Container

_A fundamental layout element that manages child UI components. Containers handle element organization, event propagation, _ rendering hierarchy, and coordinate space management. They serve as the backbone of Basalt's UI structure by providing:- Child element management and organization- Event bubbling and distribution- Visibility calculations and clipping- Focus management- Coordinate space transformation

Extends: VisualElement

Properties

Property	Type	Default	Description
children	table	{}	Collection of all child elements
childrenSorted	boolean	true	Indicates if children are sorted by z-index
childrenEventsSorted	boolean	true	Indicates if event handlers are properly sorted
childrenEvents	table	{}	Registered event handlers for all children
eventListenerCount	table	{}	Number of listeners per event type
focusedChild	table	nil	Currently focused child element (receives keyboard events)
visibleChildren	table	{}	Currently visible child elements (calculated based on viewport)
visibleChildrenEvents	table	{}	Event handlers for currently visible children
offsetX	number	0	Horizontal scroll/content offset
offsetY	number	0	Vertical scroll/content offset

Functions

Method	Returns	Description
Container:isChildVisible	boolean	Checks if a child element is visible
Container:addChild	Container	Adds a child element to the container
Container:clear	Container	Removes all children and resets container
Container:sortChildren	Container	Updates child element ordering
Container:sortChildrenEvents	Container	Sorts the children events of the container
Container:registerChildrenEvents	Container	Registers the children events of the container
Container:registerChildEvent	Container	Sets up event handling for a child
Container:removeChildrenEvents	Container	Unregisters the children events of the container
Container:unregisterChildEvent	Container	Unregisters the children events of the container
Container:removeChild	Container	Removes a child element from the container
Container:getChild	child	Finds a child element by its path
Container:callChildrenEvent	boolean, child	Calls a event on all children

Container:isChildVisible(child)

Tests whether a child element is currently visible within the container's viewport

Parameters

• child table The child element to check

Returns

• boolean isVisible Whether the child is within view bounds

Container:addChild(child)

Adds a new element to this container's hierarchy

Parameters

• child table The element to add as a child

Returns

• Container self For method chaining

Container:clear()

Removes all child elements and resets the container's state

Returns

• Container self For method chaining

Container:sortChildren()

Re-sorts children by their z-index and updates visibility

Returns

• Container self For method chaining

Container:sortChildrenEvents(eventName)

Sorts the children events of the container

Parameters

• eventName string The event name to sort

Returns

• Container self The container instance

Container:registerChildrenEvents(child)

Registers the children events of the container

Parameters

• child table The child to register events for

Returns

• Container self The container instance

Container:registerChildEvent(child, eventName)

Registers an event handler for a specific child element

Parameters

• child table The child element to register events for
• eventName string The name of the event to register

Returns

• Container self For method chaining

Container:removeChildrenEvents(child)

Unregisters the children events of the container

Parameters

• child table The child to unregister events for

Returns

• Container self The container instance

Container:unregisterChildEvent(child, eventName)

Unregisters the children events of the container

Parameters

• child table The child to unregister events for
• eventName string The event name to unregister

Returns

• Container self The container instance

Container:removeChild(child)

Removes an element from this container's hierarchy and cleans up its events

Parameters

• child table The element to remove

Returns

• Container self For method chaining

Container:getChild(path)

Locates a child element using a path-like syntax (e.g. "panel/button1")

Parameters

• path string Path to the child (e.g. "panel/button1", "header/title")

Returns

• child The found element or nil if not found

Container:callChildrenEvent(visibleOnly, event)

Calls a event on all children

Parameters

• visibleOnly boolean Whether to only call the event on visible children
• event string The event to call

Returns

• boolean handled Whether the event was handled
• child The child that handled the event