[Digikam-devel] Experimental : image preview on main interface

[Caulier Gilles]

Hi all,

Following some reports from B.K.O and discussions by IRC/mails, some users 
would to have a preview mode of current album item, directly in main 
interface, without to start an instance of image editor. Image editor take a 
while with old computer to just previewing a RAW picture.

I have search a simple solution to do it.... and this is my proposal :

http://digikam3rdparty.free.fr/Screenshots/image_preview_on_main_interface.png

I have make an experimental patch using QWidgetStack to embed into album 
collection area a new image preview. You toogle between preview and album 
view using F3. 

The patch is here :

http://digikam3rdparty.free.fr/misc.tarballs/preview.patch

The RAW preview use the -e dcraw option to load the embedded JPEG image in RAW 
file (used to display a RAW picture on TV screen)

This patch separate Preview mode (F3) and the Edit mode (F4) on Image menu 
entries. If you enable the ImageProperties sidebar, use the navigate button 
to change the current image to preview.

This code is simple and not finalized. For example the code :

- don't use a cache to speed up rendering.
- don't use the embedded preview from JPEG/TIFF/PNG files available in 
Makernote metadata. Canon, Nikon, Minolta, etc, record a small preview image 
in Camera Settings. This is must be used instead to load the whole image. In 
fact, Exiv2 need to be improved for that. i'm currently working with Andreas 
about this subject.
- use QImage, not Dimg.
- don't load the preview using a separate thread to unfreeze ther GUI (Image 
Editor do it). We can use a new KIO slave for that but not sure (Marcel, your 
viewpoint ?)

Please don't ask me to create a very advanced new feature for 0.9.0. I have 
not commited this code in svn because i'm not sure if this is the right way 
to implement an image previewing. Also to finalize properlly this code, we 
need more time, and i would delay this implementation later 0.9.0.

To patch your local source repository, use these command lines :

# cd digikam
# patch -p0 < preview.patch

Note : You need to re-install digiKam before to use this version because a new 
menu item have been added in main interface (digikamrc file changed)

Please, give me a feedback. Thanks in advance

Gilles