[style] New method ccss_style_hash().

Calculates a hash value that uniquely identifies a style. If two styles
have the same hash value they are equal.

A hash value of 0 is returned for NULL or empty styles.

Add example-9 for demonstration.

7 files changed, 142 insertions, 3 deletions

diff --git a/ccss-doc/ccss-sections.txt b/ccss-doc/ccss-sections.txt
index fd3074e..2ed1f1f 100644
--- a/ccss-doc/ccss-sections.txt
+++ b/ccss-doc/ccss-sections.txt
@@ -53,6 +53,7 @@ ccss_style_get_double
 ccss_style_get_property
 ccss_style_set_property
 ccss_style_get_string
+ccss_style_hash
 ccss_style_iterator_f
 ccss_style_foreach
 ccss_style_dump
diff --git a/ccss/ccss-style.c b/ccss/ccss-style.c
index e01cecb..5068bd2 100644
--- a/ccss/ccss-style.c
+++ b/ccss/ccss-style.c
@@ -72,6 +72,52 @@ ccss_style_destroy (ccss_style_t *self)
 }
 
 /**
+ * ccss_style_hash:
+ * @self: a #ccss_style_t.
+ *
+ * Calculates a hash value that uniquely identifies a style. If two styles
+ * have the same hash value they are equal.
+ *
+ * A hash value of 0 is returned for %NULL or empty styles.
+ *
+ * Returns: hash value.
+ **/
+uint32_t
+ccss_style_hash (ccss_style_t const *self)
+{
+	uint32_t hash = 0;
+
+	g_return_val_if_fail (self, 0);
+	g_return_val_if_fail (self->properties, 0);
+	g_return_val_if_fail (g_hash_table_size (self->properties), 0);
+
+	{
+	ccss_property_base_t const	*property;
+	GHashTableIter			 iter;
+	int				 n_properties = g_hash_table_size (self->properties);
+	void				*property_ptrs[n_properties * sizeof (void *) + 1];
+	char const			*property_str = (char const *) property_ptrs;
+	int				 i = 0;
+
+	/* Accumulate string of property pointers. */
+	g_hash_table_iter_init (&iter, self->properties);
+	while (g_hash_table_iter_next (&iter, NULL, (gpointer *) &property)) {
+		property_ptrs[i] = (void *) property;
+		i++;
+	}
+	property_ptrs[i] = NULL;
+
+	/* sdbm hash */
+	while (0 != (i = *property_str++)) {
+		hash = i + (hash << 6) + (hash << 16) - hash;
+	}
+
+	}
+
+	return hash;
+}
+
+/**
  * ccss_style_get_stylesheet:
  * @self: a #ccss_gramar_t.
  *
diff --git a/ccss/ccss-style.h b/ccss/ccss-style.h
index af97a7c..ce2cf97 100644
--- a/ccss/ccss-style.h
+++ b/ccss/ccss-style.h
@@ -39,7 +39,10 @@ CCSS_BEGIN_DECLS
 typedef struct ccss_style_ ccss_style_t;
 
 void
-ccss_style_destroy	(ccss_style_t *self);
+ccss_style_destroy	(ccss_style_t		*self);
+
+uint32_t
+ccss_style_hash		(ccss_style_t const     *self);
 
 /* Somewhat hackish */
 struct ccss_stylesheet_ *
diff --git a/ccss/ccss.sym b/ccss/ccss.sym
index b3af4dd..511f6b8 100644
--- a/ccss/ccss.sym
+++ b/ccss/ccss.sym
@@ -29,6 +29,7 @@ ccss_style_get_double
 ccss_style_get_property
 ccss_style_get_string
 ccss_style_set_property
+ccss_style_hash
 ccss_style_interpret_property
 ccss_stylesheet_add_from_file
 ccss_stylesheet_destroy
diff --git a/examples/Makefile.am b/examples/Makefile.am
index 93f21b1..30f4029 100644
--- a/examples/Makefile.am
+++ b/examples/Makefile.am
@@ -24,6 +24,7 @@ noinst_PROGRAMS = \
 	example-6 \
 	example-7 \
 	example-8 \
+	example-9 \
 	$(NULL)
 
 noinst_LTLIBRARIES = libexample-8-noinst.la
@@ -62,6 +63,8 @@ example_8_LDADD = libexample-8-noinst.la
 libexample_8_la_LDFLAGS = -avoid-version -export-dynamic -module -no-undefined
 libexample_8_la_SOURCES = example-8.c
 
