Import stylesheet code from hippo-canvas

Import:

  HippoCanvasTheme      => StTheme
  HippoCanvasThemeImage => StThemeImage
  HippoCanvasStyle      => StThemeNode

StThemeContext is a new class managing the theme for a stage and
global properties like resolution.

test-theme.c is a newly written test program to do verification of the
style matching and property handling rules.

Various changes are made in the import:

 - Comprehensive reindentation
 - guint32 pixels replaced with ClutterColor
 - General pseudo-class support added
 - Old-fashioned (non-bordered) background image support added, though
   with no support for repeat, etc.
 - Bug fixes for problems revealed by test program

https://bugzilla.gnome.org/show_bug.cgi?id=595990

.gitignore

@@ -38,6 +38,7 @@ src/gnomeshell-taskpanel
 src/gnome-shell
 src/test-recorder
 src/test-recorder.ogg
+src/test-theme
 stamp-h1
 tests/run-test.sh
 xmldocs.make

configure.ac

@@ -60,6 +60,7 @@ PKG_CHECK_MODULES(TIDY, clutter-1.0)
 PKG_CHECK_MODULES(ST, clutter-1.0 gtk+-2.0 libccss-1 >= 0.3.1 clutter-imcontext-0.1)
 PKG_CHECK_MODULES(BIG, clutter-1.0 gtk+-2.0 librsvg-2.0)
 PKG_CHECK_MODULES(GDMUSER, dbus-glib-1 gtk+-2.0)
+PKG_CHECK_MODULES(TOOLKIT, clutter-1.0 libcroco-0.6)
 PKG_CHECK_MODULES(TRAY, gtk+-2.0)
 
 MUTTER_BIN_DIR=`$PKG_CONFIG --variable=exec_prefix mutter-plugins`/bin

src/Makefile-st.am

@@ -73,7 +73,6 @@ st_source_h =					\
     st/st-clipboard.h				\
     st/st-entry.h				\
     st/st-label.h				\
-    st/st-private.h				\
     st/st-stylable.h				\
     st/st-style.h				\
     st/st-scrollable.h				\
@@ -82,11 +81,19 @@ st_source_h =					\
     st/st-subtexture.h				\
     st/st-texture-cache.h			\
     st/st-texture-frame.h			\
+    st/st-theme.h				\
+    st/st-theme-context.h			\
+    st/st-theme-image.h				\
+    st/st-theme-node.h				\
     st/st-tooltip.h				\
     st/st-types.h				\
     st/st-widget.h				\
     $(NULL)
 
+st_source_private_h =				\
+    st/st-private.h				\
+    st/st-theme-private.h
+
 # please, keep this sorted alphabetically
 st_source_c =					\
     st/st-adjustment.c				\
@@ -106,6 +113,10 @@ st_source_c =					\
     st/st-subtexture.c				\
     st/st-texture-cache.c			\
     st/st-texture-frame.c			\
+    st/st-theme.c				\
+    st/st-theme-context.c			\
+    st/st-theme-image.c				\
+    st/st-theme-node.c				\
     st/st-tooltip.c				\
     st/st-widget.c				\
     $(NULL)
@@ -115,8 +126,16 @@ noinst_LTLIBRARIES += libst-1.0.la
 libst_1_0_la_LIBADD = $(ST_LIBS)
 libst_1_0_la_SOURCES =				\
     $(st_source_c)				\
+    $(st_source_private_c)			\
     $(st_source_h)				\
     $(st_built_sources)				\
     $(NULL)
 libst_1_0_la_CPPFLAGS = $(st_cflags)
 libst_1_0_la_LDFLAGS = $(LDADD)
+
+noinst_PROGRAMS += test-theme
+
+test_theme_CPPFLAGS = $(st_cflags)
+test_theme_LDADD = libst-1.0.la
+
+test_theme_SOURCES = st/test-theme.c

src/Makefile.am

@@ -4,6 +4,7 @@ CLEANFILES =
 EXTRA_DIST =
 libexec_PROGRAMS =
 noinst_LTLIBRARIES =
+noinst_PROGRAMS =
 
 .AUTOPARALLEL:
 
@@ -95,7 +96,7 @@ libgnome_shell_la_SOURCES =			\
 	shell-wm.c				\
 	shell-wm.h
 
-non_gir_sources =						\
+non_gir_sources =				\
 	shell-embedded-window-private.h
 
 shell_recorder_sources =        \
@@ -113,7 +114,7 @@ if BUILD_RECORDER
 libgnome_shell_la_SOURCES += $(shell_recorder_sources)
 non_gir_sources += $(shell_recorder_non_gir_sources)
 
-noinst_PROGRAMS = test-recorder
+noinst_PROGRAMS += test-recorder
 
 test_recorder_CPPFLAGS = $(TEST_SHELL_RECORDER_CFLAGS)
 test_recorder_LDADD = $(TEST_SHELL_RECORDER_LIBS)

