Qt Namespace Reference
[QtCore module]

Detailed Description

The Qt namespace contains miscellaneous identifiers used throughout the Qt library.

Type Documentation

enum Qt::AlignmentFlag
flags Qt::Alignment

This enum type is used to describe alignment. It contains horizontal and vertical flags that can be combined to produce the required effect.

The TextElideMode enum can also be used in many situations to fine-tune the appearance of aligned text.

The horizontal flags are:

The vertical flags are:

You can use only one of the horizontal flags at a time. There is one two-dimensional flag:

You can use at most one horizontal and one vertical flag at a time. Qt::AlignCenter counts as both horizontal and vertical.

Three enum values are useful in applications that can be run in right-to-left mode:

Masks:

Conflicting combinations of flags have undefined meanings.

The Alignment type is a typedef for QFlags<AlignmentFlag>. It stores an OR combination of AlignmentFlag values.

enum Qt::AnchorAttribute

An anchor has one or more of the following attributes:

enum Qt::ApplicationAttribute

This enum describes attributes that change the behavior of application-wide features. These are enabled and disabled using QCoreApplication::setAttribute(), and can be tested for with QCoreApplication::testAttribute().

Menus that are currently open or menus already created in the native Mac OS X menubar MAY NOT pick up a change in this attribute. Changes in the QAction::iconVisibleInMenu property will always be picked up.

enum Qt::ArrowType

enum Qt::AspectRatioMode

This enum type defines what happens to the aspect ratio when scaling an rectangle.

See also QSize::scale() and QImage::scaled().

enum Qt::Axis

This enum type defines three values to represent the three axes in the cartesian coordinate system.

See also QTransform::rotate() and QTransform::rotateRadians().

enum Qt::BGMode

Background mode:

enum Qt::BrushStyle

This enum type defines the brush styles supported by Qt, i.e. the fill pattern of shapes drawn using QPainter.

See also QBrush.

enum Qt::CaseSensitivity

enum Qt::CheckState

This enum describes the state of checkable items, controls, and widgets.

See also QCheckBox, Qt::ItemFlags, and Qt::ItemDataRole.

enum Qt::ClipOperation

enum Qt::ConnectionType

This enum describes the types of connection that can be used between signals and slots. In particular, it determines whether a particular signal is delivered to a slot immediately or queued for delivery at a later time.

With queued connections, the parameters must be of types that are known to Qt's meta-object system, because Qt needs to copy the arguments to store them in an event behind the scenes. If you try to use a queued connection and get the error message

 QObject::connect: Cannot queue arguments of type 'MyType'

call qRegisterMetaType() to register the data type before you establish the connection.

See also Thread Support in Qt, QObject::connect(), and qRegisterMetaType().

enum Qt::ContextMenuPolicy

This enum type defines the various policies a widget can have with respect to showing a context menu.

enum Qt::Corner

This enum type specifies a corner in a rectangle:

enum Qt::CursorShape

This enum type defines the various cursors that can be used.

The standard arrow cursor is the default for widgets in a normal state.

