMetric metric, const QStyleOption *opt,
                         const QWidget *w) const {
    switch (metric) {
    case PM_ButtonMargin:
        // 水平 16px，垂直通过 sizeFromContents 控制
        return 16;
    case PM_ButtonDefaultIndicator:
        return 0;  // 扁平设计，不需要额外指示器
    case PM_ButtonShiftHorizontal:
        return 0;  // 按下不位移（用颜色变化代替）
    case PM_ButtonShiftVertical:
        return 0;
    default:
        return QProxyStyle::pixelMetric(metric, opt, w);
    }
}

// 示例：统一管理所有边框宽度
int MyStyle::pixelMetric(PixelMetric metric, ...) const {
    switch (metric) {
    case PM_DefaultFrameWidth:  return 1;  // 细边框设计
    case PM_SpinBoxFrameWidth:  return 1;
    case PM_ComboBoxFrameWidth: return 1;
    default: return QProxyStyle::pixelMetric(metric, opt, w);
    }
}

// 示例：让焦点框稍微超出按钮边缘
int MyStyle::pixelMetric(PixelMetric metric, ...) const {
    switch (metric) {
    case PM_FocusFrameHMargin: return -2;  // 向外扩展 2px
    case PM_FocusFrameVMargin: return -2;
    default: return QProxyStyle::pixelMetric(metric, opt, w);
    }
}

// 示例：窄滚动条（现代 UI 风格）
case PM_ScrollBarExtent: return 8;
case PM_ScrollBarSliderMin: return 30;  // 滑块最小 30px

// 示例：自定义滑块外观
case PM_SliderThickness:       return 4;   // 细轨道
case PM_SliderControlThickness: return 20;  // 圆形手柄直径
case PM_SliderLength:           return 20;  // 手柄沿轨道方向 20px
case PM_SliderTickmarkOffset:   return 6;   // 刻度离轨道 6px

// 示例：自定义标签栏间距
case PM_TabBarTabOverlap:  return 0;   // 标签不重叠
case PM_TabBarTabHSpace:   return 20;  // 标签左右宽松
case PM_TabBarTabVSpace:   return 10;  // 标签上下宽松
case PM_TabBarBaseHeight:  return 2;   // 底部细线
case PM_TabBarBaseOverlap: return 0;   // 不重叠

// 示例：紧凑型菜单
case PM_MenuHMargin:          return 4;
case PM_MenuVMargin:          return 2;
case PM_MenuScrollerHeight:   return 12;
case PM_MenuTearoffHeight:    return 0;  // 禁用 tear-off
case PM_MenuDesktopFrameWidth: return 1;  // 细边框
case PM_SubMenuOverlap:       return -2; // 子菜单稍微向左偏移

case PM_ToolBarHandleExtent:    return 4;   // 窄拖拽手柄
case PM_ToolBarItemMargin:      return 2;   // 紧凑间距
case PM_ToolBarItemSpacing:     return 4;
case PM_ToolBarSeparatorExtent: return 8;   // 分隔线 8px 粗细
case PM_ToolBarExtensionExtent: return 16;  // >> 按钮 16px

case PM_DockWidgetSeparatorExtent: return 4;
case PM_DockWidgetFrameWidth:      return 0;  // 无边框设计
case PM_DockWidgetTitleMargin:     return 8;

// 示例：统一对话框内边距
case PM_LayoutLeftMargin:   return 12;
case PM_LayoutTopMargin:    return 12;
case PM_LayoutRightMargin:  return 12;
case PM_LayoutBottomMargin: return 12;
case PM_LayoutHorizontalSpacing: return 8;
case PM_LayoutVerticalSpacing:   return 8;

// 示例：统一图标尺寸为 24px
case PM_SmallIconSize:   return 24;
case PM_LargeIconSize:   return 32;
case PM_ButtonIconSize:  return 24;
case PM_ToolBarIconSize: return 24;

// 示例：自定义复选框样式
case PM_IndicatorWidth:            return 20;
case PM_IndicatorHeight:           return 20;
case PM_CheckBoxLabelSpacing:      return 8;
case PM_RadioButtonLabelSpacing:   return 8;
case PM_ExclusiveIndicatorWidth:   return 16;
case PM_ExclusiveIndicatorHeight:  return 16;

// 示例：自定义表头
case PM_HeaderMargin:   return 8;   // 宽松内边距
case PM_HeaderMarkSize: return 12;  // 大排序箭头

int QStyle::styleHint(StyleHint hint,
                      const QStyleOption *option = nullptr,
                      const QWidget *widget = nullptr,
                      QStyleHintReturn *returnData = nullptr) const;

// 示例
case SH_EtchDisabledText:    return 0;  // 不用浮雕，用透明度
case SH_UnderlineShortcut:   return 0;  // 始终显示下划线（不隐藏）
case SH_ScrollBar_ContextMenu: return 0; // 禁用右键菜单

case SH_TabBar_Alignment:       return Qt::AlignCenter;
case SH_TabBar_ElideMode:       return Qt::ElideRight;

case SH_Menu_SubMenuPopupDelay: return 200;  // 子菜单延迟 200ms
case SH_Menu_KeyboardSearch:   return 1;     // 启用键盘搜索

case SH_ItemView_ActivateItemOnSingleClick: return 0; // 双击才激活
case SH_ItemView_ScrollMode:                return QAbstractItemView::ScrollPerPixel;

void QStyle::drawPrimitive(PrimitiveElement element,
                           const QStyleOption *option,
                           QPainter *painter,
                           const QWidget *widget = nullptr) const;

