前言

本文翻译自Qt官方文档，详细介绍了各成员/类型的作用，包含部分示例代码。

QStyle类的内容非常庞大，如需快速了解类成员和使用简介，请参见 QStyle简介。

一、QStyle Class

QStyle是一个抽象基类，封装了GUI的外观。

Qt包含一组QStyle子类，这些子类模拟了Qt支持的不同平台的样式（QWindowStyle、QMacStyle等）。默认情况下，这些样式内置在Qt GUI模块中。样式也可以作为插件提供。Qt的内置小部件使用 QStyle来执行几乎所有的绘图操作 （这意味着几乎所有内置控件的部分，都有可能通过样式来控制），确保它们看起来与原生小部件完全相同。

下图显示了一个QComboBox在九种不同样式下的外观。

1. 设置Style

整个应用程序的样式可以使用QApplication::setStyle()函数设置。用户也可以使用-style命令行选项来指定样式：

./myapplication -style windows

如果未指定样式，Qt将为用户的平台或桌面环境选择最合适的样式。也可以使用QWidget::setStyle()函数在单个小部件上设置样式。

2. 创建样式感知的自定义Widgets

如果您正在开发自定义小部件并希望它们在所有平台上看起来都很好，可以使用QStyle函数来执行小部件绘图的部分操作，例如drawItemText()、drawItemPixmap()、drawPrimitive()、drawControl()和drawComplexControl()。

大多数QStyle绘图函数需要四个参数：

1. 一个枚举值。
   • 用于指定要绘制的图形元素。
2. 一个QStyleOption
   • 指定如何、在何处渲染元素。
3. 一个QPainter
   • 用于绘制元素。
4. 一个QWidget（可选的）
   • 在其上执行绘制操作。

举个例子，如果你想在控件上画一个焦点矩形框，可以这样写：

	void paintEvent (QPaintEvent *event) override
	{
		QPainter painter (this);
		QStyleOptionFocusRect option;
		option.initFrom (this);
		option.backgroundColor = palette().color (QPalette::Background);

		style()->drawPrimitive (QStyle::PE_FrameFocusRect, &option, &painter, this);
	}

QStyle从QStyleOption获取渲染图形元素所需的所有信息。widget作为最后一个参数传递，以防样式需要它来执行特殊效果（例如macOS上的动画默认按钮），但这不是强制的。实际上，通过正确设置QPainter，您可以使用QStyle在任何绘图设备上绘图，而不仅仅是小部件。

QStyleOption有各种各样的子类，用于不同类型的可绘制图形元素。例如，PE_FrameFocusRect需要一个QStyleOptionFocusRect参数。

为了确保绘图操作尽可能快，QStyleOption及其子类具有公共数据成员。有关如何使用它的详细信息，请参阅QStyleOption类文档。

为了方便起见，Qt提供了QStylePainter类，它结合了QStyle、QPainter和QWidget。这使得编写以下代码成为可能：

QStylePainter painter(this);
...
painter.drawPrimitive(QStyle::PE_FrameFocusRect, option);

而不是：

QPinter painter(this);
style()->drawPrimitive(QStyle::PE_FrameFocusRect, &option, &painter, this);

3. 创建一个自定义Style

您可以创建自定义样式，来为您的应用程序创建自定义外观。

创建自定义样式有两种方法：

1. 静态方法
   • 可以选择现有的QStyle类，子类化它，并重新实现虚函数以提供自定义行为，或者从头开始创建整个QStyle类。
2. 动态方法
   • 可以在运行时修改系统样式的行为。

下面描述了静态方法。

动态方法在QProxyStyle中描述。

静态方法的第一步是选择一个Qt提供的样式，作为构建您的自定义样式的基础。您选择的QStyle类将取决于哪个样式最接近您想要的样式。您可以使用的最通用的类是QCommonStyle（而不是QStyle）。这是因为Qt要求其样式是QCommonStyles。

根据想要更改的基样式的那些部分，必须重新实现用于绘制这些界面部分的函数。为了说明这一点，我们将修改由QWindowsStyle绘制的微调框箭头的外观。箭头是由drawPrimitive()函数绘制的原始元素，因此我们需要重新实现该函数。我们需要以下类声明：

class CustomStyle : public QProxyStyle {
	Q_OBJECT
public:
	CustomStyle();
	~CustomStyle(){}
	void drawPrimitive (PrimitiveElement element,
						const QStyleOption *option,
						QPainter *painter,
						const QWidget *wodget) const override;
};

为了绘制其向上和向下箭头，QSpinBox使用了PE_IndicatorSpinUp和PE_IndicatorSpinDown基本元素。以下是如何重新实现drawPrimitive()函数以不同方式绘制它们：

void
CustomStyle::drawPrimitive (
	PrimitiveElement element, const QStyleOption *option, QPainter *painter, const QWidget *widget
) const
{
	if (element == PE_IndicatorSpinUp || element == PE_IndicatorSpinDown) {
		QPolygon points (3);
		int x = option->rect.x();
		int y = option->rect.y();
		int w = option->rect.width() / 2;
		int h = option->rect.height() / 2;
		x += (option->rect.width() - w) / 2;
		y += (option->rect.height() - h) / 2;

		if (element == PE_IndicatorSpinUp) {
			points[0] = QPoint (x, y + h);
			points[1] = QPoint (x + w, y + h);
			points[2] = QPoint (x + w / 2, y);
		} else { // PE_SpinBoxDown
			points[0] = QPoint (x, y);
			points[1] = QPoint (x + w, y);
			points[2] = QPoint (x + w / 2, y + h);
		}

		if (option->state & State_Enabled) {
			painter->setPen (option->palette.mid().color());
			painter->setBrush (option->palette.buttonText());
		} else {
			painter->setPen (option->palette.buttonText().color());
			painter->setBrush (option->palette.mid());
		}
		painter->drawPolygon (points);
	} else {
		QProxyStyle::drawPrimitive (element, option, painter, widget);
	}
}

请注意，我们没有使用widget参数，除了将其传递给QCommonStyle::drawPrimitive()函数。正如前面提到的，有关要绘制的内容和绘制方式的信息由QStyleOption对象指定，因此不需要询问小部件。

如果您需要使用widget参数来获取其他信息，请确保它不是空指针，并且它是正确的类型，然后再使用它。例如：

const QSpinBox* spinBox = qobject_cast<const QSpinBox*>(widget);
if(spinBox){
	...
}

在实现自定义样式时，不能仅仅因为枚举值被称为PE_IndicatorSpinUp或PE_IndicatorSpinDown就假定该小部件是QSpinBox`。

关于这个主题的更多细节，请参阅The documentation for the Styles example 。

4. 使用自定义Style

在Qt应用程序中使用自定义样式有几种方法。最简单的方法是在创建QApplication对象之前，将自定义样式传递给QApplication::setStyle()静态函数：

 #include <QtWidgets>

 #include "customstyle.h"

 int main(int argc, char *argv[])
 {
     QApplication::setStyle(new CustomStyle);
     QApplication app(argc, argv);
     QSpinBox spinBox;
     spinBox.show();
     return app.exec();
 }

原生的：

自定义的：

您可以随时调用QApplication::setStyle()，但通过在构造函数之前调用它，可以确保不违背用户使用-style命令行选项设置的首选项。

您可能希望使您的自定义样式可用于其他应用程序，这些应用程序可能不是您的，因此无法重新编译。Qt插件系统使得可以将样式创建为插件。作为插件创建的样式在运行时由Qt本身作为共享对象加载。

有关如何创建样式插件的更多信息，请参阅 Qt Plugin documentation 。

编译您的插件并将其放入Qt的plugins/styles目录。现在，我们有一个可插拔的样式，Qt可以自动加载。要在现有应用程序中使用您的新样式，只需使用以下参数启动应用程序：

./myapplication -style custom

应用程序将使用您实现的自定义样式的外观。

5. Item Views中的Styles

视图中项目的绘制由委托完成。Qt的默认委托QStyledItemDelegate也用于计算项目的边界矩形及其子元素的各种项目数据角色。

请参阅QStyledItemDelegate类描述，以了解支持哪些数据类型和角色。您可以在Model/View编程中阅读更多关于项目数据角色的信息。

当QStyledItemDelegate绘制它的项目时，它会绘制CE_ItemViewItem，并使用CT_ItemViewItem计算它们的大小。

此外，它使用SE_ItemViewItemText来设置编辑器的大小。在实现用于自定义Item Views绘制的样式时，您需要检查QCommonStyle的实现（以及您的样式继承的任何其他子类）。

通过这种方式，您可以了解哪些样式元素以及如何绘制，然后您可以重新实现那些需要以不同方式绘制的元素的绘制。

此处提供一个小示例，其中自定义了项目背景的绘制：

	switch (element) {
	case PE_PanelItemViewItem: {

		painter->save();
		QPoint topLeft	   = option->rect.topLeft();
		QPoint bottomRight = option->rect.topRight();

		QLinearGradient backgroundGradient (topLeft, bottomRight);
		backgroundGradient.setColorAt (0.0, QColor (Qt::yellow).lighter (190));
		backgroundGradient.setColorAt (1.0, Qt::white);
		painter->fillRect(option->rect, QBrush(backgroundGradient);
		painter->restore();

		break;
	}
	default:
		QProxyStyle::drawPrimitive (element, option, painter, widget);
	}

基本元素PE_PanelItemViewItem负责绘制项目的背景，并在QCommonStyle的CE_ItemViewItem实现中被调用。

要支持对新数据类型和项目数据角色的绘制，有必要创建一个自定义委托（Custom Delegate）。但如果您只需要支持默认委托实现的数据类型，自定义样式则不需要再伴随一个委托。

QStyledItemDelegate类描述提供了有关自定义委托的更多信息。

Item View的headers的绘制也是由样式完成的，这使得可以控制标题项的大小以及行和列的大小。

另外可以看看 QStyleOption, QStylePainter, Styles Example, Styles and Style Aware Widgets, QStyledItemDelegate, and Styling.

二、QStyle Member Type文档

1. enum QStyle::ComplexControl

enum QStyle::ComplexControl

此枚举描述了可用的复杂控件。复杂控件会因用户点击的位置或按下的键而表现不同行为。

Constant	Value	Description
QStyle::CC_SpinBox	0	A spinbox, like QSpinBox.
QStyle::CC_ComboBox	1	A combobox, like QComboBox.
QStyle::CC_ScrollBar	2	A scroll bar, like QScrollBar.
QStyle::CC_Slider	3	A slider, like QSlider.
QStyle::CC_ToolButton	4	A tool button, like QToolButton.
QStyle::CC_TitleBar	5	A title bar, like those used in QMdiSubWindow.
QStyle::CC_GroupBox	7	A group box, like QGroupBox.
QStyle::CC_Dial	6	A dial, like QDial.
QStyle::CC_MdiControls	8	The minimize, close, and normal button in the menu bar for a maximized MDI subwindow.
QStyle::CC_CustomBase	0xf0000000	Base value for custom complex controls. Custom values must be greater than this value.

可以看看 SubControl and drawComplexControl().

