Contents

• Public Types
• Public Functions
• Static Public Members
• Protected Slots
• Detailed Description
• Setting a Style
• Developing Style-Aware Custom Widgets
• Creating a Custom Style
• Using a Custom Style
• Right-to-Left Desktops
• Styles in Item Views

Detailed Description

TheQStyle class is an abstract base class that encapsulates the look and feel of a GUI.

Qt contains a set ofQStyle subclasses that emulate the styles of the different platforms supported by Qt (QWindowsStyle,QMacStyle,QMotifStyle, etc.). By default, these styles are built into theQtGui library. Styles can also be made available as plugins.

Qt's built-in widgets useQStyle to perform nearly all of their drawing, ensuring that they look exactly like the equivalent native widgets. The diagram below shows aQComboBox in eight different styles.

Topics:

Setting a Style

The style of the entire application can be set using theQApplication::setStyle() function. It can also be specified by the user of the application, using the-style command-line option:

./myapplication-style motif

If no style is specified, Qt will choose the most appropriate style for the user's platform or desktop environment.

A style can also be set on an individual widget using theQWidget::setStyle() function.

Developing Style-Aware Custom Widgets

If you are developing custom widgets and want them to look good on all platforms, you can useQStyle functions to perform parts of the widget drawing, such asdrawItemText(),drawItemPixmap(),drawPrimitive(),drawControl(), anddrawComplexControl().

MostQStyle draw functions take four arguments:

• an enum value specifying which graphical element to draw
• aQStyleOption specifying how and where to render that element
• aQPainter that should be used to draw the element
• aQWidget on which the drawing is performed (optional)

For example, if you want to draw a focus rectangle on your widget, you can write:

void MyWidget::paintEvent(QPaintEvent*/* event */){QPainter painter(this);QStyleOptionFocusRect option;    option.initFrom(this);    option.backgroundColor= palette().color(QPalette::Background);    style()->drawPrimitive(QStyle::PE_FrameFocusRect,&option,&painter,this);}

QStyle gets all the information it needs to render the graphical element fromQStyleOption. The widget is passed as the last argument in case the style needs it to perform special effects (such as animated default buttons on Mac OS X), but it isn't mandatory. In fact, you can useQStyle to draw on any paint device, not just widgets, by setting theQPainter properly.

QStyleOption has various subclasses for the various types of graphical elements that can be drawn. For example,PE_FrameFocusRect expects aQStyleOptionFocusRect argument.

To ensure that drawing operations are as fast as possible,QStyleOption and its subclasses have public data members. See theQStyleOption class documentation for details on how to use it.

For convenience, Qt provides theQStylePainter class, which combines aQStyle, aQPainter, and aQWidget. This makes it possible to write

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

instead of

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

Creating a Custom Style

You can create a custom look and feel for your application by creating a custom style. There are two approaches to creating a custom style. In the static approach, you either choose an existingQStyle class, subclass it, and reimplement virtual functions to provide the custom behavior, or you create an entireQStyle class from scratch. In the dynamic approach, you modify the behavior of your system style at runtime. The static approach is described below. The dynamic approach is described inQProxyStyle.

The first step in the static approach is to pick one of the styles provided by Qt from which you will build your custom style. Your choice ofQStyle class will depend on which style resembles your desired style the most. The most general class that you can use as a base isQCommonStyle (notQStyle). This is because Qt requires its styles to beQCommonStyles.

