ex11, plotting and Cairo ...

Jouni Rynö <>
Wed Jul 20 21:06:39 CEST 2005


Finding a simple subset from a huge parameter space may not be possible.
But how about different backends for canvas. All primitives could have
options list, default values given upon canvas initialisation.
Application could then mix different canvas types, fast for window user
interface, slow and fancy, where it matters. So the it would still be
simple

        draw(Win, character, X, Y, font, glyfNumber)
AND
        draw(Win, character, X, Y, font, glyfNumber, [tag=fancy,
render=xlib, kern=[], alpha=0.9, justification=right, ...])

Written that, I don't know, if it's a good idea to allow primitives so
much. Changing the rendering backend, really not. But something like
that. Anyway, it must be possible to make out something with the basic
command. If it comes out bad looking, one can start twiddling with
options. Usually, at first you don't care. (like "make it first to work,
then make it fast")

And about the canvas item tags. Those without tags would be like labels,
no activity expected. With tags, user action to be done i.e. active
objects. Or something like this.

Jouni

----- Original Message ----- 
From: "Jouni Rynö" <>
> We could have the cairo model on top of ex11 with some extensions.
Like
> adding the item tags. And keeping a list of item enclosures. Then a
> click point to the canvas would be send through the item list. To see
if
> any item under the mouse is interested. Something like that must
already
> happen under the Tk-hood.

I have the very basics of such an event handling system, modeled after
the 
QNX Photon library. If there is interest, I can make it available for 
inspiration.

One basic question is also: will these items or regions be active
objects? 
There are pros and cons with both alternatives.

/Vlad

-- 

  Jouni Rynö                            mailto://Jouni.Ryno@fmi.fi/
                                        http://www.geo.fmi.fi/~ryno/
  Finnish Meteorological Institute      http://www.fmi.fi/
  Space Research                        http://www.geo.fmi.fi/
  P.O.BOX 503                           Tel      (+358)-9-19294656
  FIN-00101 Helsinki                    FAX      (+358)-9-19294603
  Finland                               priv-GSM (+358)-50-5302903
  
  "It's just zeros and ones, it cannot be hard"





More information about the erlang-questions mailing list