BBjSysGui::flushEvents

Description

Flushes all pending events from the queue.

Syntax

Return Value	Method
void	flushEvents()

Parameters

None.

Return Value

None.

Remarks

Calling flushEvents() affects the timing of Java repaint() events.

Any change (e.g. BBjControl::setText()) that changes the visual appearance of a window generates a repaint event on the Java EventDispatchThread. Internally Java accumulates all repaint events until it determines that there are no more outstanding events on the EventQueue and only when the EventQueue is empty does Java actually paint the areas of the screen that have changed. This allows Java to collapse all the outstanding repaint requests into a single paint operation and is an important optimization since paint is an expensive operation.

When a program calls flushEvents(), BBj stops placing events onto the Java EventQueu until the EventQueue becomes empty. This means that a call to flushEvents() will cause Java to execute any repaint() requests that are outstanding at the time flushEvents() is called.

A program that makes a large number of method calls that modify the appearance of Windows and intersperces calls to flushEvents() within that list of method calls may suffer performance degradation because each call to flushEvents() will result in a paint of the screen. Without the flushEvents() calls, all the screen changes will be collapsed to a single paint.

A repaint will typically take a couple hundred milliseconds so this is only an issue when there are a large number of screen changes with a large number of flushEvents() interspersed in the list of screen changes.

Example

rem 'Flush all pending events from the queue

rem 'Obtain the instance of the BBjAPI object
let myAPI! = BBjAPI()

rem 'Open the SysGui device
SYSGUI = UNT
OPEN (SYSGUI)"X0"

rem 'Obtain the instance of the BBjSysGui object
let mySysGui! = myAPI!.getSysGui()

rem 'Set common addWindow param values
X = 10
Y = 10
WIDTH = 200
HEIGHT = 200
TITLE$="BBjWindow Example"

rem 'Create a window with a title in the specified context
myWindow! = mySysGui!.addWindow(CONTEXT,X,Y,WIDTH,HEIGHT,TITLE$)

rem 'Flush all pending events
mySysGui!.flushEvents()
release