Depending on which parts of the base style you want to change, you must reimplement the functions that are used to draw those parts of the interface. To illustrate this, we will modify the look of the spin box arrows drawn byQWindowsStyle. The arrows areprimitive elements that are drawn by thedrawPrimitive() function, so we need to reimplement that function. We need the following class declaration:

class CustomStyle :publicQWindowsStyle{    Q_OBJECTpublic:    CustomStyle()~CustomStyle() {}void drawPrimitive(PrimitiveElement element,constQStyleOption*option,QPainter*painter,constQWidget*widget)const;};

To draw its up and down arrows,QSpinBox uses thePE_IndicatorSpinUp andPE_IndicatorSpinDown primitive elements. Here's how to reimplement thedrawPrimitive() function to draw them differently:

void CustomStyle::drawPrimitive(PrimitiveElement element,constQStyleOption*option,QPainter*painter,constQWidget*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 {QWindowsStyle::drawPrimitive(element, option, painter, widget);    }}

Notice that we don't use thewidget argument, except to pass it on to the QWindowStyle::drawPrimitive() function. As mentioned earlier, the information about what is to be drawn and how it should be drawn is specified by aQStyleOption object, so there is no need to ask the widget.

If you need to use thewidget argument to obtain additional information, be careful to ensure that it isn't 0 and that it is of the correct type before using it. For example:

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

When implementing a custom style, you cannot assume that the widget is aQSpinBox just because the enum value is calledPE_IndicatorSpinUp orPE_IndicatorSpinDown.

The documentation for theStyles example covers this topic in more detail.

Warning: Qt style sheets are currently not supported for customQStyle subclasses. We plan to address this in some future release.

Using a Custom Style

There are several ways of using a custom style in a Qt application. The simplest way is to pass the custom style to theQApplication::setStyle() static function before creating theQApplication object:

#include <QtGui>#include "customstyle.h"int main(int argc,char*argv[]){QApplication::setStyle(new CustomStyle);QApplication app(argc, argv);QSpinBox spinBox;    spinBox.show();return app.exec();}

You can callQApplication::setStyle() at any time, but by calling it before the constructor, you ensure that the user's preference, set using the-style command-line option, is respected.

You may want to make your custom style available for use in other applications, which may not be yours and hence not available for you to recompile. The Qt Plugin system makes it possible to create styles as plugins. Styles created as plugins are loaded as shared objects at runtime by Qt itself. Please refer to theQt Plugin documentation for more information on how to go about creating a style plugin.

Compile your plugin and put it into Qt'splugins/styles directory. We now have a pluggable style that Qt can load automatically. To use your new style with existing applications, simply start the application with the following argument:

./myapplication-style custom

The application will use the look and feel from the custom style you implemented.

Right-to-Left Desktops

Languages written from right to left (such as Arabic and Hebrew) usually also mirror the whole layout of widgets, and require the light to come from the screen's top-right corner instead of top-left.

If you create a custom style, you should take special care when drawing asymmetric elements to make sure that they also look correct in a mirrored layout. An easy way to test your styles is to run applications with the-reverse command-line option or to callQApplication::setLayoutDirection() in yourmain() function.

Here are some things to keep in mind when making a style work well in a right-to-left environment:

• subControlRect() andsubElementRect() return rectangles in screen coordinates
• QStyleOption::direction indicates in which direction the item should be drawn in
• If a style is not right-to-left aware it will display items as if it were left-to-right
• visualRect(),visualPos(), andvisualAlignment() are helpful functions that will translate from logical to screen representations.
• alignedRect() will return a logical rect aligned for the current direction

Styles in Item Views

The painting of items in views is performed by a delegate. Qt's default delegate,QStyledItemDelegate, is also used for calculating bounding rectangles of items, and their sub-elements for the various kind of itemdata rolesQStyledItemDelegate supports. See theQStyledItemDelegate class description to find out which datatypes and roles are supported. You can read more about item data roles inModel/View Programming.

WhenQStyledItemDelegate paints its items, it drawsCE_ItemViewItem, and calculates their size withCT_ItemViewItem. Note also that it usesSE_ItemViewItemText to set the size of editors. When implementing a style to customize drawing of item views, you need to check the implementation ofQCommonStyle (and any other subclasses from which your style inherits). This way, you find out which and how other style elements are painted, and you can then reimplement the painting of elements that should be drawn differently.

We include a small example where we customize the drawing of item backgrounds.

