Source code modification

[Gilles Caulier]

Hi Andrey,

This have been a long history in bugzilla about to be able to display
or edit some properties over the canvas (editor and preview mode), as
rating, tags, or labels.

The result is a shared point to implement or not this feature, as the
possibility already exist every where : context menu, sidebar, and
keyboard shortcuts.  And of course nothing have be done as it's
delcate to take a clear decision about.

But, something as been implemented in slideshow, as only keyboard
shortcuts was available to apply main properties to images. On the
botoom corner of the image while slide show, if the right option is
turned on in setup dialog, you are able to rate, tags, or change color
labels.So, the techical solution exists in slide show widget, and can
be backported to image preview.

But take a care, it's not the most simple task to do to start coding
in digiKam and to learn the implementation.

If rate/tags/labels will become available over canvas, well all of
then must be optional in setup preview section, to be homogeneous.
this will touch more code.

Also, the preview canvas, is also used in Light table and must be also
patched to provide this feature.

Even that you are right. The preview canvas, is partially implemented
in imagepreviewview.cpp. This is the derivated class to manage the
preview with F3 key from album view. There are parent classes in
core/libs/widgets/graphicsview/. The preview view is an item loaded in
canvas and implemented with imagepreviewviewitem.cpp (it's Qt
model/view based).

Something similar is implemented with Light Table with some difference
and customizations. Mostly the main code is located in core lib
classes, and customization is located in derivated classes. The parent
classes are free of database to be usable in Showfoto as this one
don't use the database. So with your proposal, the code to change is
mandatory located in customization classes.

Now the implementation from slideshow to be able to show and edit
rate/tags/labels over the preview is located in
core/utilities/slideshow/slideosd.cpp.There are 3 magic widgets which
perform 90 of the job with the properties to show/edit : RatingWidget,
ColorLabelSelector, and PickLabelsSelector. This one are usable as
well without change as it's done with slideosd.cpp.

But the real question, is more ambitious : why not to reuse as well
the slideosd implementation as an overlay widget for preview canvas.
This will be homogenous everwhere and factorize/simplify all codes

So the questions are open...

Best

Gilles Caulier

2017-07-26 1:03 GMT+02:00 Andrey Goreev <aegoreev at gmail.com>:
> Hello,
>
> I want to make an image star rating visible in image preview view and
> wondering which file should I be modifying.
> I am looking at imagepreviewview.cpp in
> https://github.com/KDE/digikam/tree/master/app/views
> Is this the right one? Any tip would be greatly appreciated.
>
> Best regards,
> Andrey