Widget Callbacks

Widget Callbacks

Two ways to register a callback:

• Method override - define the bare method on a subclass. Called by the framework as part of internal widget behaviour. This is for stuff like a blinking cursor on a TextInput or normal drawing code for this type of widget.
• Registration wrapper - call widget:onSomething(fn) to append a user-defined handler. Multiple handlers can be registered. Use this for stuff like defining what happens when you press a specific Button.

Event types

Event

• type - event name
• timestamp - creation time
• target - original widget target
• currentTarget - widget currently handling this phase
• consumed - whether a handler consumed the event
• stopsPropagation - whether propagation is stopped
• consume() - marks consumed and stops propagation

MouseEvent

• x/y - screen coordinates
• localX/localY - coordinates relative to target
• button - mouse button index
• dx/dy - optional movement or wheel delta
• isTouch - whether source input is touch

KeyboardEvent

• key - logical key name
• scancode - physical key identifier
• isRepeat - whether this is a repeated key press
• modifiers.shift/ctrl/alt - modifier-key state
• value - optional text/value payload (if present)

TextInputEvent

• text - entered printable text
• modifiers.shift/ctrl/alt - modifier-key state

FocusEvent

• target/currentTarget - focus target

Lifecycle

See: Lifecycle.

Mouse

• mousePressed(MouseEvent) / onMousePressed(fn)

• mouseReleased(MouseEvent) / onMouseReleased(fn)

• mouseMoved(MouseEvent) / onMouseMoved(fn)

• mouseEntered(MouseEvent) / onMouseEntered(fn) / onHover(fn)

• mouseExited(MouseEvent) / onMouseExited(fn)

• mouseWheel(MouseEvent) / onMouseWheel(fn)

• clicked(MouseEvent) / onClick(fn)

Keyboard & Text

• keyPressed(KeyboardEvent) / onKeyPressed(fn)
• keyReleased(KeyboardEvent) / onKeyReleased(fn)
• textInput(TextInputEvent) / onTextInput(fn)

Focus

• focusGained(FocusEvent) / onFocusGained(fn)
• focusLost(FocusEvent) / onFocusLost(fn)

Drag (draggable widgets)

Registration wrappers append to __handlers; property assignment (widget.dragStart = fn) sets a single overrideable callback. Both fire.

• dragStart(MouseEvent) / onDragStart(fn)
• drag(MouseEvent, deltaX, deltaY) / onDrag(fn)
• dragEnd(MouseEvent) / onDragEnd(fn)

Drag (drop targets)

Registration wrappers append to __handlers. Property assignment (widget.dragOver = fn) sets a single overrideable callback.

• dragOver(MouseEvent, draggedWidget) / onDragOver(fn)
• dragLeave(MouseEvent, draggedWidget) / onDragLeave(fn)
• drop(MouseEvent, draggedWidget) / onDrop(fn)