How to do_size_allocate properly in a gtk.Viewport subclass

[Joel Hedlund]

Hi!

I've raised this issue on #pygtk and #gtk+ but with no luck. I haven't
been able to solve this even with aid of google, the pygtk reference and
the gtk C source, so pretty please help?

I'm making an application that you can think of as an image viewer. I
want to display a widget in a gtk.Viewport. The widget can have any size
from tiny to humungous. I don't want the viewport to ever give the
widget a larger size allocation than requested, and I don't want the
viewport to ever resize to accomodate a large widget. It should rather
leave grey areas around the widget/show only a portion of the widget.

To do this I have subclassed gtk.Viewport (MyViewport) and overrided the
do_size_allocat e method:

def do_size_allocat e(self, allocation):
self.allocation = allocation
child_req = self.child.get_ child_requisiti on()
child_alloc = gtk.gdk.Rectang le(0, 0, *child_req)
self.child.size _allocate(child _alloc)
self.props.hadj ustment.update( allocation.widt h, child_alloc.wid th)
self.props.vadj ustment.update( allocation.heig ht, child_alloc.hei ght)
if self.flags() & gtk.REALIZED:
self.window.mov e_resize(*self. allocation)
self.child.wind ow()

When I add a very large widget (a gtk.DrawingArea ) to MyViewport only
the originally visible portion of the widget is redrawn when I resize
the window using the mouse, and the grey area around widget gets
littered with grey lines that are not redrawn if you minimize and
restore the window. I assume this comes from that the proper gdk windows
haven't been updated, and that the grey lines are remnants of old
Viewport borders.

In gtk_viewport_si ze_allocate in gtkviewport.c, gdk_window_move _resize
is called on three gdk windows: viewport->window, viewport->view_window
and viewport->bin_window, but in pygtk I only have gtk.Viewport.wi ndow.
I assume that this is the problem? If so, how can I fix this? Or is
there something else that I have overlooked?

And another relevant question: am I overcomplicatin g this? Is there some
kind of flag that I could set on a vanilla viewport to accomplish this?

Thanks in advance,
Joel

[Hrvoje Niksic]

Re: How to do_size_allocat e properly in a gtk.Viewport subclass

Joel Hedlund <joel.hedlund@g mail.comwrites:

I've raised this issue on #pygtk and #gtk+ but with no luck.

Note that there's a mailing list dedicated to PyGTK,
<pygtk@daa.com. au>, so you might also want to ask your question there.

[Joel Hedlund]

Re: How to do_size_allocat e properly in a gtk.Viewport subclass

Hrvoje Niksic wrote:

Note that there's a mailing list dedicated to PyGTK,
<pygtk@daa.com. au>, so you might also want to ask your question there.

Thanks. I'll try that and hope people won't take offense from
cross-posting. I'll be wathching this thread for answers too though. In
my experience, c.l.p usually delivers.

Cheers!
/Joel

[Joel Hedlund]

Re: How to do_size_allocat e properly in a gtk.Viewport subclass

Joel Hedlund wrote:

And another relevant question: am I overcomplicatin g this?

Yes. :-)

The proper way of doing this is to pack the widget in a container, and
then add the container (with viewport) to a scrolledwindow.

For example, for a centered widget choose a 1x1 gtk.Table and attach the
widget using xoptions = yoptions = gtk.EXPAND (and not gtk.FILL). For a
widget glued to the upper left corner choose a gtk.Alignment() .

Thanks John Finlay at pygtk@daa.com.a u!

/Joel