+example_9_SOURCES = example-9.c
+
 EXTRA_DIST = \
 	example-3.png \
 	example-5.svg \
diff --git a/examples/example-1.c b/examples/example-1.c
index 1a29357..4642135 100644
--- a/examples/example-1.c
+++ b/examples/example-1.c
@@ -42,6 +42,7 @@ main (int	  argc,
 	ccss_stylesheet_t	*stylesheet;
 	ccss_style_t		*style;
 	GtkWidget		*window;
+	GtkWidget		*area;
 
 	gtk_init (&argc, &argv);
 
@@ -58,10 +59,12 @@ main (int	  argc,
 #endif
 	window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
 	gtk_window_set_default_size (GTK_WINDOW (window), 160, 90);
-	gtk_widget_set_app_paintable (window, TRUE);
 	g_signal_connect (G_OBJECT (window), "delete-event", 
 			  G_CALLBACK (gtk_main_quit), NULL);
-	g_signal_connect (G_OBJECT (window), "expose-event", 
+
+	area = gtk_drawing_area_new ();
+	gtk_container_add (GTK_CONTAINER (window), area);
+	g_signal_connect (G_OBJECT (area), "expose-event",
 			  G_CALLBACK (expose_cb), style);
 
 	gtk_widget_show_all (window);
diff --git a/examples/example-9.c b/examples/example-9.c
new file mode 100644
index 0000000..60980ba
--- /dev/null
+++ b/examples/example-9.c
@@ -0,0 +1,82 @@
+/* vim: set ts=8 sw=8 noexpandtab: */
+
+#include <stdlib.h>
+#include <cairo.h>
+#include <ccss-cairo/ccss-cairo.h>
+#include <gtk/gtk.h>
+#include "config.h"
+
+static gboolean
+expose_cb (GtkWidget		*widget,
+	   GdkEventExpose       *event,
+	   ccss_stylesheet_t	*stylesheet)
+{
+	ccss_style_t	*style;
+	cairo_t		*cr;
+	uint32_t	 hash;
+
+	style = ccss_stylesheet_query_type (stylesheet, "box");
+	g_return_val_if_fail (style, FALSE);
+
+	hash = ccss_style_hash (style);
+	g_debug ("%s() style instance='%p' hash='%u'",
+		 __FUNCTION__,
+		 (void *) style,
+		 hash);
+
+	cr = gdk_cairo_create (widget->window);
+	ccss_cairo_style_draw_rectangle (style, cr, 
+					 widget->allocation.x + 10,
+					 widget->allocation.y + 10,
+					 widget->allocation.width - 20, 
+					 widget->allocation.height - 20);
+
+	cairo_destroy (cr);
+	ccss_style_destroy (style);
+
+	return FALSE;
+}
+
+static char const _css[] = "			\
+	box { 					\
+		border: 3px solid black;	\
+		border-top: 3px dotted red;	\
+		border-radius: 3px;		\
+	}					\
+";
+
+int
+main (int	  argc,
+      char	**argv)
+{
+	ccss_grammar_t		*grammar;
+	ccss_stylesheet_t	*stylesheet;
+	GtkWidget		*window;
+	GtkWidget		*area;
+
+	gtk_init (&argc, &argv);
+
+	grammar = ccss_cairo_grammar_create ();
+	stylesheet = ccss_grammar_create_stylesheet_from_buffer (grammar,
+							_css, sizeof (_css),
+							NULL);
+
+	window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+	gtk_window_set_default_size (GTK_WINDOW (window), 160, 90);
+	g_signal_connect (G_OBJECT (window), "delete-event", 
+			  G_CALLBACK (gtk_main_quit), NULL);
+
+	area = gtk_drawing_area_new ();
+	gtk_container_add (GTK_CONTAINER (window), area);
+	g_signal_connect (G_OBJECT (area), "expose-event", 
+			  G_CALLBACK (expose_cb), stylesheet);
+
+	gtk_widget_show_all (window);
+	gtk_main ();
+
+	ccss_stylesheet_destroy (stylesheet);
+	ccss_grammar_destroy (grammar);
+
+	return EXIT_SUCCESS;
+}
+