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FutureBasic 5
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FlushWindowBuffer
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statement
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Syntax:
FlushWindowBuffer [ wNum | _FBAutoFlushOff | _FBAutoFlushOn ]
Description:
Under MacOS X, all drawing to a window is intercepted and stored ("buffered") by the Window Server. The Window Server normally transfers the drawing to the screen only when your program executes a HandleEvents
statement. You can force an early update with FlushWindowBuffer
.
If wNum
is omitted, or is 0, the current output window is flushed by the MacOS X Window Server. If wNum
is non-zero, window wNum
is flushed.
The default behavior of the FutureBasic runtime is to flush the current output window each time a print
statement is performed. You can control that behavior: FlushWindowBuffer _FBAutoFlushOff
will turn off the automatic flushing. You still can force the flushing for a specific window with FlushWindowBuffer wNum
. FlushWindowBuffer _FBAutoFlushOn
will restore the automatic flushing.
The FlushWindowBuffer
command has no effect unless the program is running under MacOS X. Because of coalesced updates in MacOS X 10.4 Macho-O binaries, this does nothing if called too soon (0 or 1 tick) after the previous call.
Example:
// In this example, there is no HandleEvents,
// and so FlushWindowBuffer is needed to
// make the drawing visible under MacOS X.
window 1
plot 0,0 to 500,500
FlushWindowBuffer
until fn button // wait for mouse-down