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Re: inaccessible treeviews and tables

Hello,
Issue in transmission-gtk is just my guess I haven't yet tryed to tinker with its source code so I may really be absolutelly wrong with my assumption. Venom developers are subclassing GTK_CellRenderer here https://github.com/naxuroqa/Venom/blob/master/src/ui/ContactListCellRenderer.vala . I can see they are also using GtkCellRendererText in order to change a GTK_COMBOBOX which remains accessible here https://github.com/naxuroqa/Venom/blob/master/src/ui/ContactListWindow.vala . While creating my CustomCellRendererAccessible do I really have to do everything that is recommended here https://developer.gnome.org/accessibility-devel-guide/stable/gad-custom.html.en ? As I said I have tried to retrieve a coresponding accessible by calling gtk_get_accessible(MyCustomCellRendererObject). I was able to manipulate that accessible and set its name and description however by testing with orca I have discovered changes I am trying to make result in changes to the parent object treeview in this case not individual rows which as I understand are represented by the CustomCellRenderer. Then I have tried to subclass a GTK_TreeViewColumn where the CustomCellRenderer is connected to by trying to create empty ATK_Object, overridding Get_Accessible() in my subclass. Of course this does not work. I haven't really understood where is the problem however I think It is just not possible to instantiate ATK_Object like all the other objects using new operator.
So Now I am lost again and I have no idea on how to possibly move forward. Frankly I don't feel confortable following the article Making Custom Components Accessible on the gnome developers wiki, it's why I have started exploring these things on my own hopefully asking more concrete questions. The only lesson I have learned so far is that I really need CustomCellRendererAccessible. But I don't have an idea on how to do that. 

Thanks your patience and helpfull hints.


Greetings

Peter

On 07.07.2014 14:02, Piñeiro wrote:

Hi,

I will try to answer your question as best as I can.

As you say, sometimes a 3rd party gtk app developer creates a custom
cell renderer in order to add some new visual stuff. The accessibility
related are not skipped. The already in place cell renderer
accessibility is used. But if the new cell renderer uses something
totally different to render text, then the gtk+ cell render accessible
object would not be valid. In that case you would need to provide a
custom accessibility object for that custom cell renderer. For the rest
of this email, I will call them CustomCellRenderer and
CustomCellRendererAccessible

gtk_cell_renderer_class_set_accessible_type, is just the method that
relates a cell renderer with his accessible method. Is just a utility
method to avoid the need to redefine the method get_accessible for any
custom object. So for this case, once you have a
CustomCellRendererAccessible, you would need to call
gtk_cell_renderer_class_set_accessible_type on your CustomCellRenderer.

About caring on CellRenderer: as I said, there is already an
accessibility support of CellRenderer. So probably you just need to
focus on that CustomCellRenderer, where the information about name and
state are stored there (that would be the difference with a "vanilla"
CellRenderer), and then try to expose it via a CustomCellRenderAccessible.

About that transmission-gtk: after a quick look on Venom. I don't see
any custom cell renderer being created. As far as I see, they are using
GtkCellRendererText, that should be already supported. Are you sure that
in that case you are under a custom cell renderer problem?

Best regards

[1] https://developer.gnome.org/gtk3/3.12/GtkCellRendererText.html

On 07/05/2014 06:20 PM, Peter Vágner wrote:

Hello,
A while ago I was trying to get some understanding on how to make 3rt
party gtk apps accessible. At that time Alejandro Piñeiro pointed me
to some docs and bugzilla entries describing the current situation.
Unfortunatelly I haven't still mastered that. I have at least realized
and hopefully understood at least some verry basic things related to
this.
For example currently I am able to set accessible labels and I am able
to add / tweak relations between labels and the interactive controls
they are supposed to label. I know this is not a big deal but I have
already tweaked an app or two this way and I know it works fine.
Another thing what's currently on my radar are widgets that are often
reported as tables or treeviews. Individual rows appear to be keyboard
focusable however orca is unable to report their role and text.
I guess the common scenario is that the app developers tend to
subclass Gtk.CellRenderer to create more visually appealing design. In
this case if I understand correctly the content is directly drawn to
the widget surface and proper accessibility related properties are
skipped from the implementation entirely.
By reading gtk reference docs I have came accross a method
gtk_cell_renderer_class_set_accessible_type () . That appears to be
only info I was able to find related to Gtk.CellRenderer and
accessibility. Can anyone please give me a hint so I might try move
forward and try learning how to implement accessibility for a widget
where Gtk.CellRenderer is used?
Do I need to care about Gtk.CellRenderer or should I just set
accessibility related properties such as label and description for the
affected widgets without looking at Gtk.CellRenderer? How do I refer
to multiple treeview colums or table cells in such implementation? Is
there an app or just a code example I should look into to see this in
action?
I have seen widgets with incomplete accessibility like this in many
apps but if my explanation is not accurate enough here are two from
the top of my head. One is the list of torrents in the
transmission-gtk svn://svn.transmissionbt.com/Transmission/trunk and
the other is a contact list widget in a gtk3 based tox client called
venom https://github.com/naxuroqa/Venom .
I will be looking into this some more, it may take me a while like it
took me ages to figure out and get used to labelling and related stuff
so I am just trying maybe with some hint I might master it better this
time.

Thanks

Peter

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