Constant	Value	Description
Qt::ArrowCursor	0	The standard arrow cursor.
Qt::UpArrowCursor	1	An arrow pointing upwards toward the top of the screen.
Qt::CrossCursor	2	A crosshair cursor, typically used to help the user accurately select a point on the screen.
Qt::WaitCursor	3	An hourglass or watch cursor, usually shown during operations that prevent the user from interacting with the application.
Qt::IBeamCursor	4	A caret or ibeam cursor, indicating that a widget can accept and display text input.
Qt::SizeVerCursor	5	A cursor used for elements that are used to vertically resize top-level windows.
Qt::SizeHorCursor	6	A cursor used for elements that are used to horizontally resize top-level windows.
Qt::SizeBDiagCursor	7	A cursor used for elements that are used to diagonally resize top-level windows at their top-right and bottom-left corners.
Qt::SizeFDiagCursor	8	A cursor used for elements that are used to diagonally resize top-level windows at their top-left and bottom-right corners.
Qt::SizeAllCursor	9	A cursor used for elements that are used to resize top-level windows in any direction.
Qt::BlankCursor	10	A blank/invisible cursor, typically used when the cursor shape needs to be hidden.
Qt::SplitVCursor	11	A cursor used for vertical splitters, indicating that a handle can be dragged horizontally to adjust the use of available space.
Qt::SplitHCursor	12	A cursor used for horizontal splitters, indicating that a handle can be dragged vertically to adjust the use of available space.
Qt::PointingHandCursor	13	A pointing hand cursor that is typically used for clickable elements such as hyperlinks.
Qt::ForbiddenCursor	14	A slashed circle cursor, typically used during drag and drop operations to indicate that dragged content cannot be dropped on particular widgets or inside certain regions.
Qt::OpenHandCursor	17	A cursor representing an open hand, typically used to indicate that the area under the cursor is the visible part of a canvas that the user can click and drag in order to scroll around.
Qt::ClosedHandCursor	18	A cursor representing a closed hand, typically used to indicate that a dragging operation is in progress that involves scrolling.
Qt::WhatsThisCursor	15	An arrow with a question mark, typically used to indicate the presence of What's This? help for a widget.
Qt::BusyCursor	16	An hourglass or watch cursor, usually shown during operations that allow the user to interact with the application while they are performed in the background.
Qt::BitmapCursor	24

enum Qt::DateFormat

Note: For ISODate formats, each Y, M and D represents a single digit of the year, month and day used to specify the date. Each H, M and S represents a single digit of the hour, minute and second used to specify the time. The presence of a literal T character is used to separate the date and time when both are specified.

enum Qt::DayOfWeek

enum Qt::DockWidgetArea
flags Qt::DockWidgetAreas

The DockWidgetAreas type is a typedef for QFlags<DockWidgetArea>. It stores an OR combination of DockWidgetArea values.

enum Qt::DropAction
flags Qt::DropActions

The DropActions type is a typedef for QFlags<DropAction>. It stores an OR combination of DropAction values.

enum Qt::EventPriority

This enum can be used to specify event priorities.

Note that these values are provided purely for convenience, since event priorities can be any value between INT_MAX and INT_MIN, inclusive. For example, you can define custom priorities as being relative to each other:

 enum CustomEventPriority
 {
     // An important event
     ImportantEventPriority = Qt::HighEventPriority,

     // A more important event
     MoreImportantEventPriority = ImportantEventPriority + 1,

     // A critical event
     CriticalEventPriority = 100 * MoreImportantEventPriority,

     // Not that important
     StatusEventPriority = Qt::LowEventPriority,

     // These are less important than Status events
     IdleProcessingDoneEventPriority = StatusEventPriority - 1
 };

See also QCoreApplication::postEvent().

enum Qt::FillRule

Specifies which method should be used to fill the paths and polygons.

enum Qt::FocusPolicy

This enum type defines the various policies a widget can have with respect to acquiring keyboard focus.

enum Qt::FocusReason

This enum specifies why the focus changed. It will be passed through QWidget::setFocus and can be retrieved in the QFocusEvent sent to the widget upon focus change.

See also Keyboard Focus.

enum Qt::GlobalColor

Qt's predefined QColor objects:

See also QColor.

typedef Qt::HANDLE

Platform-specific handle type for system objects. This is equivalent to void * on Windows and Mac OS X, and embedded Linux, and to unsigned long on X11.

Warning: Using this type is not portable.

enum Qt::HitTestAccuracy

This enum contains the types of accuracy that can be used by the QTextDocument class when testing for mouse clicks on text documents.