2. enum QStyle::ContentsType

enum QStyle::ContentsType

此枚举描述了可用的内容类型。这些内容类型用于计算各种小部件的内容大小。

Constant	Value	Description
QStyle::CT_CheckBox	1	A check box, like QCheckBox.
QStyle::CT_ComboBox	4	A combo box, like QComboBox.
QStyle::CT_HeaderSection	19	A header section, like QHeader.
QStyle::CT_LineEdit	14	A line edit, like QLineEdit.
QStyle::CT_Menu	10	A menu, like QMenu.
QStyle::CT_MenuBar	9	A menu bar, like QMenuBar.
QStyle::CT_MenuBarItem	8	A menu bar item, like the buttons in a QMenuBar.
QStyle::CT_MenuItem	7	A menu item, like QMenuItem.
QStyle::CT_ProgressBar	6	A progress bar, like QProgressBar.
QStyle::CT_PushButton	0	A push button, like QPushButton.
QStyle::CT_RadioButton	2	A radio button, like QRadioButton.
QStyle::CT_SizeGrip	16	A size grip, like QSizeGrip.
QStyle::CT_Slider	12	A slider, like QSlider.
QStyle::CT_ScrollBar	13	A scroll bar, like QScrollBar.
QStyle::CT_SpinBox	15	A spin box, like QSpinBox.
QStyle::CT_Splitter	5	A splitter, like QSplitter.
QStyle::CT_TabBarTab	11	A tab on a tab bar, like QTabBar.
QStyle::CT_TabWidget	17	A tab widget, like QTabWidget.
QStyle::CT_ToolButton	3	A tool button, like QToolButton.
QStyle::CT_GroupBox	20	A group box, like QGroupBox.
QStyle::CT_ItemViewItem	22	An item inside an item view.
QStyle::CT_CustomBase	0xf0000000	Base value for custom contents types. Custom values must be greater than this value.
QStyle::CT_MdiControls	21	The minimize, normal, and close button in the menu bar for a maximized MDI subwindow.

可以看看 sizeFromContents()。

3. enum QStyle::ControlElement

enum QStyle::ControlElement

此枚举表示一个控件元素。控件元素是小部件的一部分，用于执行某些操作或向用户显示信息。

Constant	Value	Description
QStyle::CE_PushButton	0	A QPushButton, draws CE_PushButtonBevel, CE_PushButtonLabel and PE_FrameFocusRect.
QStyle::CE_PushButtonBevel	1	The bevel and default indicator of a QPushButton.
QStyle::CE_PushButtonLabel	2	The label (an icon with text or pixmap) of a QPushButton.
QStyle::CE_DockWidgetTitle	30	Dock window title.
QStyle::CE_Splitter	28	Splitter handle; see also QSplitter.
QStyle::CE_CheckBox	3	A QCheckBox, draws a PE_IndicatorCheckBox, a CE_CheckBoxLabel and a PE_FrameFocusRect.
QStyle::CE_CheckBoxLabel	4	The label (text or pixmap) of a QCheckBox.
QStyle::CE_RadioButton	5	A QRadioButton, draws a PE_IndicatorRadioButton, a CE_RadioButtonLabel and a PE_FrameFocusRect.
QStyle::CE_RadioButtonLabel	6	The label (text or pixmap) of a QRadioButton.
QStyle::CE_TabBarTab	7	The tab and label within a QTabBar.
QStyle::CE_TabBarTabShape	8	The tab shape within a tab bar.
QStyle::CE_TabBarTabLabel	9	The label within a tab.
QStyle::CE_ProgressBar	10	A QProgressBar, draws CE_ProgressBarGroove, CE_ProgressBarContents and CE_ProgressBarLabel.
QStyle::CE_ProgressBarGroove	11	The groove where the progress indicator is drawn in a QProgressBar.
QStyle::CE_ProgressBarContents	12	The progress indicator of a QProgressBar.
QStyle::CE_ProgressBarLabel	13	The text label of a QProgressBar.
QStyle::CE_ToolButtonLabel	22	A tool button’s label.
QStyle::CE_MenuBarItem	20	A menu item in a QMenuBar.
QStyle::CE_MenuBarEmptyArea	21	The empty area of a QMenuBar.
QStyle::CE_MenuItem	14	A menu item in a QMenu.
QStyle::CE_MenuScroller	15	Scrolling areas in a QMenu when the style supports scrolling.
QStyle::CE_MenuTearoff	18	A menu item representing the tear off section of a QMenu.
QStyle::CE_MenuEmptyArea	19	The area in a menu without menu items.
QStyle::CE_MenuHMargin	17	The horizontal extra space on the left/right of a menu.
QStyle::CE_MenuVMargin	16	The vertical extra space on the top/bottom of a menu.
QStyle::CE_ToolBoxTab	26	The toolbox’s tab and label within a QToolBox.
QStyle::CE_SizeGrip	27	Window resize handle; see also QSizeGrip.
QStyle::CE_Header	23	A header.
QStyle::CE_HeaderSection	24	A header section.
QStyle::CE_HeaderLabel	25	The header’s label.
QStyle::CE_ScrollBarAddLine	31	Scroll bar line increase indicator. (i.e., scroll down); see also QScrollBar.
QStyle::CE_ScrollBarSubLine	32	Scroll bar line decrease indicator (i.e., scroll up).
QStyle::CE_ScrollBarAddPage	33	Scolllbar page increase indicator (i.e., page down).
QStyle::CE_ScrollBarSubPage	34	Scroll bar page decrease indicator (i.e., page up).
QStyle::CE_ScrollBarSlider	35	Scroll bar slider.
QStyle::CE_ScrollBarFirst	36	Scroll bar first line indicator (i.e., home).
QStyle::CE_ScrollBarLast	37	Scroll bar last line indicator (i.e., end).
QStyle::CE_RubberBand	29	Rubber band used in for example an icon view.
QStyle::CE_FocusFrame	38	Focus frame that is style controlled.
QStyle::CE_ItemViewItem	45	An item inside an item view.
QStyle::CE_CustomBase	0xf0000000	Base value for custom control elements; custom values must be greater than this value.
QStyle::CE_ComboBoxLabel	39	The label of a non-editable QComboBox.
QStyle::CE_ToolBar	40	A toolbar like QToolBar.
QStyle::CE_ToolBoxTabShape	41	The toolbox’s tab shape.
QStyle::CE_ToolBoxTabLabel	42	The toolbox’s tab label.
QStyle::CE_HeaderEmptyArea	43	The area of a header view where there are no header sections.
QStyle::CE_ShapedFrame	46	The frame with the shape specified in the QStyleOptionFrame; see QFrame.

可以看看drawControl()

