Generic FunctionPackage: cgToCDocOverviewCGDocRelNotesFAQIndexPermutedIndex
Allegro CL version 8.1
Unrevised from 8.0 to 8.1.
8.0 version

use-bitmap-stream

Arguments: drawable

Returns (or sets with setf) whether a drawable uses a bitmap-stream on which output is drawn before being copied to the visible window of the control. To use a bitmap-stream, an application need only turn this property on, either by passing the :use-bitmap-stream initarg as true when creating the drawable, or calling (setf use-bitmap-stream) later. The drawable will automatically create a bitmap-stream of the proper size as needed.

If a drawable uses a bitmap-stream, it is returned by the bitmap-stream function. The function drawable-stream applied to a drawable returns the bitmap-stream if there is one.

A drawable will work just fine without a bitmap-stream, but a bitmap-stream may be used for various special reasons. Here are the steps involved for a few of these reasons after turning the use-bitmap-stream property on:

If use-bitmap-stream is toggled on and off, a new bitmap-stream is created only if the most recent one is not large enough either horizontally or vertically. So toggling this property should not be inefficient.

The bitmap-stream is also grown as needed automatically when the page size of the drawable is increased. This includes the case where (1) the scrollbar in either direction is not enabled, (2) no explicit page size has been given in that direction, and (3) the drawable itself is sized larger in that direction; in this case the default page size follows the interior size of the drawable, and the bitmap-stream is made larger as needed.


Copyright (c) 1998-2009, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 8.1. This page was not revised from the 8.0 page.
Created 2009.7.29.

ToCDocOverviewCGDocRelNotesFAQIndexPermutedIndex
Allegro CL version 8.1
Unrevised from 8.0 to 8.1.
8.0 version