Difference between revisions of "Features/Evince Introspection Bindings"

Revision as of 08:15, 4 November 2011

Summary

The pygtk bindings used until F14 to use the evince backend in Read activity, are no longer present in F16. We need use the new gi based bindings

Owner

Gonzalo Odiard

Current status

Targeted release: 0.96
Last updated: 25/10/2011
Percentage of completion: 0%

Initial information

The bindings are not ready to use. We need work closely with upstream to solve the remaining issues.

There are a bug related https://bugzilla.gnome.org/show_bug.cgi?id=635705 the evince developers know we need it, and there are working on this. The patches are against evince 3.4 (shipped in F17), after review of the patches, we need look if can be backported to evince 3.2 to update Fedora 16.

Implementation plan

The first step is port this simple demo to gtk3:

e = evince.View()
docmodel = evince.DocumentModel()
doc = evince.document_factory_get_document('file:///path/to/file/example.pdf')
docmodel.set_document(doc)
e.set_model(model)

With gtk 3 is:

from gi.repository import Gtk, Gio
from gi.repository import EvinceDocument
from gi.repository import EvinceView

class HelloWorldApp(Gtk.Application):
   def __init__(self):
       Gtk.Application.__init__(self, application_id="apps.test.helloevince",
                                flags=Gio.ApplicationFlags.FLAGS_NONE)
       self.connect("activate", self.on_activate)
       
   def on_activate(self, data=None):
       window = Gtk.Window(type=Gtk.WindowType.TOPLEVEL)
       window.set_title("Evince Gtk3 Python Example")
       window.set_border_width(24)

       scroll = Gtk.ScrolledWindow()
       window.add(scroll)

       EvinceDocument.init()
       doc = EvinceDocument.Document.factory_get_document('file:///home/gonzalo/Desktop/AjedrezyLeyendas-Postmortem.pdf')
       view = EvinceView.View()
       model = EvinceView.DocumentModel()
       model.set_document(doc)
       view.set_model(model)
       scroll.add(view)

       window.show_all()
       self.add_window(window)
   
if __name__ == "__main__":
   app = HelloWorldApp()
   app.run(None)

More information

Simon did tests and report:

what I did today to get a bit of a feeling of what is needed to port Read was looking at the evince bidings through introspection. So first, hmmm what is the gi repository called?

In Fedora you can have a look at '/usr/lib/girepository-1.0/' and find out that there is a EvinceDocument-3.0.typelib and a EvinceDocument-3.0.typelib. If we have a quick look at [1] we find out that the .typelib is a Binary version of the invocation info. Ok let's try this:

from gi.repository import EvinceDocument
dir(EvinceDocument)

from gi.repository import EvinceView
dir(EvinceView)

Works!

Looking at the invokations in read/evinceadapter.py I did extract the calls we did previously on the evince module (e.g. evince.View()) and checked if they were present, too.

The evince.View() is now EvinceView.View().

Furthermore are present:

help(view)
view.set_model
view.can_zoom_in, view.can_zoom_out
view.zoom_in
view_zoom_out
view.find_next
view.find_previous
view.scroll
view.copy
view.find_set_highlight_search

I could not find: update_view_size, find_changed

Some further transitions:

evince.JobFind -> EvinceView.JobFind
evince.Job.scheduler_push_job -> EvinceView.Job

I could not find: evince.SIZING_* (e.g. evince.SIZING_BEST_FIT)

More info on the EvinceView API are at [2].

And then I came across an hard one (which I have not solved yet):

I could not find out how 'evince.document_factory_get_document(file_path)' should be called now. Looking at the API it should be maybe something like EvinceDocument.factory_get_document, trying that:

>>> EvinceDocument.factory_get_document
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.7/site-packages/gi/module.py", line 243, in __getattr__
  return getattr(self._introspection_module, name)
File "/usr/lib/python2.7/site-packages/gi/module.py", line 105, in __getattr__
  self.__name__, name))
AttributeError: 'gi.repository.EvinceDocument' object has no attribute 'factory_get_document'
>>>

Hmm, I did get the sources, then to have a look because the .typelib is a Binary version of the invocation info and therefore I need to have a look at the .gir file to dig a bit deeper. After installing all the dependencies I did a './autogen.sh --enable-introspection' and run 'make' and had a .gir file placed in libdocument/EvinceDocument-3.0.gir. Looking at the definition it says:

<function name="factory_get_document"
              c:identifier="ev_document_factory_get_document"
              introspectable="0"
              throws="1">

Hmm, so it should not be available 'introspectable="0"'. Why, how, this exercise is left to the reader, I am a bit stuck on this :)

A good resource for asking related is questions is #introspection on GimpNet. I have attached the chat I had with Tomeu about that issue.

Regards,

 Simon

[1] http://live.gnome.org/GObjectIntrospection/Architecture

[2] http://developer.gnome.org/libevview/stable/

[3] http://developer.gnome.org/libevdocument/stable/libevdocument-ev-document-factory.html

The gir file is installed with the package evince-devel in /usr/share/gir-1.0/EvinceDocument-3.0.gir

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