Legacy Document

Inside Macintosh: Imaging With QuickDraw /

Chapter 4 - Color QuickDraw / Color QuickDraw Reference

Color QuickDraw Routines

Customizing Color QuickDraw Operations

For each shape that QuickDraw can draw, there are procedures that perform these basic graphics operations on the shape: framing, painting, erasing, inverting, and filling. As described in the chapter "QuickDraw Drawing" in this book, those procedures in turn call a low-level drawing routine for the shape. For example, the FrameOval, PaintOval, EraseOval, InvertOval, and FillOval procedures all call the low-level procedure StdOval, which draws the oval.

The grafProcs field of a CGrafPort record determines which low-level routines are called. If that field contains the value of NIL, the standard routines are called. You can set the grafProcs field to point to a record of pointers to your own routines. This record of pointers is defined by a data structure of type CQDProcs. By changing these pointers, you can install your own routines, and either completely override the standard ones or call them after your routines have modified their parameters as necessary.

To assist you in setting up a record, QuickDraw provides the SetStdCProcs procedure. You can use the SetStdCProcs procedure to set all the fields of the CQDProcs record to point to the standard routines. You can then reset the ones with which you are concerned.

---

Subtopics

SetStdCProcs