// 示例：自定义复选框绘制
void MyStyle::drawPrimitive(PrimitiveElement elem,
                            const QStyleOption *opt,
                            QPainter *p,
                            const QWidget *w) const {
    switch (elem) {
    case PE_IndicatorCheckBox: {
        const auto *cb = qstyleoption_cast<const QStyleOptionButton*>(opt);
        if (!cb) break;
        
        bool checked = cb->state & State_On;
        bool partial = cb->state & State_NoChange;
        
        // 画方框
        p->setPen(checked ? accentColor : borderColor);
        p->setBrush(checked ? accentColor : Qt::NoBrush);
        p->drawRoundedRect(cb->rect.adjusted(2,2,-2,-2), 4, 4);
        
        // 画对勾
        if (checked && !partial) {
            p->setPen(QPen(Qt::white, 2));
            // 绘制 √ 路径
            QPainterPath path;
            path.moveTo(cb->rect.left()+5,  cb->rect.center().y());
            path.lineTo(cb->rect.center().x(), cb->rect.bottom()-5);
            path.lineTo(cb->rect.right()-4, cb->rect.top()+4);
            p->drawPath(path);
        }
        break;
    }
    default:
        QProxyStyle::drawPrimitive(elem, opt, p, w);
    }
}

void QStyle::drawControl(ControlElement element,
                         const QStyleOption *option,
                         QPainter *painter,
                         const QWidget *widget = nullptr) const;

// 示例：自定义按钮绘制
void MyStyle::drawControl(ControlElement elem,
                          const QStyleOption *opt,
                          QPainter *p,
                          const QWidget *w) const {
    switch (elem) {
    case CE_PushButton: {
        const auto *btn = qstyleoption_cast<const QStyleOptionButton*>(opt);
        if (!btn) break;
        
        // 1. 通过 drawPrimitive 画背景
        drawPrimitive(PE_PanelButtonCommand, opt, p, w);
        
        // 2. 通过 drawControl 画标签（文字+图标）
        if (!btn->text.isEmpty() || !btn->icon.isNull()) {
            QStyleOptionButton sub = *btn;
            sub.rect = subElementRect(SE_PushButtonContents, opt, w);
            drawControl(CE_PushButtonLabel, &sub, p, w);
        }
        
        // 3. 画焦点框
        if (btn->state & State_HasFocus) {
            QStyleOptionFocusRect fropt;
            fropt.QStyleOption::operator=(*btn);
            fropt.rect = subElementRect(SE_PushButtonFocusRect, opt, w);
            drawPrimitive(PE_FrameFocusRect, &fropt, p, w);
        }
        break;
    }
    default:
        QProxyStyle::drawControl(elem, opt, p, w);
    }
}

// 示例：自定义 SpinBox 按钮布局（macOS 风格——并排按钮）
QRect MyStyle::subControlRect(ComplexControl control,
                              const QStyleOptionComplex *opt,
                              SubControl sc,
                              const QWidget *w) const {
    if (control == CC_SpinBox) {
        const auto *spin = qstyleoption_cast<const QStyleOptionSpinBox*>(opt);
        int btnW = 16;
        QRect r = opt->rect;
        
        // 两个按钮并排在右侧
        QRect upRect(r.right() - btnW, r.top(), btnW, r.height() / 2);
        QRect downRect(r.right() - btnW, r.center().y() + 1, btnW, r.height() / 2);
        
        switch (sc) {
        case SC_SpinBoxUp:   return upRect;
        case SC_SpinBoxDown: return downRect;
        case SC_SpinBoxEditField:
            return r.adjusted(0, 0, -btnW, 0);
        default: break;
        }
    }
    return QProxyStyle::subControlRect(control, opt, sc, w);
}

QSize QStyle::sizeFromContents(ContentsType type,
                               const QStyleOption *option,
                               const QSize &contentsSize,
                               const QWidget *widget = nullptr) const;

// 示例：自定义按钮尺寸计算
QSize MyStyle::sizeFromContents(ContentsType type,
                                const QStyleOption *opt,
                                const QSize &contentsSize,
                                const QWidget *w) const {
    switch (type) {
    case CT_PushButton: {
        const auto *btn = qstyleoption_cast<const QStyleOptionButton*>(opt);
        QSize sz = contentsSize;
        
        // 获取 button margin
        int hMargin = pixelMetric(PM_ButtonMargin, opt, w);
        int vMargin = hMargin / 2;
        
        // 加上边距
        sz += QSize(hMargin * 2, vMargin * 2);
        
        // 设置最小尺寸
        sz = sz.expandedTo(QSize(80, 32));
        
        return sz;
    }
    default:
        return QProxyStyle::sizeFromContents(type, opt, contentsSize, w);
    }
}

QPixmap QStyle::standardPixmap(StandardPixmap standardPixmap,
                                const QStyleOption *option = nullptr,
                                const QWidget *widget = nullptr) const;

// 常见状态判断模式
bool isHovered  = opt->state & QStyle::State_MouseOver;
bool isPressed  = opt->state & QStyle::State_Sunken;
bool isDisabled = !(opt->state & QStyle::State_Enabled);
bool hasFocus   = opt->state & QStyle::State_HasFocus;
bool isChecked  = opt->state & QStyle::State_On;
bool isActive   = opt->state & QStyle::State_Active;

// 经典按钮颜色决策
QColor bg = isDisabled ? disabledColor
          : isPressed  ? pressedColor
          : isHovered  ? hoverColor
          : isChecked  ? checkedColor
          : normalColor;