Re: Teaching application: need guidance

[James Henstridge <james daa com au>]

Franck Martin wrote:

> I would like to develop a very simple application, but I'd like to get 
> some pointers on how it should be done. I will do it with glade and 
> anjuta.
>
> The application is simple, when you click on an icon in a toolbar it 
> will bring a transparent layer over the whole screen upon which you 
> will be able to draw.
>
> The purpose, you bring a spreadsheet on your screen, project your 
> screen on the wall and then you can highlight some areas with your 
> pen/mouse....
>
> When you click on an icon then all the action on the screen are passed 
> to the applications behind the layer...
>
> How do you i do a transparent layer (style gnome canvas)?

X does not support transparent windows like you want, but there is a way 
you could possibly do this.

You would want to display a window covering the whole screen, and set 
its background pixmap to NULL.  This tells the X server to not clear the 
background before asking the client to redraw itself.  This way, the 
screen sized window will essentially get a snapshot of what was 
underneath.  You can then draw on top of it.

James.

--
Email: james daa com au
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