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:QWindowsStyle::drawPrimitive(element, option, painter, widget);    }

The primitive elementPE_PanelItemViewItem is responsible for painting the background of items, and is called fromQCommonStyle's implementation ofCE_ItemViewItem.

To add support for drawing of new datatypes and item data roles, it is necessary to create a custom delegate. But if you only need to support the datatypes implemented by the default delegate, a custom style does not need an accompanying delegate. TheQStyledItemDelegate class description gives more information on custom delegates.

The drawing of item view headers is also done by the style, giving control over size of header items and row and column sizes.

Member Type Documentation

enum QStyle::ComplexControl

This enum describes the available complex controls. Complex controls have different behavior depending upon where the user clicks on them or which keys are pressed.

See alsoSubControl anddrawComplexControl().

enum QStyle::ContentsType

This enum describes the available contents types. These are used to calculate sizes for the contents of various widgets.

See alsosizeFromContents().

enum QStyle::ControlElement

This enum represents a control element. A control element is a part of a widget that performs some action or displays information to the user.

See alsodrawControl().

enum QStyle::PixelMetric

This enum describes the various available pixel metrics. A pixel metric is a style dependent size represented by a single pixel value.

The following values are obsolete:

See alsopixelMetric().

enum QStyle::PrimitiveElement

This enum describes the various primitive elements. A primitive element is a common GUI element, such as a checkbox indicator or button bevel.

See alsodrawPrimitive().

enum QStyle::RequestSoftwareInputPanel

This enum describes under what circumstances a software input panel will be requested by input capable widgets.

See alsoQEvent::RequestSoftwareInputPanel andQInputContext.

enum QStyle::StandardPixmap

This enum describes the available standard pixmaps. A standard pixmap is a pixmap that can follow some existing GUI style or guideline.

See alsostandardIcon().

enum QStyle::StateFlag
flags QStyle::State

This enum describes flags that are used when drawing primitive elements.

Note that not all primitives use all of these flags, and that the flags may mean different things to different items.

The State type is a typedef forQFlags<StateFlag>. It stores an OR combination of StateFlag values.

See alsodrawPrimitive().

enum QStyle::StyleHint

This enum describes the available style hints. A style hint is a general look and/or feel hint.

See alsostyleHint().

enum QStyle::SubControl
flags QStyle::SubControls

This enum describes the available sub controls. A subcontrol is a control element within a complex control (ComplexControl).

The SubControls type is a typedef forQFlags<SubControl>. It stores an OR combination of SubControl values.

See alsoComplexControl.

enum QStyle::SubElement

This enum represents a sub-area of a widget. Style implementations use these areas to draw the different parts of a widget.

See alsosubElementRect().

Member Function Documentation

QStyle::QStyle()

Constructs a style object.

[virtual]QStyle::~QStyle()

Destroys the style object.

[static]QRect QStyle::alignedRect(Qt::LayoutDirection direction,Qt::Alignment alignment, constQSize & size, constQRect & rectangle)

Returns a new rectangle of the specifiedsize that is aligned to the givenrectangle according to the specifiedalignment anddirection.

int QStyle::combinedLayoutSpacing(QSizePolicy::ControlTypes controls1,QSizePolicy::ControlTypes controls2,Qt::Orientation orientation,QStyleOption * option = 0,QWidget * widget = 0) const

Returns the spacing that should be used betweencontrols1 andcontrols2 in a layout.orientation specifies whether the controls are laid out side by side or stacked vertically. Theoption parameter can be used to pass extra information about the parent widget. Thewidget parameter is optional and can also be used ifoption is 0.

controls1 andcontrols2 are OR-combination of zero or morecontrol types.

This function is called by the layout system. It is used only ifPM_LayoutHorizontalSpacing orPM_LayoutVerticalSpacing returns a negative value.

This function was introduced in Qt 4.3.

See alsolayoutSpacing() andlayoutSpacingImplementation().

