Re: inaccessible treeviews and tables

[Peter Vágner <pvdeejay gmail com>]

Hello,
Definatelly calling set_accessible_type is working well over here. I 
have tried to append a randomly generated number to the string I am 
getting and I got different results for different entries in the 
get_name method on my custom GTKRendererCellAccessible subclass.
Also I have tried to examine if the results are all right while drawing 
on the renderer and they definatelly are.
Do I have to have implement something more on the 
GTKRendererCellAccessible subclass to make it work? Currently I do only 
have get_name in there. I assume GTKRendererCellAccessible has a 
property named renderer and that is the reference to coresponding 
GTKCellRenderer object.
I am trying to compare my implementation to that found in the 
gtktextcellaccessible.c however I am really confused as none of the 
GTK_Text_Cell_Accessible... methods are accessing renderer property so 
how do they access the renderer data?

Greetings

Peter

On 09.07.2014 17:55, Peter Vágner wrote:
> Hello,
> I am reading a bit on vala ownership and I am afraid that's not my 
> issue here.
> Now a speculation.
> Do I have to pass Gtype of a class to the set_accessible_type or do I 
> have to first instantiate an object of that class?
> In vala all this is just a bit of code that generates quite a lot of c 
> code. Heh but in order to make it work it has to be understood I am 
> afraid.
>
> Thanks and greetings
>
> Peter
>
>
>
> On 09.07.2014 17:50, Piñeiro wrote:
> > Good to see that you are advancing here. It is also good that for for
> > the first time someone is facing implementing extra accessibility
> > support on vala, and you even found a problem (lack of some gtk-a11y
> > headers on vala)
> >
> > Thanks for your interest and your work on fixing this 3rd party
> > applications and vala.
> >
> > Best regards
> >
> > On 07/09/2014 05:03 PM, Peter Vágner wrote:
> > > Hello,
> > > Awesome It did not take methat long to add another bit of the puzzle.
> > > Again this is a vala specific issue. It appears I need to cast
> > > renderer property inside my derived RendererCellAccessible class to my
> > > derived CellRenderer class.
> > > Now I am getting the same return value for all the treeview entries.
> > > Again to sum it up there is a treeview, that treeview has a
> > > treeviewcolumn which has a cell renderer. I am trying to implement a
> > > proper RendererCellAccessible so the same data that is drawn using the
> > > cellrender will become accessible.
> > > I suspect this has something to do with the fact name property on the
> > > accessible is a weakref. In vala that's called the ownership. I have
> > > created a local variable holding the result and maybe that is not
> > > getting cleaned or something. This is really something I need to
> > > understand better.
> > >
> > > Greetings
> > >
> > > Peter
> > >
> > >
> > >
> > > On 09.07.2014 14:33, Peter Vágner wrote:
> > > > Hello,
> > > > Okay now I have got it working to some degree.
> > > > My recent issue was that I had put the constructor of my derived
> > > > RenderCellAccessible class wrong thus set_accessible_type was never
> > > > called on my CellRender subclass.
> > > > Heh guess what, now I am facing another issue.
> > > > I am unable to get a reference to the coresponding CellRenderer
> > > > object. There is a renderer property on my resulting accessible
> > > > object but it most likelly points to some generic CellRenderer
> > > > instead of my custom derived one. Shouldn't I be able to get that via
> > > > its constructor for free?
> > > >
> > > > Thanks and greetings
> > > >
> > > > Peter
> > > >
> > > >
> > > >
> > > >
> > > > On 08.07.2014 23:18, Peter Vágner wrote:
> > > > > Hello,
> > > > > This is really strange. I thought I have more or less understood how
> > > > > this should work finally.
> > > > > Then I have found out that vala hides all the GLib stuff because in
> > > > > most cases it's not really usefull but still there is a simple
> > > > > typeof() method which creates GType of a given class. Then I have
> > > > > managed to talk to helpfull guys at #vala and finally found out
> > > > > vala-0.24 does not include gtk-a11y.h so I had to tweak that locally
> > > > > until I try to report a bug and it'll get adressed.
> > > > > Now it all compiles fine but unfortunatelly it appears not to work
> > > > > as intended. Also I assumed that renderer property on my custom
> > > > > GTKRendererCellAccessible subclass will point to the corresponding
> > > > > CellRenderer. Unfortunatelly it does not.
