Developer's Guide: The class GraphicsObject

Class Hierarchy | The Document and Graphics Classes | The class Bounded

## The class `GraphicsObject`

Base Classes: `Bounded`, `HierarchyNode`, `Selectable` and `Protocols`.

The class `GraphicsObject` defines the interface common to all graphics objects.

For convenience of implementation, and because their interfaces are needed elsewhere in the class hierarchy as well, some parts of this interface are defined by the base classes:

`Bounded`

  provides instance variables for the vertical and horizontal dimensions of a graphics object and some related methods.

`HierarchyNode`

  provides the default behavior for all methods related to the management of the object hierarchy in the document.

`Selectable`

  defines the generic interface and default behavior for selection.

`Protocols`

  has some variables that describe the object's capabilities.

### Instance Variables

`GraphicsObject` maintains no instance variables of its own, but uses those managed by its base classes.

### Methods

Methods defined in `GraphicsObject`:

`Blend(other, frac1, frac2)`

  Return the weighted average of self and other. frac1 and frac2 are the weights (if self and other were numbers this should be frac1 * self + frac2 * other).

  This method is used by the function `Blend` in `blend.py`. If self and other can't be blended, raise the `blend.Mismatch` exception. This is the default behaviour.

`AsBezier()`

  Return self as a `PolyBezier` object if possible. If this is not possible, return `None`.

The following methods are not implemented in `GraphicsObject` directly, but must be defined for every graphics object. The derived classes `Primitive` and `Compound` provide a default implementation for most objects.

`Transform(trafo)`

  Apply the transformation object trafo to self. Return undo info.

`Translate(offset)`

  Translate (move) self by offset. offset is a point object. Return undo info.

`DrawShape(device [, clip])`

  Draw self on device. device is a graphics device .

  The optional parameter clip is only provided if the object is used as a clip mask. If it is provided its value is 1. Objects that can be used as clip masks (their `is_clip` flag is true) request appropriate clipping from the graphics device. Objects that cannot be used as clip masks don't need to accept it.

  (Note: The clipping interface for the high level drawing operations of the graphics devices is somewhat experimental)

`SaveToFile(file)`

  Save self to file. The argument file is currently an instance of the class `SKSaver` which provides special methods for the object types currently implemented in Sketch.

Class Hierarchy | The Document and Graphics Classes | The class Bounded