Interface EventHandler

Handles mouse and keyboard events for a Simulation. Converts mouse or key events on a SimObject to changes in the Simulation state.

See SimController which is usually the entity that supplies events to the EventHandler.

interface EventHandler {
    finishDrag(simObject, location, offset): void;
    handleKeyEvent(evt, pressed, modifiers): void;
    mouseDrag(simObject, location, offset): void;
    startDrag(simObject, location, offset, dragBody, modifiers): boolean;
    toStringShort(): string;
}

Hierarchy (view full)

Implemented by

Methods

finishDrag handleKeyEvent mouseDrag startDrag toStringShort

Methods

finishDrag

  • finishDrag(simObject, location, offset): void

  • Called at the end of a mouse drag operation, performs whatever action is appropriate. Only called if startDrag returned true.

    Parameters

    • simObject: null | SimObject

      the SimObject being dragged, or null if no SimObject was found

    • location: Vector

      the location of the mouse in simulation coordinates of the SimView where simObject was found, or in the focus view if simObject is null.

    • offset: Vector

      distance from the initial object position to the mouse location at start of drag.

    Returns void

handleKeyEvent

  • handleKeyEvent(evt, pressed, modifiers): void

  • Called when a key is pressed or released, performs whatever action is appropriate for that event.

    Parameters

    • evt: KeyboardEvent

      the KeyboardEvent that happened

    • pressed: boolean

      true means this is a key-down event; false means a key-up event

    • modifiers: ModifierKeys

      the modifier keys down during event

    Returns void

mouseDrag

  • mouseDrag(simObject, location, offset): void

  • Called at each movement during a mouse drag, performs whatever action is appropriate. Only called if startDrag returned true. The SimObject being moved is passed in, along with the current mouse position, in simulation coordinates, and an offset calculated at the start of the drag.

    Setting the SimObject position to (x - offsetX, y - offsetY) will move the SimObject smoothly along with the mouse movement.

    Parameters

    • simObject: null | SimObject

      the SimObject being dragged, or null if no SimObject was found

    • location: Vector

      the location of the mouse in simulation coordinates of the SimView where simObject was found, or in the focus view if simObject is null.

    • offset: Vector

      distance from the initial object position (from DisplayObject.getPosition) to the mouse location at start of drag.

    Returns void

startDrag

  • startDrag(simObject, location, offset, dragBody, modifiers): boolean

  • Called at the start of a mouse drag. The nearest dragable SimObject is passed in, along with mouse position in simulation coordinates. If no dragable SimObject was found, null is passed for the first argument. If the EventHandler does not recognize the SimObject then it should return false.

    Parameters

    • simObject: null | SimObject

      the SimObject that is nearest to the mouse drag coordinates, or null if no SimObject was found

    • location: Vector

      the location of the mouse in simulation coordinates of the SimView where simObject was found, or in the focus view if simObject is null.

    • offset: Vector

      distance from the initial object position (from DisplayObject.getPosition) to the mouse location at start of drag

    • dragBody: null | Vector

      location of 'drag point' on the SimObject in body coordinates of the SimObject; this is where for example a spring will be attached on the SimObject when dragging; or null when no SimObject was found

    • modifiers: ModifierKeys

      the modifier keys down during event

    Returns boolean

    true if the EventHandler will handle dragging the SimObject

toStringShort

  • toStringShort(): string

  • Returns a minimal string representation of this object, usually giving just identity information like the class name and name of the object.

    For an object whose main purpose is to represent another Printable object, it is recommended to include the result of calling toStringShort on that other object. For example, calling toStringShort() on a DisplayShape might return something like this:

    DisplayShape{polygon:Polygon{'chain3'}}

    Returns string

    a minimal string representation of this object.

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