Re: Overriding CSS style

[cecashon aol com]

Hi Yannick,

You have some options here. You can set a priority with

https://developer.gnome.org/gtk3/stable/GtkStyleContext.html#gtk-style-context-add-provider

with CSS.

If you want to just stick with drawing in C, connect your "draw" handler for the window. If you need a pixbuf 
you can use

https://developer.gnome.org/gdk3/stable/gdk3-Cairo-Interaction.html#gdk-cairo-set-source-pixbuf

to add a pixbuf to the background.

Also, the CSS GTK+ recognizes is a little different between versions. I am still using GTK3.18 and it 
understands a little different CSS string than GTK3.22. Something to keep in mind if you are using CSS 
strings in code.

Eric

/*
   gcc -Wall css1.c -o css1 `pkg-config --cflags --libs gtk+-3.0`
   Tested with GTK3.18 and GTK3.22 on Ubuntu16.04
*/
#include<gtk/gtk.h>

static gboolean draw_window(GtkWidget *window, cairo_t *cr, gpointer user_data)
  {
    //A green window.
    cairo_set_source_rgb(cr, 0.0, 1.0, 0.0);
    cairo_paint(cr);
    return FALSE;
  }
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), "CSS");
    gtk_window_set_default_size(GTK_WINDOW(window), 200, 200);
    gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
    g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);

    //Uncomment the following two line for drawing with cairo.
    //gtk_widget_set_app_paintable(window, TRUE);
    //g_signal_connect(window, "draw", G_CALLBACK(draw_window), NULL);

    gtk_widget_show_all(window);

    //Setup CSS for the program.
    GError *css_error=NULL;
    gint minor_version=gtk_get_minor_version();
    gchar *css_string1=NULL;
    //GTK CSS changed in 3.20.
    if(minor_version>20)
      {
        css_string1=g_strdup("window{background: blue;}");
      }
    else
      {
        css_string1=g_strdup("GtkWindow{background: blue;}");
      }
    GtkCssProvider *provider=gtk_css_provider_new();
    GdkDisplay *display=gdk_display_get_default();
    GdkScreen *screen=gdk_display_get_default_screen(display);
    gtk_style_context_add_provider_for_screen(screen, GTK_STYLE_PROVIDER(provider), 
GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
    gtk_css_provider_load_from_data(provider, css_string1, -1, &css_error);

    if(css_error!=NULL)
      {
        g_print("CSS loader error %s\n", css_error->message);
        g_error_free(css_error);
      }
    g_object_unref(provider);
    if(css_string1!=NULL) g_free(css_string1);

    gtk_main();

    return 0;
  }