gnome-scan report - 2007 may 05

[Étienne Bersac <bersace03 laposte net>]

Hi all,

This week i did nothing due to exams and end study project (due this
week). However, i worked some weeks ago on gnome-scan rewrite
( http://www.gnome.org/projects/gnome-scan/index ).

Currently, the project has a working files backend which allow to scan
from files. The dynamic backend loading is ok. Acquisition works, not
mass acquisition.

The project is documented using Gtk-Doc, and each widgets documentation
provide a screenshot. Widget screenshots effects (drop shadow, border,
…) are generated using Gegl ( http://www.gegl.org ). This is a key point
since all effects in gnome-scan will be executed by Gegl.

I suffer from a lake of public API from Gegl, especially GeglBuffer. I'm
stuck to GdkPixbuf which is not designed for large image. For example a
GeglBuffer can represent a 11G images while you have only 1G of RAM.
Scanning at high resolution like 2400dpi leads to very huge picture.
Also, the GeglOperation API is not public and won't be before summer.
This mean i won't implement scan src and sink as a GeglOperation. That
may imply some code refactorization in future release, but.

Another key point of the new gnome-scan is thread. gnome-scan 0.5 is
fully multithread. This give make the overall software far more reactive
(try to open 40 images using the files devices and see how preview are
generated without blocking the UI). Probe and acquisition is threaded.

One more key point of this release is hotplug. The backend/device model
allow hot plug. Even if HAL and SANE are not well integrated yet, i
designed gnome-scan to handle hotplug. Triggering device probe does not
return a list of device after blocking the overall software during the
probe. Now probe trigger "coldhotplug" of each detected device. Also,
device probe is transparently threaded, this mean backend does not have
to care about threading. I dropped the "waiting" popup.

I really expect more in the future :

     1. sane backend (very huge amount of work)
     2. mass acquisition (very easy)
     3. GeglBuffer

I would like to develop gnome-scan asap, but i have exams :(. I'll do my
best to work on it a few hours a week.

Étienne.
-- 
Verso l'Alto !