[pure virtual]void QStyle::drawComplexControl(ComplexControl control, constQStyleOptionComplex * option,QPainter * painter, constQWidget * widget = 0) const

Draws the givencontrol using the providedpainter with the style options specified byoption.

Thewidget argument is optional and can be used as aid in drawing the control.

Theoption parameter is a pointer to aQStyleOptionComplex object that can be cast to the correct subclass using theqstyleoption_cast() function. Note that therect member of the specifiedoption must be in logical coordinates. Reimplementations of this function should usevisualRect() to change the logical coordinates into screen coordinates before calling thedrawPrimitive() ordrawControl() function.

The table below is listing the complex control elements and their associated style option subclass. The style options contain all the parameters required to draw the controls, includingQStyleOption::state which holds thestyle flags that are used when drawing. The table also describes which flags that are set when casting the givenoption to the appropriate subclass.

See alsodrawPrimitive() anddrawControl().

[pure virtual]void QStyle::drawControl(ControlElement element, constQStyleOption * option,QPainter * painter, constQWidget * widget = 0) const

Draws the givenelement with the providedpainter with the style options specified byoption.

Thewidget argument is optional and can be used as aid in drawing the control. Theoption parameter is a pointer to aQStyleOption object that can be cast to the correct subclass using theqstyleoption_cast() function.

The table below is listing the control elements and their associated style option subclass. The style options contain all the parameters required to draw the controls, includingQStyleOption::state which holds the style flags that are used when drawing. The table also describes which flags that are set when casting the given option to the appropriate subclass.

Note that if a control element is not listed here, it is because it uses a plainQStyleOption object.

See alsodrawPrimitive() anddrawComplexControl().

[virtual]void QStyle::drawItemPixmap(QPainter * painter, constQRect & rectangle,int alignment, constQPixmap & pixmap) const

Draws the givenpixmap in the specifiedrectangle, according to the specifiedalignment, using the providedpainter.

See alsodrawItemText().

[virtual]void QStyle::drawItemText(QPainter * painter, constQRect & rectangle,int alignment, constQPalette & palette,bool enabled, constQString & text,QPalette::ColorRole textRole = QPalette::NoRole) const

Draws the giventext in the specifiedrectangle using the providedpainter andpalette.

The text is drawn using the painter's pen, and aligned and wrapped according to the specifiedalignment. If an explicittextRole is specified, the text is drawn using thepalette's color for the given role. Theenabled parameter indicates whether or not the item is enabled; when reimplementing this function, theenabled parameter should influence how the item is drawn.

See alsoQt::Alignment anddrawItemPixmap().

[pure virtual]void QStyle::drawPrimitive(PrimitiveElement element, constQStyleOption * option,QPainter * painter, constQWidget * widget = 0) const

Draws the given primitiveelement with the providedpainter using the style options specified byoption.

Thewidget argument is optional and may contain a widget that may aid in drawing the primitive element.

The table below is listing the primitive elements and their associated style option subclasses. The style options contain all the parameters required to draw the elements, includingQStyleOption::state which holds the style flags that are used when drawing. The table also describes which flags that are set when casting the given option to the appropriate subclass.

Note that if a primitive element is not listed here, it is because it uses a plainQStyleOption object.

See alsodrawComplexControl() anddrawControl().

[pure virtual]QPixmap QStyle::generatedIconPixmap(QIcon::Mode iconMode, constQPixmap & pixmap, constQStyleOption * option) const

Returns a copy of the givenpixmap, styled to conform to the specifiediconMode and taking into account the palette specified byoption.

Theoption parameter can pass extra information, but it must contain a palette.

Note that not all pixmaps will conform, in which case the returned pixmap is a plain copy.

See alsoQIcon.

[pure virtual]SubControl QStyle::hitTestComplexControl(ComplexControl control, constQStyleOptionComplex * option, constQPoint & position, constQWidget * widget = 0) const

Returns the sub control at the givenposition in the given complexcontrol (with the style options specified byoption).

