About Transform Objects
A transform object exists to modify, or transform, the appearance or behavior of a shape. Each QuickDraw GX shape consists of a shape object, a style object, an ink object, and a transform object; the transform object specifies where the shape is drawn, how its appearance is transformed when drawn, and how the user can interact with the drawn shape. You can think of a transform object as a filter between the shape object and its drawing destination of one or more view ports.QuickDraw GX identifies an individual transform object through a transform reference. To obtain information about a transform object, you must send its reference as a parameter to a QuickDraw GX function (except that you can determine if two references identify the same transform object simply by comparing them for equality, and you can examine a reference to see if it is
nil).A shape (other than a picture shape) always refers to a single transform object. Several shapes, however, can refer to the same transform object. When they do, the transform object is shared and its transformations apply to all of those shapes. If you use a function that directly manipulates the transform object, the behavior of all shape objects associated with it changes.
Subtopics
- Transform Object Properties
- Default Transform Objects