src/st/st-theme-context.c

@@ -0,0 +1,287 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+#include <config.h>
+
+#include "st-theme.h"
+#include "st-theme-context.h"
+
+struct _StThemeContext {
+  GObject parent;
+
+  double resolution;
+  PangoFontDescription *font;
+  StThemeNode *root_node;
+  StTheme *theme;
+};
+
+struct _StThemeContextClass {
+  GObjectClass parent_class;
+};
+
+#define DEFAULT_RESOLUTION 96.
+#define DEFAULT_FONT "sans-serif 10"
+
+enum
+{
+  CHANGED,
+
+  LAST_SIGNAL
+};
+
+static guint signals[LAST_SIGNAL] = { 0, };
+
+G_DEFINE_TYPE (StThemeContext, st_theme_context, G_TYPE_OBJECT)
+
+static void
+st_theme_context_finalize (GObject *object)
+{
+  StThemeContext *context = ST_THEME_CONTEXT (object);
+
+  if (context->root_node)
+    g_object_unref (context->root_node);
+  if (context->theme)
+    g_object_unref (context->theme);
+
+  pango_font_description_free (context->font);
+
+  G_OBJECT_CLASS (st_theme_context_parent_class)->finalize (object);
+}
+
+static void
+st_theme_context_class_init (StThemeContextClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = st_theme_context_finalize;
+
+  signals[CHANGED] =
+    g_signal_new ("changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  0, /* no default handler slot */
+                  NULL, NULL,
+                  g_cclosure_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+}
+
+static void
+st_theme_context_init (StThemeContext *context)
+{
+  context->resolution = DEFAULT_RESOLUTION;
+  context->font = pango_font_description_from_string (DEFAULT_FONT);
+}
+
+/**
+ * st_theme_context_new:
+ *
+ * Create a new theme context not associated with any #ClutterStage.
+ * This can be useful in testing scenarios, or if using StThemeContext
+ * with something other than #ClutterActor objects, but you generally
+ * should use st_theme_context_get_for_stage() instead.
+ */
+StThemeContext *
+st_theme_context_new (void)
+{
+  StThemeContext *context;
+
+  context = g_object_new (ST_TYPE_THEME_CONTEXT, NULL);
+
+  return context;
+}
+
+static void
+on_stage_destroy (ClutterStage *stage)
+{
+  StThemeContext *context = st_theme_context_get_for_stage (stage);
+
+  g_object_set_data (G_OBJECT (stage), "st-theme-context", NULL);
+  g_object_unref (context);
+}
+
+static void
+st_theme_context_changed (StThemeContext *context)
+{
+  StThemeNode *old_root = context->root_node;
+  context->root_node = NULL;
+
+  g_signal_emit (context, signals[CHANGED], 0);
+
+  if (old_root)
+    g_object_unref (old_root);
+}
+
+/**
+ * st_theme_context_get_for_stage:
+ * @stage: a #ClutterStage
+ *
+ * Gets a singleton theme context associated with the stage.
+ *
+ * Return value: (transfer none): the singleton theme context for the stage
+ */
+StThemeContext *
+st_theme_context_get_for_stage (ClutterStage *stage)
+{
+  StThemeContext *context;
+
+  g_return_val_if_fail (CLUTTER_IS_STAGE (stage), NULL);
+
+  context = g_object_get_data (G_OBJECT (stage), "st-theme-context");
+  if (context)
+    return context;
+
+  context = st_theme_context_new ();
+  g_object_set_data (G_OBJECT (stage), "st-theme-context", context);
+  g_signal_connect (stage, "destroy",
+                    G_CALLBACK (on_stage_destroy), NULL);
+
+  return context;
+}
+
+/**
+ * st_theme_context_set_theme:
+ * @context: a #StThemeContext
+ *
+ * Sets the default set of theme stylesheets for the context. This theme will
+ * be used for the root node and for nodes descending from it, unless some other
+ * style is explicitely specified.
+ */
+void
+st_theme_context_set_theme (StThemeContext          *context,
+                            StTheme                 *theme)
+{
+  g_return_if_fail (ST_IS_THEME_CONTEXT (context));
+  g_return_if_fail (theme == NULL || ST_IS_THEME (theme));
+
+  if (context->theme != theme)
+    {
+      if (context->theme)
+        g_object_unref (context->theme);
+
+      context->theme = theme;
+
+      if (context->theme)
+        g_object_ref (context->theme);
+
+      st_theme_context_changed (context);
+    }
+}
+
+/**
+ * st_theme_context_get_theme:
+ * @context: a #StThemeContext
+ *
+ * Gets the default theme for the context. See st_theme_context_set_theme()
+ *
+ * Return value: (transfer none): the default theme for the context
+ */
+StTheme *
+st_theme_context_get_theme (StThemeContext *context)
+{
+  g_return_val_if_fail (ST_IS_THEME_CONTEXT (context), NULL);
+
+  return context->theme;
+}
+
+/**
+ * st_theme_context_set_resolution:
+ * @context: a #StThemeContext
+ * @resolution: resolution of the context (number of pixels in an "inch")
+ *
+ * Sets the resolution of the theme context. This is the scale factor
+ * used to convert between points and the length units pt, in, and cm.
+ * This does not necessarily need to correspond to the actual number
+ * resolution of the device. A value of 72. means that points and
+ * pixels are identical. The default value is 96.
+ */
+void
+st_theme_context_set_resolution (StThemeContext *context,
+                                 double          resolution)
+{
+  g_return_if_fail (ST_IS_THEME_CONTEXT (context));
+
+  if (resolution == context->resolution)
+    return;
+
+  context->resolution = resolution;
+  st_theme_context_changed (context);
+}
+
+/**
+ * st_theme_context_set_resolution:
+ * @context: a #StThemeContext
+ *
+ * Gets the current resolution of the theme context.
+ * See st_theme_context_set_resolution().
+ *
+ * Return value: the resolution (in dots-per-"inch")
+ */
+double
+st_theme_context_get_resolution (StThemeContext *context)
+{
+  g_return_val_if_fail (ST_IS_THEME_CONTEXT (context), DEFAULT_RESOLUTION);
+
+  return context->resolution;
+}
+
+/**
+ * st_theme_context_set_font:
+ * @context: a #StThemeContext
+ * @font: the default font for theme context
+ *
+ * Sets the default font for the theme context. This is the font that
+ * is inherited by the root node of the tree of theme nodes. If the
+ * font is not overriden, then this font will be used. If the font is
+ * partially modified (for example, with 'font-size: 110%', then that
+ * modification is based on this font.
+ */
+void
+st_theme_context_set_font (StThemeContext             *context,
+                           const PangoFontDescription *font)
+{
+  g_return_if_fail (ST_IS_THEME_CONTEXT (context));
+  g_return_if_fail (font != NULL);
+
+  if (context->font == font ||
+      pango_font_description_equal (context->font, font))
+    return;
+
+  pango_font_description_free (context->font);
+  context->font = pango_font_description_copy (font);
+  st_theme_context_changed (context);
+}
+
+/**
+ * st_theme_context_get_font:
+ * @context: a #StThemeContext
+ *
+ * Gets the default font for the theme context. See st_theme_context_set_font().
+ *
+ * Return value: the default font for the theme context.
+ */
+const PangoFontDescription *
+st_theme_context_get_font (StThemeContext *context)
+{
+  g_return_val_if_fail (ST_IS_THEME_CONTEXT (context), NULL);
+
+  return context->font;
+}
+
+/**
+ * st_theme_context_get_root_node:
+ * @context: a #StThemeContext
+ *
+ * Gets the root node of the tree of theme style nodes that associated with this
+ * context. For the node tree associated with a stage, this node represents
+ * styles applied to the stage itself.
+ *
+ * Return value: (transfer none): the root node of the context's style tree
+ */
+StThemeNode *
+st_theme_context_get_root_node (StThemeContext *context)
+{
+  if (context->root_node == NULL)
+    context->root_node = st_theme_node_new (context, NULL, context->theme,
+                                            G_TYPE_NONE, NULL, NULL, NULL);
+
+  return context->root_node;
+}

src/st/st-theme-context.h

@@ -0,0 +1,50 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+#ifndef __ST_THEME_CONTEXT_H__
+#define __ST_THEME_CONTEXT_H__
+
+#include <clutter/clutter.h>
+#include <pango/pango.h>
+#include "st-theme-node.h"
+
+G_BEGIN_DECLS
+
+/**
+ * SECTION:StThemeContext
+ * @short_description: holds global information about a tree of styled objects
+ *
+ * #StThemeContext is responsible for managing information global to a tree of styled objects,
+ * such as the set of stylesheets or the default font. In normal usage, a #StThemeContext
+ * is bound to a #ClutterStage; a singleton #StThemeContext can be obtained for a #ClutterStage
+ * by using st_theme_context_get_for_stage().
+ */
+
+typedef struct _StThemeContextClass StThemeContextClass;
+
+#define ST_TYPE_THEME_CONTEXT             (st_theme_context_get_type ())
+#define ST_THEME_CONTEXT(object)          (G_TYPE_CHECK_INSTANCE_CAST ((object), ST_TYPE_THEME_CONTEXT, StThemeContext))
+#define ST_THEME_CONTEXT_CLASS(klass)     (G_TYPE_CHECK_CLASS_CAST ((klass), ST_TYPE_THEME_CONTEXT, StThemeContextClass))
+#define ST_IS_THEME_CONTEXT(object)       (G_TYPE_CHECK_INSTANCE_TYPE ((object), ST_TYPE_THEME_CONTEXT))
+#define ST_IS_THEME_CONTEXT_CLASS(klass)  (G_TYPE_CHECK_CLASS_TYPE ((klass), ST_TYPE_THEME_CONTEXT))
+#define ST_THEME_CONTEXT_GET_CLASS(obj)   (G_TYPE_INSTANCE_GET_CLASS ((obj), ST_TYPE_THEME_CONTEXT, StThemeContextClass))
+
+GType st_theme_context_get_type (void) G_GNUC_CONST;
+
+StThemeContext *st_theme_context_new           (void);
+StThemeContext *st_theme_context_get_for_stage (ClutterStage *stage);
+
+void                        st_theme_context_set_theme      (StThemeContext             *context,
+                                                             StTheme                    *theme);
+StTheme *                   st_theme_context_get_theme      (StThemeContext             *context);
+
+void                        st_theme_context_set_resolution (StThemeContext             *context,
+                                                             gdouble                     resolution);
+double                      st_theme_context_get_resolution (StThemeContext             *context);
+void                        st_theme_context_set_font       (StThemeContext             *context,
+                                                             const PangoFontDescription *font);
+const PangoFontDescription *st_theme_context_get_font       (StThemeContext             *context);
+
+StThemeNode *               st_theme_context_get_root_node  (StThemeContext             *context);
+
+G_END_DECLS
+
+#endif /* __ST_THEME_CONTEXT_H__ */

src/st/st-theme-image.c

@@ -0,0 +1,92 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+#include <config.h>
+
+#include "st-theme-image.h"
+
+struct _StThemeImage {
+  GObject parent;
+
+  char *filename;
+  int border_top;
+  int border_right;
+  int border_bottom;
+  int border_left;
+};
+
+struct _StThemeImageClass {
+  GObjectClass parent_class;
+
+};
+
+G_DEFINE_TYPE (StThemeImage, st_theme_image, G_TYPE_OBJECT)
+
+static void
+st_theme_image_finalize (GObject *object)
+{
+  StThemeImage *image = ST_THEME_IMAGE (object);
+
+  g_free (image->filename);
+
+  G_OBJECT_CLASS (st_theme_image_parent_class)->finalize (object);
+}
+
+static void
+st_theme_image_class_init (StThemeImageClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = st_theme_image_finalize;
+}
+
+static void
+st_theme_image_init (StThemeImage *image)
+{
+}
+
+StThemeImage *
+st_theme_image_new (const char *filename,
+                    int         border_top,
+                    int         border_right,
+                    int         border_bottom,
+                    int         border_left)
+{
+  StThemeImage *image;
+
+  image = g_object_new (ST_TYPE_THEME_IMAGE, NULL);
+
+  image->filename = g_strdup (filename);
+  image->border_top = border_top;
+  image->border_right = border_right;
+  image->border_bottom = border_bottom;
+  image->border_left = border_left;
+
+  return image;
+}
+
+const char *
+st_theme_image_get_filename (StThemeImage *image)
+{
+  g_return_val_if_fail (ST_IS_THEME_IMAGE (image), NULL);
+
+  return image->filename;
+}
+
+void
+st_theme_image_get_borders (StThemeImage *image,
+                            int          *border_top,
+                            int          *border_right,
+                            int          *border_bottom,
+                            int          *border_left)
+{
+  g_return_if_fail (ST_IS_THEME_IMAGE (image));
+
+  if (border_top)
+    *border_top = image->border_top;
+  if (border_right)
+    *border_right = image->border_right;
+  if (border_bottom)
+    *border_bottom = image->border_bottom;
+  if (border_left)
+    *border_left = image->border_left;
+}

