StackLayout

Since: BlackBerry 10.0.0

#include <bb/cascades/StackLayout>

A layout that is used to position a container's children in a stack.

The stack can be either vertical or horizontal, depending on the orientation. The default orientation is LayoutOrientation::TopToBottom. The StackLayoutProperties class contains additional layout properties that you can set on the individual children within the Container.

By using the Control::horizontalAlignment and Control::verticalAlignment properties you can specify where controls are positioned horizontally (left, center, or right) and vertically (top, center, bottom) within the containers area in the StackLayout. Controls can also be expanded/contracted to fill the container in a specified direction.

In cases where children must not extend outside a container's borders, the padding property can be used to create some separation between the boundary of the container and its child controls. Each boundary of a container (left, right, top and bottom) can have a different value set on it.

For example, setting the left padding to 10 would mean that the left-most 10 pixels of the layout container will not be available to the child controls.

In the following examples, a StackLayout is used to position some buttons in a vertical stack, centered on the screen.

QML:

Container {
    layout: StackLayout {}

    Button {
        text: "Button1"
        layoutProperties: StackLayoutProperties {}
        horizontalAlignment: HorizontalAlignment.Center
    }
    Button {
        text: "Button2"
        layoutProperties: StackLayoutProperties {}
        horizontalAlignment: HorizontalAlignment.Center
    }
    Button {
        text: "Button3"
        layoutProperties: StackLayoutProperties {}
        horizontalAlignment: HorizontalAlignment.Center
    }               
}

C++:

Container* pContainer = new Container();
StackLayout *pStackLayout = new StackLayout();
pStackLayout->setOrientation( LayoutOrientation::TopToBottom );
pContainer->setLayout(pStackLayout);

Button* pButton1 = Button::create().text("Button1");
Button* pButton2 = Button::create().text("Button2");
Button* pButton3 = Button::create().text("Button3");

pButton1->setLayoutProperties( StackLayoutProperties::create()
        .horizontal( HorizontalAlignment::Center ) );
pButton2->setLayoutProperties( StackLayoutProperties::create()
        .horizontal( HorizontalAlignment::Center ) );
pButton3->setLayoutProperties( StackLayoutProperties::create()
        .horizontal( HorizontalAlignment::Center ) );

pContainer->add( pButton1 );
pContainer->add( pButton2 );
pContainer->add( pButton3 );

Overview

Inheritance

bb::cascades::BaseObject
bb::cascades::UIObject
bb::cascades::Layout
bb::cascades::StackLayout

QML properties

orientation: bb::cascades::LayoutOrientation::Type
attachedObjects: QDeclarativeListProperty< QObject > [read-only]Inherited
objectName: QStringInherited
parent: QObject [read-only]Inherited

QML signals

onOrientationChanged: {}
onCreationCompletedInherited: {}
onObjectNameChangedInherited: {}

Properties Index

bb::cascades::LayoutOrientation::Typeorientation
QDeclarativeListProperty< QObject >attachedObjects [read-only]Inherited
QStringobjectNameInherited
QObjectparent [read-only]Inherited

Public Functions Index

StackLayout ()
virtual ~StackLayout ()
bb::cascades::LayoutOrientation::Typeorientation () const
Q_SLOT voidresetOrientation ()
Q_SLOT voidsetOrientation (bb::cascades::LayoutOrientation::Type orientation)
virtual boolevent (QEvent *event)Inherited
voidsetObjectName (const QString &name)Inherited
virtual Q_INVOKABLE QStringtoDebugString () const Inherited

Static Public Functions Index

Buildercreate ()

Protected Functions Index

Only has inherited protected functions

BaseObject (QObject *parent=0)Inherited
virtual voidconnectNotify (const char *signal)Inherited
virtual voiddisconnectNotify (const char *signal)Inherited

Signals Index

voidorientationChanged (bb::cascades::LayoutOrientation::Type newOrientation)
voidcreationCompleted ()Inherited
voidobjectNameChanged (const QString &objectName)Inherited

Properties

bb::cascades::LayoutOrientation::Type orientation

The orientation for the stack layout.

The default value is Default

QML example for a Container with a left-to-right StackLayout: 
Container {
    layout: StackLayout {
        orientation: LayoutOrientation.LeftToRight;
    }
}
The default orientation is TopToBottom, but LeftToRight, RightToLeft, and BottomToTop can also be used.
See also:

LayoutOrientation

Since:

BlackBerry 10.0.0

QDeclarativeListProperty< QObject > attachedObjectsInherited[read-only]

A hierarchical list of the UIObject's attached objects.

This QDeclarativeListProperty can contain any QObject. When a QObject is added to property, the UIObject takes ownership of the attached object.

This feature is typically used from QML to specify business logic object or any other shared objects for the subnodes of this UIObject. In C++ the same functionality can be achived by setting a parent of a QObject to be attached to the QObject which is going to own it.

