Object I/O Instructions

Object Instructions

PLBCMP GUI Only

A number of object variables have been added to PL/B to support the Graphical User Interface. Accordingly, several new verbs have been added to manipulate these various objects.

ACTIVATE	Makes an object visible and allows the user to interact with it.
CHECKITEM	Set or clear a check mark beside a menu item.
CHECKPROP	Determine if a property is valid for an object.
CREATE	Creates all necessary data structures for an object.
DEACTIVATE	Hides the object from the user.
DELETEITEM	Delete an item from an object.
DESTROY	Release the data structures obtained for an object.
DISABLEITEM	Prevents user interaction.
DRAGITEM	Enable or disable an object's drag and drop capabilities.
ENABLEITEM	Allows user interaction.
EVENTREGISTER	Associates an event with a program execution label.
EVENTSEND	Sends an event to a specified object.
FORMLOAD	Load and activate a PLFORM.
GETFOCUS	Obtain the identification number of the object that currently has focus.
GETITEM	Obtain the value of an object item.
GETPROP	Obtain the value of a specific property.
INSERTITEM	Add a new item to an object.
LISTCNT	Count objects in a COLLECTION.
LISTDEL	Delete an object from a COLLECTION.
LISTGET	Retrieve an object from a COLLECTION.
LISTINS	Insert an object into a COLLECTION.
SETFOCUS	Changes the current focus.
SETITEM	Set the value of an object item.
SETPROP	Set the value of a specific property.

The following is the minimum number of instructions required for object variables:

CREATE	{object}...	;Allocates memory
...
ACTIVATE	{object}...	;Displays on screen
...
DEACTIVATE	{object}	;Takes off screen
...
DESTROY	{object}	;Deallocates memory

The other instructions change the state of an active object or to add or delete items in an object.

Following on the next page is a simple program to create a single button, a menu item and a submenu item. A check mark is placed beside the menu items when they are selected and the check mark is deleted when they are selected again.

*
. Sample PL/B program to demonstrate SUBMENU usage.
.
HALT	BUTTON
MENU1	MENU
MENUOPT	FORM	1(3)
SUBMNU	SUBMENU
SUBMNUD	INIT	"/SSubOptions;":
		"/1Test1;":
		"/2Test2;":
		"/3Test3"
RESULT	FORM	2
INS	INTEGER	1,"1"
*
. Initialize the Window
.
	DISPLAY	BGCOLOR=CYAN,FGCOLOR=BLACK:
		ES,P33:1,*BLACK,"SubMenu Test"
*
. Create HALT button selection to Exit in a nice mode.
.
	CREATE	HALT=9:10:35:45,"HALT"
	ACTIVATE	HALT,EXIT,RESULT
*
. Create a MENU item named "Menu".
.
	CREATE	MENU1,"/OOptions;/DDisplay;/LList;/NNone"
	ACTIVATE	MENU1,MENUEXC,RESULT
*
. Create SUBMENU
.
	CREATE	SUBMNU,SUBMNUD,MENU1,2
	ACTIVATE	SUBMNU,SUBEXC,RESULT
*
. This is the primary event processing point.
.
	LOOP
	EVENTWAIT
	REPEAT
*
. Exit Point. This routine is called when
. the STOP button is clicked on.
.
EXIT	STOP
*
. MENU1 items processed. Toggle check mark
. beside menu item selected.
.
MENUEXC
	IF	( MENUOPT(RESULT) = 1 )
	CHECKITEM	MENU1,RESULT,OFF
	CLEAR	MENUOPT(RESULT)
	ELSE
	CHECKITEM	MENU1,RESULT,ON
	MOVE	"1",MENUOPT(RESULT)
	ENDIF
	RETURN
*
. SUBMNU items processed.
.
SUBEXC
	...
	RETURN