4. enum QStyle::PixelMetric

enum QStyle::PixelMetric

这个枚举描述了各种可用的像素度量。像素度量是一种与样式相关的尺寸，由单个像素值表示。

Constant	Value	Description
QStyle::PM_ButtonMargin	0	Amount of whitespace between push button labels and the frame.
QStyle::PM_DockWidgetTitleBarButtonMargin	76	Amount of whitespace between dock widget’s title bar button labels and the frame.
QStyle::PM_ButtonDefaultIndicator	1	Width of the default-button indicator frame.
QStyle::PM_MenuButtonIndicator	2	Width of the menu button indicator proportional to the widget height.
QStyle::PM_ButtonShiftHorizontal	3	Horizontal contents shift of a button when the button is down.
QStyle::PM_ButtonShiftVertical	4	Vertical contents shift of a button when the button is down.
QStyle::PM_DefaultFrameWidth	5	Default frame width (usually 2).
QStyle::PM_SpinBoxFrameWidth	6	Frame width of a spin box, defaults to PM_DefaultFrameWidth.
QStyle::PM_ComboBoxFrameWidth	7	Frame width of a combo box, defaults to PM_DefaultFrameWidth.
QStyle::PM_MDIFrameWidth	PM_MdiSubWindowFrameWidth	Obsolete. Use PM_MdiSubWindowFrameWidth instead.
QStyle::PM_MdiSubWindowFrameWidth	44	Frame width of an MDI window.
QStyle::PM_MDIMinimizedWidth	PM_MdiSubWindowMinimizedWidth	Obsolete. Use PM_MdiSubWindowMinimizedWidth instead.
QStyle::PM_MdiSubWindowMinimizedWidth	45	Width of a minimized MDI window.
QStyle::PM_LayoutLeftMargin	78	Default left margin for a QLayout.
QStyle::PM_LayoutTopMargin	79	Default top margin for a QLayout.
QStyle::PM_LayoutRightMargin	80	Default right margin for a QLayout.
QStyle::PM_LayoutBottomMargin	81	Default bottom margin for a QLayout.
QStyle::PM_LayoutHorizontalSpacing	82	Default horizontal spacing for a QLayout.
QStyle::PM_LayoutVerticalSpacing	83	Default vertical spacing for a QLayout.
QStyle::PM_MaximumDragDistance	8	The maximum allowed distance between the mouse and a scrollbar when dragging. Exceeding the specified distance will cause the slider to jump back to the original position; a value of -1 disables this behavior.
QStyle::PM_ScrollBarExtent	9	Width of a vertical scroll bar and the height of a horizontal scroll bar.
QStyle::PM_ScrollBarSliderMin	10	The minimum height of a vertical scroll bar’s slider and the minimum width of a horizontal scroll bar’s slider.
QStyle::PM_SliderThickness	11	Total slider thickness.
QStyle::PM_SliderControlThickness	12	Thickness of the slider handle.
QStyle::PM_SliderLength	13	Length of the slider.
QStyle::PM_SliderTickmarkOffset	14	The offset between the tickmarks and the slider.
QStyle::PM_SliderSpaceAvailable	15	The available space for the slider to move.
QStyle::PM_DockWidgetSeparatorExtent	16	Width of a separator in a horizontal dock window and the height of a separator in a vertical dock window.
QStyle::PM_DockWidgetHandleExtent	17	Width of the handle in a horizontal dock window and the height of the handle in a vertical dock window.
QStyle::PM_DockWidgetFrameWidth	18	Frame width of a dock window.
QStyle::PM_DockWidgetTitleMargin	73	Margin of the dock window title.
QStyle::PM_MenuBarPanelWidth	33	Frame width of a menu bar, defaults to PM_DefaultFrameWidth.
QStyle::PM_MenuBarItemSpacing	34	Spacing between menu bar items.
QStyle::PM_MenuBarHMargin	36	Spacing between menu bar items and left/right of bar.
QStyle::PM_MenuBarVMargin	35	Spacing between menu bar items and top/bottom of bar.
QStyle::PM_ToolBarFrameWidth	52	Width of the frame around toolbars.
QStyle::PM_ToolBarHandleExtent	53	Width of a toolbar handle in a horizontal toolbar and the height of the handle in a vertical toolbar.
QStyle::PM_ToolBarItemMargin	55	Spacing between the toolbar frame and the items.
QStyle::PM_ToolBarItemSpacing	54	Spacing between toolbar items.
QStyle::PM_ToolBarSeparatorExtent	56	Width of a toolbar separator in a horizontal toolbar and the height of a separator in a vertical toolbar.
QStyle::PM_ToolBarExtensionExtent	57	Width of a toolbar extension button in a horizontal toolbar and the height of the button in a vertical toolbar.
QStyle::PM_TabBarTabOverlap	19	Number of pixels the tabs should overlap. (Currently only used in styles, not inside of QTabBar)
QStyle::PM_TabBarTabHSpace	20	Extra space added to the tab width.
QStyle::PM_TabBarTabVSpace	21	Extra space added to the tab height.
QStyle::PM_TabBarBaseHeight	22	Height of the area between the tab bar and the tab pages.
QStyle::PM_TabBarBaseOverlap	23	Number of pixels the tab bar overlaps the tab bar base.
QStyle::PM_TabBarScrollButtonWidth	51
QStyle::PM_TabBarTabShiftHorizontal	49	Horizontal pixel shift when a tab is selected.
QStyle::PM_TabBarTabShiftVertical	50	Vertical pixel shift when a tab is selected.
QStyle::PM_ProgressBarChunkWidth	24	Width of a chunk in a progress bar indicator.
QStyle::PM_SplitterWidth	25	Width of a splitter.
QStyle::PM_TitleBarHeight	26	Height of the title bar.
QStyle::PM_IndicatorWidth	37	Width of a check box indicator.
QStyle::PM_IndicatorHeight	38	Height of a checkbox indicator.
QStyle::PM_ExclusiveIndicatorWidth	39	Width of a radio button indicator.
QStyle::PM_ExclusiveIndicatorHeight	40	Height of a radio button indicator.
QStyle::PM_MenuPanelWidth	30	Border width (applied on all sides) for a QMenu.
QStyle::PM_MenuHMargin	28	Additional border (used on left and right) for a QMenu.
QStyle::PM_MenuVMargin	29	Additional border (used for bottom and top) for a QMenu.
QStyle::PM_MenuScrollerHeight	27	Height of the scroller area in a QMenu.
QStyle::PM_MenuTearoffHeight	31	Height of a tear off area in a QMenu.
QStyle::PM_MenuDesktopFrameWidth	32	The frame width for the menu on the desktop.
QStyle::PM_HeaderMarkSize	47	The size of the sort indicator in a header.
QStyle::PM_HeaderGripMargin	48	The size of the resize grip in a header.
QStyle::PM_HeaderMargin	46	The size of the margin between the sort indicator and the text.
QStyle::PM_SpinBoxSliderHeight	58	The height of the optional spin box slider.
QStyle::PM_ToolBarIconSize	PM_SpinBoxSliderHeight + 4	Default tool bar icon size
QStyle::PM_SmallIconSize	65	Default small icon size
QStyle::PM_LargeIconSize	66	Default large icon size
QStyle::PM_FocusFrameHMargin	68	Horizontal margin that the focus frame will outset the widget by.
QStyle::PM_FocusFrameVMargin	67	Vertical margin that the focus frame will outset the widget by.
QStyle::PM_IconViewIconSize	64	The default size for icons in an icon view.
QStyle::PM_ListViewIconSize	63	The default size for icons in a list view.
QStyle::PM_ToolTipLabelFrameWidth	69	The frame width for a tool tip label.
QStyle::PM_CheckBoxLabelSpacing	70	The spacing between a check box indicator and its label.
QStyle::PM_RadioButtonLabelSpacing	77	The spacing between a radio button indicator and its label.
QStyle::PM_TabBarIconSize	71	The default icon size for a tab bar.
QStyle::PM_SizeGripSize	72	The size of a size grip.
QStyle::PM_MessageBoxIconSize	74	The size of the standard icons in a message box
QStyle::PM_ButtonIconSize	75	The default size of button icons
QStyle::PM_TextCursorWidth	85	The width of the cursor in a line edit or text edit
QStyle::PM_TabBar_ScrollButtonOverlap	84	The distance between the left and right buttons in a tab bar.
QStyle::PM_TabCloseIndicatorWidth	86	The default width of a close button on a tab in a tab bar.
QStyle::PM_TabCloseIndicatorHeight	87	The default height of a close button on a tab in a tab bar.
QStyle::PM_ScrollView_ScrollBarSpacing	88	Distance between frame and scrollbar with SH_ScrollView_FrameOnlyAroundContents set.
QStyle::PM_ScrollView_ScrollBarOverlap	89	Overlap between scroll bars and scroll content
QStyle::PM_SubMenuOverlap	90	The horizontal overlap between a submenu and its parent.
QStyle::PM_TreeViewIndentation	91	The indentation of items in a tree view. This enum value has been introduced in Qt 5.4.
QStyle::PM_HeaderDefaultSectionSizeHorizontal	92	The default size of sections in a horizontal header. This enum value has been introduced in Qt 5.5.
QStyle::PM_HeaderDefaultSectionSizeVertical	93	The default size of sections in a vertical header. This enum value has been introduced in Qt 5.5.
QStyle::PM_TitleBarButtonIconSize	94	The size of button icons on a title bar. This enum value has been introduced in Qt 5.8.
QStyle::PM_TitleBarButtonSize	95	The size of buttons on a title bar. This enum value has been introduced in Qt 5.8.
QStyle::PM_CustomBase	0xf0000000	Base value for custom pixel metrics. Custom values must be greater than this value.

5. enum QStyle::PrimitiveElement

enum QStyle::PrimitiveElement

这个枚举描述了各种原始元素。原始元素是常见的图形用户界面元素，例如复选框指示器或按钮斜角。

Constant	Value	Description
QStyle::PE_FrameStatusBar	PE_FrameStatusBarItem	Obsolete. Use PE_FrameStatusBarItem instead.
QStyle::PE_PanelButtonCommand	13	Button used to initiate an action, for example, a QPushButton.
QStyle::PE_FrameDefaultButton	1	This frame around a default button, e.g. in a dialog.
QStyle::PE_PanelButtonBevel	14	Generic panel with a button bevel.
QStyle::PE_PanelButtonTool	15	Panel for a Tool button, used with QToolButton.
QStyle::PE_PanelLineEdit	18	Panel for a QLineEdit.
QStyle::PE_IndicatorButtonDropDown	24	Indicator for a drop down button, for example, a tool button that displays a menu.
QStyle::PE_FrameFocusRect	3	Generic focus indicator.
QStyle::PE_IndicatorArrowUp	22	Generic Up arrow.
QStyle::PE_IndicatorArrowDown	19	Generic Down arrow.
QStyle::PE_IndicatorArrowRight	21	Generic Right arrow.
QStyle::PE_IndicatorArrowLeft	20	Generic Left arrow.
QStyle::PE_IndicatorSpinUp	35	Up symbol for a spin widget, for example a QSpinBox.
QStyle::PE_IndicatorSpinDown	32	Down symbol for a spin widget.
QStyle::PE_IndicatorSpinPlus	34	Increase symbol for a spin widget.
QStyle::PE_IndicatorSpinMinus	33	Decrease symbol for a spin widget.
QStyle::PE_IndicatorItemViewItemCheck	25	On/off indicator for a view item.
QStyle::PE_IndicatorCheckBox	26	On/off indicator, for example, a QCheckBox.
QStyle::PE_IndicatorRadioButton	31	Exclusive on/off indicator, for example, a QRadioButton.
QStyle::PE_IndicatorDockWidgetResizeHandle	27	Resize handle for dock windows.
QStyle::PE_Frame	0	Generic frame
QStyle::PE_FrameMenu	6	Frame for popup windows/menus; see also QMenu.
QStyle::PE_PanelMenuBar	16	Panel for menu bars.
QStyle::PE_PanelScrollAreaCorner	40	Panel at the bottom-right (or bottom-left) corner of a scroll area.
QStyle::PE_FrameDockWidget	2	Panel frame for dock windows and toolbars.
QStyle::PE_FrameTabWidget	8	Frame for tab widgets.
QStyle::PE_FrameLineEdit	5	Panel frame for line edits.
QStyle::PE_FrameGroupBox	4	Panel frame around group boxes.
QStyle::PE_FrameButtonBevel	10	Panel frame for a button bevel.
QStyle::PE_FrameButtonTool	11	Panel frame for a tool button.
QStyle::PE_IndicatorHeaderArrow	28	Arrow used to indicate sorting on a list or table header.
QStyle::PE_FrameStatusBarItem	7	Frame for an item of a status bar; see also QStatusBar.
QStyle::PE_FrameWindow	9	Frame around a MDI window or a docking window.
QStyle::PE_IndicatorMenuCheckMark	29	Check mark used in a menu.
QStyle::PE_IndicatorProgressChunk	30	Section of a progress bar indicator; see also QProgressBar.
QStyle::PE_IndicatorBranch	23	Lines used to represent the branch of a tree in a tree view.
QStyle::PE_IndicatorToolBarHandle	36	The handle of a toolbar.
QStyle::PE_IndicatorToolBarSeparator	37	The separator in a toolbar.
QStyle::PE_PanelToolBar	17	The panel for a toolbar.
QStyle::PE_PanelTipLabel	38	The panel for a tip label.
QStyle::PE_FrameTabBarBase	12	The frame that is drawn for a tab bar, ususally drawn for a tab bar that isn’t part of a tab widget.
QStyle::PE_IndicatorTabTear	39	Deprecated. Use PE_IndicatorTabTearLeft instead.
QStyle::PE_IndicatorTabTearLeft	PE_IndicatorTabTear	An indicator that a tab is partially scrolled out on the left side of the visible tab bar when there are many tabs.
QStyle::PE_IndicatorTabTearRight	49	An indicator that a tab is partially scrolled out on the right side of the visible tab bar when there are many tabs.
QStyle::PE_IndicatorColumnViewArrow	42	An arrow in a QColumnView.
QStyle::PE_Widget	41	A plain QWidget.
QStyle::PE_CustomBase	0xf000000	Base value for custom primitive elements. All values above this are reserved for custom use. Custom values must be greater than this value.
QStyle::PE_IndicatorItemViewItemDrop	43	An indicator that is drawn to show where an item in an item view is about to be dropped during a drag-and-drop operation in an item view.
QStyle::PE_PanelItemViewItem	44	The background for an item in an item view.
QStyle::PE_PanelItemViewRow	45	The background of a row in an item view.
QStyle::PE_PanelStatusBar	46	The panel for a status bar.
QStyle::PE_IndicatorTabClose	47	The close button on a tab bar.
QStyle::PE_PanelMenu	48	The panel for a menu.

可以看看drawPrimitive();

6. enum QStyle::RequestSoftwareInputPanel

enum QStyle::RequestSoftwareInputPanel

这个枚举描述了在什么情况下具有输入功能的小部件会请求软件输入面板。

Constant	Value	Description
QStyle::RSIP_OnMouseClickAndAlreadyFocused	0	Requests an input panel if the user clicks on the widget, but only if it is already focused.
QStyle::RSIP_OnMouseClick	1	Requests an input panel if the user clicks on the widget.

