GetCTable

GetCTable
Header:	Quickdraw.h		Carbon status:	Supported

Obtains a color table stored in a 'clut' resource.

CTabHandle GetCTable (
    SInt16 ctID
);

ctID: The resource ID of a 'clut' resource.

function result: A handle to the color table. If the 'clut' resource with that ID is not found, GetCTable returns NULL.Before you place this handle in the pmTable field of a PixMap structure, first use the DisposeCTable function to dispose of the handle already there.

DISCUSSION

Before you modify a ColorTable structure, change its ctSeed field to invalidate it. To do this, use the CTabChanged function.

The GetCTable function recognizes a number of standard 'clut' resource IDs. You can obtain the default grayscale color table for a given pixel depth by calling GetCTable, adding 32 (decimal) to the pixel depth, and passing these values in the ctID parameter:

A pixel depth of 1

Pass a resource ID of 33. Color table composition: black, white.
A pixel depth of 2

Pass a resource ID of 34. Color table composition: black, 33% gray, 66% gray, white.
A pixel depth of 3

Pass a resource ID of 35. Color table composition: black, 14 shades of gray, white.
A pixel depth of 4

Pass a resource ID of 36. Color table composition: black, 254 shades of gray, white.

For full color, obtain the default color tables by adding 64 to the pixel depth and passing these values in the ctID parameter:

A pixel depth of 2

Pass a resource ID of 66. Color table composition: black, 50% gray, highlight color, white.
A pixel depth of 4

Pass a resource ID of 68. Color table composition: black, 14 colors including the highlight color, white.
A pixel depth of 8

Pass a resource ID of 72. Color table composition: black, 254 colors including the highlight color, white.

SPECIAL CONSIDERATIONS

The GetCTable function may move or purge memory blocks in the application heap; do not call this function at interrupt time.

AVAILABILITY

Supported in Carbon. Available in CarbonLib 1.0 and later when InterfaceLib 7.1 or later is installed. Exported by CarbonLib 1.0 and later and by InterfaceLib 7.1 and later.