Apple II
File Type Notes
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                                                  Developer Technical Support


File Type:         $CA (202)
Auxiliary Type:    Reserved

Full Name:     Finder Icons File
Short Name:    Icons

Written by:    Matt Deatherage                                      July 1989

Files of this type and auxiliary type contain icons.
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The Apple IIGS Finder keeps the icons it uses in files of type $CA.  The 
Finder searches for these files in a directory named Icons on each volume 
mounted.  Each icon contains information not only describing the icon and its 
mask (both regular and "small icon" sizes), but also information to match the 
icon to files from their file type, auxiliary type, and filename.

The Finder first attempts to load the file Finder.Icons from the Icons 
directory on the boot disk, stopping with a fatal error if it is not present 
(this file contains icons for devices as well as the icon to match files with 
no other icon).  It then loads other icon files from that directory, and then 
from other disks.

The format of icon files is as follows:

+000    iBlkNext   Long     When loaded by the Finder, this is the 
                            handle to the next icon file (a linked 
                            list terminated by zero).  On disk, this 
                            field should be zero.
+004    iBlkID     Word     ID number of this type of icon file.  This 
                            field must be $0001 for the Finder to 
                            recognize the icon file.
+006    iBlkPath   Long     When loaded by the Finder, this is the 
                            handle to the pathname of this icon file.  
                            On disk, this field should be zero.
+010    iBlkName   16 Bytes A 16-byte String of the name of the icon 
                            file.
+026    iBlkIcons  IconData A list of Icon Data records.

The format of Icon Data records is as follows:

+000    iDataLen    Word    The length of this Icon Data record.  A 
                            value of zero in this field terminates the 
                            list of Icon Data records.
+002    iDataBoss   64 Bytes  The pathname of the 
                            application that owns this icon.  If this 
                            String has non-zero length, and the file 
                            this icon is associated with is a document 
                            (not an application, folder, device, or 
                            trash can), the Finder attempts to launch 
                            a file with this pathname when this icon 
                            is opened or printed.  This string should 
                            be empty for non-documents.  This is a 
                            full pathname, and most developers 
                            creating icons will wish to set this to 
                            the full pathname of the application on 
                            the shipping disk.
+066    iDataName   16 Bytes  A 16-byte String containing a 
                            file name.  Files on disk must match the 
                            specification of this string or this icon 
                            will not be displayed for the files.  The 
                            asterisk (*) serves as a wildcard 
                            character.  For example, the string *.ASM 
                            matches all filenames ending with the 
                            characters .ASM.
+082    iDatatype    Word   File type associated with this icon.  
                            Files on disk must have this file type for 
                            this icon to be displayed.  A file type of 
                            $0000 in this field matches any file type 
                            on disk.  As an example, an application 
                            icon would want to have the filename of 
                            the application in the iDataName field and 
                            the file type $00B3 (GS/OS Application) in 
                            this field.  Without the file type 
                            specification, the icon would show up for 
                            any file with the application's file name, 
                            including a folder on a hard disk in which 
                            the user has placed the application.
+084    iDataAux     Word   Auxiliary type associated with this icon.  
                            Similar to the file type field, a value of 
                            $0000 here matches any auxiliary type on 
                            disk.
+086    iDataBig     Icon   The normal size icon image data.
        iDataSmall   Icon   The small size icon image data.

The format of Icon records is the same as that listed in the QuickDraw II 
Auxiliary chapter of the Apple IIGS Toolbox Reference Manual.  Previous icon 
structure documentation stated the iconType field of the Icon record (also 
known as the imType field) had to be zero.  This is no longer true; the Finder 
respects color icons (bit 15 of iconType set) by not coloring the icon in 
funny ways, even if the user asks for it.  The Finder still does this if bit 
15 of iconType says the icon is a black-and-white icon.


Further Reference
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    o    Apple IIGS Toolbox Reference, Volume 2
    o    Apple IIGS Icon Editor