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QStyleOption Class

The QStyleOption class stores the parameters used by QStyle functions.

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Publié le - Mis à jour le 27 décembre 2024 

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QStyleOption Class▲

Detailed Description▲

QStyleOption and its subclasses contain all the information that QStyle functions need to draw a graphical element.

For performance reasons, there are few member functions and the access to the member variables is direct (i.e., using the . or -> operator). This makes the structures straightforward to use and emphasizes that these are simply parameters used by the style functions.

The caller of a QStyle function usually creates QStyleOption objects on the stack. This combined with Qt's extensive use of implicit sharing for types such as QString, QPalette, and QColor ensures that no memory allocation needlessly takes place.

The following code snippet shows how to use a specific QStyleOption subclass to paint a push button:

 
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void MyPushButton::paintEvent(QPaintEvent *)
{
    QStyleOptionButton option;
    option.initFrom(this);
    option.state = isDown() ? QStyle::State_Sunken : QStyle::State_Raised;
    if (isDefault())
        option.features |= QStyleOptionButton::DefaultButton;
    option.text = text();
    option.icon = icon();

    QPainter painter(this);
    style()->drawControl(QStyle::CE_PushButton, &option, &painter, this);
}

In our example, the control is a QStyle::CE_PushButton, and according to the QStyle::drawControl() documentation the corresponding class is QStyleOptionButton.

When reimplementing QStyle functions that take a QStyleOption parameter, you often need to cast the QStyleOption to a subclass. For safety, you can use qstyleoption_cast() to ensure that the pointer type is correct. For example:

 
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void MyStyle::drawPrimitive(PrimitiveElement element,
                            const QStyleOption *option,
                            QPainter *painter,
                            const QWidget *widget)
{
    if (element == PE_FrameFocusRect) {
        const QStyleOptionFocusRect *focusRectOption =
                qstyleoption_cast<const QStyleOptionFocusRect *>(option);
        if (focusRectOption) {
            // ...
        }
    }
    // ...
}

The qstyleoption_cast() function will return 0 if the object to which option points is not of the correct type.

See Also▲

See also QStyle, QStylePainter

Member Type Documentation▲

 

enum QStyleOption::OptionType▲

This enum is used internally by QStyleOption, its subclasses, and qstyleoption_cast() to determine the type of style option. In general you do not need to worry about this unless you want to create your own QStyleOption subclass and your own styles.

Constant

Value

Description

QStyleOption::SO_Button

2

QStyleOptionButton

QStyleOption::SO_ComboBox

0xf0004

QStyleOptionComboBox

QStyleOption::SO_Complex

0xf0000

QStyleOptionComplex

QStyleOption::SO_Default

0

QStyleOption

QStyleOption::SO_DockWidget

9

QStyleOptionDockWidget

QStyleOption::SO_FocusRect

1

QStyleOptionFocusRect

QStyleOption::SO_Frame

5

QStyleOptionFrame

QStyleOption::SO_GraphicsItem

15

QStyleOptionGraphicsItem

QStyleOption::SO_GroupBox

0xf0006

QStyleOptionGroupBox

QStyleOption::SO_Header

8

QStyleOptionHeader

QStyleOption::SO_MenuItem

4

QStyleOptionMenuItem

QStyleOption::SO_ProgressBar

6

QStyleOptionProgressBar

QStyleOption::SO_RubberBand

13

QStyleOptionRubberBand

QStyleOption::SO_SizeGrip

0xf0007

QStyleOptionSizeGrip

QStyleOption::SO_Slider

0xf0001

QStyleOptionSlider

QStyleOption::SO_SpinBox

0xf0002

QStyleOptionSpinBox

QStyleOption::SO_Tab

3

QStyleOptionTab

QStyleOption::SO_TabBarBase

12

QStyleOptionTabBarBase

QStyleOption::SO_TabWidgetFrame

11

QStyleOptionTabWidgetFrame

QStyleOption::SO_TitleBar

0xf0005

QStyleOptionTitleBar

QStyleOption::SO_ToolBar

14

QStyleOptionToolBar

QStyleOption::SO_ToolBox

7

QStyleOptionToolBox

QStyleOption::SO_ToolButton

0xf0003

QStyleOptionToolButton

QStyleOption::SO_ViewItem

10

QStyleOptionViewItem (used in Interviews)

The following values are used for custom controls:

Constant

Value

Description

QStyleOption::SO_CustomBase

0xf00

Reserved for custom QStyleOptions; all custom controls values must be above this value

QStyleOption::SO_ComplexCustomBase

0xf000000

Reserved for custom QStyleOptions; all custom complex controls values must be above this value
See Also▲

See also type

enum QStyleOption::StyleOptionType▲

This enum is used to hold information about the type of the style option, and is defined for each QStyleOption subclass.