Note that theposition is expressed in screen coordinates.

Theoption argument is a pointer to aQStyleOptionComplex object (or one of its subclasses). The object can be cast to the appropriate type using theqstyleoption_cast() function. SeedrawComplexControl() for details. Thewidget argument is optional and can contain additional information for the function.

See alsodrawComplexControl() andsubControlRect().

[virtual]QRect QStyle::itemPixmapRect(constQRect & rectangle,int alignment, constQPixmap & pixmap) const

Returns the area within the givenrectangle in which to draw the specifiedpixmap according to the definedalignment.

[virtual]QRect QStyle::itemTextRect(constQFontMetrics & metrics, constQRect & rectangle,int alignment,bool enabled, constQString & text) const

Returns the area within the givenrectangle in which to draw the providedtext according to the specified fontmetrics andalignment. Theenabled parameter indicates whether or not the associated item is enabled.

If the givenrectangle is larger than the area needed to render thetext, the rectangle that is returned will be offset withinrectangle according to the specifiedalignment. For example, ifalignment isQt::AlignCenter, the returned rectangle will be centered withinrectangle. If the givenrectangle is smaller than the area needed, the returned rectangle will be the smallest rectangle large enough to render thetext.

See alsoQt::Alignment.

int QStyle::layoutSpacing(QSizePolicy::ControlType control1,QSizePolicy::ControlType control2,Qt::Orientation orientation, constQStyleOption * option = 0, constQWidget * widget = 0) const

Returns the spacing that should be used betweencontrol1 andcontrol2 in a layout.orientation specifies whether the controls are laid out side by side or stacked vertically. Theoption parameter can be used to pass extra information about the parent widget. Thewidget parameter is optional and can also be used ifoption is 0.

This function is called by the layout system. It is used only ifPM_LayoutHorizontalSpacing orPM_LayoutVerticalSpacing returns a negative value.

For binary compatibility reasons, this function is not virtual. If you want to specify custom layout spacings in aQStyle subclass, implement a slot calledlayoutSpacingImplementation().QStyle will discover the slot at run-time (using Qt'smeta-object system) and direct all calls to layoutSpacing() tolayoutSpacingImplementation().

This function was introduced in Qt 4.3.

See alsocombinedLayoutSpacing() andlayoutSpacingImplementation().

[protected slot]int QStyle::layoutSpacingImplementation(QSizePolicy::ControlType control1,QSizePolicy::ControlType control2,Qt::Orientation orientation, constQStyleOption * option = 0, constQWidget * widget = 0) const

This slot is called bylayoutSpacing() to determine the spacing that should be used betweencontrol1 andcontrol2 in a layout.orientation specifies whether the controls are laid out side by side or stacked vertically. Theoption parameter can be used to pass extra information about the parent widget. Thewidget parameter is optional and can also be used ifoption is 0.

If you want to provide custom layout spacings in aQStyle subclass, implement a slot called layoutSpacingImplementation() in your subclass. Be aware that this slot will only be called ifPM_LayoutHorizontalSpacing orPM_LayoutVerticalSpacing returns a negative value.

The default implementation returns -1.

This function was introduced in Qt 4.3.

See alsolayoutSpacing() andcombinedLayoutSpacing().

[pure virtual]int QStyle::pixelMetric(PixelMetric metric, constQStyleOption * option = 0, constQWidget * widget = 0) const

Returns the value of the given pixelmetric.

The specifiedoption andwidget can be used for calculating the metric. In general, thewidget argument is not used. Theoption can be cast to the appropriate type using theqstyleoption_cast() function. Note that theoption may be zero even for PixelMetrics that can make use of it. See the table below for the appropriateoption casts:

Some pixel metrics are called from widgets and some are only called internally by the style. If the metric is not called by a widget, it is the discretion of the style author to make use of it. For some styles, this may not be appropriate.

