Class “Composite”

Object > NativeObject > Widget > Composite

An empty widget that can contain other widgets.

Composite on Android
Android
Composite on iOS
iOS
Type: Composite<ChildType> extends Widget
Generics: ChildType: The common widget class of the children this composite can contain. Must be a subclass of Widget and defaults to Widget.
Constructor: public
Singleton: No
Namespace: tabris
Direct subclasses: Canvas, Cell, CollectionView, ContentView, NavigationView, Page, RefreshComposite, Row, ScrollView, Stack, Tab, TabFolder
JSX Support: Element: <Composite/>
Parent Elements: <Canvas/>, <Cell/>, <Composite/>, <Page/>, <RefreshComposite/>, <Row/>, <ScrollView/>, <Stack/>, <Tab/>
Child Elements: Any standalone widget element

Examples

JavaScript

import {Composite, contentView} from 'tabris';

new Composite({left: 0, top: 0, width: 128, height: 256})
  .appendTo(contentView);

See also:

JSX Creating a simple Composite
TSX composite-apply-jsx.tsx
TS composite-apply.ts

Constructor

new Composite(properties?)

Parameter Type Description
properties Properties<Composite> Sets all key-value pairs in the properties object as widget properties. Optional.

Methods

append(…widgets)

Adds the given widgets to the composite.

Parameter Type Description
…widgets Widget[]  

Returns: this

append(widgets)

Adds all widgets in the given array to the composite.

Parameter Type Description
widgets Widget[]  

Returns: this

append(widgets)

Adds all widgets in the given collection to the composite.

Parameter Type Description
widgets WidgetCollection  

Returns: this

apply(options, rules)

See also the article “Selector API”.

Applies the given attributes to all descendants that match the associated selector(s). Each attributes object may contain properties to be set and listeners to be registered. An entry will be treated as a listener if it follows the naming scheme “onEventType”. IMPORTANT: Listeners previously registered (for the same type) via the apply method, a JSX element attribute or a widget factory call will be de-registered. This means you can call apply repeatedly and have a deterministic outcome. Listeners registered programmatically (e.g. widget.onTap(...) are not affected by this.)

For better type safety enable strict mode and use Setter to create properties objects.

If you wish to always exclude specific “internal” children from this, overwrite the children method on their parent. See “Encapsulation”.

When using declarative UI syntax “apply” is a special attribute that calls this function.

Parameter Type Description
options {
  mode?: 'default'|'strict',
  trigger?: string
}
If mode is set to 'strict' the function checks that all selector match at least one widget, and that id selector match exactly one widget.
A trigger is string to be associated with the given rulset. If set to 'update', the ruleset will be applied once immediately and then again every time apply('update') is called. If set to any event-attribute name, such as 'onTap', it will automatically re-apply the ruleset when this event is triggered. If set to '*' if the widget mutates as described here.
rules RuleSet The ruleset to apply. May also be given as a callback which is passed to the widget instance and must return the actual ruleset. This parameter can also be null if the trigger option is set. This will stop re-applying the ruleset previously associated with that trigger.

Returns: this

See also:

TSX composite-apply-jsx.tsx
TS composite-apply.ts

apply(rules)

Shorthand for apply({mode: 'default'}, rules)

Parameter Type Description
rules RuleSet The ruleset to apply. May also be given as a callback which is passed to the widget instance and must return the actual ruleset.

Returns: this

See also:

TSX composite-apply-jsx.tsx
TS composite-apply.ts

apply(mode, rules)

Shorthand for apply({mode: mode}, rules})

Parameter Type Description
mode 'default' | 'strict' If this is set to 'strict' the function checks that all selector match at least one widget, and that id selector match exactly one widget.
rules RuleSet The ruleset to apply. May also be given as a callback which is passed to the widget instance and must return the actual ruleset.

Returns: this

See also:

TSX composite-apply-jsx.tsx
TS composite-apply.ts

apply(trigger)

Applies the ruleset from the last call with trigger set to 'update' or '*'.

Parameter Type Description
trigger 'update' | '*'  

Returns: this

See also:

TSX composite-apply-jsx.tsx
TS composite-apply.ts

children(selector?)

Returns a (possibly empty) collection of all children of this widget that match the given selector.

When writing custom UI components it may be useful to overwrite this method to prevent access to the internal children by external code. Doing so also affects find and apply, on this widget as well as on all parents, thereby preventing accidental clashes of widget id or class values. See “Encapsulation”.

Parameter Type Description
selector Selector A selector expression or a predicate function to filter the results. Optional.

Returns: WidgetCollection<ChildType>

find(selector?)

Returns a collection containing all descendants of all widgets in this collection that match the given selector.

If you wish to always exclude specific “internal” children from the result, overwrite the children method (details) to return an empty WidgetCollection, or use the @component decorator. These children will then only be visible via the protected _find method. See “Encapsulation

Parameter Type Description
selector Selector A selector expression or a predicate function to filter the results. Optional.

Returns: WidgetCollection

Protected Methods

These methods are accessible only in classes extending Composite.

_acceptChild(child)

Called by the framework with each widget that is about to be added as a child of this composite. May be overwritten to reject some or all children by returning false.