src/st/st-theme-image.h

@@ -0,0 +1,38 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+#ifndef __ST_THEME_IMAGE_H__
+#define __ST_THEME_IMAGE_H__
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+/* A StThemeImage encapsulates an image with specified unscaled borders on each edge.
+ */
+typedef struct _StThemeImage      StThemeImage;
+typedef struct _StThemeImageClass StThemeImageClass;
+
+#define ST_TYPE_THEME_IMAGE             (st_theme_image_get_type ())
+#define ST_THEME_IMAGE(object)          (G_TYPE_CHECK_INSTANCE_CAST ((object), ST_TYPE_THEME_IMAGE, StThemeImage))
+#define ST_THEME_IMAGE_CLASS(klass)     (G_TYPE_CHECK_CLASS_CAST ((klass), ST_TYPE_THEME_IMAGE, StThemeImageClass))
+#define ST_IS_THEME_IMAGE(object)       (G_TYPE_CHECK_INSTANCE_TYPE ((object), ST_TYPE_THEME_IMAGE))
+#define ST_IS_THEME_IMAGE_CLASS(klass)  (G_TYPE_CHECK_CLASS_TYPE ((klass), ST_TYPE_THEME_IMAGE))
+#define ST_THEME_IMAGE_GET_CLASS(obj)   (G_TYPE_INSTANCE_GET_CLASS ((obj), ST_TYPE_THEME_IMAGE, StThemeImageClass))
+
+GType             st_theme_image_get_type          (void) G_GNUC_CONST;
+
+StThemeImage *st_theme_image_new (const char *filename,
+                                  int         border_top,
+                                  int         border_right,
+                                  int         border_bottom,
+                                  int         border_left);
+
+const char *st_theme_image_get_filename (StThemeImage *image);
+void        st_theme_image_get_borders  (StThemeImage *image,
+                                         int          *border_top,
+                                         int          *border_right,
+                                         int          *border_bottom,
+                                         int          *border_left);
+
+G_END_DECLS
+
+#endif /* __ST_THEME_IMAGE_H__ */

src/st/st-theme-node.h

@@ -0,0 +1,125 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+#ifndef __ST_THEME_NODE_H__
+#define __ST_THEME_NODE_H__
+
+#include <clutter/clutter.h>
+#include "st-theme-image.h"
+
+G_BEGIN_DECLS
+
+/**
+ * SECTION:StThemeNode
+ * @short_description: style information for one node in a tree of themed objects
+ *
+ * A #StThemeNode represents the CSS style information (the set of CSS properties) for one
+ * node in a tree of themed objects. In typical usage, it represents the style information
+ * for a single #ClutterActor. A #StThemeNode is immutable: attributes such as the
+ * CSS classes for the node are passed in at construction. If the attributes of the node
+ * or any parent node change, the node should be discarded and a new node created.
+ * #StThemeNode has generic accessors to look up properties by name and specific
+ * accessors for standard CSS properties that add caching and handling of various
+ * details of the CSS specification. #StThemeNode also has convenience functions to help
+ * in implementing a #ClutterActor with borders and padding.
+ */
+
+typedef struct _StTheme          StTheme;
+typedef struct _StThemeContext   StThemeContext;
+
+typedef struct _StThemeNode      StThemeNode;
+typedef struct _StThemeNodeClass StThemeNodeClass;
+
+#define ST_TYPE_THEME_NODE              (st_theme_node_get_type ())
+#define ST_THEME_NODE(object)           (G_TYPE_CHECK_INSTANCE_CAST ((object), ST_TYPE_THEME_NODE, StThemeNode))
+#define ST_THEME_NODE_CLASS(klass)      (G_TYPE_CHECK_CLASS_CAST ((klass),     ST_TYPE_THEME_NODE, StThemeNodeClass))
+#define ST_IS_THEME_NODE(object)        (G_TYPE_CHECK_INSTANCE_TYPE ((object), ST_TYPE_THEME_NODE))
+#define ST_IS_THEME_NODE_CLASS(klass)   (G_TYPE_CHECK_CLASS_TYPE ((klass),     ST_TYPE_THEME_NODE))
+#define ST_THEME_NODE_GET_CLASS(obj)    (G_TYPE_INSTANCE_GET_CLASS ((obj),     ST_TYPE_THEME_NODE, StThemeNodeClass))
+
+typedef enum {
+    ST_SIDE_LEFT,
+    ST_SIDE_RIGHT,
+    ST_SIDE_TOP,
+    ST_SIDE_BOTTOM
+} StSide;
+
+/* These are the CSS values; that doesn't mean we have to implement blink... */
+typedef enum {
+    ST_TEXT_DECORATION_UNDERLINE    = 1 << 0,
+    ST_TEXT_DECORATION_OVERLINE     = 1 << 1,
+    ST_TEXT_DECORATION_LINE_THROUGH = 1 << 2,
+    ST_TEXT_DECORATION_BLINK        = 1 << 3
+} StTextDecoration;
+
+GType st_theme_node_get_type (void) G_GNUC_CONST;
+
+StThemeNode *st_theme_node_new (StThemeContext *context,
+                                StThemeNode    *parent_node,   /* can be null */
+                                StTheme        *theme,         /* can be null */
+                                GType           element_type,
+                                const char     *element_id,
+                                const char     *element_class,
+                                const char     *pseudo_class);
+
+StThemeNode *st_theme_node_get_parent (StThemeNode *node);
+
+StTheme *st_theme_node_get_theme (StThemeNode *node);
+
+GType       st_theme_node_get_element_type  (StThemeNode *node);
+const char *st_theme_node_get_element_id    (StThemeNode *node);
+const char *st_theme_node_get_element_class (StThemeNode *node);
+const char *st_theme_node_get_pseudo_class  (StThemeNode *node);
+
+/* Generic getters ... these are not cached so are less efficient. The other
+ * reason for adding the more specific version is that we can handle the
+ * details of the actual CSS rules, which can be complicated, especially
+ * for fonts
+ */
+gboolean st_theme_node_get_color  (StThemeNode  *node,
+                                   const char   *property_name,
+                                   gboolean      inherit,
+                                   ClutterColor *color);
+
+gboolean st_theme_node_get_double (StThemeNode  *node,
+                                   const char   *property_name,
+                                   gboolean      inherit,
+                                   double       *value);
+
+gboolean st_theme_node_get_length (StThemeNode *node,
+                                   const char  *property_name,
+                                   gboolean     inherit,
+                                   gdouble     *length);
+
+/* Specific getters for particular properties: cached
+ */
+void st_theme_node_get_background_color (StThemeNode  *node,
+                                         ClutterColor *color);
+void st_theme_node_get_foreground_color (StThemeNode  *node,
+                                         ClutterColor *color);
+
+const char *st_theme_node_get_background_image (StThemeNode *node);
+
+double st_theme_node_get_border_width (StThemeNode  *node,
+                                       StSide        side);
+void   st_theme_node_get_border_color (StThemeNode  *node,
+                                       StSide        side,
+                                       ClutterColor *color);
+double st_theme_node_get_padding      (StThemeNode  *node,
+                                       StSide        side);
+
+StTextDecoration st_theme_node_get_text_decoration (StThemeNode *node);
+
+/* Font rule processing is pretty complicated, so we just hardcode it
+ * under the standard font/font-family/font-size/etc names. This means
+ * you can't have multiple separate styled fonts for a single item,
+ * but that should be OK.
+ */
+const PangoFontDescription *st_theme_node_get_font (StThemeNode *node);
+
+/* This is the getter for -st-background-image, which is different from
+ * background-image in having provisions for unscaled borders.
+ */
+StThemeImage *st_theme_node_get_background_theme_image (StThemeNode *node);
+
+G_END_DECLS
+
+#endif /* __ST_THEME_NODE_H__ */

