Re: gtk3 layout background image

[Emmanuele Bassi <ebassi gmail com>]

On 14 March 2017 at 14:31, Rúben Rodrigues <ruben_gr live com pt> wrote:
> Just window can have background?

I was referring to GdkWindow, not GtkWindow.

GtkBox draws background, for instance; GtkGrid does as well.

> I don't know why is a violation, because in my case my
> applicationdoesn't make sense without background image..

I think the issue, here, is that you're not aware that 15 years passed
in the internals of GTK+.

Changing the background pixmap of a GdkWindow is a layering violation
because it assumes that you're essentially working on X11 and you
control the X server as well; on X11, you're telling the X server to
clear the contents of the native window used by GtkLayout using the
bytes you're passing. This worked in 1997, but it's not how modern
toolkits work — and it's not even how different windowing systems
work. Widgets do not have their own native window for rendering any
more, for instance.

If your application window has a background image then use the
background-image CSS property on your GtkWindow widget.

Ciao,
 Emmanuele.

> On 14-03-2017 14:01, Emmanuele Bassi wrote:
> > You were not changing the background with your theme: you were
> > programmatically replacing the base pixmap of the GdkWindow used by
> > GtkLayout. It was essentially a layering violation, and would actually
> > break your theme.
> >
> > The API reference for each GTK widget should tell you the CSS styling
> > available; see the "CSS nodes" section, for instance, of GtkBox:
> > https://developer.gnome.org/gtk3/stable/GtkBox.html
> >
> > Ciao,
> >   Emmanuele.
> >
> >
> > On 14 March 2017 at 13:55, Rúben Rodrigues <ruben_gr live com pt> wrote:
> > > Thanks!
> > >
> > > But in GTK+2 we could change background in layout with this:
> > >
> > > // Set picture as background.
> > > //        gdk_pixbuf_render_pixmap_and_mask (pixbuf, &background, NULL, 0);
> > > //        style = gtk_style_new ();
> > > //        style->bg_pixmap[0] = background;
> > > //        homeWindow = GTK_WIDGET(gtk_builder_get_object(builder,
> > > "layout_Home"));
> > > //        gtk_widget_set_style (GTK_WIDGET(homeWindow), GTK_STYLE(style));
> > >
> > > How i know witch containers draw background?
> > >
> > > THanks
> > >
> > >
> > > On 14-03-2017 12:55, Emmanuele Bassi wrote:
> > > > Not all GTK containers draw a background, mostly for historical
> > > > reasons. This has been true for GTK 1.x, 2.x, and 3.x.
> > > >
> > > > In particular, GtkLayout does not draw any background with CSS, so you
> > > > will need to either subclass GtkLayout, override the GtkWidget::draw
> > > > virtual function, and call gtk_render_* functions yourself; or you
> > > > will need to put a GtkLayout into a parent container that does draw a
> > > > background. You will, of course, need to style the parent container's
> > > > background, not the GtkLayout itself.
> > > >
> > > > Ciao,
> > > >    Emmanuele.
> > > >
> > > >
> > > > On 14 March 2017 at 12:43, Rúben Rodrigues <ruben_gr live com pt> wrote:
> > > > > I verify that i can't use css provider, don't works.
> > > > >
> > > > > My css file is :
> > > > >
> > > > > GtkLayout#layout_Home.background{
> > > > >        background-image: url('background.png');
> > > > > }
> > > > >
> > > > > GtkLabel#Home_Cooling_Tunnel1_Cooler_label1{
> > > > >        color: white;
> > > > > }
> > > > >
> > > > > GtkLabel#Home_Sensors_MoistAvg_value{
> > > > >        font-family: Segoe UI;
> > > > >        font-weight: lighter;
> > > > >        font-size: 25px;
> > > > > }
> > > > >
> > > > > And this code:
> > > > >
> > > > > static void apply_css(GtkWidget *widget, GtkStyleProvider *provider)
> > > > > {
> > > > > gtk_style_context_add_provider(gtk_widget_get_style_context(widget),
> > > > > GTK_STYLE_PROVIDER(provider),G_MAXUINT);
> > > > >        if(GTK_IS_CONTAINER(widget))
> > > > >            gtk_container_forall(GTK_CONTAINER(widget),(GtkCallback)
> > > > > apply_css,provider);
> > > > >
> > > > > }
> > > > >
> > > > > GFile *file= g_file_new_for_path("custom.css");
> > > > >            GtkStyleProvider *css_provider =
> > > > > GTK_STYLE_PROVIDER(gtk_css_provider_new());
> > > > > gtk_css_provider_load_from_file(GTK_CSS_PROVIDER(css_provider), file,
> > > > > &error);
> > > > > apply_css(gtk_builder_get_object(builder,"window_Main"),css_provider);
> > > > >
> > > > > This is the code used in gtk3-demo and don't works for me.. Why????
> > > > >
> > > > > THanks
> > > > >
> > > > > On 14-03-2017 10:00, Rúben Rodrigues wrote:
> > > > > > Hi guys,
> > > > > >
> > > > > > Finnaly i migrate my application to gtk+3. So, now i neet to change some
> > > > > > things like image background. I used css provider like in this :
> > > > > >
> > > > > > custom.css file:
> > > > > >
> > > > > > GtkLayout:layout_Home{
> > > > > >         background-color: black;
> > > > > > }
> > > > > >
> > > > > >
> > > > > > C Program:
> > > > > >
> > > > > > GFile *file= g_file_new_for_path("custom.css");
> > > > > >             GtkCssProvider *css_provider = gtk_css_provider_get_default();
> > > > > >             gtk_css_provider_load_from_file(css_provider, file, &error);
> > > > > >             GtkStyleContext *context = gtk_style_context_new();
> > > > > >             gtk_style_context_add_provider(context,
> > > > > > GTK_STYLE_PROVIDER(css_provider),GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
> > > > > >
> > > > > > But nothing happens. I tried this too:
> > > > > >
> > > > > > http://stackoverflow.com/questions/7375624/gtk3-window-background-image
> > > > > >
> > > > > >
> > > > > > Someone can help me?
> > > > > >
> > > > > >
> > > > > > THanks
> > > > > >
> > > > > > _______________________________________________
> > > > > > gtk-app-devel-list mailing list
> > > > > > gtk-app-devel-list gnome org
> > > > > > https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
> > > > > _______________________________________________
> > > > > gtk-app-devel-list mailing list
> > > > > gtk-app-devel-list gnome org
> > > > > https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list



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