GEOS SDK TechDocs
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2.5 Event Messages
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2.7 Notification Messages
Variable data is instance data that can appear or not appear within the object's instance chunk. For information on variable data and how these three messages are used, see the GEOS Programming chapter.
void MSG_META_ADD_VAR_DATA(@stack
word dataType,
word dataSize,
word *data)
This message adds a variable data type to the recipient object's instance data. If the variable data field was already present, this will change its value. This is useful for adding hints to generic objects at run-time.
If it is possible that you are adding the object's first/only field of
variable data, set the object's OCF_VARDATA_RELOC flag by means
of the
ObjSetFlags()
routine or
MSG_META_SET_FLAGS.
Note that the object will be marked dirty even if nothing was changed.
NOTE: The dataType should have VDF_SAVE_TO_STATE set as desired. VDF_EXTRA_DATA is ignored; it will be set correctly by this routine.
Source: Unrestricted.
Destination: Any object.
Interception: Generally not intercepted; default
MetaClass
handling performs the desired function.
Parameters: dataType Data type (e.g. ATTR_PRINT_CONTROL_APP_UI).
Return: Nothing. Object marked dirty even if data type already exists.
Boolean MSG_META_DELETE_VAR_DATA(
word dataType);
This message removes a particular variable data entry from the recipient object's instance data. This is useful for removing hints from generic objects at run-time.
Source: Unrestricted.
Destination: Any object.
Interception: Generally not intercepted; default
MetaClass
handling performs the desired function.
Parameters: dataType Data type to delete.
VarDataFlags
ignored.
Return: Returns
false
if data deleted,
true
if data was not found. Object marked dirty if data type found and deleted.
word MSG_META_INITIALIZE_VAR_DATA(
word dataType);
This message is sent to an object any time the
ObjVarDerefData()
routine is called and the data type is not found. It should be subclassed by any object that defines a variable type that will be used with
ObjVarDerefData()
. The object must create and initialize the data and return its offset.
Sent to an object having a variable data entry which code somewhere is attempting to access via
ObjVarDerefData()
. It is the object that defines the variable data entry type's responsibility to create the data entry and initialize it at this time, and to return a pointer to the extra data (if any), as returned by
ObjVarAddData()
.
Source:
ObjVarDerefData()
routine. Should not be used as a replacement for
ObjVarAddData()
, or
MSG_ADD_VAR_DATA_ENTRY
, but may be used any time code is ready to access a particular piece of variable data instance data, knows that the variable data has not yet been created, and wishes to ensure that it does exist.
Destination: Any object stored in an LMem Object block.
Interception: Required by any class which defines a variable data entry type that needs to be initialized before usage. Objects handling this message should first compare the passed data type against variable data types it understands, and pass any unknown types onto the superclass for handling.
Parameters: Variable data type.
Return: Offset to extra data created (or, if no extra data, the start of data entry plus the size of
VarDataEntry
). Normally, this would just be the offset returned by the call to
ObjVarAddData()
.
word MSG_META_GET_VAR_DATA( /* returns size of data returned in buf;
* -1 if not found */
word dataType,
word bufSize,
void *buf);
This message fetches variable data of a given type from an object.
Source: Unrestricted.
Destination: Any object.
Interception: Generally not intercepted; default
MetaClass
handling performs the desired function.
Parameters: dataType The variable data category to return.
Return: The size of the data returned. If the vardata entry was not found, then message will return -1.
GEOS SDK TechDocs
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| 2.5 Event Messages
| 2.7 Notification Messages