src/st/st-theme-private.h

@@ -0,0 +1,22 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+#ifndef __ST_THEME_PRIVATE_H__
+#define __ST_THEME_PRIVATE_H__
+
+#include <libcroco/libcroco.h>
+#include "st-theme.h"
+
+G_BEGIN_DECLS
+
+void _st_theme_get_matched_properties (StTheme         *theme,
+                                       StThemeNode     *node,
+                                       CRDeclaration ***properties,
+                                       int             *n_properties);
+
+/* Resolve an URL from the stylesheet to a filename */
+char *_st_theme_resolve_url (StTheme      *theme,
+                             CRStyleSheet *base_stylesheet,
+                             const char   *url);
+
+G_END_DECLS
+
+#endif /* __ST_THEME_PRIVATE_H__ */

src/st/st-theme.c

@@ -0,0 +1,971 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/* This file started as a cut-and-paste of cr-sel-eng.c from libcroco.
+ *
+ * In moving it to hippo-canvas:
+ * - Reformatted and otherwise edited to match our coding style
+ * - Switched from handling xmlNode to handling HippoStyle
+ * - Simplified by removing things that we don't need or that don't
+ *   make sense in our context.
+ * - The code to get a list of matching properties works quite differently;
+ *   we order things in priority order, but we don't actually try to
+ *   coalesce properties with the same name.
+ *
+ * In moving it to GNOME Shell:
+ *  - Renamed again to StTheme
+ *  - Reformatted to match the gnome-shell coding style
+ *  - Removed notion of "theme engine" from hippo-canvas
+ *  - pseudo-class matching changed from link enum to strings
+ *  - Some code simplification
+ */
+
+/*
+ * This file is part of The Croco Library
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2.1 of the GNU Lesser General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser
+ * General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ * USA
+ *
+ * Copyright (C) 2003-2004 Dodji Seketeli.  All Rights Reserved.
+ */
+
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "st-theme-node.h"
+#include "st-theme-private.h"
+
+static GObject *st_theme_constructor (GType                  type,
+                                      guint                  n_construct_properties,
+                                      GObjectConstructParam *construct_properties);
+
+static void st_theme_finalize     (GObject      *object);
+static void st_theme_set_property (GObject      *object,
+                                   guint         prop_id,
+                                   const GValue *value,
+                                   GParamSpec   *pspec);
+static void st_theme_get_property (GObject      *object,
+                                   guint         prop_id,
+                                   GValue       *value,
+                                   GParamSpec   *pspec);
+
+struct _StTheme
+{
+  GObject parent;
+
+  char *application_stylesheet;
+  char *default_stylesheet;
+  char *theme_stylesheet;
+
+  GHashTable *stylesheets_by_filename;
+  GHashTable *filenames_by_stylesheet;
+
+  CRCascade *cascade;
+};
+
+struct _StThemeClass
+{
+  GObjectClass parent_class;
+};
+
+enum
+{
+  PROP_0,
+  PROP_APPLICATION_STYLESHEET,
+  PROP_THEME_STYLESHEET,
+  PROP_DEFAULT_STYLESHEET
+};
+
+G_DEFINE_TYPE (StTheme, st_theme, G_TYPE_OBJECT)
+
+/* Quick strcmp.  Test only for == 0 or != 0, not < 0 or > 0.  */
+#define strqcmp(str,lit,lit_len) \
+  (strlen (str) != (lit_len) || memcmp (str, lit, lit_len))
+
+static void
+st_theme_init (StTheme *theme)
+{
+  theme->stylesheets_by_filename = g_hash_table_new_full (g_str_hash, g_str_equal,
+                                                          (GDestroyNotify)g_free, (GDestroyNotify)cr_stylesheet_unref);
+  theme->filenames_by_stylesheet = g_hash_table_new (g_direct_hash, g_direct_equal);
+}
+
+static void
+st_theme_class_init (StThemeClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->constructor = st_theme_constructor;
+  object_class->finalize = st_theme_finalize;
+  object_class->set_property = st_theme_set_property;
+  object_class->get_property = st_theme_get_property;
+
+  /**
+   * StTheme:application-stylesheet:
+   *
+   * The highest priority stylesheet, representing application-specific
+   * styling; this is associated with the CSS "author" stylesheet.
+   */
+  g_object_class_install_property (object_class,
+                                   PROP_APPLICATION_STYLESHEET,
+                                   g_param_spec_string ("application-stylesheet",
+                                                        "Application Stylesheet",
+                                                        "Stylesheet with application-specific styling",
+                                                        NULL,
+                                                        G_PARAM_READABLE | G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY));
+
+  /**
+   * StTheme:theme-stylesheet:
+   *
+   * The second priority stylesheet, representing theme-specific styling;
+   * this is associated with the CSS "user" stylesheet.
+   */
+  g_object_class_install_property (object_class,
+                                   PROP_THEME_STYLESHEET,
+                                   g_param_spec_string ("theme-stylesheet",
+                                                        "Theme Stylesheet",
+                                                        "Stylesheet with theme-specific styling",
+                                                        NULL,
+                                                        G_PARAM_READABLE | G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY));
+
+  /**
+   * StTheme:default-stylesheet:
+   *
+   * The lowest priority stylesheet, representing global default
+   * styling; this is associated with the CSS "user agent" stylesheet.
+   */
+  g_object_class_install_property (object_class,
+                                   PROP_DEFAULT_STYLESHEET,
+                                   g_param_spec_string ("default-stylesheet",
+                                                        "Default Stylesheet",
+                                                        "Stylesheet with global default styling",
+                                                        NULL,
+                                                        G_PARAM_READABLE | G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY));
+
+}
+
+static CRStyleSheet *
+parse_stylesheet (const char *filename)
+{
+  enum CRStatus status;
+  CRStyleSheet *stylesheet;
+
+  if (filename == NULL)
+    return NULL;
+
+  status = cr_om_parser_simply_parse_file ((const guchar *) filename,
+                                           CR_UTF_8,
+                                           &stylesheet);
+
+  if (status != CR_OK)
+    {
+      g_warning ("Error parsing stylesheet '%s'", filename);
+      return NULL;
+    }
+
+  return stylesheet;
+}
+
+static void
+insert_stylesheet (StTheme      *theme,
+                   const char   *filename,
+                   CRStyleSheet *stylesheet)
+{
+  char *filename_copy;
+
+  if (stylesheet == NULL)
+    return;
+
+  filename_copy = g_strdup(filename);
+  cr_stylesheet_ref (stylesheet);
+
+  g_hash_table_insert (theme->stylesheets_by_filename, filename_copy, stylesheet);
+  g_hash_table_insert (theme->filenames_by_stylesheet, stylesheet, filename_copy);
+}
+
+static GObject *
+st_theme_constructor (GType                  type,
+                      guint                  n_construct_properties,
+                      GObjectConstructParam *construct_properties)
+{
+  GObject *object;
+  StTheme *theme;
+  CRStyleSheet *application_stylesheet;
+  CRStyleSheet *theme_stylesheet;
+  CRStyleSheet *default_stylesheet;
+
+  object = (*G_OBJECT_CLASS (st_theme_parent_class)->constructor) (type,
+                                                                      n_construct_properties,
+                                                                      construct_properties);
+  theme = ST_THEME (object);
+
+  application_stylesheet = parse_stylesheet (theme->application_stylesheet);
+  theme_stylesheet = parse_stylesheet (theme->theme_stylesheet);
+  default_stylesheet = parse_stylesheet (theme->default_stylesheet);
+
+  theme->cascade = cr_cascade_new (application_stylesheet,
+                                   theme_stylesheet,
+                                   default_stylesheet);
+
+  if (theme->cascade == NULL)
+    g_error ("Out of memory when creating cascade object");
+
+  insert_stylesheet (theme, theme->application_stylesheet, application_stylesheet);
+  insert_stylesheet (theme, theme->theme_stylesheet, theme_stylesheet);
+  insert_stylesheet (theme, theme->default_stylesheet, default_stylesheet);
+
+  return object;
+}
+
+static void
+st_theme_finalize (GObject * object)
+{
+  StTheme *theme = ST_THEME (object);
+
+  g_hash_table_destroy (theme->stylesheets_by_filename);
+  g_hash_table_destroy (theme->filenames_by_stylesheet);
+
+  g_free (theme->application_stylesheet);
+  g_free (theme->theme_stylesheet);
+  g_free (theme->default_stylesheet);
+
+  if (theme->cascade)
+    {
+      cr_cascade_unref (theme->cascade);
+      theme->cascade = NULL;
+    }
+
+  G_OBJECT_CLASS (st_theme_parent_class)->finalize (object);
+}
+
+static void
+st_theme_set_property (GObject      *object,
+                       guint         prop_id,
+                       const GValue *value,
+                       GParamSpec   *pspec)
+{
+  StTheme *theme = ST_THEME (object);
+
+  switch (prop_id)
+    {
+    case PROP_APPLICATION_STYLESHEET:
+      {
+        const char *path = g_value_get_string (value);
+
+        if (path != theme->application_stylesheet)
+          {
+            g_free (theme->application_stylesheet);
+            theme->application_stylesheet = g_strdup (path);
+          }
+
+        break;
+      }
+    case PROP_THEME_STYLESHEET:
+      {
+        const char *path = g_value_get_string (value);
+
+        if (path != theme->theme_stylesheet)
+          {
+            g_free (theme->theme_stylesheet);
+            theme->theme_stylesheet = g_strdup (path);
+          }
+
+        break;
+      }
+    case PROP_DEFAULT_STYLESHEET:
+      {
+        const char *path = g_value_get_string (value);
+
+        if (path != theme->default_stylesheet)
+          {
+            g_free (theme->default_stylesheet);
