Legacy Document

Inside Macintosh: Imaging With QuickDraw /

Chapter 4 - Color QuickDraw / Color QuickDraw Reference

Color QuickDraw Routines / Opening and Closing Color Graphics Ports

OpenCPort

The OpenCPort procedure allocates space for and initializes a color graphics port. The Window Manager calls OpenCPort for every color window that it creates, and the NewGWorld procedure calls OpenCPort for every offscreen graphics world that it creates on a Color QuickDraw computer.

PROCEDURE OpenCPort (port: CGrafPtr);

port

A pointer to a CGrafPort record.

DESCRIPTION

The OpenCPort procedure is analogous to OpenPort (described in the chapter "Basic QuickDraw"), except that OpenCPort opens a CGrafPort record instead of a GrafPort record. The OpenCPort procedure is called by the Window Manager's NewCWindow and GetNewCWindow procedures, as well as by the Dialog Manager when the appropriate color resources are present. The OpenCPort procedure allocates storage for all the structures in the CGrafPort record, and then calls InitCPort to initialize them. The InitCPort procedure does not allocate a color table for the PixMap record for the color graphics port; instead, InitCPort copies the handle to the current device's CLUT into the PixMap record. The initial values for the CGrafPort record are shown in Table 4-3.

Initial values in the CGrafPort record (Continued)

Field	Data type	Initial setting
device	Integer	0 (the screen)
portPixMap	PixMapHandle	Handle to the port's PixMap record
portVersion	Integer	$C000
grafVars	Handle	Handle to a GrafVars record where black is assigned to the rgbOpColor field, the default highlight color is assigned to the rgbHiliteColor field, and all other fields are set to 0
chExtra	Integer	0
pnLocHFrac	Integer	The value in this field represents the low word of a Fixed number; in decimal, its initial value is 0.5.
portRect	Rect	screenBits.bounds (boundary for entire main screen)
visRgn	RgnHandle	Handle to a rectangular region coincident with screenBits.bounds
clipRgn	RgnHandle	Handle to the rectangular region (-32768,-32768,32767,32767)
bkPixPat	Pattern	White
rgbFgColor	RGBColor	Black
rgbBkColor	RGBColor	White
pnLoc	Point	(0,0)
pnSize	Point	(1,1)
pnMode	Integer	patCopy
pnPixPat	PixPatHandle	Black
fillPixPat	PixPatHandle	Black
pnVis	Integer	0 (visible)
txFont	Integer	0 (system font)
txFace	Style	Plain
txMode	Integer	srcOr
txSize	Integer	0 (system font size)
spExtra	Fixed	0
fgColor	LongInt	blackColor
bkColor	LongInt	whiteColor
colrBit	Integer	0
patStretch	Integer	0
picSave	Handle	NIL
rgnSave	Handle	NIL
polySave	Handle	NIL
grafProcs	CQDProcsPtr	NIL

The additional structures allocated are the portPixMap, pnPixPat, fillPixPat, bkPixPat, and grafVars handles, as well as the fields of the GrafVars record.

SPECIAL CONSIDERATIONS

The OpenCPort procedure may move or purge memory blocks in the application heap. Your application should not call this procedure at interrupt time.