QML usage example (MyObject is a custom class registered for QML using the qmlRegisterType() function):

Container {
    Label { text: "Title: " + myObject.title } 
    Label { text: "Subject: " + myObject.subject }
    attachedObjects: [
        MyObject { id: myObject
            title: "Hello World"
            subject: "Nice Day"
        }
    ]
}

Since:

BlackBerry 10.0.0

QString objectNameInherited

This property is overridden from QObject.

As the objectName property is overridden from the QObject class, this signal will not be emitted if setObjectName() function is called directly on QObject.

The default value of this property is QString::null.

See also:

QObject::objectName().

Since:

BlackBerry 10.0.0

QObject parentInherited[read-only]

A read-only property that represents this object's parent.

The parent of an object is specified using QObject::setParent(QObject*). The purpose of the property is to expose the object's parent to QML.

This property is read-only to prevent modifications from QML, where typically the parent is declaratively set. In C++ code, the parent can be explicitly set using QObject::setParent(QObject*), or implicitly set by adding it to a visual container.

The default value of this property is 0.

Since:

BlackBerry 10.0.0

Public Functions

StackLayout ()

Constructs a StackLayout object.

When you set a layout on a container using Container::setLayout the container assumes ownership of this instance.

Since:

BlackBerry 10.0.0

virtual~StackLayout ()

Destructor.

bb::cascades::LayoutOrientation::Type orientation ()

Returns the orientation for the stack layout.

Return:

The orientation.

Since:

BlackBerry 10.0.0

Q_SLOT void resetOrientation ()

Resets the orientation to its default.

The default orientation is LayoutOrientation::TopToBottom.

After the orientation is reset, the orientationChanged() signal is emitted.

Since:

BlackBerry 10.0.0

Q_SLOT void setOrientation (

Sets the orientation for the stack layout.

After the orientation is set, the orientationChanged() signal is emitted.

Parameters
orientation

The new orientation.
Since:

BlackBerry 10.0.0

virtual bool event (Inherited

Overloaded to implement the event mechanism in Cascades.

Warning!

If this function is overridden, it must be called by the derived class for events to work properly in Cascades.

Parameters
event

The received event.

Return:

True if the received event was recognized and processed, false otherwise.

Since:

BlackBerry 10.0.0

void setObjectName (Inherited

Sets the objectName property.

Parameters
name

The new name for the object.
Since:

BlackBerry 10.0.0

virtual Q_INVOKABLE QString toDebugString ()Inherited

Returns a debug string representing this object.

Return:

A debug string for the object.

Since:

BlackBerry 10.0.0

Static Public Functions

Builder create ()

Creates and returns a builder for constructing a stack layout.

Using the builder to create a stack layout: 
StackLayout* stackLayout = StackLayout::create()
        .orientation(LayoutOrientation::LeftToRight);
Return:

A builder used for constructing a stack layout.

Since:

BlackBerry 10.0.0

Protected Functions

(Only has inherited protected functions)

BaseObject (Inherited

Constructs an instance of BaseObject's subclass.

Parameters
parent

An optional parent, defaults to 0.
Since:

BlackBerry 10.0.0

virtual void connectNotify (
  • const char *signal)
Inherited

Overloaded to implement the event mechanism in Cascades.

If this function is overridden, it must be called by the derived class for events to work properly in Cascades.

Parameters
signal

The connected signal.
Since:

BlackBerry 10.0.0

virtual void disconnectNotify (
  • const char *signal)
Inherited

Overloaded to implement the event mechanism in Cascades.

If this function is overridden, it must be called by the derived class for events to work properly in Cascades.

Parameters
signal

The disconnected signal.
Since:

BlackBerry 10.0.0

Signals

void orientationChanged (

Emitted when the orientation property changes.

Note:

Due to a work around for a Qt Core issue with accessing enums from QML the argument of this signal doesn't follow naming convention for signals in which the signal arguments are typically named to match the associated property's name. Use the object's property to access current property value instead of the signal argument to avoid runtime errors (i.e. use orientation instead of newOrientation).

Parameters
newOrientation

The new orientation.
Since:

BlackBerry 10.0.0

void creationCompleted ()Inherited

This signal is emitted only when this object is instantiated as a result of loading a QML document and creating the root node, or when an object is being constructed using its builder class.

This signal is emitted only when this object is instantiated as a result of loading a QML document and creating the root node (only after the root component that caused this instantiation has completed construction), or when the object is being constructed from its builder class. This signal is emitted to indicate that the construction and initialization of the object has been completed, the properties are initialized, and any QML binding values have been assigned to the object.

This signal is not emitted when the object is constructed from C++ using the constructor. If the object is constructed using its builder class, the signal is emitted when the the builder class returns the fully constructed object.

This signal can be used when there is an activity that needs to be performed, such as a property state integrity verification after the object is instantiated from a QML document or a builder, but before control is returned to the application.

See also:

QmlDocument

Since:

BlackBerry 10.0.0

void objectNameChanged (Inherited

This signal is emitted when the objectName property is changed.

See also:

QObject, BaseObject::objectName.

Since:

BlackBerry 10.0.0

Last modified: 2014-03-13

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