W3C home > Mailing lists > Public > www-svg@w3.org > April 2004

Re: questions about clipping

From: Jean-Claude Dufourd <jean-claude.dufourd@enst.fr>
Date: Sat, 17 Apr 2004 16:22:11 +0200
Message-ID: <40813D93.5030207@enst.fr>
To: Dean Jackson <dean@w3.org>
Cc: www-svg@w3.org

G'day Dean

Dean Jackson wrote:

> We'll take this as a feature request. My opinion is that it isn't trivial
> to implement, although it isn't difficult to implement. The problem
> is that when you're talking about such small devices, it really must
> have a large benefit if it isn't trivial.

OK then, for a feature request, you need a "why" and a "how much":

- why:
-- to roughly double the number of transitions that can be implemented 
efficiently (box in/out, wipe, curtain...) in slide shows
-- to implement popup menus or pull-down menus (just other kinds of 
transitions)
-- to ensure that a text does not spill out of a certain rectangle (when 
you do not control the font)
-- to be able to split your screen in regions and show objects larger 
than the current region
-- to have scrolling windows or menus: you place the whole menu/window 
content in a clipping rectangle and you move the content up or down

- how much: in the 3 or 4 Java renderers I have implemented that have 
this feature, the overhead was negligible. It consists in passing an 
additional parameter "clipRect" to the rendering methods, and deal with 
the really simple problem of intersection of two rectangles with 
vertical and horizontal borders. The necessary primitives are available 
in Java and C/C++ on all platforms I heard about. The last time I 
requested that feature, the guys responsible for the Java and C++ 
players both implemented it in a few hours (two days max). Now the 
players I am talking about are for some format "smaller" that SVG Tiny, 
but they are relevant for a cost estimation.

Best regards
JC
Received on Saturday, 17 April 2004 10:22:04 GMT

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