This enum is defined in the <QTextDocument> header file.

enum Qt::ImageConversionFlag
flags Qt::ImageConversionFlags

The options marked "(default)" are set if no other values from the list are included (since the defaults are zero):

Color/Mono preference (ignored for QBitmap):

Dithering mode preference for RGB channels:

Dithering mode preference for alpha channel:

Color matching versus dithering preference:

The ImageConversionFlags type is a typedef for QFlags<ImageConversionFlag>. It stores an OR combination of ImageConversionFlag values.

enum Qt::InputMethodQuery

enum Qt::ItemDataRole

Each item in the model has a set of data elements associated with it, each with its own role. The roles are used by the view to indicate to the model which type of data it needs.

The general purpose roles are:

Roles describing appearance and meta data:

Accessibility roles:

User roles:

enum Qt::ItemFlag
flags Qt::ItemFlags

This enum describes the properties of an item:

Note that checkable items need to be given both a suitable set of flags and an initial state, indicating whether the item is checked or not. This is handled automatically for model/view components, but needs to be explicitly set for instances of QListWidgetItem, QTableWidgetItem, and QTreeWidgetItem.

The ItemFlags type is a typedef for QFlags<ItemFlag>. It stores an OR combination of ItemFlag values.

See also QAbstractItemModel.

enum Qt::ItemSelectionMode

This enum is used in QGraphicsItem, QGraphicsScene and QGraphicsView to specify how items are selected, or how to determine if a shapes and items collide.

See also QGraphicsScene::items(), QGraphicsScene::collidingItems(), QGraphicsView::items(), QGraphicsItem::collidesWithItem(), and QGraphicsItem::collidesWithPath().

enum Qt::Key

The key names used by Qt.

See also QKeyEvent::key().

enum Qt::KeyboardModifier
flags Qt::KeyboardModifiers

This enum describes the modifier keys.

Note: On Mac OS X, the ControlModifier value corresponds to the Command keys on the Macintosh keyboard, and the MetaModifier value corresponds to the Control keys. The KeypadModifier value will also be set when an arrow key is pressed as the arrow keys are considered part of the keypad.

Note: On Windows Keyboards, Qt::MetaModifier and Qt::Key_Meta are mapped to the Windows key.

The KeyboardModifiers type is a typedef for QFlags<KeyboardModifier>. It stores an OR combination of KeyboardModifier values.

See also MouseButton and Modifier.

enum Qt::LayoutDirection

Specifies the direction of Qt's layouts:

Right-to-left layouts are necessary for certain languages, notably Arabic and Hebrew.

See also QApplication::setLayoutDirection() and QWidget::setLayoutDirection().

enum Qt::MaskMode

This enum specifies the behavior of the QPixmap::createMaskFromColor() and QImage::createMaskFromColor() functions.

enum Qt::MatchFlag
flags Qt::MatchFlags

This enum describes the type of matches that can be used when searching for items in a model.

The MatchFlags type is a typedef for QFlags<MatchFlag>. It stores an OR combination of MatchFlag values.

See also QString::compare() and QRegExp.

enum Qt::Modifier

This enum provides shorter names for the keyboard modifier keys supported by Qt.

Note: On Mac OS X, the CTRL value corresponds to the Command keys on the Macintosh keyboard, and the META value corresponds to the Control keys.

See also KeyboardModifier and MouseButton.

enum Qt::MouseButton
flags Qt::MouseButtons

This enum type describes the different mouse buttons.

The MouseButtons type is a typedef for QFlags<MouseButton>. It stores an OR combination of MouseButton values.

See also KeyboardModifier and Modifier.

enum Qt::Orientation
flags Qt::Orientations

This type is used to signify an object's orientation.

Orientation is used with QScrollBar for example.

The Orientations type is a typedef for QFlags<Orientation>. It stores an OR combination of Orientation values.

enum Qt::PenCapStyle

This enum type defines the pen cap styles supported by Qt, i.e. the line end caps that can be drawn using QPainter.