[virtual]void QStyle::polish(QWidget * widget)

Initializes the appearance of the givenwidget.

This function is called for every widget at some point after it has been fully created but justbefore it is shown for the very first time.

Note that the default implementation does nothing. Reasonable actions in this function might be to call theQWidget::setBackgroundMode() function for the widget. Do not use the function to set, for example, the geometry. Reimplementing this function provides a back-door through which the appearance of a widget can be changed, but with Qt's style engine it is rarely necessary to implement this function; reimplementdrawItemPixmap(),drawItemText(),drawPrimitive(), etc. instead.

TheQWidget::inherits() function may provide enough information to allow class-specific customizations. But because newQStyle subclasses are expected to work reasonably with all current andfuture widgets, limited use of hard-coded customization is recommended.

See alsounpolish().

[virtual]void QStyle::polish(QApplication * application)

This is an overloaded function.

Late initialization of the givenapplication object.

[virtual]void QStyle::polish(QPalette & palette)

This is an overloaded function.

Changes thepalette according to style specific requirements for color palettes (if any).

See alsoQPalette andQApplication::setPalette().

constQStyle * QStyle::proxy() const

This function returns the current proxy for this style. By default most styles will return themselves. However when a proxy style is in use, it will allow the style to call back into its proxy.

This function was introduced in Qt 4.6.

[pure virtual]QSize QStyle::sizeFromContents(ContentsType type, constQStyleOption * option, constQSize & contentsSize, constQWidget * widget = 0) const

Returns the size of the element described by the specifiedoption andtype, based on the providedcontentsSize.

Theoption argument is a pointer to aQStyleOption or one of its subclasses. Theoption can be cast to the appropriate type using theqstyleoption_cast() function. Thewidget is an optional argument and can contain extra information used for calculating the size.

See the table below for the appropriateoption casts:

See alsoContentsType andQStyleOption.

[static]int QStyle::sliderPositionFromValue(int min,int max,int logicalValue,int span,bool upsideDown = false)

Converts the givenlogicalValue to a pixel position. Themin parameter maps to 0,max maps tospan and other values are distributed evenly in-between.

This function can handle the entire integer range without overflow, providing thatspan is less than 4096.

By default, this function assumes that the maximum value is on the right for horizontal items and on the bottom for vertical items. Set theupsideDown parameter to true to reverse this behavior.

See alsosliderValueFromPosition().

[static]int QStyle::sliderValueFromPosition(int min,int max,int position,int span,bool upsideDown = false)

Converts the given pixelposition to a logical value. 0 maps to themin parameter,span maps tomax and other values are distributed evenly in-between.

This function can handle the entire integer range without overflow.

By default, this function assumes that the maximum value is on the right for horizontal items and on the bottom for vertical items. Set theupsideDown parameter to true to reverse this behavior.

See alsosliderPositionFromValue().

QIcon QStyle::standardIcon(StandardPixmap standardIcon, constQStyleOption * option = 0, constQWidget * widget = 0) const

Returns an icon for the givenstandardIcon.

ThestandardIcon is a standard pixmap which can follow some existing GUI style or guideline. Theoption argument can be used to pass extra information required when defining the appropriate icon. Thewidget argument is optional and can also be used to aid the determination of the icon.

Warning: Because of binary compatibility constraints, this function is not virtual. If you want to provide your own icons in aQStyle subclass, reimplement thestandardIconImplementation() slot in your subclass instead. The standardIcon() function will dynamically detect the slot and call it.

This function was introduced in Qt 4.1.

See alsostandardIconImplementation().

[protected slot]QIcon QStyle::standardIconImplementation(StandardPixmap standardIcon, constQStyleOption * option = 0, constQWidget * widget = 0) const

Returns an icon for the givenstandardIcon.

