cdev
cdev Function entry for Control Panel Devices long main( message, Item, numItems, CPanelID, theEvent, cdevValue,
CPDialog );
short message ; number indicating type of event (see below)
short Item ; which dialog item was clicked?
short numItems ; number of Control Panel's dialog items
short CPanelID ; control Panel driver's ID
EventRecord *theEvent ; was the Event a: hit, null, activate, deactivate, or key?
long cdevValue ; most recent long returned by this call
DialogPtr CPDialog ; pointer to Control Panel dialog returns One of three function values indicating: display or
not; error; data to be retained until next call
This is the main entry point for a code resource that implements a
message is chosen from a list of predefined values that lets the Control Panel
tell the cdev what action it should take. For more information, see
About the Control Panel.
Item is only used when the Control Panel delivers a hitDev message and gives the Item Number of the dialog item that was clicked.
numItems tells how many Control Panel items are in 'DITL' and precede the control device's dialog items.
theEvent is a pointer to the event record for the action that caused the
message.
cdevValue can be either the 32-bit long last returned by main or a return
CPDialog is a pointer to the Control Panel Dialog that the cdev is running in.
Returns: a 32-bit long which indicates either: 1) whether or not the cdev can run on this Macintosh or not; or 2) an error code; or 3) data (such
as state information) to be stored until the next call by the
parameter
Notes: This function is called with the active resource file set to the cdev file, the
active grafPort set to the Control Panel's dialog and the default volume set to the System Folder on the startup disk. In order for a cdev to work
properly, it must leave these settings as they are.
If your control panel device uses dialogs or alert boxes the cdev function and SystemTask, possibly resulting in a nulDev or updateDev message while your cdev is still running.