+            theme->default_stylesheet = g_strdup (path);
+          }
+
+        break;
+      }
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+st_theme_get_property (GObject    *object,
+                       guint       prop_id,
+                       GValue     *value,
+                       GParamSpec *pspec)
+{
+  StTheme *theme = ST_THEME (object);
+
+  switch (prop_id)
+    {
+    case PROP_APPLICATION_STYLESHEET:
+      g_value_set_string (value, theme->application_stylesheet);
+      break;
+    case PROP_THEME_STYLESHEET:
+      g_value_set_string (value, theme->theme_stylesheet);
+      break;
+    case PROP_DEFAULT_STYLESHEET:
+      g_value_set_string (value, theme->default_stylesheet);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+/**
+ * st_theme_new:
+ * @application_stylesheet: The highest priority stylesheet, representing application-specific
+ *   styling; this is associated with the CSS "author" stylesheet, may be %NULL
+ * @theme_stylesheet: The second priority stylesheet, representing theme-specific styling ;
+ *   this is associated with the CSS "user" stylesheet, may be %NULL
+ * @default_stylesheet: The lowest priority stylesheet, representing global default styling;
+ *   this is associated with the CSS "user agent" stylesheet, may be %NULL
+ *
+ * Return value: the newly created theme object
+ **/
+StTheme *
+st_theme_new (const char       *application_stylesheet,
+              const char       *theme_stylesheet,
+              const char       *default_stylesheet)
+{
+  StTheme *theme = g_object_new (ST_TYPE_THEME,
+                                    "application-stylesheet", application_stylesheet,
+                                    "theme-stylesheet", theme_stylesheet,
+                                    "default-stylesheet", default_stylesheet,
+                                    NULL);
+
+  return theme;
+}
+
+static gboolean
+string_in_list (GString    *stryng,
+                const char *list)
+{
+  const char *cur;
+
+  for (cur = list; *cur;)
+    {
+      while (*cur && cr_utils_is_white_space (*cur))
+        cur++;
+
+      if (strncmp (cur, stryng->str, stryng->len) == 0)
+        {
+          cur +=  stryng->len;
+          if ((!*cur) || cr_utils_is_white_space (*cur))
+            return TRUE;
+        }
+
+      /*  skip to next whitespace character  */
+      while (*cur && !cr_utils_is_white_space (*cur))
+        cur++;
+    }
+
+  return FALSE;
+}
+
+static gboolean
+pseudo_class_add_sel_matches_style (StTheme         *a_this,
+                                    CRAdditionalSel *a_add_sel,
+                                    StThemeNode     *a_node)
+{
+  const char *node_pseudo_class;
+
+  g_return_val_if_fail (a_this
+                        && a_add_sel
+                        && a_add_sel->content.pseudo
+                        && a_add_sel->content.pseudo->name
+                        && a_add_sel->content.pseudo->name->stryng
+                        && a_add_sel->content.pseudo->name->stryng->str
+                        && a_node, FALSE);
+
+  node_pseudo_class = st_theme_node_get_pseudo_class (a_node);
+
+  if (node_pseudo_class == NULL)
+    return FALSE;
+
+  return string_in_list (a_add_sel->content.pseudo->name->stryng, node_pseudo_class);
+}
+
+/**
+ *@param a_add_sel the class additional selector to consider.
+ *@param a_node the style node to consider.
+ *@return TRUE if the class additional selector matches
+ *the style node given in argument, FALSE otherwise.
+ */
+static gboolean
+class_add_sel_matches_style (CRAdditionalSel *a_add_sel,
+                             StThemeNode     *a_node)
+{
+  const char *element_class;
+
+  g_return_val_if_fail (a_add_sel
+                        && a_add_sel->type == CLASS_ADD_SELECTOR
+                        && a_add_sel->content.class_name
+                        && a_add_sel->content.class_name->stryng
+                        && a_add_sel->content.class_name->stryng->str
+                        && a_node, FALSE);
+
+  element_class = st_theme_node_get_element_class (a_node);
+  if (element_class == NULL)
+    return FALSE;
+
+  return string_in_list (a_add_sel->content.class_name->stryng, element_class);
+}
+
+/**
+ *@return TRUE if the additional attribute selector matches
+ *the current style node given in argument, FALSE otherwise.
+ *@param a_add_sel the additional attribute selector to consider.
+ *@param a_node the style node to consider.
+ */
+static gboolean
+id_add_sel_matches_style (CRAdditionalSel *a_add_sel,
+                          StThemeNode     *a_node)
+{
+  gboolean result = FALSE;
+  const char *id;
+
+  g_return_val_if_fail (a_add_sel
+                        && a_add_sel->type == ID_ADD_SELECTOR
+                        && a_add_sel->content.id_name
+                        && a_add_sel->content.id_name->stryng
+                        && a_add_sel->content.id_name->stryng->str
+                        && a_node, FALSE);
+  g_return_val_if_fail (a_add_sel
+                        && a_add_sel->type == ID_ADD_SELECTOR
+                        && a_node, FALSE);
+
+  id = st_theme_node_get_element_id (a_node);
+
+  if (id != NULL)
+    {
+      if (!strqcmp (id, a_add_sel->content.id_name->stryng->str,
+                    a_add_sel->content.id_name->stryng->len))
+        {
+          result = TRUE;
+        }
+    }
+
+  return result;
+}
+
+/**
+ *Evaluates if a given additional selector matches an style node.
+ *@param a_add_sel the additional selector to consider.
+ *@param a_node the style node to consider.
+ *@return TRUE is a_add_sel matches a_node, FALSE otherwise.
+ */
+static gboolean
+additional_selector_matches_style (StTheme         *a_this,
+                                   CRAdditionalSel *a_add_sel,
+                                   StThemeNode     *a_node)
+{
+  CRAdditionalSel *cur_add_sel = NULL;
+
+  g_return_val_if_fail (a_add_sel, FALSE);
+
+  for (cur_add_sel = a_add_sel; cur_add_sel; cur_add_sel = cur_add_sel->next)
+    {
+      switch (cur_add_sel->type)
+        {
+        case NO_ADD_SELECTOR:
+          return FALSE;
+        case CLASS_ADD_SELECTOR:
+          if (!class_add_sel_matches_style (cur_add_sel, a_node))
+            return FALSE;
+          break;
+        case ID_ADD_SELECTOR:
+          if (!id_add_sel_matches_style (cur_add_sel, a_node))
+            return FALSE;
+          break;
+        case ATTRIBUTE_ADD_SELECTOR:
+          g_warning ("Attribute selectors not supported");
+          return FALSE;
+        case  PSEUDO_CLASS_ADD_SELECTOR:
+          if (!pseudo_class_add_sel_matches_style (a_this, cur_add_sel, a_node))
+            return FALSE;
+          break;
+        }
+    }
+
+  return TRUE;
+}
+
+static gboolean
+element_name_matches_type (const char *element_name,
+                           GType       element_type)
+{
+  if (element_type == G_TYPE_NONE)
+    {
+      return strcmp (element_name, "stage") == 0;
+    }
+  else
+    {
+      GType match_type = g_type_from_name (element_name);
+      if (match_type == G_TYPE_INVALID)
+        return FALSE;
+
+      return g_type_is_a (element_type, match_type);
+    }
+}
+
+/**
+ *Evaluate a selector (a simple selectors list) and says
+ *if it matches the style node given in parameter.
+ *The algorithm used here is the following:
+ *Walk the combinator separated list of simple selectors backward, starting
+ *from the end of the list. For each simple selector, looks if
+ *if matches the current style.
+ *
+ *@param a_this the selection engine.
+ *@param a_sel the simple selection list.
+ *@param a_node the style node.
+ *@param a_result out parameter. Set to true if the
+ *selector matches the style node, FALSE otherwise.
+ *@param a_recurse if set to TRUE, the function will walk to
+ *the next simple selector (after the evaluation of the current one)
+ *and recursively evaluate it. Must be usually set to TRUE unless you
+ *know what you are doing.
+ */
+static enum CRStatus
+sel_matches_style_real (StTheme     *a_this,
+                        CRSimpleSel *a_sel,
+                        StThemeNode *a_node,
+                        gboolean    *a_result,
+                        gboolean     a_eval_sel_list_from_end,
+                        gboolean     a_recurse)
+{
+  CRSimpleSel *cur_sel = NULL;
+  StThemeNode *cur_node = NULL;
+  GType cur_type;
+
+  *a_result = FALSE;
+
+  if (a_eval_sel_list_from_end)
+    {
+      /*go and get the last simple selector of the list */
+      for (cur_sel = a_sel; cur_sel && cur_sel->next; cur_sel = cur_sel->next)
+        ;
+    }
+  else
+    {
+      cur_sel = a_sel;
+    }
+
+  cur_node = a_node;
+  cur_type = st_theme_node_get_element_type (cur_node);
+
+  while (cur_sel)
+    {
+      if (((cur_sel->type_mask & TYPE_SELECTOR)
+           && (cur_sel->name
+               && cur_sel->name->stryng
+               && cur_sel->name->stryng->str)
+           &&
+           (element_name_matches_type (cur_sel->name->stryng->str, cur_type)))
+          || (cur_sel->type_mask & UNIVERSAL_SELECTOR))
+        {
+          /*
+           *this simple selector
+           *matches the current style node
+           *Let's see if the preceding
+           *simple selectors also match
+           *their style node counterpart.
+           */
+          if (cur_sel->add_sel)
+            {
+              if (additional_selector_matches_style (a_this, cur_sel->add_sel, cur_node))
+                goto walk_a_step_in_expr;
+              else
+                goto done;
+            }
+          else
+            goto walk_a_step_in_expr;
+        }
+      if (!(cur_sel->type_mask & TYPE_SELECTOR)
+          && !(cur_sel->type_mask & UNIVERSAL_SELECTOR))
+        {
+          if (!cur_sel->add_sel)
+            goto done;
+          if (additional_selector_matches_style (a_this, cur_sel->add_sel, cur_node))
+            goto walk_a_step_in_expr;
+          else
+            goto done;
+        }
+      else
+        {
+          goto done;
+        }
+
+    walk_a_step_in_expr:
+      if (a_recurse == FALSE)
+        {
+          *a_result = TRUE;
+          goto done;
+        }
+
+      /*
+       *here, depending on the combinator of cur_sel
+       *choose the axis of the element tree traversal
+       *and walk one step in the element tree.
+       */
+      if (!cur_sel->prev)
+        break;
+
+      switch (cur_sel->combinator)
+        {
