icontheme: Add support for high resolution icons

An optional OutputScale integer key has been added to index.theme
subdirs description, so icon themes may provide icons that are
more suitable to render at a (typically 2x) integer upscaled
resolution. This way it is possible to make eg. a 16x16@2x icon has a
real size of 32x32, but contains a similar level of detail to the
16x16 icon so things don't look any more cluttered on high-dpi
screens.

The pixbuf lookup has changed so it prefers a minimal scale change
that yields the minimal real size difference, so if looking up for
a 16x16 icon at 2x, it would first prefer 16x16@2x, then 32x32, and
then any other icon that's closest to match

There is now *_for_scale() variants for all GtkIconTheme ways
to directly or indirectly fetch a GdkPixbuf.

This is based on code by Carlos Garnacho with changes by Alexander
Larsson

2 files changed, 387 insertions, 114 deletions

diff --git a/gtk/gtkicontheme.c b/gtk/gtkicontheme.c
index 2414257034..566688dad0 100644
--- a/gtk/gtkicontheme.c
+++ b/gtk/gtkicontheme.c
@@ -55,6 +55,10 @@
 
 #include "deprecated/gtkstyle.h"
 
+/* this is in case round() is not provided by the compiler, 
+ * such as in the case of C89 compilers, like MSVC
+ */
+#include "fallback-c89.c"
 
 /**
  * SECTION:gtkicontheme
@@ -208,6 +212,7 @@ struct _GtkIconThemePrivate
 typedef struct {
   gchar **icon_names;
   gint size;
+  gint scale;
   GtkIconLookupFlags flags;
 } IconInfoKey;
 
@@ -252,11 +257,13 @@ struct _GtkIconInfo
    */
   IconThemeDirType dir_type;
   gint dir_size;
+  gint dir_scale;
   gint threshold;
 
   /* Parameters influencing the scaled icon
    */
   gint desired_size;
+  gint desired_scale;
   guint raw_coordinates : 1;
   guint forced_size     : 1;
   guint emblems_applied : 1;
@@ -294,6 +301,7 @@ typedef struct
   int min_size;
   int max_size;
   int threshold;
+  int scale;
 
   char *dir;
   char *subdir;
@@ -332,6 +340,7 @@ static void         theme_destroy     (IconTheme        *theme);
 static GtkIconInfo *theme_lookup_icon (IconTheme        *theme,
 				       const char       *icon_name,
 				       int               size,
+                                       gint              scale,
 				       gboolean          allow_svg,
 				       gboolean          use_default_icons);
 static void         theme_list_icons  (IconTheme        *theme,
@@ -367,8 +376,8 @@ static IconSuffix suffix_from_name (const char *name);
 
 static BuiltinIcon *find_builtin_icon (const gchar *icon_name,
 				       gint        size,
-				       gint        *min_difference_p,
-				       gboolean    *has_larger_p);
+				       gint        scale,
+				       gint        *min_difference_p);
 static void remove_from_lru_cache (GtkIconTheme *icon_theme,
 				   GtkIconInfo *icon_info);
 
@@ -390,7 +399,8 @@ icon_info_key_hash (gconstpointer _key)
     h ^= g_str_hash (key->icon_names[i]);
 
   h ^= key->size * 0x10001;
-  h ^= key->flags * 0x1000010;
+  h ^= key->scale * 0x1000010;
+  h ^= key->flags * 0x100000100;
 
   return h;
 }
@@ -406,6 +416,9 @@ icon_info_key_equal (gconstpointer  _a,
   if (a->size != b->size)
     return FALSE;
 
+  if (a->scale != b->scale)
+    return FALSE;
+
   if (a->flags != b->flags)
     return FALSE;
 
