Legacy Document

Inside Macintosh: Imaging With QuickDraw /

Chapter 2 - Basic QuickDraw / Basic QuickDraw Reference

Routines / Opening and Closing Basic Graphics Ports

OpenPort

The OpenPort procedure allocates space for and initializes a basic graphics port. The Window Manager calls OpenPort for each black-and-white window it creates, and the NewGWorld procedure calls OpenPort for every offscreen graphics world containing a basic graphics port that it creates.

PROCEDURE OpenPort (port: GrafPtr);

port

A pointer to a GrafPort record.

DESCRIPTION

The OpenPort procedure allocates space for visible and clipping regions for the graphics port specified in the port parameter, initializes the fields of the port's GrafPort record as indicated in Table 2-2, and makes that graphics port the current port (by calling SetPort). The Window Manager calls OpenPort when you create a black-and-white window; you normally won't call it yourself. You can create the graphics port pointer with the Memory Manager's NewPtr procedure.

Table 2-2 Initial values of a basic graphics port (Continued)

Variable	Type	Initial setting
device	Integer	0 (the screen)
portBits	BitMap	screenBits (global variable for main screen)
portRect	Rect	screenBits.bounds
visRgn	RgnHandle	Handle to a rectangular region coincident with screenBits.bounds
clipRgn	RgnHandle	Handle to the rectangular region (-32768,-32768,32767,32767)
bkPat	Pattern	White
fillPat	Pattern	Black
pnLoc	Point	(0,0)
pnSize	Point	(1,1)
pnMode	Integer	patCopy pattern mode
pnPat	Pattern	Black
pnVis	Integer	0 (visible)
txFont	Integer	0 (system font)
txFace	Style	Plain
txMode	Integer	srcOr source mode
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	QDProcsPtr	NIL

SPECIAL CONSIDERATIONS

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

SEE ALSO

The GrafPort record is described beginning on page 2-27. Listing 2-2 on page 2-15 illustrates how to use the Window Manager function GetNewWindow to create a basic graphics port. The OpenCPort procedure (described in the chapter "Color QuickDraw") creates a color graphics port.