> > > > > So I  have tried to just return plain statically typed string as a
> > > > > result of get_name method on my RendererCellAccessible subclass.
> > > > > That is not seen when testing with orca.
> > > > >
> > > > > Here is the vala code: http://pastie.org/9369194
> > > > > And here is the resulting c code: http://pastie.org/9369215
> > > > >
> > > > > I know that's not verry clever way posting automagically generated c
> > > > > code but now I have verry mixed feelings and hopefully I only need
> > > > > to take a break. Might this be really that unintuitive or is it
> > > > > likelly I am too .... You know what I mean.
> > > > > Or alternativelly might the vala bindings be somewhat buggy? I am
> > > > > afraid that's not verry likelly at least not in this case.
> > > > >
> > > > > Greetings
> > > > >
> > > > > Peter
> > > > >
> > > > >
> > > > > On 08.07.2014 14:38, Piñeiro wrote:
> > > > > > Hello,
> > > > > >
> > > > > > no, your problem is not related at all with that thread. The 
> > > > > > problem I
> > > > > > pointed on that thread was solved (take into account that that 
> > > > > > thread
> > > > > > has almost 2 years old).
> > > > > >
> > > > > > On Glib every class (GObject) has a given GType (see [1][2]). For 
> > > > > > the
> > > > > > task that you are doing, take as reference gtkcellrenderertext and
> > > > > > gtktextcellaccessible.h. In this case "text" is the "custom" cell
> > > > > > renderer I was talking about. As usual (usual glib boilerplate for
> > > > > > C-code), gtktextcellaccessible define some macros related to the new
> > > > > > type. One is GTK_TYPE_CELL_ACCESSIBLE, that points to an also new
> > > > > > method
> > > > > > gtk_text_cell_accessible_get_type. In general, when you declare a 
> > > > > > new
> > > > > > GType, you need to provide a method that returns this new GType. In
> > > > > > order to provide the implementation of that method, right now 
> > > > > > there is
> > > > > > some utility macros like G_DEFINE_TYPE [3].
> > > > > >
> > > > > > In summary, what GtkTextAccessible does is declare
> > > > > > GTK_TYPE_CELL_ACCESSIBLE and gtk_text_accessible_get_type on his
> > > > > > header,
> > > > > > use G_DEFINE_TYPE to implement the get_type method on his source 
> > > > > > code.
> > > > > > Then GtkCellRendererText calls
> > > > > > gtk_cell_renderer_class_set_accessible_type using
> > > > > > GTK_TYPE_CELL_ACCESSIBLE.
> > > > > >
> > > > > > So, for the case of C, you have some examples of how to do this. The
> > > > > > different is that custom cell renderer is written on Vala. Being 
> > > > > > as it
> > > > > > is Vala, when created the equivalent C-code, all this would be the
> > > > > > same,
> > > > > > so it is really likely that you would be able to get the GType 
> > > > > > from a
> > > > > > class that you are defining (in this case this 
> > > > > > ContactListCellRenderer
> > > > > > accessible class). Unfourtunately, my experience with Vala is 
> > > > > > zero. I
> > > > > > just know what it is. So I would not be able to tell you how to do
> > > > > > that.
> > > > > > In any case, #vala channel at Gimpnet seems full of people. Probably
> > > > > > they could help you.
> > > > > >
> > > > > > About your question in relation to init methods: GObjects are an
> > > > > > Object
> > > > > > Oriented add-on to C, so they need to do some manual handling in 
> > > > > > order
> > > > > > to register the type and create the new object and class. You can
> > > > > > find a
> > > > > > detaile information here [4], but probably for now you can just 
> > > > > > forget
> > > > > > that, and just follow the rules. That method needs to be called 
> > > > > > on the
> > > > > > class_init method. Take a look to what GtkTextAccessible and
> > > > > > GtkCellRendererText are doing. Those are an example of a custom cell
> > > > > > renderer and his accessible object.
> > > > > >
> > > > > > Best regards
> > > > > >
> > > > > > [1] https://developer.gnome.org/gobject/stable/
> > > > > > [2] https://developer.gnome.org/glib/2.40/
> > > > > > [3]
> > > > > > https://developer.gnome.org/gobject/stable/gobject-Type-Information.html#G-DEFINE-TYPE:CAPS 
> > > > > >
> > > > > >
> > > > > > [4]
> > > > > > https://developer.gnome.org/gobject/2.40/chapter-gobject.html#gobject-instantiation 
> > > > > >
> > > > > >
> > > > > >
> > > > > > On 07/08/2014 08:36 AM, Peter Vágner wrote:
> > > > > > > Hello,
> > > > > > > I have subclassed GTKRendererCellAccessible, implemented basic
> > > > > > > get_name method in my subclass taking advantage of reference to the
