Re: [orca-list] Video interceptor

[Peter Vágner <pvdeejay gmail com>]

Hello,
Back in the days when Windows 3.1 and later on Windows 95 came out, 
there was no accessibility API. Screen reader users over the world were 
afraid to use a new system because initially it was not accessible.
Makers of commercial screen readers tried to used all the available 
API's to make the OS at least basically accessible. They have used 
Windows specific API's and even used video interceptor for so called 
screen scraping.
However in linux the situation is completelly different and is even not 
derived from what we are tallking about here.
On linux since orca exists there is an accessibility API orca can use in 
order to inspect the desktop and running applications.
Orca is using a library called at-spi2-core which started as at-spi back 
in the days. This library is a kind of a bridge between orca or any 
other AT and the accessibility toolkit doing all the work. It's called 
ATK. Then at the other side of ATK to say it easily are individual 
graphical toolkits creating their controls such as Gnome shell, GTK, QT 
and others.

This may not be perfectly accurate how the accessibility is working in 
linux, but it at least gives basic overview. Additionally I am not 
expert on this and this is just how I understand it.

Greetings

Peter



On 16.11.2013 23:30, MENGUAL Jean-Philippe wrote:
> Hi,
>
> I have to do a talk soon about the screen readers, and I'll talk about 
> ORCA, of course. I wonder if someone can help me about a technical
> point: video interceptor.
> I'd like to know what's this and how it works (in the guidelines), to 
> compare with commercial screen readers such as Jaws for Windows. If I
> understand, it's an utility which enables a screen reader to understand
> the widgets that are not connected to the MSAA. Am I right? Could I be
> more precise or more exact technically  ? On Linux, could an 
> equivalent exist or is it excluded?
>
> Thanks for your help.
>
> Regards,