7. enum QStyleStandardPixmap

enum QStyle::StandardPixmap

这个枚举描述了可用的标准像素图。标准像素图是可以遵循某些现有GUI样式或指南的像素图。

Constant	Value	Description
QStyle::SP_TitleBarMinButton	1	Minimize button on title bars (e.g., in QMdiSubWindow).
QStyle::SP_TitleBarMenuButton	0	Menu button on a title bar.
QStyle::SP_TitleBarMaxButton	2	Maximize button on title bars.
QStyle::SP_TitleBarCloseButton	3	Close button on title bars.
QStyle::SP_TitleBarNormalButton	4	Normal (restore) button on title bars.
QStyle::SP_TitleBarShadeButton	5	Shade button on title bars.
QStyle::SP_TitleBarUnshadeButton	6	Unshade button on title bars.
QStyle::SP_TitleBarContextHelpButton	7	The Context help button on title bars.
QStyle::SP_MessageBoxInformation	9	The “information” icon.
QStyle::SP_MessageBoxWarning	10	The “warning” icon.
QStyle::SP_MessageBoxCritical	11	The “critical” icon.
QStyle::SP_MessageBoxQuestion	12	The “question” icon.
QStyle::SP_DesktopIcon	13	The “desktop” icon.
QStyle::SP_TrashIcon	14	The “trash” icon.
QStyle::SP_ComputerIcon	15	The “My computer” icon.
QStyle::SP_DriveFDIcon	16	The floppy icon.
QStyle::SP_DriveHDIcon	17	The harddrive icon.
QStyle::SP_DriveCDIcon	18	The CD icon.
QStyle::SP_DriveDVDIcon	19	The DVD icon.
QStyle::SP_DriveNetIcon	20	The network icon.
QStyle::SP_DirHomeIcon	56	The home directory icon.
QStyle::SP_DirOpenIcon	21	The open directory icon.
QStyle::SP_DirClosedIcon	22	The closed directory icon.
QStyle::SP_DirIcon	38	The directory icon.
QStyle::SP_DirLinkIcon	23	The link to directory icon.
QStyle::SP_DirLinkOpenIcon	24	The link to open directory icon.
QStyle::SP_FileIcon	25	The file icon.
QStyle::SP_FileLinkIcon	26	The link to file icon.
QStyle::SP_FileDialogStart	29	The “start” icon in a file dialog.
QStyle::SP_FileDialogEnd	30	The “end” icon in a file dialog.
QStyle::SP_FileDialogToParent	31	The “parent directory” icon in a file dialog.
QStyle::SP_FileDialogNewFolder	32	The “create new folder” icon in a file dialog.
QStyle::SP_FileDialogDetailedView	33	The detailed view icon in a file dialog.
QStyle::SP_FileDialogInfoView	34	The file info icon in a file dialog.
QStyle::SP_FileDialogContentsView	35	The contents view icon in a file dialog.
QStyle::SP_FileDialogListView	36	The list view icon in a file dialog.
QStyle::SP_FileDialogBack	37	The back arrow in a file dialog.
QStyle::SP_DockWidgetCloseButton	8	Close button on dock windows (see also QDockWidget).
QStyle::SP_ToolBarHorizontalExtensionButton	27	Extension button for horizontal toolbars.
QStyle::SP_ToolBarVerticalExtensionButton	28	Extension button for vertical toolbars.
QStyle::SP_DialogOkButton	39	Icon for a standard OK button in a QDialogButtonBox.
QStyle::SP_DialogCancelButton	40	Icon for a standard Cancel button in a QDialogButtonBox.
QStyle::SP_DialogHelpButton	41	Icon for a standard Help button in a QDialogButtonBox.
QStyle::SP_DialogOpenButton	42	Icon for a standard Open button in a QDialogButtonBox.
QStyle::SP_DialogSaveButton	43	Icon for a standard Save button in a QDialogButtonBox.
QStyle::SP_DialogCloseButton	44	Icon for a standard Close button in a QDialogButtonBox.
QStyle::SP_DialogApplyButton	45	Icon for a standard Apply button in a QDialogButtonBox.
QStyle::SP_DialogResetButton	46	Icon for a standard Reset button in a QDialogButtonBox.
QStyle::SP_DialogDiscardButton	47	Icon for a standard Discard button in a QDialogButtonBox.
QStyle::SP_DialogYesButton	48	Icon for a standard Yes button in a QDialogButtonBox.
QStyle::SP_DialogNoButton	49	Icon for a standard No button in a QDialogButtonBox.
QStyle::SP_ArrowUp	50	Icon arrow pointing up.
QStyle::SP_ArrowDown	51	Icon arrow pointing down.
QStyle::SP_ArrowLeft	52	Icon arrow pointing left.
QStyle::SP_ArrowRight	53	Icon arrow pointing right.
QStyle::SP_ArrowBack	54	Equivalent to SP_ArrowLeft when the current layout direction is Qt::LeftToRight, otherwise SP_ArrowRight.
QStyle::SP_ArrowForward	55	Equivalent to SP_ArrowRight when the current layout direction is Qt::LeftToRight, otherwise SP_ArrowLeft.
QStyle::SP_CommandLink	57	Icon used to indicate a Vista style command link glyph.
QStyle::SP_VistaShield	58	Icon used to indicate UAC prompts on Windows Vista. This will return a null pixmap or icon on all other platforms.
QStyle::SP_BrowserReload	59	Icon indicating that the current page should be reloaded.
QStyle::SP_BrowserStop	60	Icon indicating that the page loading should stop.
QStyle::SP_MediaPlay	61	Icon indicating that media should begin playback.
QStyle::SP_MediaStop	62	Icon indicating that media should stop playback.
QStyle::SP_MediaPause	63	Icon indicating that media should pause playback.
QStyle::SP_MediaSkipForward	64	Icon indicating that media should skip forward.
QStyle::SP_MediaSkipBackward	65	Icon indicating that media should skip backward.
QStyle::SP_MediaSeekForward	66	Icon indicating that media should seek forward.
QStyle::SP_MediaSeekBackward	67	Icon indicating that media should seek backward.
QStyle::SP_MediaVolume	68	Icon indicating a volume control.
QStyle::SP_MediaVolumeMuted	69	Icon indicating a muted volume control.
QStyle::SP_LineEditClearButton	70	Icon for a standard clear button in a QLineEdit. This enum value was added in Qt 5.2.
QStyle::SP_DialogYesToAllButton	71	Icon for a standard YesToAll button in a QDialogButtonBox. This enum value was added in Qt 5.14.
QStyle::SP_DialogNoToAllButton	72	Icon for a standard NoToAll button in a QDialogButtonBox. This enum value was added in Qt 5.14.
QStyle::SP_DialogSaveAllButton	73	Icon for a standard SaveAll button in a QDialogButtonBox. This enum value was added in Qt 5.14.
QStyle::SP_DialogAbortButton	74	Icon for a standard Abort button in a QDialogButtonBox. This enum value was added in Qt 5.14.
QStyle::SP_DialogRetryButton	75	Icon for a standard Retry button in a QDialogButtonBox. This enum value was added in Qt 5.14.
QStyle::SP_DialogIgnoreButton	76	Icon for a standard Ignore button in a QDialogButtonBox. This enum value was added in Qt 5.14.
QStyle::SP_RestoreDefaultsButton	77	Icon for a standard RestoreDefaults button in a QDialogButtonBox. This enum value was added in Qt 5.14.
QStyle::SP_CustomBase	0xf0000000	Base value for custom standard pixmaps; custom values must be greater than this value.

可以看看 standardIcon().

8. enum QStyle::StateFlag

enum QStyle::StateFlag
flags QStyle::State

这个枚举描述了绘制原始元素（Primitive Elements）时使用的flags。

请注意，并不是所有原始元素都会使用所有这些标志，并且这些标志对不同的项目可能有不同的含义。

Constant	Value	Description
QStyle::State_None	0x00000000	Indicates that the widget does not have a state.
QStyle::State_Active	0x00010000	Indicates that the widget is active.
QStyle::State_AutoRaise	0x00001000	Used to indicate if auto-raise appearance should be used on a tool button.
QStyle::State_Children	0x00080000	Used to indicate if an item view branch has children.
QStyle::State_DownArrow	0x00000040	Used to indicate if a down arrow should be visible on the widget.
QStyle::State_Editing	0x00400000	Used to indicate if an editor is opened on the widget.
QStyle::State_Enabled	0x00000001	Used to indicate if the widget is enabled.
QStyle::State_HasEditFocus	0x01000000	Used to indicate if the widget currently has edit focus.
QStyle::State_HasFocus	0x00000100	Used to indicate if the widget has focus.
QStyle::State_Horizontal	0x00000080	Used to indicate if the widget is laid out horizontally, for example. a tool bar.
QStyle::State_KeyboardFocusChange	0x00800000	Used to indicate if the focus was changed with the keyboard, e.g., tab, backtab or shortcut.
QStyle::State_MouseOver	0x00002000	Used to indicate if the widget is under the mouse.
QStyle::State_NoChange	0x00000010	Used to indicate a tri-state checkbox.
QStyle::State_Off	0x00000008	Used to indicate if the widget is not checked.
QStyle::State_On	0x00000020	Used to indicate if the widget is checked.
QStyle::State_Raised	0x00000002	Used to indicate if a button is raised.
QStyle::State_ReadOnly	0x02000000	Used to indicate if a widget is read-only.
QStyle::State_Selected	0x00008000	Used to indicate if a widget is selected.
QStyle::State_Item	0x00100000	Used by item views to indicate if a horizontal branch should be drawn.
QStyle::State_Open	0x00040000	Used by item views to indicate if the tree branch is open.
QStyle::State_Sibling	0x00200000	Used by item views to indicate if a vertical line needs to be drawn (for siblings).
QStyle::State_Sunken	0x00000004	Used to indicate if the widget is sunken or pressed.
QStyle::State_UpArrow	0x00004000	Used to indicate if an up arrow should be visible on the widget.
QStyle::State_Mini	0x08000000	Used to indicate a mini style Mac widget or button.
QStyle::State_Small	0x04000000	Used to indicate a small style Mac widget or button.

