ubuntu-phone team mailing list archive

[Robert Schroll <rschroll@xxxxxxxxx>]

Hi all,

This email is going to run on a bit, so let me put my questions here at 
the top and motivate them afterwards:

1) Is it possible to adjust the style of a single compound widget?  
(That is, a QML element with several sub-elements.  I don't know the 
terminology here.)

2) If not (and I haven't found one), should there be?

I'm working on an epub reader for the app showdown [1].  One of the 
options I provide is the font in which the epub will be displayed.  I 
want to do this with an OptionSelector, and I'd like to display the 
name of each font in that font.  It looks like this is impossible with 
the SDK as it currently stands.  (Please correct me if I'm wrong.)

With simple QML widgets, like a Rectangle, you can adjust the 
properties of the widget to change its styling.  But the widget I need 
to adjust, an OptionSelectorDelegate, is a compound widget -- the text 
is in a Label inside of the OptionSelectorDelegate, and there's no way 
for me to access this.  These Labels don't have ids, and even if they 
did those ids wouldn't be accessible outside of that .qml file, for 
some reason.

I came up with a simple fix to this: Give the Labels ids, and then give 
the OptionSelectorDelegate properties referencing the label.  Then when 
I make an OptionSelectorDelegate, I can adjust the font of the label 
through the textLabel.fontFamily property.  I've written up a patch and 
submitted it to Launchpad [2].

I asked about this on IRC, and mzanetti opined that this was not the 
right approach.  Internals shouldn't be exposed like this.  And while I 
disagree, this is not an unreasonable position.  Instead, mzanetti 
suggested that the OptionSelectorDelegate should become themable, and 
then I could provide my own theme to do the styling.

It may be that it should be themable, but this wouldn't solve my 
problem.  I don't want to redo the theming of the widget; I just want 
to tweak the font.  I could do this, theoretically, by creating a new 
widget based on the OptionSelectorDelegateStyle widget and tweaking the 
font there.  But this runs into three problems:

1) Not all the *Style widgets are exposed in the Theme directories.  (I 
recently ran into this problem when trying to theme a Slider; see [3].)

2) I would have to inherit from a specific theme.  If that changes in 
the future, due to system changes or user choice, my styling would be 
completely wrong.

3) I would still need access to the internal Label of the style widget, 
which is the very thing that got us going down this path!

Hence my questions: Is there a way to set the font in an 
OptionSelectorDelegate?  There doesn't seem to be.  Should there be?  I 
think so.  How should this work?  This I don't know enough about to 
comment.

Thanks,
Robert

[1] https://github.com/rschroll/beru
[2] https://bugs.launchpad.net/ubuntu-ui-toolkit/+bug/1220533
[3] 
https://github.com/rschroll/beru/commit/927b2fd377d7cc86b0633a2707b03c3a79a330db