[Digikam-devel] [Bug 163286] Accurate histogram preview required

Gilles Caulier caulier.gilles at gmail.com
Thu Feb 11 09:43:14 CET 2010


--- Comment #11 from Gilles Caulier <caulier gilles gmail com>  2010-02-11 09:43:09 ---
>- If I need histogramdata of a square area on my 16:9 display I do not want to
>buy a new monitor or adjust digikam window size

But there is no regression why new code compared to old one based on imageguide
widget. before to use zoomable preview, you cannot do that too.

Also, this is not the goal to show a specific region rectangle (with a specific
ratio) of image. When you use BCG tool, you just want to see a preview relevant
of future change. For technical reason, we use geometry of preview widget to
render that. It's more simple. 

>- In canvas we have full histogram and selection histogram regardless of zoom.
>If I switch now to a tool this should be the pure opposite?

Yes, and you can do it again. This feature is not removed.

>So why not reuse selection histogram in tools? That would be consistent.

Because, all preveiw widget are not yet factorized. I have alredy factored a
lots of code there, but i must take a care to not break all faster.

Your idea will be possible when editor canvas and preview widget implementation
will be merged, and also ported to pure Qt4. This is not yet the case.

Editor canvas as selection code, preview widget no.

To be clear here, preview widget are :

- previewwidget (root code Q3Scrollview based zoomable but without preview
- imageregionwidget (based on preview widget, used by editor tools,
implementing preview modes)
- canvas (based on Q3Scrollview, used for main editor view, zoomable,
implementing selection)
- rawpreview (used by RawImport tool, based on previewwidget)
- lighttablepreview (used by LT, based on previewwidget)
- imagepreviewview (used by AlbumGUI preview, based on previewwidget)

Image editor use too imageguidewidget with some tools which need a preview fit
on window. All color correction tools are based on this, and i currently port
all on imageregionwidget.

The pure Qt4 port of preview widget is very important to the future.
QScrollArea API must be used there. My first plan is to polish all digiKam API
before to have a cleaned code to port. I think i have review all and Qt4 port
can be done as well... but you can imagine all regression tests to do there.
This will require a digiKam release only for that. So, like there are a lots of
changes done with 1.2, i will wait 1.3 a little bit.

If you is interrested to help me here, let's me hear.

Gilles Caulier

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