State 类型是 QFlags<StateFlag> 的 typedef。它存储 StateFlag 值的 OR 组合。

可以看看 drawPrimitive()

9. enum QStyle::StyleHint

enum QStyle::StyleHint

这句话描述了可用的样式hints。样式提示是一种整体外观和/或feel的提示。

Constant	Value	Description
QStyle::SH_EtchDisabledText	0	Disabled text is “etched” as it is on Windows.
QStyle::SH_DitherDisabledText	1	Disabled text is dithered as it is on Motif.
QStyle::SH_ScrollBar_ContextMenu	62	Whether or not a scroll bar has a context menu.
QStyle::SH_ScrollBar_MiddleClickAbsolutePosition	2	A boolean value. If true, middle clicking on a scroll bar causes the slider to jump to that position. If false, middle clicking is ignored.
QStyle::SH_ScrollBar_LeftClickAbsolutePosition	39	A boolean value. If true, left clicking on a scroll bar causes the slider to jump to that position. If false, left clicking will behave as appropriate for each control.
QStyle::SH_ScrollBar_ScrollWhenPointerLeavesControl	3	A boolean value. If true, when clicking a scroll bar SubControl, holding the mouse button down and moving the pointer outside the SubControl, the scroll bar continues to scroll. If false, the scollbar stops scrolling when the pointer leaves the SubControl.
QStyle::SH_ScrollBar_RollBetweenButtons	63	A boolean value. If true, when clicking a scroll bar button (SC_ScrollBarAddLine or SC_ScrollBarSubLine) and dragging over to the opposite button (rolling) will press the new button and release the old one. When it is false, the original button is released and nothing happens (like a push button).
QStyle::SH_TabBar_Alignment	5	The alignment for tabs in a QTabWidget. Possible values are Qt::AlignLeft, Qt::AlignCenter and Qt::AlignRight.
QStyle::SH_Header_ArrowAlignment	6	The placement of the sorting indicator may appear in list or table headers. Possible values are Qt::Alignment values (that is, an OR combination of Qt::AlignmentFlag flags).
QStyle::SH_Slider_SnapToValue	7	Sliders snap to values while moving, as they do on Windows.
QStyle::SH_Slider_SloppyKeyEvents	8	Key presses handled in a sloppy manner, i.e., left on a vertical slider subtracts a line.
QStyle::SH_ProgressDialog_CenterCancelButton	9	Center button on progress dialogs, otherwise right aligned.
QStyle::SH_ProgressDialog_TextLabelAlignment	10	The alignment for text labels in progress dialogs; Qt::AlignCenter on Windows, Qt::AlignVCenter otherwise.
QStyle::SH_PrintDialog_RightAlignButtons	11	Right align buttons in the print dialog, as done on Windows.
QStyle::SH_MainWindow_SpaceBelowMenuBar	12	One or two pixel space between the menu bar and the dockarea, as done on Windows.
QStyle::SH_FontDialog_SelectAssociatedText	13	Select the text in the line edit, or when selecting an item from the listbox, or when the line edit receives focus, as done on Windows.
QStyle::SH_Menu_KeyboardSearch	66	Typing causes a menu to be search for relevant items, otherwise only mnemnonic is considered.
QStyle::SH_Menu_AllowActiveAndDisabled	14	Allows disabled menu items to be active.
QStyle::SH_Menu_SpaceActivatesItem	15	Pressing the space bar activates the item, as done on Motif.
QStyle::SH_Menu_SubMenuPopupDelay	16	The number of milliseconds to wait before opening a submenu (256 on Windows, 96 on Motif).
QStyle::SH_Menu_Scrollable	30	Whether popup menus must support scrolling.
QStyle::SH_Menu_SloppySubMenus	33	Whether popup menus must support the user moving the mouse cursor to a submenu while crossing other items of the menu. This is supported on most modern desktop platforms.
QStyle::SH_Menu_SubMenuUniDirection	106	Since Qt 5.5. If the cursor has to move towards the submenu (like it is on macOS), or if the cursor can move in any direction as long as it reaches the submenu before the sloppy timeout.
QStyle::SH_Menu_SubMenuUniDirectionFailCount	107	Since Qt 5.5. When SH_Menu_SubMenuUniDirection is defined this enum defines the number of failed mouse moves before the sloppy submenu is discarded. This can be used to control the “strictness” of the uni direction algorithm.
QStyle::SH_Menu_SubMenuSloppySelectOtherActions	108	Since Qt 5.5. Should other action items be selected when the mouse moves towards a sloppy submenu.
QStyle::SH_Menu_SubMenuSloppyCloseTimeout	109	Since Qt 5.5. The timeout used to close sloppy submenus.
QStyle::SH_Menu_SubMenuResetWhenReenteringParent	110	Since Qt 5.5. When entering parent from child submenu, should the sloppy state be reset, effectively closing the child and making the current submenu active.
QStyle::SH_Menu_SubMenuDontStartSloppyOnLeave	111	Since Qt 5.5. Do not start sloppy timers when the mouse leaves a sub-menu.
QStyle::SH_ScrollView_FrameOnlyAroundContents	17	Whether scrollviews draw their frame only around contents (like Motif), or around contents, scroll bars and corner widgets (like Windows).
QStyle::SH_MenuBar_AltKeyNavigation	18	Menu bars items are navigable by pressing Alt, followed by using the arrow keys to select the desired item.
QStyle::SH_ComboBox_ListMouseTracking	19	Mouse tracking in combobox drop-down lists.
QStyle::SH_Menu_MouseTracking	20	Mouse tracking in popup menus.
QStyle::SH_MenuBar_MouseTracking	21	Mouse tracking in menu bars.
QStyle::SH_Menu_FillScreenWithScroll	45	Whether scrolling popups should fill the screen as they are scrolled.
QStyle::SH_Menu_SelectionWrap	74	Whether popups should allow the selections to wrap, that is when selection should the next item be the first item.
QStyle::SH_ItemView_ChangeHighlightOnFocus	22	Gray out selected items when losing focus.
QStyle::SH_Widget_ShareActivation	23	Turn on sharing activation with floating modeless dialogs.
QStyle::SH_TabBar_SelectMouseType	4	Which type of mouse event should cause a tab to be selected.
QStyle::SH_ListViewExpand_SelectMouseType	40	Which type of mouse event should cause a list view expansion to be selected.
QStyle::SH_TabBar_PreferNoArrows	38	Whether a tab bar should suggest a size to prevent scoll arrows.
QStyle::SH_ComboBox_Popup	25	Allows popups as a combobox drop-down menu.
QStyle::SH_Workspace_FillSpaceOnMaximize	24	The workspace should maximize the client area.
QStyle::SH_TitleBar_NoBorder	26	The title bar has no border.
QStyle::SH_ScrollBar_StopMouseOverSlider	SH_Slider_StopMouseOverSlider	Obsolete. Use SH_Slider_StopMouseOverSlider instead.
QStyle::SH_Slider_StopMouseOverSlider	27	Stops auto-repeat when the slider reaches the mouse position.
QStyle::SH_BlinkCursorWhenTextSelected	28	Whether cursor should blink when text is selected.
QStyle::SH_RichText_FullWidthSelection	29	Whether richtext selections should extend to the full width of the document.
QStyle::SH_GroupBox_TextLabelVerticalAlignment	31	How to vertically align a group box’s text label.
QStyle::SH_GroupBox_TextLabelColor	32	How to paint a group box’s text label.
QStyle::SH_DialogButtons_DefaultButton	36	Which button gets the default status in a dialog’s button widget.
QStyle::SH_ToolBox_SelectedPageTitleBold	37	Boldness of the selected page title in a QToolBox.
QStyle::SH_LineEdit_PasswordCharacter	35	The Unicode character to be used for passwords.
QStyle::SH_LineEdit_PasswordMaskDelay	104	Determines the delay before visible character is masked with password character, in milliseconds. This enum value was added in Qt 5.4.
QStyle::SH_Table_GridLineColor	34	The RGBA value of the grid for a table.
QStyle::SH_UnderlineShortcut	41	Whether shortcuts are underlined.
QStyle::SH_SpellCheckUnderlineStyle	72	Obsolete. Use SpellCheckUnderlineStyle hint in QPlatformTheme instead.
QStyle::SH_SpinBox_AnimateButton	42	Animate a click when up or down is pressed in a spin box.
QStyle::SH_SpinBox_KeyPressAutoRepeatRate	43	Auto-repeat interval for spinbox key presses.
QStyle::SH_SpinBox_ClickAutoRepeatRate	44	Auto-repeat interval for spinbox mouse clicks.
QStyle::SH_SpinBox_ClickAutoRepeatThreshold	84	Auto-repeat threshold for spinbox mouse clicks.
QStyle::SH_ToolTipLabel_Opacity	46	An integer indicating the opacity for the tip label, 0 is completely transparent, 255 is completely opaque.
QStyle::SH_DrawMenuBarSeparator	47	Indicates whether or not the menu bar draws separators.
QStyle::SH_TitleBar_ModifyNotification	48	Indicates if the title bar should show a ‘*’ for windows that are modified.
QStyle::SH_Button_FocusPolicy	49	The default focus policy for buttons.
QStyle::SH_CustomBase	0xf0000000	Base value for custom style hints. Custom values must be greater than this value.
QStyle::SH_MessageBox_UseBorderForButtonSpacing	50	A boolean indicating what the to use the border of the buttons (computed as half the button height) for the spacing of the button in a message box.
QStyle::SH_MessageBox_CenterButtons	73	A boolean indicating whether the buttons in the message box should be centered or not (see QDialogButtonBox::setCentered()).
QStyle::SH_MessageBox_TextInteractionFlags	70	A boolean indicating if the text in a message box should allow user interfactions (e.g. selection) or not.
QStyle::SH_TitleBar_AutoRaise	51	A boolean indicating whether controls on a title bar ought to update when the mouse is over them.
QStyle::SH_ToolButton_PopupDelay	52	An int indicating the popup delay in milliseconds for menus attached to tool buttons.
QStyle::SH_FocusFrame_Mask	53	The mask of the focus frame.
QStyle::SH_RubberBand_Mask	54	The mask of the rubber band.
QStyle::SH_WindowFrame_Mask	55	The mask of the window frame.
QStyle::SH_SpinControls_DisableOnBounds	56	Determines if the spin controls will shown as disabled when reaching the spin range boundary.
QStyle::SH_Dial_BackgroundRole	57	Defines the style’s preferred background role (as QPalette::ColorRole) for a dial widget.
QStyle::SH_ComboBox_LayoutDirection	58	The layout direction for the combo box. By default it should be the same as indicated by the QStyleOption::direction variable.
QStyle::SH_ItemView_EllipsisLocation	59	The location where ellipses should be added for item text that is too long to fit in an view item.
QStyle::SH_ItemView_ShowDecorationSelected	60	When an item in an item view is selected, also highlight the branch or other decoration.
QStyle::SH_ItemView_ActivateItemOnSingleClick	61	Emit the activated signal when the user single clicks on an item in an item in an item view. Otherwise the signal is emitted when the user double clicks on an item.
QStyle::SH_Slider_AbsoluteSetButtons	64	Which mouse buttons cause a slider to set the value to the position clicked on.
QStyle::SH_Slider_PageSetButtons	65	Which mouse buttons cause a slider to page step the value.
QStyle::SH_TabBar_ElideMode	67	The default eliding style for a tab bar.
QStyle::SH_DialogButtonLayout	68	Controls how buttons are laid out in a QDialogButtonBox, returns a QDialogButtonBox::ButtonLayout enum.
QStyle::SH_WizardStyle	79	Controls the look and feel of a QWizard. Returns a QWizard::WizardStyle enum.
QStyle::SH_FormLayoutWrapPolicy	86	Provides a default for how rows are wrapped in a QFormLayout. Returns a QFormLayout::RowWrapPolicy enum.
QStyle::SH_FormLayoutFieldGrowthPolicy	89	Provides a default for how fields can grow in a QFormLayout. Returns a QFormLayout::FieldGrowthPolicy enum.
QStyle::SH_FormLayoutFormAlignment	90	Provides a default for how a QFormLayout aligns its contents within the available space. Returns a Qt::Alignment enum.
QStyle::SH_FormLayoutLabelAlignment	91	Provides a default for how a QFormLayout aligns labels within the available space. Returns a Qt::Alignment enum.
QStyle::SH_ItemView_ArrowKeysNavigateIntoChildren	80	Controls whether the tree view will select the first child when it is exapanded and the right arrow key is pressed.
QStyle::SH_ComboBox_PopupFrameStyle	69	The frame style used when drawing a combobox popup menu.
QStyle::SH_DialogButtonBox_ButtonsHaveIcons	71	Indicates whether or not StandardButtons in QDialogButtonBox should have icons or not.
QStyle::SH_ItemView_MovementWithoutUpdatingSelection	75	The item view is able to indicate a current item without changing the selection.
QStyle::SH_ToolTip_Mask	76	The mask of a tool tip.
QStyle::SH_FocusFrame_AboveWidget	77	The FocusFrame is stacked above the widget that it is “focusing on”.
QStyle::SH_TextControl_FocusIndicatorTextCharFormat	78	Specifies the text format used to highlight focused anchors in rich text documents displayed for example in QTextBrowser. The format has to be a QTextCharFormat returned in the variant of the QStyleHintReturnVariant return value. The QTextFormat::OutlinePen property is used for the outline and QTextFormat::BackgroundBrush for the background of the highlighted area.
QStyle::SH_Menu_FlashTriggeredItem	82	Flash triggered item.
QStyle::SH_Menu_FadeOutOnHide	83	Fade out the menu instead of hiding it immediately.
QStyle::SH_TabWidget_DefaultTabPosition	87	Default position of the tab bar in a tab widget.
QStyle::SH_ToolBar_Movable	88	Determines if the tool bar is movable by default.
QStyle::SH_ItemView_PaintAlternatingRowColorsForEmptyArea	85	Whether QTreeView paints alternating row colors for the area that does not have any items.
QStyle::SH_Menu_Mask	81	The mask for a popup menu.
QStyle::SH_ItemView_DrawDelegateFrame	92	Determines if there should be a frame for a delegate widget.
QStyle::SH_TabBar_CloseButtonPosition	93	Determines the position of the close button on a tab in a tab bar.
QStyle::SH_DockWidget_ButtonsHaveFrame	94	Determines if dockwidget buttons should have frames. Default is true.
QStyle::SH_ToolButtonStyle	95	Determines the default system style for tool buttons that uses Qt::ToolButtonFollowStyle.
QStyle::SH_RequestSoftwareInputPanel	96	Determines when a software input panel should be requested by input widgets. Returns an enum of type QStyle::RequestSoftwareInputPanel.
QStyle::SH_ScrollBar_Transient	97	Determines if the style supports transient scroll bars. Transient scroll bars appear when the content is scrolled and disappear when they are no longer needed.
QStyle::SH_Menu_SupportsSections	98	Determines if the style displays sections in menus or treat them as plain separators. Sections are separators with a text and icon hint.
QStyle::SH_ToolTip_WakeUpDelay	99	Determines the delay before a tooltip is shown, in milliseconds.
QStyle::SH_ToolTip_FallAsleepDelay	100	Determines the delay (in milliseconds) before a new wake time is needed when a tooltip is shown (notice: shown, not hidden). When a new wake isn’t needed, a user-requested tooltip will be shown nearly instantly.
QStyle::SH_Widget_Animate	101	Deprecated. Use SH_Widget_Animation_Duration instead.
QStyle::SH_Splitter_OpaqueResize	102	Determines if widgets are resized dynamically (opaquely) while interactively moving the splitter. This enum value was introduced in Qt 5.2.
QStyle::SH_TabBar_ChangeCurrentDelay	105	Determines the delay before the current tab is changed while dragging over the tabbar, in milliseconds. This enum value has been introduced in Qt 5.4
QStyle::SH_ItemView_ScrollMode	112	The default vertical and horizontal scroll mode as specified by the style. Can be overridden with QAbstractItemView::setVerticalScrollMode() and QAbstractItemView::setHorizontalScrollMode(). This enum value has been introduced in Qt 5.7.
QStyle::SH_TitleBar_ShowToolTipsOnButtons	113	Determines if tool tips are shown on window title bar buttons. The Mac style, for example, sets this to false. This enum value has been introduced in Qt 5.10.
QStyle::SH_Widget_Animation_Duration	114	Determines how much an animation should last (in ms). A value equal to zero means that the animations will be disabled. This enum value has been introduced in Qt 5.10.
QStyle::SH_ComboBox_AllowWheelScrolling	115	Determines if the mouse wheel can be used to scroll inside a QComboBox. This is on by default in all styles except the Mac style. This enum value has been introduced in Qt 5.10.
QStyle::SH_SpinBox_ButtonsInsideFrame	116	Determines if the spin box buttons are inside the line edit frame. This enum value has been introduced in Qt 5.11.
QStyle::SH_SpinBox_StepModifier	117	Determines which Qt::KeyboardModifier increases the step rate of QAbstractSpinBox. Possible values are Qt::NoModifier, Qt::ControlModifier (default) or Qt::ShiftModifier. Qt::NoModifier disables this feature. This enum value has been introduced in Qt 5.12.