Reimplement this slot to provide your own icons in aQStyle subclass; because of binary compatibility constraints, thestandardIcon() function (introduced in Qt 4.1) is not virtual. Instead,standardIcon() will dynamically detect and callthis slot.

ThestandardIcon is a standard pixmap which can follow some existing GUI style or guideline. Theoption argument can be used to pass extra information required when defining the appropriate icon. Thewidget argument is optional and can also be used to aid the determination of the icon.

This function was introduced in Qt 4.1.

See alsostandardIcon().

[virtual]QPalette QStyle::standardPalette() const

Returns the style's standard palette.

Note that on systems that support system colors, the style's standard palette is not used. In particular, the Windows XP, Vista, and Mac styles do not use the standard palette, but make use of native theme engines. With these styles, you should not set the palette with QApplication::setStandardPalette().

[pure virtual]int QStyle::styleHint(StyleHint hint, constQStyleOption * option = 0, constQWidget * widget = 0,QStyleHintReturn * returnData = 0) const

Returns an integer representing the specified stylehint for the givenwidget described by the provided styleoption.

returnData is used when the querying widget needs more detailed data than the integer that styleHint() returns. See theQStyleHintReturn class description for details.

[pure virtual]QRect QStyle::subControlRect(ComplexControl control, constQStyleOptionComplex * option,SubControl subControl, constQWidget * widget = 0) const

Returns the rectangle containing the specifiedsubControl of the given complexcontrol (with the style specified byoption). The rectangle is defined in screen coordinates.

Theoption argument is a pointer toQStyleOptionComplex or one of its subclasses, and can be cast to the appropriate type using theqstyleoption_cast() function. SeedrawComplexControl() for details. Thewidget is optional and can contain additional information for the function.

See alsodrawComplexControl().

[pure virtual]QRect QStyle::subElementRect(SubElement element, constQStyleOption * option, constQWidget * widget = 0) const

Returns the sub-area for the givenelement as described in the provided styleoption. The returned rectangle is defined in screen coordinates.

Thewidget argument is optional and can be used to aid determining the area. TheQStyleOption object can be cast to the appropriate type using theqstyleoption_cast() function. See the table below for the appropriateoption casts:

[virtual]void QStyle::unpolish(QWidget * widget)

Uninitialize the givenwidget's appearance.

This function is the counterpart topolish(). It is called for every polished widget whenever the style is dynamically changed; the former style has to unpolish its settings before the new style can polish them again.

Note that unpolish() will only be called if the widget is destroyed. This can cause problems in some cases, e.g, if you remove a widget from the UI, cache it, and then reinsert it after the style has changed; some of Qt's classes cache their widgets.

See alsopolish().

[virtual]void QStyle::unpolish(QApplication * application)

This is an overloaded function.

Uninitialize the givenapplication.

[static]Qt::Alignment QStyle::visualAlignment(Qt::LayoutDirection direction,Qt::Alignment alignment)

Transforms analignment ofQt::AlignLeft orQt::AlignRight withoutQt::AlignAbsolute intoQt::AlignLeft orQt::AlignRight withQt::AlignAbsolute according to the layoutdirection. The other alignment flags are left untouched.

If no horizontal alignment was specified, the function returns the default alignment for the given layoutdirection.

QWidget::layoutDirection

[static]QPoint QStyle::visualPos(Qt::LayoutDirection direction, constQRect & boundingRectangle, constQPoint & logicalPosition)

Returns the givenlogicalPosition converted to screen coordinates based on the specifieddirection. TheboundingRectangle is used when performing the translation.

See alsoQWidget::layoutDirection.

[static]QRect QStyle::visualRect(Qt::LayoutDirection direction, constQRect & boundingRectangle, constQRect & logicalRectangle)

Returns the givenlogicalRectangle converted to screen coordinates based on the specifieddirection. TheboundingRectangle is used when performing the translation.

This function is provided to support right-to-left desktops, and is typically used in implementations of thesubControlRect() function.

See alsoQWidget::layoutDirection.