# Component

See also

Notifications:

  The Component object uses notifications to notify observers of changes.

## Tasks

### Reference Data

- `bounds`

### Properties

- `baseGlyph`

- `transformation`

### Hit Testing

- `pointInside()`

### Drawing

- `draw()`

- `drawPoints()`

### Changed State

- `dirty`

### Notifications

- `dispatcher`

- `addObserver()`

- `removeObserver()`

- `hasObserver()`

### Parent

- `getParent()`

- `setParent()`

#### Component

class defcon.Component(glyph=None)

  This object represents a reference to another glyph.

  This object posts the following notifications:

  - Component.Changed

  - Component.BaseGlyphChanged

  - Component.BaseGlyphDataChanged

  - Component.TransformationChanged

  - Component.IdentifierChanged

  addObserver(observer, methodName, notification, identifier=None)

    Add an observer to this object’s notification dispatcher.

    - observer An object that can be referenced with weakref.

    - methodName A string representing the method to be called when the notification is posted.

    - notification The notification that the observer should be notified of.

    - identifier None or a string identifying the observation. There is no requirement that the string be unique. A reverse domain naming scheme is recommended, but there are no requirements for the structure of the string.

    The method that will be called as a result of the action must accept a single notification argument. This will be a `defcon.tools.notifications.Notification` object.

    This is a convenience method that does the same thing as:

        dispatcher = anObject.dispatcher
        dispatcher.addObserver(observer=observer, methodName=methodName,
            notification=notification, observable=anObject, identifier=identifier)

  property baseGlyph

    The glyph that the components references. Setting this will post Component.BaseGlyphChanged and Component.Changed notifications.

  property bounds

    The bounds of the components’s outline expressed as a tuple of form (xMin, yMin, xMax, yMax).

  canRedo()

    Returns a boolean indicating whether the undo manager is able to perform a redo.

  canUndo()

    Returns a boolean indicating whether the undo manager is able to perform an undo.

  property controlPointBounds

    The control bounds of all points in the components. This only measures the point positions, it does not measure curves. So, curves without points at the extrema will not be properly measured.

  destroyAllRepresentations(notification=None)

    Destroy all representations.

  destroyRepresentation(name, **kwargs)

    Destroy the stored representation for name and **kwargs. If no kwargs are given, any representation with name will be destroyed regardless of the kwargs passed when the representation was created.

  property dirty

    The dirty state of the object. True if the object has been changed. False if not. Setting this to True will cause the base changed notification to be posted. The object will automatically maintain this attribute and update it as you change the object.

  disableNotifications(notification=None, observer=None)

    Disable this object’s notifications until told to resume them.

    - notification The specific notification to disable. This is optional. If no notification is given, all notifications will be disabled.

    This is a convenience method that does the same thing as:

        dispatcher = anObject.dispatcher
        dispatcher.disableNotifications(
            observable=anObject, notification=notification, observer=observer)

  property dispatcher

    The `defcon.tools.notifications.NotificationCenter` assigned to the parent of this object.

  draw(pen)

    Draw the component with pen.

  drawPoints(pointPen)

    Draw the component with pointPen.

  enableNotifications(notification=None, observer=None)

    Enable this object’s notifications.

    - notification The specific notification to enable. This is optional.

    This is a convenience method that does the same thing as:

        dispatcher = anObject.dispatcher
        dispatcher.enableNotifications(
            observable=anObject, notification=notification, observer=observer)

  findObservations(observer=None, notification=None, observable=None, identifier=None)

    Find observations of this object matching the given arguments based on the values that were passed during addObserver. A value of None for any of these indicates that all should be considered to match the value. In the case of identifier, strings will be matched using fnmatch.fnmatchcase. The returned value will be a list of dictionaries with this format:

    > [
    >   {

    >     observer=<…> observable=<…> methodName=”…” notification=”…” identifier=”…”

    >   }

    > ]

    This is a convenience method that does the same thing as:

        dispatcher = anObject.dispatcher
        dispatcher.findObservations(
            observer=observer, observable=anObject,
            notification=notification, identifier=identifier
        )

  property font

    The `Font` that this component belongs to.

  generateIdentifier()

    Create a new, unique identifier for and assign it to the contour. This will post Component.IdentifierChanged and Component.Changed notifications.

  getDataForSerialization(**kwargs)

    Return a dict of data that can be pickled.

  getRepresentation(name, **kwargs)

    Get a representation. name must be a registered representation name. **kwargs will be passed to the appropriate representation factory.

  property glyph

    The `Glyph` that this component belongs to. This should not be set externally.

  hasCachedRepresentation(name, **kwargs)

    Returns a boolean indicating if a representation for name and **kwargs is cached in the object.

  hasObserver(observer, notification)

    Returns a boolean indicating is the observer is registered for notification.

    This is a convenience method that does the same thing as:

        dispatcher = anObject.dispatcher
        dispatcher.hasObserver(observer=observer,
            notification=notification, observable=anObject)

  holdNotifications(notification=None, note=None)

    Hold this object’s notifications until told to release them.

    - notification The specific notification to hold. This is optional. If no notification is given, all notifications will be held.

    - note An arbitrary string containing information about why the hold has been requested, the requester, etc. This is used for reference only.

    This is a convenience method that does the same thing as:

        dispatcher = anObject.dispatcher
        dispatcher.holdNotifications(
            observable=anObject, notification=notification, note=note)

  property identifier

    The identifier. Setting this will post Component.IdentifierChanged and Component.Changed notifications.

  property identifiers

    Set of identifiers for the glyph that this component belongs to. This is primarily for internal use.

  property layer

    The `Layer` that this component belongs to.

  property layerSet

    The `LayerSet` that this component belongs to.

  move(values)

    Move the component by (x, y).

    This posts Component.TransformationChanged and Component.Changed notifications.

  pointInside(coordinates, evenOdd=False)

    Returns a boolean indicating if (x, y) is in the “black” area of the component.

  postNotification(notification, data=None)

    Post a notification through this object’s notification dispatcher.

    > - notification The name of the notification.

    > - data Arbitrary data that will be stored in the `Notification` object.

    This is a convenience method that does the same thing as:

        dispatcher = anObject.dispatcher
        dispatcher.postNotification(
            notification=notification, observable=anObject, data=data)

  redo()

    Perform a redo if possible, or return. If redo is performed, this will post BaseObject.BeginRedo and BaseObject.EndRedo notifications.

  releaseHeldNotifications(notification=None)

    Release this object’s held notifications.

    - notification The specific notification to hold. This is optional.

    This is a convenience method that does the same thing as:

        dispatcher = anObject.dispatcher
        dispatcher.releaseHeldNotifications(
            observable=anObject, notification=notification)

  removeObserver(observer, notification)

    Remove an observer from this object’s notification dispatcher.

    - observer A registered object.

    - notification The notification that the observer was registered to be notified of.

    This is a convenience method that does the same thing as:

        dispatcher = anObject.dispatcher
        dispatcher.removeObserver(observer=observer,
            notification=notification, observable=anObject)

  representationKeys()

    Get a list of all representation keys that are currently cached.

  setDataFromSerialization(data)

    Restore state from the provided data-dict.

  property transformation

    The transformation matrix for the component. Setting this will post Component.TransformationChanged and Component.Changed notifications.

  undo()

    Perform an undo if possible, or return. If undo is performed, this will post BaseObject.BeginUndo and BaseObject.EndUndo notifications.

  property undoManager

    The undo manager assigned to this object.