可以看看styleHint().

10. enum QStyle::SubControl

enum QStyle::SubControl
flags QStyle::SubControls

这个枚举类型描述了可用的子控件枚举类型。子控件是复合控件（ComplexControl）中的控件元素。

Constant	Value	Description
QStyle::SC_None	0x00000000	Special value that matches no other sub control.
QStyle::SC_ScrollBarAddLine	0x00000001	Scroll bar add line (i.e., down/right arrow); see also QScrollBar.
QStyle::SC_ScrollBarSubLine	0x00000002	Scroll bar sub line (i.e., up/left arrow).
QStyle::SC_ScrollBarAddPage	0x00000004	Scroll bar add page (i.e., page down).
QStyle::SC_ScrollBarSubPage	0x00000008	Scroll bar sub page (i.e., page up).
QStyle::SC_ScrollBarFirst	0x00000010	Scroll bar first line (i.e., home).
QStyle::SC_ScrollBarLast	0x00000020	Scroll bar last line (i.e., end).
QStyle::SC_ScrollBarSlider	0x00000040	Scroll bar slider handle.
QStyle::SC_ScrollBarGroove	0x00000080	Special sub-control which contains the area in which the slider handle may move.
QStyle::SC_SpinBoxUp	0x00000001	Spin widget up/increase; see also QSpinBox.
QStyle::SC_SpinBoxDown	0x00000002	Spin widget down/decrease.
QStyle::SC_SpinBoxFrame	0x00000004	Spin widget frame.
QStyle::SC_SpinBoxEditField	0x00000008	Spin widget edit field.
QStyle::SC_ComboBoxEditField	0x00000002	Combobox edit field; see also QComboBox.
QStyle::SC_ComboBoxArrow	0x00000004	Combobox arrow button.
QStyle::SC_ComboBoxFrame	0x00000001	Combobox frame.
QStyle::SC_ComboBoxListBoxPopup	0x00000008	The reference rectangle for the combobox popup. Used to calculate the position of the popup.
QStyle::SC_SliderGroove	0x00000001	Special sub-control which contains the area in which the slider handle may move.
QStyle::SC_SliderHandle	0x00000002	Slider handle.
QStyle::SC_SliderTickmarks	0x00000004	Slider tickmarks.
QStyle::SC_ToolButton	0x00000001	Tool button (see also QToolButton).
QStyle::SC_ToolButtonMenu	0x00000002	Sub-control for opening a popup menu in a tool button.
QStyle::SC_TitleBarSysMenu	0x00000001	System menu button (i.e., restore, close, etc.).
QStyle::SC_TitleBarMinButton	0x00000002	Minimize button.
QStyle::SC_TitleBarMaxButton	0x00000004	Maximize button.
QStyle::SC_TitleBarCloseButton	0x00000008	Close button.
QStyle::SC_TitleBarLabel	0x00000100	Window title label.
QStyle::SC_TitleBarNormalButton	0x00000010	Normal (restore) button.
QStyle::SC_TitleBarShadeButton	0x00000020	Shade button.
QStyle::SC_TitleBarUnshadeButton	0x00000040	Unshade button.
QStyle::SC_TitleBarContextHelpButton	0x00000080	Context Help button.
QStyle::SC_DialHandle	0x00000002	The handle of the dial (i.e. what you use to control the dial).
QStyle::SC_DialGroove	0x00000001	The groove for the dial.
QStyle::SC_DialTickmarks	0x00000004	The tickmarks for the dial.
QStyle::SC_GroupBoxFrame	0x00000008	The frame of a group box.
QStyle::SC_GroupBoxLabel	0x00000002	The title of a group box.
QStyle::SC_GroupBoxCheckBox	0x00000001	The optional check box of a group box.
QStyle::SC_GroupBoxContents	0x00000004	The group box contents.
QStyle::SC_MdiNormalButton	0x00000002	The normal button for a MDI subwindow in the menu bar.
QStyle::SC_MdiMinButton	0x00000001	The minimize button for a MDI subwindow in the menu bar.
QStyle::SC_MdiCloseButton	0x00000004	The close button for a MDI subwindow in the menu bar.
QStyle::SC_All	0xffffffff	Special value that matches all sub-controls.