@@ -1342,11 +1355,11 @@ _gtk_icon_theme_ensure_builtin_cache (void)
   IconThemeDir *dir;
   static IconThemeDir dirs[5] = 
     {
-      { ICON_THEME_DIR_THRESHOLD, 0, 16, 16, 16, 2, NULL, "16", -1, NULL, NULL, NULL },
-      { ICON_THEME_DIR_THRESHOLD, 0, 20, 20, 20, 2, NULL, "20", -1,  NULL, NULL, NULL },
-      { ICON_THEME_DIR_THRESHOLD, 0, 24, 24, 24, 2, NULL, "24", -1, NULL, NULL, NULL },
-      { ICON_THEME_DIR_THRESHOLD, 0, 32, 32, 32, 2, NULL, "32", -1, NULL, NULL, NULL },
-      { ICON_THEME_DIR_THRESHOLD, 0, 48, 48, 48, 2, NULL, "48", -1, NULL, NULL, NULL }
+      { ICON_THEME_DIR_THRESHOLD, 0, 16, 16, 16, 2, 1, NULL, "16", -1, NULL, NULL, NULL },
+      { ICON_THEME_DIR_THRESHOLD, 0, 20, 20, 20, 2, 1, NULL, "20", -1,  NULL, NULL, NULL },
+      { ICON_THEME_DIR_THRESHOLD, 0, 24, 24, 24, 2, 1, NULL, "24", -1, NULL, NULL, NULL },
+      { ICON_THEME_DIR_THRESHOLD, 0, 32, 32, 32, 2, 1, NULL, "32", -1, NULL, NULL, NULL },
+      { ICON_THEME_DIR_THRESHOLD, 0, 48, 48, 48, 2, 1, NULL, "48", -1, NULL, NULL, NULL }
     };
   gint i;
 
@@ -1574,6 +1587,7 @@ static GtkIconInfo *
 choose_icon (GtkIconTheme       *icon_theme,
 	     const gchar        *icon_names[],
 	     gint                size,
+             gint                scale,
 	     GtkIconLookupFlags  flags)
 {
   GtkIconThemePrivate *priv;
@@ -1591,6 +1605,7 @@ choose_icon (GtkIconTheme       *icon_theme,
 
   key.icon_names = (char **)icon_names;
   key.size = size;
+  key.scale = scale;
   key.flags = flags;
 
   icon_info = g_hash_table_lookup (priv->info_cache, &key);
@@ -1628,7 +1643,7 @@ choose_icon (GtkIconTheme       *icon_theme,
       for (l = priv->themes; l; l = l->next)
         {
           IconTheme *theme = l->data;
-          icon_info = theme_lookup_icon (theme, icon_names[0], size, allow_svg, use_builtin);
+          icon_info = theme_lookup_icon (theme, icon_names[0], size, scale, allow_svg, use_builtin);
           if (icon_info)
             goto out;
         }
@@ -1640,7 +1655,7 @@ choose_icon (GtkIconTheme       *icon_theme,
       
       for (i = 0; icon_names[i]; i++)
         {
-          icon_info = theme_lookup_icon (theme, icon_names[i], size, allow_svg, use_builtin);
+          icon_info = theme_lookup_icon (theme, icon_names[i], size, scale, allow_svg, use_builtin);
           if (icon_info)
             goto out;
         }
@@ -1674,6 +1689,7 @@ choose_icon (GtkIconTheme       *icon_theme,
 	  DestroyIcon (hIcon);
           icon_info->dir_type = ICON_THEME_DIR_UNTHEMED;
           icon_info->dir_size = size;
+          icon_info->dir_scale = 1;
 	}
       g_strfreev (resources);
     }
@@ -1698,16 +1714,19 @@ choose_icon (GtkIconTheme       *icon_theme,
 
       icon_info->dir_type = ICON_THEME_DIR_UNTHEMED;
       icon_info->dir_size = size;
+      icon_info->dir_scale = 1;
     }
 
  out:
   if (icon_info)
     {
       icon_info->desired_size = size;
+      icon_info->desired_scale = scale;
       icon_info->forced_size = (flags & GTK_ICON_LOOKUP_FORCE_SIZE) != 0;
 
