Re: [Vala] Use alpha in GtkColorButton in GTK3 with Vala

[Evan Nemerson <evan coeus-group com>]

On Sat, 2013-06-01 at 22:27 +0200, Jonas Kulla wrote:
> 2013/6/1 Satyajit Sahoo <satyajit happy gmail com>
>
> > I want to use an alpha value in the color buttons in my app -
> > https://github.com/satya164/elegance-colors
> >
> > Currently I'm using colorbutton.set_use_alpha (true);, as documented in
> > http://www.valadoc.org/#!api=gtk+-3.0/Gtk.ColorButton
> >
> > But, while compiling, I get warnings saying,
> >
> > /home/satya/Workspace/elegance-colors/elegance-colors-prefs.vala.c:4706:2:
> > warning: ‘gtk_color_button_set_use_alpha’ is deprecated (declared at
> > /usr/include/gtk-3.0/gtk/gtkcolorbutton.h:95): Use
> > 'gtk_color_chooser_set_use_alpha' instead [-Wdeprecated-declarations]
> >
> > The code samples in the valadoc website are outdated and the sample on
> > gnome's website doesn't use alpha. Can anyone help me fix the warning
> > messages?
> >
> > I'm using GTK 3.8 and Vala 0.20.1.
>
> Hi,
>
> looking at the documentation, it seems that the "use-alpha" property
> was moved out of ColorButton (and probably other color widgets)
> and unified in the ColorChooser interface, but left in those concrete
> classes for backwards compatibility. The problem I think is that
> when you do "myButton.set_use_alpha()" valac cannot know if you
> mean ColorButton::set_use_alpha or ColorChooser::set_use_alpha
> and just defaults to the former.
>
> Normally I would tell you to just ignore warnings that gcc spits out
> (as there are others caused by bugs in valac), but if you really want
> them gone you could remove all the use-alpha related calls from
> the ColorButton class in the gtk3 vapi (although others compiling
> your project would still get them).

You can cast to Gtk.ColorChooser:

  ((Gtk.ColorChooser) myButton).set_use_alpha (true);

Unfortunately, we can't really "fix" the bindings right now since
removing Gtk.ColorButton.set_use_alpha means that the bindings stop
working for older versions of GTK+.

At some point we may be able to mostly resolve this in valac (after
switching GTK+ to GIR and once Florian's recent work on the [Version]
attribute lands) by introducing a flag to remove deprecated items from
the tree when targeting a newer version of the library.


-Evan