SubControls类型是 QFlags<SubControl>的typedef，存储了 SubControl值的OR运算集合。

可以看看 ComplexControl

11. enum QStyle::SubElement

这个枚举表示了一个小部件的子区域。样式实现使用这些区域来绘制小部件的不同部分。

Constant	Value	Description
QStyle::SE_PushButtonContents	0	Area containing the label (icon with text or pixmap).
QStyle::SE_PushButtonFocusRect	1	Area for the focus rect (usually larger than the contents rect).
QStyle::SE_PushButtonLayoutItem	38	Area that counts for the parent layout.
QStyle::SE_PushButtonBevel	57	[since 5.15] Area used for the bevel of the button.
QStyle::SE_CheckBoxIndicator	2	Area for the state indicator (e.g., check mark).
QStyle::SE_CheckBoxContents	3	Area for the label (text or pixmap).
QStyle::SE_CheckBoxFocusRect	4	Area for the focus indicator.
QStyle::SE_CheckBoxClickRect	5	Clickable area, defaults to SE_CheckBoxFocusRect.
QStyle::SE_CheckBoxLayoutItem	32	Area that counts for the parent layout.
QStyle::SE_DateTimeEditLayoutItem	34	Area that counts for the parent layout.
QStyle::SE_RadioButtonIndicator	6	Area for the state indicator.
QStyle::SE_RadioButtonContents	7	Area for the label.
QStyle::SE_RadioButtonFocusRect	8	Area for the focus indicator.
QStyle::SE_RadioButtonClickRect	9	Clickable area, defaults to SE_RadioButtonFocusRect.
QStyle::SE_RadioButtonLayoutItem	39	Area that counts for the parent layout.
QStyle::SE_ComboBoxFocusRect	10	Area for the focus indicator.
QStyle::SE_SliderFocusRect	11	Area for the focus indicator.
QStyle::SE_SliderLayoutItem	40	Area that counts for the parent layout.
QStyle::SE_SpinBoxLayoutItem	41	Area that counts for the parent layout.
QStyle::SE_ProgressBarGroove	12	Area for the groove.
QStyle::SE_ProgressBarContents	13	Area for the progress indicator.
QStyle::SE_ProgressBarLabel	14	Area for the text label.
QStyle::SE_ProgressBarLayoutItem	37	Area that counts for the parent layout.
QStyle::SE_FrameContents	27	Area for a frame’s contents.
QStyle::SE_ShapedFrameContents	52	Area for a frame’s contents using the shape in QStyleOptionFrame; see QFrame
QStyle::SE_FrameLayoutItem	43	Area that counts for the parent layout.
QStyle::SE_HeaderArrow	17	Area for the sort indicator for a header.
QStyle::SE_HeaderLabel	16	Area for the label in a header.
QStyle::SE_LabelLayoutItem	SE_DateTimeEditLayoutItem + 2	Area that counts for the parent layout.
QStyle::SE_LineEditContents	26	Area for a line edit’s contents.
QStyle::SE_TabWidgetLeftCorner	21	Area for the left corner widget in a tab widget.
QStyle::SE_TabWidgetRightCorner	22	Area for the right corner widget in a tab widget.
QStyle::SE_TabWidgetTabBar	18	Area for the tab bar widget in a tab widget.
QStyle::SE_TabWidgetTabContents	20	Area for the contents of the tab widget.
QStyle::SE_TabWidgetTabPane	19	Area for the pane of a tab widget.
QStyle::SE_TabWidgetLayoutItem	45	Area that counts for the parent layout.
QStyle::SE_ToolBoxTabContents	15	Area for a toolbox tab’s icon and label.
QStyle::SE_ToolButtonLayoutItem	42	Area that counts for the parent layout.
QStyle::SE_ItemViewItemCheckIndicator	23	Area for a view item’s check mark.
QStyle::SE_TabBarTearIndicator	24	Deprecated. Use SE_TabBarTearIndicatorLeft instead.
QStyle::SE_TabBarTearIndicatorLeft	SE_TabBarTearIndicator	Area for the tear indicator on the left side of a tab bar with scroll arrows.
QStyle::SE_TabBarTearIndicatorRight	56	Area for the tear indicator on the right side of a tab bar with scroll arrows.
QStyle::SE_TabBarScrollLeftButton	54	Area for the scroll left button on a tab bar with scroll buttons.
QStyle::SE_TabBarScrollRightButton	55	Area for the scroll right button on a tab bar with scroll buttons.
QStyle::SE_TreeViewDisclosureItem	25	Area for the actual disclosure item in a tree branch.
QStyle::SE_GroupBoxLayoutItem	44	Area that counts for the parent layout.
QStyle::SE_CustomBase	0xf0000000	Base value for custom sub-elements. Custom values must be greater than this value.
QStyle::SE_DockWidgetFloatButton	29	The float button of a dock widget.
QStyle::SE_DockWidgetTitleBarText	30	The text bounds of the dock widgets title.
QStyle::SE_DockWidgetCloseButton	28	The close button of a dock widget.
QStyle::SE_DockWidgetIcon	31	The icon of a dock widget.
QStyle::SE_ComboBoxLayoutItem	33	Area that counts for the parent layout.
QStyle::SE_ItemViewItemDecoration	46	Area for a view item’s decoration (icon).
QStyle::SE_ItemViewItemText	47	Area for a view item’s text.
QStyle::SE_ItemViewItemFocusRect	48	Area for a view item’s focus rect.
QStyle::SE_TabBarTabLeftButton	49	Area for a widget on the left side of a tab in a tab bar.
QStyle::SE_TabBarTabRightButton	50	Area for a widget on the right side of a tab in a tab bar.
QStyle::SE_TabBarTabText	51	Area for the text on a tab in a tab bar.
QStyle::SE_ToolBarHandle	53	Area for the handle of a tool bar.

可以看看subElementRect()

三、QStyle Member Function文档

1. alignedRect()

static QRect
QStyle::alignedRect (
	Qt::LayoutDirection direction,
	Qt::Alignment alignment,
	const QSize &size,
	const QRect &rectangle
);

返回一个指定大小的矩形，大小由size指定。
该矩形会根据指定的对齐方式alignment和方向direction与给定的矩形rectangle对齐。

2. combinedLayoutSpacing()

int
QStyle::combinedLayoutSpacing (
	QSizePolicy::ControlTypes controls1,
	QSizePolicy::ControlTypes controls2,
	Qt::Orientation orientation,
	QStyleOption *option = nullptr,
	QWidget *widget		 = nullptr
) const;

返回在布局中应该用于 controls1 和 controls2 之间的间距。

1. orientation 指定控件是并排布置还是垂直堆叠。
2. option 参数可以用来传递有关父小部件的额外信息。
3. widget 参数是可选的，如果 option 为 nullptr，也可以使用 widget 参数。
4. controls1 和 controls2 是一个或多个控件类型的（enum QSizePolicy::ControlType） OR 组合。

此函数由布局系统调用。仅当 PM_LayoutHorizontalSpacing 或 PM_LayoutVerticalSpacing 返回负值时使用此函数。

此函数在 Qt 4.3 中引入。

可以看看layoutSpacing()

3. drawComplexControl()

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

使用所提供的painter和指定的option样式选项绘制给定的控件。
widget参数是可选的，可以在绘制控件时作为辅助使用。
option参数是指向QStyleOptionComplex对象的指针，可以使用 qstyleoption_cast()函数将其转换为正确的子类。

请注意，指定的option的rect成员必须是逻辑坐标。此函数的重新实现应使用visualRect()将逻辑坐标转换为屏幕坐标，然后调用drawPrimitive()或drawControl()函数。

下表列出了复杂控件元素及其关联的样式选项子类。样式选项包含绘制控件所需的所有参数，包括QStyleOption::state（其中包含在绘制时使用的样式标志），。该表还描述了将给定的option转换为适当的子类时设置的标志。

Complex Control	QStyleOptionComplex Subclass	Style Flag	Remark
CC_SpinBox	QStyleOptionSpinBox	State_Enabled	Set if the spin box is enabled.
State_HasFocus	Set if the spin box has input focus.
CC_ComboBox	QStyleOptionComboBox	State_Enabled	Set if the combobox is enabled.
State_HasFocus	Set if the combobox has input focus.
CC_ScrollBar	QStyleOptionSlider	State_Enabled	Set if the scroll bar is enabled.
State_HasFocus	Set if the scroll bar has input focus.
CC_Slider	QStyleOptionSlider	State_Enabled	Set if the slider is enabled.
State_HasFocus	Set if the slider has input focus.
CC_Dial	QStyleOptionSlider	State_Enabled	Set if the dial is enabled.
State_HasFocus	Set if the dial has input focus.
CC_ToolButton	QStyleOptionToolButton	State_Enabled	Set if the tool button is enabled.
State_HasFocus	Set if the tool button has input focus.
State_DownArrow	Set if the tool button is down (i.e., a mouse button or the space bar is pressed).
State_On	Set if the tool button is a toggle button and is toggled on.
State_AutoRaise	Set if the tool button has auto-raise enabled.
State_Raised	Set if the button is not down, not on, and doesn’t contain the mouse when auto-raise is enabled.
CC_TitleBar	QStyleOptionTitleBar	State_Enabled	Set if the title bar is enabled.

可以看看 drawPrimitive() and drawControl().

4. drawControl()

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

使用所提供的painter和指定的option样式选项绘制给定的元素。
widget参数是可选的，可以在绘制控件时作为辅助使用。
option参数是指向QStyleOption对象的指针，可以使用qstyleoption_cast()函数将其转换为正确的子类。

下表列出了控件元素及其关联的样式选项子类。样式选项包含绘制控件所需的所有参数，包括QStyleOption::state（其中包含在绘制时使用的样式标志）。该表还描述了将给定的option转换为适当的子类时设置的标志。

请注意，如果某个控件元素未在此列出，则是因为它使用的是普通的QStyleOption对象。

可以看看 drawPrimitive() and drawComplexControl().

5. drawItemPixmap()

virtual void
QStyle::drawItemPixmap (
	QPainter *painter,
	const QRect &rectangle,
	int alignment,
	const QPixmap &pixmap
) const;

使用所提供的painter，根据指定的alignment，在指定的rectangle中绘制给定的pixmap。

另请参见drawItemText()。

6. drawItemText()

virtual void
QStyle::drawItemText (
	QPainter *painter,
	const QRect &rectangle,
	int alignment,
	const QPalette &palette,
	bool enabled,
	const QString &text,
	QPalette::ColorRole textRole = QPalette::NoRole
) const;

在指定的矩形内使用提供的painter和调色板（palette）绘制给定的文本。

1. 文本使用painter的笔绘制，并根据指定的对齐方式进行对齐和换行。
2. 如果指定了明确的文本角色（textRole），则使用调色板中该角色的颜色绘制文本。
3. 启用参数（enabled）表示项目是否启用；在重新实现此函数时，启用参数应影响项目的绘制方式。

7. drawPrimitive()

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

使用提供的painter和指定的样式选项（option）绘制给定的基本元素（primitive element）。

widget参数是可选的，可能持有一个在绘制基本元素时有帮助的窗口部件。

下表列出了基本元素（primitive element）及其相关的样式选项子类。样式选项（option）包含绘制元素所需的所有参数，包括 QStyleOption::state，它包含在绘制时使用的样式标志。表格还描述了当将给定的选项转换为适当的子类时设置了哪些标志。

请注意，如果基本元素未在此处列出，则是因为它使用的是普通的 QStyleOption 对象。

另请参考 drawComplexControl() and drawControl().

8. generatedIconPixmap()

virtual QPixmap
generatedIconPixmap (
	QIcon::Mode iconMode,
	const QPixmap &pixmap, 
	const QStyleOption *option
) const = 0;

返回给定图像（pixmap）的副本，该副本经过样式化以符合指定的图标模式（iconMode），并考虑由option指定的调色板（palette）。

option参数可以传递额外的信息，但它必须包含一个调色板。

请注意，并非所有的图像都会符合这种样式化，在这种情况下，返回的图像是一个普通的副本。

另请参见 QIcon

9. hitTestComplexControl()

virtual QStyle::SubControl
hitTestComplexControl (
	QStyle::ComplexControl control,
	const QStyleOptionComplex *option,
	const QPoint &position,
	const QWidget *widget = nullptr
) const =0;

返回给定复杂控件（complex control）中指定位置（position）的子控件，使用由option指定的样式选项。

请注意，位置是以屏幕坐标表示的。

option参数是一个指向QStyleOptionComplex对象（或其子类之一）的指针。可以使用qstyleoption_cast()函数将对象转换为适当的类型。详情请参见drawComplexControl()。

widget参数是可选的，可以为该函数提供额外的信息。

另请参见 drawComplexControl() and subControlRect().

10. itemPixmapRect()

virtual QRect
itemPixmapRect (
	const QRect &rectangle, 
	int alignment,
	const QPixmap &pixmap
) const;

返回在给定矩形内根据定义的对齐方式绘制指定图像（pixmap）的矩形区域。

11. itemTextRect()

virtual QRect
itemTextRect (
	const QFontMetrics &metrics,
	const QRect &rectangle,
	int alignment, 
	bool enabled, 
	const QString &text
) const;

返回在给定矩形内根据指定的字体度量（font metrics）和对齐方式绘制提供的文本（text）的区域。

enabled参数表示相关项目是否启用。

如果给定的矩形大于渲染文本所需的区域，则返回的矩形将根据指定的对齐方式在矩形内偏移。例如，如果对齐方式是Qt::AlignCenter，返回的矩形将在矩形内居中。

如果给定的矩形小于所需的区域，返回的矩形将是足够渲染文本的最小矩形。

12. layoutSpacing()

virtual int
QStyle::layoutSpacing (
	QSizePolicy::ControlType control1,
	QSizePolicy::ControlType control2,
	Qt::Orientation orientation,
	const QStyleOption *option = nullptr,
	const QWidget *widget	   = nullptr
) const = 0;

返回在布局中控制项control1和control2之间应使用的间距。

orientation指定控件是并排布置还是垂直堆叠。

option参数可以用于传递有关父窗口部件的额外信息。如果option为nullptr，也可以使用widget参数。

此函数由布局系统调用。仅当PM_LayoutHorizontalSpacing或PM_LayoutVerticalSpacing返回负值时才使用此函数。

此函数在Qt 4.3中引入。

另请参见 combinedLayoutSpacing().