> > > > > > > CellRenderer.
> > > > > > > However what I am unable to workout is how do I get a proper 
> > > > > > > GType of
> > > > > > > my subclass so I can pass it to the
> > > > > > > gtk_cell_renderer_class_set_accessible_type () on my CellRenderer
> > > > > > > subclass. I assumed I am missing something verry obvious but I then
> > > > > > > went back to the earlier discussion you pointed me to a while 
> > > > > > > ago...
> > > > > > > https://mail.gnome.org/archives/gtk-devel-list/2012-August/msg00050.html 
> > > > > > >
> > > > > > >
> > > > > > > . I can find no method get_type or similar on 
> > > > > > > GTKRenderCellAccessible
> > > > > > > either directly implemented nor inherited. So either I am missing
> > > > > > > something simple or this is more complicated than I might imagine.
> > > > > > > Also the help text for 
> > > > > > > gtk_cell_renderer_class_set_accessible_type ()
> > > > > > > states it's advised to call this from the init method on the
> > > > > > > CellRenderer. I am afraid this is really basic and I might be 
> > > > > > > able to
> > > > > > > research it else where but what is an init method in this case? Is
> > > > > > > that a constructor or a method called init? I haven't see no method
> > > > > > > like this while looking at the GTK docs.
> > > > > > >
> > > > > > > I apologize for taking your time but I am really interested in 
> > > > > > > being
> > > > > > > able to do this.
> > > > > > >
> > > > > > > Greetings
> > > > > > >
> > > > > > > Peter
> > > > > > >
> > > > > > > On 07.07.2014 16:47, Piñeiro wrote:
> > > > > > > > Good catch, I didn't realize that ContactListCellRenderer. Sorry,
> > > > > > > > I'm
> > > > > > > > not used to search through Vala source code.
> > > > > > > >
> > > > > > > > Looking at that code, there is a variable called "entry", that in
> > > > > > > > most
> > > > > > > > cases is the contact. On render_name it uses that variable to get
> > > > > > > > the
> > > > > > > > name. On render_userstatus it uses that variable to render the
> > > > > > > > status. A
> > > > > > > > ContactListCellRendererAccessible would need to use this "entry"
> > > > > > > > variable to expose the name and status on a custom 
> > > > > > > > implementation of
> > > > > > > > AtkObject.get_name and AtkObject.ref_state_set.
> > > > > > > >
> > > > > > > > Looking for
> > > > > > > > https://developer.gnome.org/accessibility-devel-guide/stable/gad-custom.html.en 
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > has two problems:
> > > > > > > >       * It is outdated.
> > > > > > > >       * It is intended as a guide to extend widgets accessibility.
> > > > > > > > A cell
> > > > > > > > renderer is not a widget.
> > > > > > > >
> > > > > > > > What do you mean for gtk_get_accessible? AFAIK, that method call
> > > > > > > > doesn't
> > > > > > > > exists. There is a public gtk_widget_get_accessible that 
> > > > > > > > returns and
> > > > > > > > accessible type, and a private one
> > > > > > > > _gtk_cell_renderer_get_accessible_type, that returns a type.
> > > > > > > >
> > > > > > > > Subclassing GtkTreeViewColumn will not get anything. As
> > > > > > > > explained, it is
> > > > > > > > the cell renderer the one that gets the focus and renders the
> > > > > > > > content,
> > > > > > > > the problem there is about the custom cell renderer.
> > > > > > > >
> > > > > > > > So, in summary, and based on your comments and a quick look on
> > > > > > > > the code,
> > > > > > > > what it is needed to do here is:
> > > > > > > >
> > > > > > > >     * Create a new subclass of GtkRendererCellAccessible something
> > > > > > > > like,
> > > > > > > > ContactListCellRendererAccessible
> > > > > > > >     * Call gtk_cell_renderer_class_set_accessible_type on
> > > > > > > > ContactListCellRenderer class_init method.
> > > > > > > >     * Reimplement AtkObject.get_name and 
> > > > > > > > AtkObject.ref_state_set on
> > > > > > > > ContactListCellRendererAccessible, using that "entry" variable to
> > > > > > > > get
> > > > > > > > the information
> > > > > > > >
> > > > > > > > Thanks for all this work
> > > > > > > >
> > > > > > > > Best regards
> > > > > > > >
> > > > > > > > On 07/07/2014 04:07 PM, Peter Vágner wrote:
> > > > > > > > > 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
> > > > > > > > > > >
> > > > > > > > > > > _______________________________________________
> > > > > > > > > > > gnome-accessibility-list mailing list
> > > > > > > > > > > gnome-accessibility-list gnome org
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