+        case NO_COMBINATOR:
+          break;
+
+        case COMB_WS:           /*descendant selector */
+          {
+            StThemeNode *n = NULL;
+
+            /*
+             *walk the element tree upward looking for a parent
+             *style that matches the preceding selector.
+             */
+            for (n = st_theme_node_get_parent (a_node); n; n = st_theme_node_get_parent (n))
+              {
+                enum CRStatus status;
+                gboolean matches = FALSE;
+
+                status = sel_matches_style_real (a_this, cur_sel->prev, n, &matches, FALSE, TRUE);
+
+                if (status != CR_OK)
+                  goto done;
+
+                if (matches)
+                  {
+                    cur_node = n;
+                    cur_type = st_theme_node_get_element_type (cur_node);
+                    break;
+                  }
+              }
+
+            if (!n)
+              {
+                /*
+                 *didn't find any ancestor that matches
+                 *the previous simple selector.
+                 */
+                goto done;
+              }
+            /*
+             *in this case, the preceding simple sel
+             *will have been interpreted twice, which
+             *is a cpu and mem waste ... I need to find
+             *another way to do this. Anyway, this is
+             *my first attempt to write this function and
+             *I am a bit clueless.
+             */
+            break;
+          }
+
+        case COMB_PLUS:
+          g_warning ("+ combinators are not supported");
+          goto done;
+
+        case COMB_GT:
+          cur_node = st_theme_node_get_parent (cur_node);
+          if (!cur_node)
+            goto done;
+          cur_type = st_theme_node_get_element_type (cur_node);
+          break;
+
+        default:
+          goto done;
+        }
+
+      cur_sel = cur_sel->prev;
+    }
+
+  /*
+   *if we reached this point, it means the selector matches
+   *the style node.
+   */
+  *a_result = TRUE;
+
+done:
+  return CR_OK;
+}
+
+static void
+add_matched_properties (StTheme      *a_this,
+                        CRStyleSheet *a_nodesheet,
+                        StThemeNode  *a_node,
+                        GPtrArray    *props)
+{
+  CRStatement *cur_stmt = NULL;
+  CRSelector *sel_list = NULL;
+  CRSelector *cur_sel = NULL;
+  gboolean matches = FALSE;
+  enum CRStatus status = CR_OK;
+
+  /*
+   *walk through the list of statements and,
+   *get the selectors list inside the statements that
+   *contain some, and try to match our style node in these
+   *selectors lists.
+   */
+  for (cur_stmt = a_nodesheet->statements; cur_stmt; cur_stmt = cur_stmt->next)
+    {
+      /*
+       *initialyze the selector list in which we will
+       *really perform the search.
+       */
+      sel_list = NULL;
+
+      /*
+       *get the the damn selector list in
+       *which we have to look
+       */
+      switch (cur_stmt->type)
+        {
+        case RULESET_STMT:
+          if (cur_stmt->kind.ruleset && cur_stmt->kind.ruleset->sel_list)
+            {
+              sel_list = cur_stmt->kind.ruleset->sel_list;
+            }
+          break;
+
+        case AT_MEDIA_RULE_STMT:
+          if (cur_stmt->kind.media_rule
+              && cur_stmt->kind.media_rule->rulesets
+              && cur_stmt->kind.media_rule->rulesets->kind.ruleset
+              && cur_stmt->kind.media_rule->rulesets->kind.ruleset->sel_list)
+            {
+              sel_list = cur_stmt->kind.media_rule->rulesets->kind.ruleset->sel_list;
+            }
+          break;
+
+        case AT_IMPORT_RULE_STMT:
+          {
+            CRAtImportRule *import_rule = cur_stmt->kind.import_rule;
+
+            if (import_rule->sheet == NULL)
+              {
+                char *filename = NULL;
+
+                if (import_rule->url->stryng && import_rule->url->stryng->str)
+                  filename = _st_theme_resolve_url (a_this,
+                                                    a_nodesheet,
+                                                    import_rule->url->stryng->str);
+
+                if (filename)
+                  import_rule->sheet = parse_stylesheet (filename);
+
+                if (import_rule->sheet)
+                  {
+                    insert_stylesheet (a_this, filename, import_rule->sheet);
+                    /* refcount of stylesheets starts off at zero, so we don't need to unref! */
+                  }
+                else
+                  {
+                    /* Set a marker to avoid repeatedly trying to parse a non-existent or
+                     * broken stylesheet
+                     */
+                    import_rule->sheet = (CRStyleSheet *) - 1;
+                  }
+
+                if (filename)
+                  g_free (filename);
+              }
+
+            if (import_rule->sheet != (CRStyleSheet *) - 1)
+              {
+                add_matched_properties (a_this, import_rule->sheet,
+                                        a_node, props);
+              }
+          }
+          break;
+        default:
+          break;
+        }
+
+      if (!sel_list)
+        continue;
+
+      /*
+       *now, we have a comma separated selector list to look in.
+       *let's walk it and try to match the style node
+       *on each item of the list.
+       */
+      for (cur_sel = sel_list; cur_sel; cur_sel = cur_sel->next)
+        {
+          if (!cur_sel->simple_sel)
+            continue;
+
+          status = sel_matches_style_real (a_this, cur_sel->simple_sel, a_node, &matches, TRUE, TRUE);
+
+          if (status == CR_OK && matches)
+            {
+              CRDeclaration *cur_decl = NULL;
+
+              /* In order to sort the matching properties, we need to compute the
+               * specificity of the selector that actually matched this
+               * element. In a non-thread-safe fashion, we store it in the
+               * ruleset. (Fixing this would mean cut-and-pasting
+               * cr_simple_sel_compute_specificity(), and have no need for
+               * thread-safety anyways.)
+               *
+               * Once we've sorted the properties, the specificity no longer
+               * matters and it can be safely overriden.
+               */
+              cr_simple_sel_compute_specificity (cur_sel->simple_sel);
+
+              cur_stmt->specificity = cur_sel->simple_sel->specificity;
+
+              for (cur_decl = cur_stmt->kind.ruleset->decl_list; cur_decl; cur_decl = cur_decl->next)
+                g_ptr_array_add (props, cur_decl);
+            }
+        }
+    }
+}
+
+#define ORIGIN_AUTHOR_IMPORTANT (ORIGIN_AUTHOR + 1)
+#define ORIGIN_USER_IMPORTANT   (ORIGIN_AUTHOR + 2)
+
+static inline int
+get_origin (const CRDeclaration * decl)
+{
+  enum CRStyleOrigin origin = decl->parent_statement->parent_sheet->origin;
+
+  if (decl->important)
+    {
+      if (origin == ORIGIN_AUTHOR)
+        return ORIGIN_AUTHOR_IMPORTANT;
+      else if (origin == ORIGIN_USER)
+        return ORIGIN_USER_IMPORTANT;
+    }
+
+  return origin;
+}
+
+/* Order of comparison is so that higher priority statements compare after
+ * lower priority statements */
+static int
+compare_declarations (gconstpointer a,
+                      gconstpointer b)
+{
+  /* g_ptr_array_sort() is broooken */
+  CRDeclaration *decl_a = *(CRDeclaration **) a;
+  CRDeclaration *decl_b = *(CRDeclaration **) b;
+
+  int origin_a = get_origin (decl_a);
+  int origin_b = get_origin (decl_b);
+
+  if (origin_a != origin_b)
+    return origin_a - origin_b;
+
+  if (decl_a->parent_statement->specificity != decl_b->parent_statement->specificity)
+    return decl_a->parent_statement->specificity - decl_b->parent_statement->specificity;
+
+  return 0;
+}
+
+void
+_st_theme_get_matched_properties (StTheme        *theme,
+                                  StThemeNode     *node,
+                                  CRDeclaration ***properties,
+                                  int             *n_properties)
+{
+  enum CRStyleOrigin origin = 0;
+  CRStyleSheet *sheet = NULL;
+  GPtrArray *props = g_ptr_array_new ();
+
+  g_return_if_fail (ST_IS_THEME (theme));
+  g_return_if_fail (ST_IS_THEME_NODE (node));
+
+  for (origin = ORIGIN_UA; origin < NB_ORIGINS; origin++)
+    {
+      sheet = cr_cascade_get_sheet (theme->cascade, origin);
+      if (!sheet)
+        continue;
+
+      add_matched_properties (theme, sheet, node, props);
+    }
+
+  /* We count on a stable sort here so that later declarations come
+   * after earlier declarations */
+  g_ptr_array_sort (props, compare_declarations);
+
+  *n_properties = props->len;
+  *properties = (CRDeclaration **) g_ptr_array_free (props, FALSE);
+}
+
+/* Resolve an url from an url() reference in a stylesheet into an absolute
+ * local filename, if possible. The resolution here is distinctly lame and
+ * will fail on many examples.
+ */
+char *
+_st_theme_resolve_url (StTheme      *theme,
+                       CRStyleSheet *base_stylesheet,
+                       const char   *url)
+{
+  const char *base_filename = NULL;
+  char *dirname;
+  char *filename;
+
+  /* Handle absolute file:/ URLs */
+  if (g_str_has_prefix (url, "file:") ||
+      g_str_has_prefix (url, "File:") ||
+      g_str_has_prefix (url, "FILE:"))
+    {
+      GError *error = NULL;
+      char *filename;
+
+      filename = g_filename_from_uri (url, NULL, &error);
+      if (filename == NULL)
+        {
+          g_warning ("%s", error->message);
+          g_error_free (error);
+        }
+
+      return NULL;
+    }
+
+  /* Guard against http:/ URLs */
+
+  if (g_str_has_prefix (url, "http:") ||
+      g_str_has_prefix (url, "Http:") ||
+      g_str_has_prefix (url, "HTTP:"))
+    {
+      g_warning ("Http URL '%s' in theme stylesheet is not supported", url);
+      return NULL;
+    }
+
+  /* Assume anything else is a relative URL, and "resolve" it
+   */
+  if (url[0] == '/')
+    return g_strdup (url);
+
+  base_filename = g_hash_table_lookup (theme->filenames_by_stylesheet, base_stylesheet);
+
+  if (base_filename == NULL)
+    {
+      g_warning ("Can't get base to resolve url '%s'", url);
+      return NULL;
+    }
+
+  dirname = g_path_get_dirname (base_filename);
+  filename = g_build_filename (dirname, url, NULL);
+  g_free (dirname);
+
+  return filename;
+}