13. pixelMetric()

virtual int
pixelMetric (
	QStyle::PixelMetric metric, 
	const QStyleOption *option = nullptr, 
	const QWidget *widget = nullptr
)const =0;

返回给定像素度量（pixel metric）的值。

指定的option和widget可以用于计算该度量。一般来说，widget参数不使用。可以使用qstyleoption_cast()函数将option转换为适当的类型。

请注意，即使对于可以使用的PixelMetrics，option也可能为零。请参见下表了解适当的option转换：

Pixel Metric	QStyleOption Subclass
PM_SliderControlThickness	QStyleOptionSlider
PM_SliderLength	QStyleOptionSlider
PM_SliderTickmarkOffset	QStyleOptionSlider
PM_SliderSpaceAvailable	QStyleOptionSlider
PM_ScrollBarExtent	QStyleOptionSlider
PM_TabBarTabOverlap	QStyleOptionTab
PM_TabBarTabHSpace	QStyleOptionTab
PM_TabBarTabVSpace	QStyleOptionTab
PM_TabBarBaseHeight	QStyleOptionTab
PM_TabBarBaseOverlap	QStyleOptionTab

一些pixel metrics是从widgets调用的，而有些则仅由样式内部调用。如果metric不是由一个widget调用的，是否使用它由样式作者自行决定。对于某些样式，可能不适合使用这个方法。

14. polish()

virtual void polish (QWidget *widget);

初始化给定窗口部件（widget）的外观。

此函数在每个窗口部件完全创建之后但在首次显示之前的某个时间点被调用。

请注意，默认实现不执行任何操作。在此函数中合理的操作可能是调用QWidget::setBackgroundMode()函数来设置widget的背景模式。不要使用此函数来设置例如几何形状。重新实现此函数提供了一种更改窗口部件外观的后门，但由于Qt的样式引擎，通常不需要实现此函数；而是重新实现drawItemPixmap()、drawItemText()、drawPrimitive()等函数。

QWidget::inherits()函数可能提供足够的信息来允许特定类的自定义。但是，由于新的QStyle子类预计会与所有当前和未来的窗口部件合理地配合使用，建议有限地使用硬编码的自定义。

另请参见unpolish()。

重载版本

virtual void polish(QApplication *application);

延迟初始化给定的应用程序对象。

virtual void polish(QPalette &palette);

根据调色板的特定样式要求（如果有）更改调色板（palette）。

15. proxy()

const QStyle *QStyle::proxy() const;

此函数返回该样式的当前代理。默认情况下，大多数样式将返回它们自己。然而，当使用代理样式时，它将允许样式回调到其代理。

16. sizeFromContents()

virtual QSize
sizeFromContents (
	QStyle::ContentsType type, 
	const QStyleOption *option,
	const QSize &contentsSize, 
	const QWidget *widget = nullptr
) const = 0;

返回由指定的option和type描述的元素的大小，基于提供的contentsSize。

option参数是指向QStyleOption或其子类之一的指针。可以使用qstyleoption_cast()函数将option转换为适当的类型。

widget是一个可选参数，可以包含用于计算大小的额外信息。
请参见下表了解适当的option转换：

Contents Type	QStyleOption Subclass
CT_CheckBox	QStyleOptionButton
CT_ComboBox	QStyleOptionComboBox
CT_GroupBox	QStyleOptionGroupBox
CT_HeaderSection	QStyleOptionHeader
CT_ItemViewItem	QStyleOptionViewItem
CT_LineEdit	QStyleOptionFrame
CT_MdiControls	QStyleOptionComplex
CT_Menu	QStyleOption
CT_MenuItem	QStyleOptionMenuItem
CT_MenuBar	QStyleOptionMenuItem
CT_MenuBarItem	QStyleOptionMenuItem
CT_ProgressBar	QStyleOptionProgressBar
CT_PushButton	QStyleOptionButton
CT_RadioButton	QStyleOptionButton
CT_ScrollBar	QStyleOptionSlider
CT_SizeGrip	QStyleOption
CT_Slider	QStyleOptionSlider
CT_SpinBox	QStyleOptionSpinBox
CT_Splitter	QStyleOption
CT_TabBarTab	QStyleOptionTab
CT_TabWidget	QStyleOptionTabWidgetFrame
CT_ToolButton	QStyleOptionToolButton

另请参见 ContentsType and QStyleOption.

16. sliderPositionFromValue()

static int
sliderPositionFromValue (
	int min, 
	int max, 
	int logicalValue,
	int span, 
	bool upsideDown = false
);

将给定的逻辑值（logicalValue）转换为像素位置。
min参数映射到0，max参数映射到span，其他值在两者之间均匀分布。

此函数可以处理整个整数范围而不会溢出，前提是span小于4096。

默认情况下，此函数假定最大值位于水平项的右侧和垂直项的底部。将upsideDown参数设置为true以反转此行为。

另请参见 sliderValueFromPosition()。

17. sliderValueFromPosition()

static int
sliderValueFromPosition(
	int min,
	int max,
	int position, 
	int span, 
	bool upsideDown = false
);

将给定的像素位置转换为逻辑值。0 映射到 min 参数，span 映射到 max，其他值则在两者之间均匀分布。

此函数可以处理整个整数范围而不会发生溢出。

默认情况下，此函数假设最大值位于水平项目的右侧和垂直项目的底部。将 upsideDown 参数设置为 true 可逆转此行为。

另请参见 sliderPositionFromValue()。

18. standardIcon()

virtual QIcon
standardIcon (
	QStyle::StandardPixmap standardIcon, 
	const QStyleOption *option = 0,
	const QWidget *widget = 0
)const =0;

返回给定标准图标（standardIcon）的图标。

standardIcon是一个标准图像，可以遵循某些现有的GUI样式或指南。

option参数可以用于传递定义适当图标时所需的额外信息。

widget参数是可选的，也可以用于帮助确定图标。

此函数在Qt 4.1中引入。

19. standardPalette()

virtual QPalette standardPalette() const;

返回样式的标准调色板。

请注意，在支持系统颜色的系统上，样式的标准调色板未被使用。特别是，Windows Vista和Mac样式不使用标准调色板，而是使用本地主题引擎。在这些样式中，不应使用QApplication::setPalette()设置调色板。

另请参见QApplication::setPalette()。

20. styleHint()

virtual int
styleHint (
	QStyle::StyleHint hint,
	const QStyleOption *option	 = nullptr,
	const QWidget *widget		 = nullptr,
	QStyleHintReturn *returnData = nullptr
) const = 0;

返回一个整数，表示由提供的样式选项描述的给定窗口部件的指定样式提示（style hint）。

当查询窗口部件需要比styleHint()返回的整数更详细的数据时，使用returnData。有关详细信息，请参阅QStyleHintReturn类描述。

21. subControlRect()

virtual QRect
subControlRect (
	QStyle::ComplexControl control,
	const QStyleOptionComplex *option,
	QStyle::SubControl subControl,
	const QWidget *widget = nullptr
) const = 0;

返回包含给定复杂控件（complex control）的指定子控件（subControl）的矩形（使用由option指定的样式）。该矩形以屏幕坐标定义。

option参数是指向QStyleOptionComplex或其子类之一的指针，可以使用qstyleoption_cast()函数将其转换为适当的类型。详情请参见drawComplexControl()。

widget参数是可选的，可以为该函数提供额外的信息。

另请参见drawComplexControl()。

22. subElementRect()

virtual QRect
subElementRect (
	QStyle::SubElement element,
	const QStyleOption *option,
	const QWidget *widget = nullptr
) const =0;

返回给定元素（element）的子区域，如提供的样式选项（style option）中所描述。返回的矩形以屏幕坐标定义。

widget参数是可选的，可以用于帮助确定区域。可以使用qstyleoption_cast()函数将QStyleOption对象转换为适当的类型。
请参见下表了解适当的option转换：

Sub Element	QStyleOption Subclass
SE_PushButtonContents	QStyleOptionButton
SE_PushButtonFocusRect	QStyleOptionButton
SE_PushButtonBevel	QStyleOptionButton
SE_CheckBoxIndicator	QStyleOptionButton
SE_CheckBoxContents	QStyleOptionButton
SE_CheckBoxFocusRect	QStyleOptionButton
SE_RadioButtonIndicator	QStyleOptionButton
SE_RadioButtonContents	QStyleOptionButton
SE_RadioButtonFocusRect	QStyleOptionButton
SE_ComboBoxFocusRect	QStyleOptionComboBox
SE_ProgressBarGroove	QStyleOptionProgressBar
SE_ProgressBarContents	QStyleOptionProgressBar
SE_ProgressBarLabel	QStyleOptionProgressBar

23. unpolish()

virtual void unpolish(QWidget *widget);

取消初始化给定窗口部件的外观。

此函数是polish()的对立面。每当样式动态更改时，它会为每个已初始化的窗口部件调用；之前的样式必须取消其设置，然后新样式才能再次初始化它们。

请注意，unpolish()只有在窗口部件被销毁时才会被调用。这在某些情况下可能会导致问题，例如，如果你从UI中移除一个窗口部件，将其缓存，然后在样式更改后重新插入它；Qt的一些类会缓存它们的窗口部件。

另请参见polish()。

重载版本

virtual void unpolish(QApplication *application);

取消对给定的应用程序的初始化。

24. visualAlignment()

static Qt::Alignment
visualAlignment (
	Qt::LayoutDirection direction, 
	Qt::Alignment alignment
);

根据布局方向，将不带Qt::AlignAbsolute的Qt::AlignLeft或Qt::AlignRight对齐方式转换为带Qt::AlignAbsolute的Qt::AlignLeft或Qt::AlignRight对齐方式。其他对齐标志保持不变。

如果未指定水平对齐方式，该函数将返回给定布局方向的默认对齐方式。

另请参见 QWidget::layoutDirection

25. visualPos()

static QPoint
visualPos (
	Qt::LayoutDirection direction, 
	const QRect &boundingRectangle, 
	const QPoint &logicalPosition
);

根据指定方向（direction），返回将给定的逻辑位置（logicalPosition）转换为屏幕坐标后的结果。转换时使用boundingRectangle。

另请参见QWidget::layoutDirection。

26. visualRect()

virtual QRect
visualRect (
	Qt::LayoutDirection direction,
	const QRect &boundingRectangle,
	const QRect &logicalRectangle
);

根据指定方向（direction），返回将给定的逻辑矩形（logicalRectangle）转换为屏幕坐标后的结果。转换时使用boundingRectangle。

提供此函数是为了支持从右到左的桌面，通常在实现subControlRect()函数时使用。

另请参见QWidget::layoutDirection。