Parameter Type Description
child Widget  

Returns: boolean

_addChild(child, index?)

Called by the framework with a child to be assigned to this composite. Triggers the ‘addChild’ event. May be overwritten to run any code prior or after the child is inserted.

Parameter Type Description
child Widget  
index number Optional.

Returns: undefined

_apply(options, rules)

Identical to the apply(options, rules) method, but intended to be used by subclasses in case the children method was overwritten . See “Encapsulation

Parameter Type Description
options {
  mode?: 'default'|'strict',
  trigger?: string
}
If mode is set to 'strict' the function checks that all selector match at least one widget, and that id selector match exactly one widget.
A trigger is string to be associated with the given rulset. If set to 'update', the ruleset will be applied once immediately and then again every time apply('update') is called. If set to any event-attribute name, such as 'onTap', it will automatically re-apply the ruleset when this event is triggered.
rules RuleSet The ruleset to apply. May also be given as a callback which is passed to the widget instance and must return the actual ruleset.

Returns: this

_apply(rules)

Identical to the apply(rules) method, but intended to be used by subclasses in case the children method was overwritten . See “Encapsulation

Parameter Type Description
rules RuleSet The ruleset to apply. May also be given as a callback which is passed to the widget instance and must return the actual ruleset.

Returns: this

_apply(mode, rules)

Identical to the apply(mode, rules) method, but intended to be used by subclasses in case the children method was overwritten . See “Encapsulation

Parameter Type Description
mode 'default' | 'strict' If this is set to 'strict' the function checks that all selector match at least one widget, and that id selector match exactly one widget.
rules RuleSet The ruleset to apply. May also be given as a callback which is passed to the widget instance and must return the actual ruleset.

Returns: this

_apply(trigger)

Applies the ruleset from the last call with trigger set to 'update' or '*'.

Parameter Type Description
trigger 'update' | '*'  

Returns: this

_checkLayout(value)

Called by the framework with the layout about to be assigned to this composite. May be overwritten to reject a layout by throwing an Error.

Parameter Type Description
value Layout  

Returns: undefined

_children(selector?)

Identical to the children method, but intended to be used by subclasses in case the children method was overwritten. See “Encapsulation”.

Parameter Type Description
selector Selector A selector expression or a predicate function to filter the results. Optional.

Returns: WidgetCollection

_find(selector?)

Identical to the find method, but intended to be used only by subclasses (custom components) that encapsulate their children. This is the case if the children method was overwritten or the @component decorator is used on the subclass.

Parameter Type Description
selector Selector A selector expression or a predicate function to filter the results. Optional.

Returns: WidgetCollection

_initLayout(props?)

Called with the constructor paramter (if any) to initialize the composite’s layout manager. May be overwritten to customize/replace the layout. The new implementation must make a super call to initialize the layout.

Parameter Type Description
props {
  layout: Layout // optional
}
Optional.

Returns: undefined

_removeChild(child)

Called by the framework with a child to be removed from this composite. Triggers the ‘removeChild’ event. May be overwritten to run any code prior or after the child is removed.

Parameter Type Description
child Widget  

Returns: undefined

Properties

layout

The layout manager responsible for interpreting the layoutData of the child widgets of this Composite.

Type: Layout | null
Default: Layout
Settable: By Constructor or JSX
Change Event: Not supported

This property can only be set via constructor or JSX. Once set, it cannot change anymore.

Events

addChild

Fired when a child is added to this widget.

EventObject Type: CompositeAddChildEvent<Composite>

Property Type Description
child Widget The widget that is added as a child.
index number Denotes the position in the children list at which the child widget is added.

removeChild

Fired when a child is removed from this widget.

EventObject Type: CompositeRemoveChildEvent<Composite>

Property Type Description
child Widget The widget that is removed.
index number The property index denotes the removed child widget’s position in the children list.`

RuleSet

  • JavaScript type: Object or Array or Function
  • TypeScript type: RuleSetStatic | RuleSetCallback;

A set of static rules (multiple via array) or a callback that returns of of the former.

See also the article “Selector API”.

RuleSetStatic

JavaScript type: Object or Array TypeScript type: RuleSetObject | Attributes | Array<RuleSetObject|Attributes>;

One or more RuleSetObject or Attributes objects. Both can be created by Setter, but an Attributes object must be created by that function so the constructor can be used as the selector.

widget.apply([
  Setter(TextView, {background: 'blue'}), // matches all TextView widgets
  Setter(TextView, '#foo', {text: 'foo'}) // matches widget with id "foo", must be a TextView
]);

RuleSetObject

JavaScript type: Object TypeScript type: {[selector]: Attributes}

A plain object with selectors as keys and attribute objects as values.

Example:

{
  '#okbutton': {text: 'OK!', onSelect: handleOk},
  '#cancelbutton': {text: 'Cancel!', onSelect: handleCancel}
}

The order in which the attribute objects are applied depends on the type of selectors being used. The order is:

  • '*' > 'Type' > '.class' > '#id'

When using child selectors, the more specific selector is applied first.

See also the article “Selector API”.

RuleSetCallback

JavaScript type: Function TypeScript type: (target: Widget) => RuleSetStatic;

A function that is given of the target widget and must return a RuleSetStatic or array of them.