'icns'

The 'icns' resource type contains data describing an entire icon family (all sizes and depths). If you specify a custom icon, Icon Services checks for an appropriate 'icns' resource before it checks individual custom icon resources ('ics#' , for example). If Icon Services finds an appropriate 'icns' resource, it obtains all icon data exclusively from that resource. In order to avoid incompatibilities with older versions of Finder, new icon features such as 32-bit deep icons are only obtained from the 'icns' resource.

To determine the driver icon for a particular device, Icon Services calls DriverGestalt with the kdgMediaIconSuite constant after calling the File System Manager. The DriverGestalt call returns a pointer to an icon family.

Figure 2-1 Structure of an icon family ('icns') resource

A compiled version of an 'icns' resource contains the following elements:

Type. A four-character code that identifies the resource. This value is always 'icns' .
Size of resource. A long integer that specifies the size of the resource in bytes.
One or more icon family elements. These elements contain the following sub-elements:
- Type. A four-character code that identifies the icon type, such as 'icl8' .
- Size of icon. A long integer that specifies the size of the element in bytes.
- The icon data.