GetCCursor

Get a handle to a specified 'crsr' resource

#include <Quickdraw.h> Color Quickdraw

CCrs rHandle GetCCursor( crsrID );

short crsrID ; resource ID of desired cursor

returns handle leading to a 'crsr' data structure; 0 if error

GetCCursor allocates a new CCrsr data structure and initializes it with

information in the new 'crsr' resource type.

crsrID is the resource identifier of the desired cursor.

Returns: a CCrs rHandle leading to the cursor data. If a resource

type with the correct crsrID can't be found, the return value is NIL.

Notes: GetCCursor creates a new CCrsr data structure every time your

application calls it, so don't call it before each SetCCursor call (as was

the case with old-style Quickdraw GetCursor and SetCursor).

Make sure that if you load the color table from a 'clut' resource using

GetCTable, mark the 'clut' resource as non-purgeable while the color

cursor is in use. You can make 'crsr' resources purgeable since

GetCCursor does not dispose or detach them.

Make sure you allocate enough space for your color cursor. If your cursor

is, say, 15 pixels tall and 9 pixels wide, you might be tempted to use these

values for the bounds.bottom and bounds.right, respectively, in your

cursor's pixel map. Don't do this! The problem is that when the cursor's

image needs to be expanded (i.e., when you specify a two bit-per- pixel

cursor and the mouse is on an eight-bit screen), SetCCursor rounds the

width of the pixel map in such a way that you'll get only the space required

for a 15 by 8 pixel map allocated for the expanded cursor data. When the

cursor's image is expanded into this too-small cursor data handle as a 15 x

9 pixel map, something will get stepped on in your heap.

The solution is to specify that the (**pixmapHandle).bounds be 16 x 16.

This will cause SetCCursor to properly allocate the expanded data area.

Since the amount of data drawn for a cursor is specified by the cursor's

pixel values and 'clut' resource, trying to save a few bytes by making the

bounds rectangle smaller than 16 x 16 will not help.

Referenced by (4):