About the Picture Utilities Package

This section describes the Picture Utilities Package, a set of routines

with which you can obtain qualitative and quantitative information about

pictures and pixel maps. You might want to find out about the text in a picture,

for example, to see if the fonts it uses are available in the system. You can

determine the number of colors a picture uses and obtain an optimal color

table or palette for displaying it.

The Picture Utilities Package is available with system 7.0. With system

7.0, the picture utilities work using the original QuickDraw, but with the

limitation that any palette handles returned are NIL.

The two most common forms of storing image information are pixel maps and

pictures. The Picture Utilities Package consists of a number of routines

for extracting information from a picture, or from a pixel map record and its

associated image.

Unless they contain specialized code for parsing pictures, many applications

deal with pictures as black boxes, perhaps imaging them into a pixel map and

then dealing with the picture as pixel map data. The Picture Utilities

Package provides a way to open that black box and deal with its contents

intelligently.

resolution information in the picture header. The Picture Utilities

Package returns this information for pictures created with OpenCPicture,

and returns the standard screen resolution (72 dots per inch) for all other

pictures.

You can use Picture Utilities Package routines and data structures to

gather information about a single pixel map or picture, or you can survey a

number of them. To get information about a single picture or pixel map, use

either the GetPictInfo or GetPixMapInfo function, and all the information

will be returned in a picture information record.

To collect information about a number of pictures and pixel maps, you need to

make at least four calls: the NewPictInfo function creates an identifier for the

collection. RecordPictInfo and RecordPixMapInfo collect information

from pictures and pixel maps, respectively. RetrievePictInfo returns the

collected information, and DisposPictInfo disposes of the data structures

private to the collection. Information about the collection of pictures and pixel

maps is returned in a picture information record.

An entire picture need not be read into memory; pictures can be spooled to the

GetPictInfo or RecordPictInfo function, following the spooling procedure