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Inside Macintosh: Imaging With QuickDraw /

Chapter 3 - QuickDraw Drawing / QuickDraw Drawing Reference

Data Structures /

QDProcs

You need to use the QDProcs record, which is a data structure of type QDProcs, only if you customize one or more of QuickDraw's low-level drawing routines. You can use the SetStdProcs procedure, described on page 3-125, to create a QDProcs record.

The QDProcs record contains pointers to low-level drawing routines. QuickDraw's standard low-level drawing routines are described in "Customizing QuickDraw Operations" beginning on page 3-124. You can change the fields of this record to point to routines of your own devising.

TYPE QDProcsPtr = ^QDProcs;
QDProcs = 
   RECORD
      textProc:   Ptr;  {text drawing}
      lineProc:   Ptr;  {line drawing}
      rectProc:   Ptr;  {rectangle drawing}
      rRectProc:  Ptr;  {roundRect drawing}
      ovalProc:   Ptr;  {oval drawing}
      arcProc:    Ptr;  {arc/wedge drawing}
      polyProc:   Ptr;  {polygon drawing}
      rgnProc:    Ptr;  {region drawing}
      bitsProc:   Ptr;  {bit transfer}
      commentProc:Ptr;  {picture comment processing}
      txMeasProc: Ptr;  {text width measurement}
      getPicProc: Ptr;  {picture retrieval}
      putPicProc: Ptr;  {picture saving}
    END;

Field Description

textProc

A pointer to the low-level routine that draws text. The standard QuickDraw routine is the StdText procedure.

lineProc

A pointer to the low-level routine that draws lines. The standard QuickDraw routine is the StdLine procedure.

rectProc

A pointer to the low-level routine that draws rectangles. The standard QuickDraw routine is the StdRect procedure.

rRectProc

A pointer to the low-level routine that draws rounded rectangles. The standard QuickDraw routine is the StdRRect procedure.

ovalProc

A pointer to the low-level routine that draws ovals. The standard QuickDraw routine is the StdOval procedure.

arcProc

A pointer to the low-level routine that draws arcs. The standard QuickDraw routine is the StdArc procedure.

polyProc

A pointer to the low-level routine that draws polygons. The standard QuickDraw routine is the StdPoly procedure.

rgnProc

A pointer to the low-level routine that draws regions. The standard QuickDraw routine is the StdRgn procedure.

bitsProc

A pointer to the low-level routine that copies bitmaps. The standard QuickDraw routine is the StdBits procedure.

commentProc

A pointer to the low-level routine for processing a picture comment. The standard QuickDraw routine is the StdComment procedure.

txMeasProc

A pointer to the low-level routine for measuring text width. The standard QuickDraw routine is the StdTxtMeas function.

getPicProc

A pointer to the low-level routine for retrieving information from the definition of a picture. The standard QuickDraw routine is the StdGetPic procedure.

putPicProc

A pointer to the low-level routine for saving information as the definition of a picture. The standard QuickDraw routine is the StdPutPic procedure.

You can use the SetStdProcs procedure to set all the fields of the QDProcs record to point to QuickDraw's standard routines, and then reset the ones for which you have your own routines.