Contents

• Public Types
• Properties
• Public Functions
• Signals
• Protected Functions
• Detailed Description

Detailed Description

TheQDeclarativeItem class provides the most basic of all visual items in QML.

All visual items in Qt Declarative inherit fromQDeclarativeItem. AlthoughQDeclarativeItem has no visual appearance, it defines all the properties that are common across visual items - such as the x and y position, the width and height,anchoring and key handling.

You can subclassQDeclarativeItem to provide your own custom visual item that inherits these features. Note that, because it does not draw anything,QDeclarativeItem sets theQGraphicsItem::ItemHasNoContents flag. If you subclassQDeclarativeItem to create a visual item, you will need to unset this flag.

Member Type Documentation

enum QDeclarativeItem::TransformOrigin

Controls the point about which simple transforms like scale apply.

Property Documentation

baselineOffset :qreal

This property holds the position of the item's baseline in local coordinates.

The baseline of aText item is the imaginary line on which the text sits. Controls containing text usually set their baseline to the baseline of their text.

For non-text items, a default baseline offset of 0 is used.

Access functions:

childrenRect : constQRectF

This property holds the geometry of an item's children.

This property holds the (collective) position and size of the item's children.

Access functions:

clip :bool

This property holds whether clipping is enabled. The default clip value isfalse.

If clipping is enabled, an item will clip its own painting, as well as the painting of its children, to its bounding rectangle. If you set clipping during an item's paint operation, remember to re-set it to prevent clipping the rest of your scene.

Non-rectangular clipping regions are not supported for performance reasons.

Access functions:

implicitHeight : constqreal

Access functions:

Notifier signal:

implicitWidth : constqreal

Access functions:

Notifier signal:

parent :QDeclarativeItem *

This property holds the parent of the item.

Access functions:

Notifier signal:

smooth :bool

This property holds whether the item is smoothly transformed.

This property is provided purely for the purpose of optimization. Turning smooth transforms off is faster, but looks worse; turning smooth transformations on is slower, but looks better.

By default smooth transformations are off.

Access functions:

Member Function Documentation

QDeclarativeItem::QDeclarativeItem(QDeclarativeItem * parent = 0)

Constructs aQDeclarativeItem with the givenparent.

[virtual]QDeclarativeItem::~QDeclarativeItem()

Destroys theQDeclarativeItem.

QDeclarativeItem * QDeclarativeItem::childAt(qreal x,qreal y) const

Returns the visible child item at point (x,y), which is in this item's coordinate system, or 0 if there is no such item.

void QDeclarativeItem::forceActiveFocus()

Forces active focus on the item.

This method sets focus on the item and makes sure that all the focus scopes higher in the object hierarchy are also given the focus.

[virtual protected]void QDeclarativeItem::geometryChanged(constQRectF & newGeometry, constQRectF & oldGeometry)

This function is called to handle this item's changes in geometry fromoldGeometry tonewGeometry. If the two geometries are the same, it doesn't do anything.

[protected]bool QDeclarativeItem::heightValid() const

Returns whether the height property has been set explicitly.

[protected]bool QDeclarativeItem::isComponentComplete() const

Returns true if construction of the QML component is complete; otherwise returns false.

It is often desirable to delay some processing until the component is completed.

See alsocomponentComplete().

bool QDeclarativeItem::keepMouseGrab() const

Returns a value indicating whether mouse input should remain with this item exclusively.

See alsosetKeepMouseGrab().

QScriptValue QDeclarativeItem::mapFromItem(constQScriptValue & item,qreal x,qreal y) const

Maps the point (x,y), which is initem's coordinate system, to this item's coordinate system, and returns a script value withx andy properties matching the mapped cooordinate.

Ifitem is anull value, this maps the point from the coordinate system of the root QML view.

See alsoItem::mapFromItem().

QScriptValue QDeclarativeItem::mapToItem(constQScriptValue & item,qreal x,qreal y) const

Maps the point (x,y), which is in this item's coordinate system, toitem's coordinate system, and returns a script value withx andy properties matching the mapped cooordinate.

Ifitem is anull value, this mapsx andy to the coordinate system of the root QML view.

See alsoItem::mapToItem().

[protected]void QDeclarativeItem::setImplicitHeight(qreal h)

Sets the implied height of the item toh. This is the height implied by other properties that determine the content.

See alsoimplicitHeight().

[protected]void QDeclarativeItem::setImplicitWidth(qreal w)

Sets the implied width of the item tow. This is the width implied by other properties that determine the content.

See alsoimplicitWidth().

void QDeclarativeItem::setKeepMouseGrab(bool keep)

The flag indicating whether the mouse should remain with this item is set tokeep.

This is useful for items that wish to grab and keep mouse interaction following a predefined gesture. For example, an item that is interested in horizontal mouse movement may setkeepMouseGrab to true once a threshold has been exceeded. OncekeepMouseGrab has been set to true, filtering items will not react to mouse events.

If the item does not indicate that it wishes to retain mouse grab, a filtering item may steal the grab. For example, Flickable may attempt to steal a mouse grab if it detects that the user has begun to move the viewport.

See alsokeepMouseGrab().

void QDeclarativeItem::setTransformOrigin(TransformOrigin origin)

Set the transformorigin.

See alsotransformOrigin().

TransformOrigin QDeclarativeItem::transformOrigin() const

Returns the current transform origin.

See alsosetTransformOrigin().

[protected]bool QDeclarativeItem::widthValid() const

Returns whether the width property has been set explicitly.