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Re: gtk3 layout background image


The layout is similar to a drawing area. Set up your "draw" callback and draw what you like. You can put your 
pictures in there also and be able to scroll them easily. 

/*   
    gcc -Wall layout1.c -o layout1 `pkg-config --cflags --libs gtk+-3.0`
    Tested on Ubuntu16.04 and GTK3.18
*/

#include<gtk/gtk.h>

static gboolean window_background(GtkWidget *widget, cairo_t *cr, gpointer data);
static gboolean layout_drawing(GtkWidget *da, cairo_t *cr, gpointer data);

int main(int argc, char **argv)
 {
   gtk_init(&argc, &argv);

   GtkWidget *window=gtk_window_new(GTK_WINDOW_TOPLEVEL);
   gtk_window_set_title(GTK_WINDOW(window), "Layout");
   gtk_window_set_default_size(GTK_WINDOW(window), 400, 400);
   gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
   gtk_container_set_border_width(GTK_CONTAINER(window), 40);
   g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
   gtk_widget_set_app_paintable(window, TRUE);
   //Try to set transparency of main window.
   if(gtk_widget_is_composited(window))
     {
       GdkScreen *screen=gtk_widget_get_screen(window);  
       GdkVisual *visual=gdk_screen_get_rgba_visual(screen);
       gtk_widget_set_visual(window, visual);
     }
   else g_print("Can't set window transparency.\n");
   g_signal_connect(window, "draw", G_CALLBACK(window_background), NULL);

   GtkWidget *layout=gtk_layout_new(NULL, NULL);
   gtk_widget_set_hexpand(layout, TRUE);
   gtk_widget_set_vexpand(layout, TRUE);
   g_signal_connect(layout, "draw", G_CALLBACK(layout_drawing), NULL);
   
   GtkWidget *grid=gtk_grid_new();
   gtk_grid_attach(GTK_GRID(grid), layout, 0, 0, 1, 1);
   
   gtk_container_add(GTK_CONTAINER(window), grid);

   gtk_widget_show_all(window);

   gtk_main();

   return 0;  
 }
static gboolean window_background(GtkWidget *widget, cairo_t *cr, gpointer data)
 {
   //Draw background window transparent blue.
   cairo_set_source_rgba(cr, 0.0, 0.0, 1.0, 0.3);
   cairo_paint(cr);
   return FALSE;
 }
static gboolean layout_drawing(GtkWidget *da, cairo_t *cr, gpointer data)
 {
   cairo_set_source_rgb(cr, 0.0, 1.0, 0.0);
   cairo_paint(cr);
   return FALSE;
 }


 

 

 

-----Original Message-----
From: Rúben Rodrigues <ruben_gr live com pt>
To: Emmanuele Bassi <ebassi gmail com>
Cc: gtk-app-devel-list <gtk-app-devel-list gnome org>
Sent: Tue, Mar 14, 2017 8:00 am
Subject: Re: gtk3 layout background image

Thanks again!

So, i will test with gtkbox. thanks for explanation..


Às 14:46 de 14/03/2017, Emmanuele Bassi escreveu:

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

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