Qt::SquareCap	Qt::FlatCap	Qt::RoundCap

See also QPen.

enum Qt::PenJoinStyle

This enum type defines the pen join styles supported by Qt, i.e. which joins between two connected lines can be drawn using QPainter.

Qt::BevelJoin	Qt::MiterJoin	Qt::RoundJoin

See also QPen.

enum Qt::PenStyle

This enum type defines the pen styles that can be drawn using QPainter. The styles are:

Qt::SolidLine	Qt::DashLine	Qt::DotLine
Qt::DashDotLine	Qt::DashDotDotLine	Qt::CustomDashLine

See also QPen.

enum Qt::ScrollBarPolicy

This enum type describes the various modes of QAbstractScrollArea's scroll bars.

(The modes for the horizontal and vertical scroll bars are independent.)

enum Qt::ShortcutContext

For a QEvent::Shortcut event to occur, the shortcut's key sequence must be entered by the user in a context where the shortcut is active. The possible contexts are these:

enum Qt::SizeHint

This enum is used by QGraphicsLayoutItem::sizeHint()

This enum was introduced in Qt 4.4.

See also QGraphicsLayoutItem::sizeHint().

enum Qt::SizeMode

This enum is used by QPainter::drawRoundedRect() and QPainterPath::addRoundedRect() functions to specify the radii of rectangle corners with respect to the dimensions of the bounding rectangles specified.

This enum was introduced in Qt 4.4.

enum Qt::SortOrder

This enum describes how the items in a widget are sorted.

enum Qt::TextElideMode

This enum specifies where the ellipsis should appear when displaying texts that don't fit:

Qt::ElideMiddle is normally the most appropriate choice for URLs (e.g., "http://www.troll...ovingto/beijing/"), whereas Qt::ElideRight is appropriate for other strings (e.g., "Deploying Applications on Ma...").

See also QAbstractItemView::textElideMode, QFontMetrics::elidedText(), AlignmentFlag, and QTabBar::elideMode.

enum Qt::TextFlag

This enum type is used to define some modifier flags. Some of these flags only make sense in the context of printing:

You can use as many modifier flags as you want, except that Qt::TextSingleLine and Qt::TextWordWrap cannot be combined.

Flags that are inappropriate for a given use are generally ignored.

enum Qt::TextFormat

This enum is used in widgets that can display both plain text and rich text, e.g. QLabel. It is used for deciding whether a text string should be interpreted as one or the other. This is normally done by passing one of the enum values to a setTextFormat() function.

enum Qt::TextInteractionFlag
flags Qt::TextInteractionFlags

This enum specifies how a text displaying widget reacts to user input.

The TextInteractionFlags type is a typedef for QFlags<TextInteractionFlag>. It stores an OR combination of TextInteractionFlag values.

enum Qt::TimeSpec

enum Qt::ToolBarArea
flags Qt::ToolBarAreas

The ToolBarAreas type is a typedef for QFlags<ToolBarArea>. It stores an OR combination of ToolBarArea values.

enum Qt::ToolButtonStyle

The style of the tool button, describing how the button's text and icon should be displayed.

enum Qt::TransformationMode

This enum type defines whether image transformations (e.g., scaling) should be smooth or not.

See also QImage::scaled().

enum Qt::UIEffect

This enum describes the available UI effects.

By default, Qt will try to use the platform specific desktop settings for each effect. Use the QApplication::setDesktopSettingsAware() function (passing false as argument) to prevent this, and the QApplication::setEffectEnabled() to enable or disable a particular effect.

Note that all effects are disabled on screens running at less than 16-bit color depth.

See also QApplication::setEffectEnabled() and QApplication::setDesktopSettingsAware().

typedef Qt::WFlags

Synonym for Qt::WindowFlags.

enum Qt::WhiteSpaceMode

This enum describes the types of whitespace mode that are used by the QTextDocument class to meet the requirements of different kinds of textual information.

This enum is defined in the <QTextDocument> header file.

enum Qt::WidgetAttribute

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