src/st/st-theme.h

@@ -0,0 +1,38 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+#ifndef __ST_THEME_H__
+#define __ST_THEME_H__
+
+#include <glib-object.h>
+
+#include "st-theme-node.h"
+
+G_BEGIN_DECLS
+
+/**
+ * SECTION:StTheme
+ * @short_description: a set of stylesheets
+ *
+ * #StTheme holds a set of stylesheets. (The "cascade" of the name
+ * Cascading Stylesheets.) A #StTheme can be set to apply to all the actors
+ * in a stage using st_theme_context_set_theme() or applied to a subtree
+ * of actors using st_widget_set_theme().
+ */
+
+typedef struct _StThemeClass StThemeClass;
+
+#define ST_TYPE_THEME              (st_theme_get_type ())
+#define ST_THEME(object)           (G_TYPE_CHECK_INSTANCE_CAST ((object), ST_TYPE_THEME, StTheme))
+#define ST_THEME_CLASS(klass)      (G_TYPE_CHECK_CLASS_CAST ((klass), ST_TYPE_THEME, StThemeClass))
+#define ST_IS_THEME(object)        (G_TYPE_CHECK_INSTANCE_TYPE ((object), ST_TYPE_THEME))
+#define ST_IS_THEME_CLASS(klass)   (G_TYPE_CHECK_CLASS_TYPE ((klass), ST_TYPE_THEME))
+#define ST_THEME_GET_CLASS(obj)    (G_TYPE_INSTANCE_GET_CLASS ((obj), ST_TYPE_THEME, StThemeClass))
+
+GType  st_theme_get_type (void) G_GNUC_CONST;
+
+StTheme *st_theme_new (const char *application_stylesheet,
+                       const char *theme_stylesheet,
+                       const char *default_stylesheet);
+
+G_END_DECLS
+
+#endif /* __ST_THEME_H__ */

