Re: filling a drawing area with a pattern

["Nickolay V. Shmyrev" <nshmyrev yandex ru>]

В Втр, 14/03/2006 в 08:09 +0100, Sander Marechal пишет:
> Hello,
> 
> I'm pretty new to gnome development and I have trouble understanding how 
> to draw your own things. My eventual objective is to make a hearts game, 
> but that's a long way off. At the moment I am having trouble to set a 
> background in my UI, much like the green striped background in AisleRiot.
> 
> I am using libglade for my UI. The main window (where the cards are 
> going to be) is a GtkDrawingArea called "table". I load up an image and 
> try to fill the drawing area with it, but it doesn't show it. I've tried 
> looking ar AilseRiot and see how they do it, but I can't figure it out. 
> Here's my code, with comments as to what each step is supposed to do.
> 
> Any idea what I am doing wrong? Probably lots :-) Thanks in advance!
> 
> int main (int argc, char *argv[])
> {
> 	GtkWidget *table_widget;
> 	GdkGC *table;
> 
> 	/* Start up glade and show the UI */
> 	gnome_init (PACKAGE, VERSION, argc, argv);
> 	glade_gnome_init ();
> 	xml = glade_xml_new (PACKAGE_SOURCE_DIR"/hearts.glade", NULL, NULL);
> 	glade_xml_signal_autoconnect (xml);
> 	
> 	/* Load the background pixmap. get_pixmap() uses 
> gdk_pixbuf_new_from_file() to load the image and returns a GdkPixmap 
> pointer. I got this from the AisleRiot code. background_pixmap is a 
> global. It does return a valid image, not NULL. */
> 	background_pixmap = get_pixmap(PACKAGE_SOURCE_DIR"/pixmaps/baize.png");
> 	
> 	/* From what I read, I need a GDK Graphics Context to draw in, so here 
> I create one. I can verify that it does return a GdkGC, and not NULL */
> 	table_widget = glade_xml_get_widget (xml, "table");
> 	table = gdk_gc_new (table_widget->window);
> 	
> 	/* This should fill the GC with the background image, right? */
> 	gdk_gc_set_tile (table, background_pixmap);
> 	gdk_gc_set_fill (table, GDK_TILED);
> 
> 	/* wait for events */
> 	gtk_main ();
> 
> 	/* bye bye */
> 	return 0;
> }
> 

Hi Sander

There are multiple ways to archive your goal. If you just need to draw a
background on GtkDrawingArea, you can use the property of all X server
windows - they may have a background set from pixmap. See the example
attached. 

That is simple and fastest way to draw some background but I suspect in
your game you'll need more advanced operations. Probably you need to
look at some canvas library like GooCanvas or another analog, they allow
much more intelligent work with drawing. 


#include <gtk/gtk.h>

static const char * xpm_data[] = {
"16 16 3 1",
"       c None",
".      c #000000000000",
"X      c #FFFFFFFFFFFF",
"                ",
"   ......       ",
"   .XXX.X.      ",
"   .XXX.XX.     ",
"   .XXX.XXX.    ",
"   .XXX.....    ",
"   .XXXXXXX.    ",
"   .XXXXXXX.    ",
"   .XXXXXXX.    ",
"   .XXXXXXX.    ",
"   .XXXXXXX.    ",
"   .XXXXXXX.    ",
"   .XXXXXXX.    ",
"   .........    ",
"                ",
"                "};

void quit ()
{
  exit (0);
}

int main( int   argc, 
          char *argv[] )
{
  GtkWidget *window;
  GtkWidget *drawing_area;
  GtkWidget *vbox;
  GtkStyle *style;
  GdkPixmap *pixmap;
  GdkBitmap *mask;
  GtkWidget *button;

  gtk_init (&argc, &argv);

  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  vbox = gtk_vbox_new (FALSE, 0);
  gtk_container_add (GTK_CONTAINER (window), vbox);
  gtk_widget_show (vbox);

  g_signal_connect (G_OBJECT (window), "destroy",
                    G_CALLBACK (quit), NULL);

  /* Create the drawing area */

  drawing_area = gtk_drawing_area_new ();
  gtk_widget_set_size_request (GTK_WIDGET (drawing_area), 200, 200);
  gtk_box_pack_start (GTK_BOX (vbox), drawing_area, TRUE, TRUE, 0);

  /* And a button */
  button = gtk_button_new_with_label ("Quit");
  gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
  g_signal_connect_swapped (G_OBJECT (button), "clicked",
			    G_CALLBACK (gtk_widget_destroy),
			    G_OBJECT (window));
  gtk_widget_show_all (window);

  /* If shown, GtkWidget is associated with GdkWindow and GtkStyle */

  style = gtk_widget_get_style (drawing_area);
  pixmap = gdk_pixmap_create_from_xpm_d (drawing_area->window,  &mask,
                                         &style->bg[GTK_STATE_NORMAL],
                                         (gchar **)xpm_data);
  
  gdk_window_set_back_pixmap (drawing_area->window, pixmap, FALSE);


  gtk_main ();

  return 0;
}