Constant

Value

Description

QStyleOption::Type

SO_Default

The type of style option provided (SO_Default for this class).

The type is used internally by QStyleOption, its subclasses, and qstyleoption_cast() to determine the type of style option. In general you do not need to worry about this unless you want to create your own QStyleOption subclass and your own styles.

See Also▲

See also StyleOptionVersion

enum QStyleOption::StyleOptionVersion▲

This enum is used to hold information about the version of the style option, and is defined for each QStyleOption subclass.

Constant

Value

Description

QStyleOption::Version

1

1

The version is used by QStyleOption subclasses to implement extensions without breaking compatibility. If you use qstyleoption_cast(), you normally do not need to check it.

See Also▲

See also StyleOptionType

Member Function Documentation▲

 

QStyleOption::QStyleOption(int version = QStyleOption::Version, int type = SO_Default)▲

Constructs a QStyleOption with the specified version and type.

The version has no special meaning for QStyleOption; it can be used by subclasses to distinguish between different version of the same option type.

The state member variable is initialized to QStyle::State_None.

See Also▲

See also version, type

QStyleOption::QStyleOption(const QStyleOption &other)▲

Constructs a copy of other.

QStyleOption::~QStyleOption()▲

Destroys this style option object.

void QStyleOption::initFrom(const QWidget *widget)▲

Initializes the state, direction, rect, palette, fontMetrics and styleObject member variables based on the specified widget.

This is a convenience function; the member variables can also be initialized manually.

See Also▲

See also QWidget::layoutDirection(), QWidget::rect(), QWidget::palette(), QWidget::fontMetrics()

QStyleOption &QStyleOption::operator=(const QStyleOption &other)▲

Assign other to this QStyleOption.

Member Variable Documentation▲

 

Qt::LayoutDirection QStyleOption::direction▲

This variable holds the text layout direction that should be used when drawing text in the control

By default, the layout direction is Qt::LeftToRight.

See Also▲

See also initFrom()

QFontMetrics QStyleOption::fontMetrics▲

This variable holds the font metrics that should be used when drawing text in the control

By default, the application's default font is used.

See Also▲

See also initFrom()

QPalette QStyleOption::palette▲

This variable holds the palette that should be used when painting the control

By default, the application's default palette is used.

See Also▲

See also initFrom()

QRect QStyleOption::rect▲

This variable holds the area that should be used for various calculations and painting

This can have different meanings for different types of elements. For example, for a QStyle::CE_PushButton element it would be the rectangle for the entire button, while for a QStyle::CE_PushButtonLabel element it would be just the area for the push button label.

The default value is a null rectangle, i.e. a rectangle with both the width and the height set to 0.

See Also▲

See also initFrom()

QStyle::State QStyleOption::state▲

This variable holds the style flags that are used when drawing the control

The default value is QStyle::State_None.

See Also▲

See also initFrom(), QStyle::drawPrimitive(), QStyle::drawControl(), QStyle::drawComplexControl(), QStyle::State

QObject * QStyleOption::styleObject▲

This variable holds the object being styled

The built-in styles support the following types: QWidget, QGraphicsObject and QQuickItem.

See Also▲

See also initFrom()

int QStyleOption::type▲

This variable holds the option type of the style option

The default value is SO_Default.

See Also▲

See also OptionType

int QStyleOption::version▲

This variable holds the version of the style option

This value can be used by subclasses to implement extensions without breaking compatibility. If you use the qstyleoption_cast() function, you normally do not need to check it.

The default value is 1.

Related Non-Members▲

 

T qstyleoption_cast(const QStyleOption *option)▲

Returns a T or nullptr depending on the type and version of the given option.

Example:

 
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void MyStyle::drawPrimitive(PrimitiveElement element,
                            const QStyleOption *option,
                            QPainter *painter,
                            const QWidget *widget)
{
    if (element == PE_FrameFocusRect) {
        const QStyleOptionFocusRect *focusRectOption =
                qstyleoption_cast<const QStyleOptionFocusRect *>(option);
        if (focusRectOption) {
            // ...
        }
    }
    // ...
}
See Also▲

See also QStyleOption::type, QStyleOption::version

T qstyleoption_cast(QStyleOption *option)▲

This is an overloaded function.

Returns a T or nullptr depending on the type of the given option.

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