src/st/test-theme.c

@@ -0,0 +1,292 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+#include <clutter/clutter.h>
+#include "st-theme.h"
+#include "st-theme-context.h"
+#include <math.h>
+#include <string.h>
+
+static StThemeNode *root;
+static StThemeNode *group1;
+static StThemeNode *text1;
+static StThemeNode *text2;
+static StThemeNode *group2;
+static StThemeNode *text3;
+static StThemeNode *text4;
+static StThemeNode *group3;
+static StThemeNode *cairo_texture;
+static gboolean fail;
+
+static const char *test;
+
+static void
+assert_font (StThemeNode *node,
+	     const char  *node_description,
+	     const char  *expected)
+{
+  char *value = pango_font_description_to_string (st_theme_node_get_font (node));
+
+  if (strcmp (expected, value) != 0)
+    {
+      g_print ("%s: %s.font: expected: %s, got: %s\n",
+	       test, node_description, expected, value);
+      fail = TRUE;
+    }
+
+  g_free (value);
+}
+
+static char *
+text_decoration_to_string (StTextDecoration decoration)
+{
+  GString *result = g_string_new (NULL);
+
+  if (decoration & ST_TEXT_DECORATION_UNDERLINE)
+    g_string_append(result, " underline");
+  if (decoration & ST_TEXT_DECORATION_OVERLINE)
+    g_string_append(result, " overline");
+  if (decoration & ST_TEXT_DECORATION_LINE_THROUGH)
+    g_string_append(result, " line_through");
+  if (decoration & ST_TEXT_DECORATION_BLINK)
+    g_string_append(result, " blink");
+
+  if (result->len > 0)
+    g_string_erase (result, 0, 1);
+  else
+    g_string_append(result, "none");
+
+  return g_string_free (result, FALSE);
+}
+
+static void
+assert_text_decoration (StThemeNode     *node,
+			const char      *node_description,
+			StTextDecoration expected)
+{
+  StTextDecoration value = st_theme_node_get_text_decoration (node);
+  if (expected != value)
+    {
+      char *es = text_decoration_to_string (expected);
+      char *vs = text_decoration_to_string (value);
+
+      g_print ("%s: %s.text-decoration: expected: %s, got: %s\n",
+	       test, node_description, es, vs);
+      fail = TRUE;
+
+      g_free (es);
+      g_free (vs);
+    }
+}
+
+static void
+assert_foreground_color (StThemeNode *node,
+			 const char  *node_description,
+			 guint32      expected)
+{
+  ClutterColor color;
+  st_theme_node_get_foreground_color (node, &color);
+  guint32 value = clutter_color_to_pixel (&color);
+
+  if (expected != value)
+    {
+      g_print ("%s: %s.color: expected: #%08x, got: #%08x\n",
+	       test, node_description, expected, value);
+      fail = TRUE;
+    }
+}
+
+static void
+assert_background_color (StThemeNode *node,
+			 const char  *node_description,
+			 guint32      expected)
+{
+  ClutterColor color;
+  st_theme_node_get_background_color (node, &color);
+  guint32 value = clutter_color_to_pixel (&color);
+
+  if (expected != value)
+    {
+      g_print ("%s: %s.background-color: expected: #%08x, got: #%08x\n",
+	       test, node_description, expected, value);
+      fail = TRUE;
+    }
+}
+
+static void
+assert_background_image (StThemeNode *node,
+			 const char  *node_description,
+			 const char  *expected)
+{
+  const char *value = st_theme_node_get_background_image (node);
+  if (expected == NULL)
+    expected = "(null)";
+  if (value == NULL)
+    value = "(null)";
+
+  if (strcmp (expected, value) != 0)
+    {
+      g_print ("%s: %s.background-image: expected: %s, got: %s\n",
+	       test, node_description, expected, value);
+      fail = TRUE;
+    }
+}
+
+#define LENGTH_EPSILON 0.001
+
+static void
+assert_length (const char     *node_description,
+	       const char     *property_description,
+	       double          expected,
+	       double          value)
+{
+  if (fabs (expected - value) > LENGTH_EPSILON)
+    {
+      g_print ("%s %s.%s: expected: %3f, got: %3f\n",
+	       test, node_description, property_description, expected, value);
+      fail = TRUE;
+    }
+}
+
+static void
+test_defaults (void)
+{
+  test = "defaults";
+  /* font comes from context */
+  assert_font (root, "stage", "sans-serif 12");
+  /* black is the default foreground color */
+  assert_foreground_color (root, "stage", 0x00000ff);
+}
+
+static void
+test_lengths (void)
+{
+  test = "lengths";
+  /* 12pt == 16px at 96dpi */
+  assert_length ("group1", "padding-top", 16.,
+		 st_theme_node_get_padding (group1, ST_SIDE_TOP));
+  /* 12px == 12px */
+  assert_length ("group1", "padding-right", 12.,
+		 st_theme_node_get_padding (group1, ST_SIDE_RIGHT));
+  /* 2em == 32px (with a 12pt font) */
+  assert_length ("group1", "padding-bottom", 32.,
+		 st_theme_node_get_padding (group1, ST_SIDE_BOTTOM));
+  /* 1in == 72pt == 96px, at 96dpi */
+  assert_length ("group1", "padding-left", 96.,
+		 st_theme_node_get_padding (group1, ST_SIDE_LEFT));
+}
+
+static void
+test_classes (void)
+{
+  test = "classes";
+  /* .special-text class overrides size and style;
+   * the ClutterTexture.special-text selector doesn't match */
+  assert_font (text1, "text1", "sans-serif Italic 32px");
+}
+
+static void
+test_type_inheritance (void)
+{
+  test = "type_inheritance";
+  /* From ClutterTexture element selector */
+  assert_length ("cairoTexture", "padding-top", 10.,
+		 st_theme_node_get_padding (cairo_texture, ST_SIDE_TOP));
+  /* From ClutterCairoTexture element selector */
+  assert_length ("cairoTexture", "padding-right", 20.,
+		 st_theme_node_get_padding (cairo_texture, ST_SIDE_RIGHT));
+}
+
+static void
+test_adjacent_selector (void)
+{
+  test = "adjacent_selector";
+  /* #group1 > #text1 matches text1 */
+  assert_foreground_color (text1, "text1", 0x00ff00ff);
+  /* stage > #text2 doesn't match text2 */
+  assert_foreground_color (text2, "text2", 0x000000ff);
+}
+
+static void
+test_background (void)
+{
+  test = "background";
+  /* group1 has a background: shortcut property setting color and image */
+  assert_background_color (group1, "group1", 0xff0000ff);
+  assert_background_image (group1, "group1", "st/some-background.png");
+  /* text1 inherits the background image but not the color */
+  assert_background_color (text1,  "text1",  0x00000000);
+  assert_background_image (text1,  "text1",  "st/some-background.png");
+  /* text1 inherits inherits both, but then background: none overrides both */
+  assert_background_color (text2,  "text2",  0x00000000);
+  assert_background_image (text2,  "text2",  NULL);
+  /* background-image property */
+  assert_background_image (group2, "group2", "st/other-background.png");
+}
+
+static void
+test_font (void)
+{
+  test = "font";
+  /* font specified with font: */
+  assert_font (group2, "group2", "serif Italic 12px");
+  /* text3 inherits and overrides individually properties */
+  assert_font (text3,  "text3",  "serif Bold Oblique Small-Caps 24px");
+}
+
+static void
+test_pseudo_class (void)
+{
+  test = "pseudo_class";
+  /* text4 has :visited and :hover pseudo-classes, so should pick up both of these */
+  assert_foreground_color (text4,   "text4",  0x888888ff);
+  assert_text_decoration  (text4,   "text4",  ST_TEXT_DECORATION_UNDERLINE);
+  /* :hover pseudo-class matches, but class doesn't match */
+  assert_text_decoration  (group3,  "group3", 0);
+}
+
+int
+main (int argc, char **argv)
+{
+  StTheme *theme;
+  StThemeContext *context;
+
+  clutter_init (&argc, &argv);
+
+  theme = st_theme_new ("st/test-theme.css",
+                        NULL, NULL);
+
+  context = st_theme_context_new ();
+  st_theme_context_set_theme (context, theme);
+  st_theme_context_set_resolution (context, 96.);
+  st_theme_context_set_font (context,
+				pango_font_description_from_string ("sans-serif 12"));
+
+  root = st_theme_context_get_root_node (context);
+  group1 = st_theme_node_new (context, root, NULL,
+                              CLUTTER_TYPE_GROUP, "group1", NULL, NULL);
+  text1 = st_theme_node_new  (context, group1, NULL,
+                              CLUTTER_TYPE_TEXT, "text1", "special-text", NULL);
+  text2 = st_theme_node_new  (context, group1, NULL,
+                              CLUTTER_TYPE_TEXT, "text2", NULL, NULL);
+  group2 = st_theme_node_new (context, root, NULL,
+                              CLUTTER_TYPE_GROUP, "group2", NULL, NULL);
+  text3 = st_theme_node_new  (context, group2, NULL,
+                              CLUTTER_TYPE_TEXT, "text3", NULL, NULL);
+  text4 = st_theme_node_new  (context, group2, NULL,
+                              CLUTTER_TYPE_TEXT, "text4", NULL, "visited hover");
+  group3 = st_theme_node_new (context, group2, NULL,
+                              CLUTTER_TYPE_GROUP, "group3", NULL, "hover");
+  cairo_texture = st_theme_node_new (context, root, NULL,
+                                     CLUTTER_TYPE_CAIRO_TEXTURE, "cairoTexture", NULL, NULL);
+
+  test_defaults ();
+  test_lengths ();
+  test_classes ();
+  test_type_inheritance ();
+  test_adjacent_selector ();
+  test_background ();
+  test_font ();
+  test_pseudo_class ();
+
+  return fail ? 1 : 0;
+}

src/st/test-theme.css

@@ -0,0 +1,68 @@
+stage {
+}
+
+#group1 {
+    padding: 12pt;
+    padding-right: 12px;
+    padding-bottom: 2em;
+    padding-left: 1in;
+
+    background: #ff0000 url('some-background.png');
+}
+
+#text1 {
+    background-image: inherit;
+}
+
+.special-text {
+    font-size: 24pt;
+    font-style: italic;
+}
+
+ClutterTexture.special-text {
+    font-weight: bold;
+}
+
+#text2 {
+    background: inherit;
+    background: none; /* also overrides the color */
+}
+
+#group2 {
+    font: italic 12px serif;
+}
+
+#text3 {
+    font-variant: small-caps;
+    font-weight: bold;
+    font-style: oblique;
+    font-size: 200%;
+}
+
+ClutterTexture {
+    padding: 10px;
+}
+
+ClutterCairoTexture {
+    padding-right: 20px;
+}
+
+#group1 > #text1 {
+    color: #00ff00;
+}
+
+stage > #text2 {
+    color: #ff0000;
+}
+
+#group2 {
+    background-image: url('other-background.png');
+}
+
+ClutterText:hover {
+    text-decoration: underline;
+}
+
+ClutterText:visited {
+    color: #888888;
+}