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List:       koffice-devel
Subject:    Re: YAKU (Yet another Krayon update)
From:       Matthias Elter <me () caldera ! de>
Date:       2000-11-20 15:36:30
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On Thursday 16 November 2000 18:23, John Califf wrote:
> The situation is this.  Krayon does NOT use the normal QPixmap and
> QImage and QPainter classes for its drawing and image processing.
> Instead, it uses custom classes and routines, all written at a low
> level.  Essentially, it's binary reading and writing of scan lines in a
> format similar to, but not exactly like, QImage.  But these scan lines
> are broken up by a number of tiles, which are updated with a timer
> which runs continuously.  Sounds complicated, and it is. Another
> difference is that Krayon access binary data by channel, like RGBA.  One
> for each color, basically. This is well encapsulated and you can access
> the data in terms of x,y coordinates and translate to QImage and QPixmap
> formats, regardless of the tiles, but writing TO the data using Qt is
> nearly impossible.  Each tile is like a piece of paper with writing on
> it, wrapping lines.  And there are hundreds of such tiles for a large
> image, like laying sheets of typewritten paper out on a desktop.  Scan
> lines are within each tile, and do not run continuously across the
> entire image as in almost every other image format.

Think of a 1MB JPG images that uses say 40MB uncompressed when in memory. You 
can't handle images of that size with QPainter drawing routines. You _need_ 
the tile system to keep only the tiles you currently work on in memory.

QImage also can't handle CYMK data. The abstract Krayon image class can (or 
can be extended to support it).

There are a bazillion reasons why you want to keep the tile system.

Greetings,
Matthias

--
Matthias Elter
me@kde.org
me@caldera.de
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