On Fri, 30 Nov 2018 at 19:09, Jeff via gtk-perl-list <
gtk-perl-list@gnome.org> wrote:
> Whilst working up a smallest working example for another bug, I've
> discovered that I cannot get subclassing working when the main package
> is in the same file as the module.
>
> Below is the Gtk2 subclassing example from Muppet which I have trivially
> converted to Gtk3.
>
>
Your GTK 3 port is wrong.
> I get the following error messages:
>
> Odd number of elements in anonymous hash at
> /usr/lib/x86_64-linux-gnu/perl5/5.28/Glib/Object/Introspection.pm line 267.
> *** unhandled exception in callback:
> *** Can't locate object method "get_colormap" via package
> "Gtk3::EventBox" at ../gtk3-subclass.pl line 93.
> *** ignoring at
> /usr/lib/x86_64-linux-gnu/perl5/5.28/Glib/Object/Introspection.pm line 67.
>
> What is going on?
>
You're calling the "get_colormap()" method on a GtkEventBox, which does not
have a "get_colormap()" method—and neither do all its parent classes.
In GTK 2.x, there is a `gtk_widget_get_colormap()` method, but it was
deprecated during the GTK 2.x API series, and thus removed once GTK 3.0 was
released.
> sub set_color {
> my $self = shift;
> my %params = @_;
> my $color = Gtk3::Gdk::Color->new ($params{red},
> $params{green},
> $params{blue});
> $self->{colorbox}->get_colormap->alloc_color ($color, 0, 1);
> $self->{colorbox}->modify_bg ('normal', $color);
> $self->{colorbox}->modify_bg ('active', $color);
> $self->{colorbox}->modify_bg ('prelight', $color);
> $self->{red} = $params{red};
> $self->{green} = $params{green};
> $self->{blue} = $params{blue};
> # emit the color-changed signal. note again that the signal
> # name treats - and _ as equivalent.
> $self->signal_emit ('color-changed');
> }
>
Creating a colormap, allocating a color, and calling `modify_bg()` was
something used in GTK 2.x (and even there, it was questionable, as it broke
themes).
In GTK 3.x you're supposed load a CSS fragment, defining the
background-color CSS property for a specific class, e.g.
.foo { background-color: red; }
.foo:active { background-color: green; }
.foo:hover { background-color: blue; }
You load this using a GtkCSSProvider associated to the GdkScreen, and
loaded when you create your application instance.
If you're trying to set the color programmatically, overriding all user
theming, you can generate a CSS fragment programmatically and associate it
to the widget itself, instead of the global GdkScreen; or you can override
the GtkWidget::draw signal, and render the color yourself using Cairo.
Doing either of those is less than great, but it respects the original
example's intent.
Ciao,
Emmanuele.
--
https://www.bassi.io
[@] ebassi [@gmail.com]
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