LDoDraw
LDoDraw Turn list drawing on or off ListHandle theList ; handle leading to a ListRec LDoDraw suspends or resumes screen updates normally performed by List Manager functions.
drawIt is a Boolean that selects how drawing should be performed. It is one of:
FALSE Turn drawing OFF. List Manager calls will not cause the screen to be updated until drawing is turned back on.
TRUE Turn drawing ON. Subsequent changes are displayed as they occur.
theList is a handle leading to a variable-length ListRec structure. It is normally a value obtained via LNew.
Notes: You may realize some performance or esthetic advantage by using
LDoDraw(FALSE,...) to turn drawing off while you create or make major modifications to a list. Use LDoDraw(TRUE,...) when you want changes to be displayed.
When you initially create the list (via LNew), you can make the choice to suspend drawing. In that case, you can use a series of LSetCell calls to fill the list with information without having any of it displayed. Then use
to be displayed. Normally, you should leave drawing ON all the time,
especially while processing List Manager events.
When drawing is off, most List Manager calls have no effect on the screen
(even LDraw and LUpdate are ignored). The only exceptions are with scroll bars: the LSize function will update them and the arrows and thumb still appear to be active (though mousing them has no effect on the display
of the list).