       icon_info->key.icon_names = g_strdupv ((char **)icon_names);
       icon_info->key.size = size;
+      icon_info->key.scale = scale;
       icon_info->key.flags = flags;
       icon_info->in_cache = icon_theme;
       DEBUG_CACHE (("adding %p (%s %d 0x%x) to cache (cache size %d)\n",
@@ -1777,12 +1796,51 @@ gtk_icon_theme_lookup_icon (GtkIconTheme       *icon_theme,
 			    gint                size,
 			    GtkIconLookupFlags  flags)
 {
+  g_return_val_if_fail (GTK_IS_ICON_THEME (icon_theme), NULL);
+  g_return_val_if_fail (icon_name != NULL, NULL);
+  g_return_val_if_fail ((flags & GTK_ICON_LOOKUP_NO_SVG) == 0 ||
+			(flags & GTK_ICON_LOOKUP_FORCE_SVG) == 0, NULL);
+
+  GTK_NOTE (ICONTHEME, 
+	    g_print ("gtk_icon_theme_lookup_icon %s\n", icon_name));
+
+  return gtk_icon_theme_lookup_icon_for_scale (icon_theme, icon_name,
+                                               size, 1, flags);
+}
+
+/**
+ * gtk_icon_theme_lookup_icon_for_scale:
+ * @icon_theme: a #GtkIconTheme
+ * @icon_name: the name of the icon to lookup
+ * @size: desired icon size
+ * @scale: the desired scale
+ * @flags: flags modifying the behavior of the icon lookup
+ *
+ * Looks up a named icon for a particular window scale and returns a
+ * structure containing information such as the filename of the
+ * icon. The icon can then be rendered into a pixbuf using
+ * gtk_icon_info_load_icon(). (gtk_icon_theme_load_icon() combines
+ * these two steps if all you need is the pixbuf.)
+ *
+ * Return value: (transfer full): a #GtkIconInfo object containing
+ * information about the icon, or %NULL if the icon wasn't found.
+ *
+ * Since: 3.10
+ */
+GtkIconInfo *
+gtk_icon_theme_lookup_icon_for_scale (GtkIconTheme       *icon_theme,
+                                      const gchar        *icon_name,
+                                      gint                size,
+                                      gint                scale,
+                                      GtkIconLookupFlags  flags)
+{
   GtkIconInfo *info;
 
   g_return_val_if_fail (GTK_IS_ICON_THEME (icon_theme), NULL);
   g_return_val_if_fail (icon_name != NULL, NULL);
   g_return_val_if_fail ((flags & GTK_ICON_LOOKUP_NO_SVG) == 0 ||
 			(flags & GTK_ICON_LOOKUP_FORCE_SVG) == 0, NULL);
+  g_return_val_if_fail (scale >= 1, NULL);
 
   GTK_NOTE (ICONTHEME, 
 	    g_print ("gtk_icon_theme_lookup_icon %s\n", icon_name));
@@ -1808,7 +1866,7 @@ gtk_icon_theme_lookup_icon (GtkIconTheme       *icon_theme,
         }
       names[dashes + 1] = NULL;
    
-      info = choose_icon (icon_theme, (const gchar **) names, size, flags);
+      info = choose_icon (icon_theme, (const gchar **) names, size, scale, flags);
       
       g_strfreev (names);
     }
@@ -1819,7 +1877,7 @@ gtk_icon_theme_lookup_icon (GtkIconTheme       *icon_theme,
       names[0] = icon_name;
       names[1] = NULL;
 
-      info = choose_icon (icon_theme, names, size, flags);
+      info = choose_icon (icon_theme, names, size, scale, flags);
     }
 
   return info;
@@ -1859,9 +1917,50 @@ gtk_icon_theme_choose_icon (GtkIconTheme       *icon_theme,
   g_return_val_if_fail ((flags & GTK_ICON_LOOKUP_NO_SVG) == 0 ||
 			(flags & GTK_ICON_LOOKUP_FORCE_SVG) == 0, NULL);
 
-  return choose_icon (icon_theme, icon_names, size, flags);
+  return choose_icon (icon_theme, icon_names, size, 1, flags);
 }
 
+/**
+ * gtk_icon_theme_choose_icon_for_scale:
+ * @icon_theme: a #GtkIconTheme
+ * @icon_names: (array zero-terminated=1): %NULL-terminated array of
+ *     icon names to lookup
+ * @size: desired icon size
+ * @scale: desired scale
+ * @flags: flags modifying the behavior of the icon lookup
+ * 
+ * Looks up a named icon for a particular window scale and returns a
+ * structure containing information such as the filename of the
+ * icon. The icon can then be rendered into a pixbuf using
+ * gtk_icon_info_load_icon(). (gtk_icon_theme_load_icon() combines
+ * these two steps if all you need is the pixbuf.)
+ *
+ * If @icon_names contains more than one name, this function 
+ * tries them all in the given order before falling back to 
+ * inherited icon themes.
+ * 
+ * Return value: (transfer full): a #GtkIconInfo object containing information
+ * about the icon, or %NULL if the icon wasn't found.
+ *
+ * Since: 3.10
+ */
+GtkIconInfo *
+gtk_icon_theme_choose_icon_for_scale (GtkIconTheme       *icon_theme,
+                                      const gchar        *icon_names[],
+                                      gint                size,
+                                      gint                scale,
+                                      GtkIconLookupFlags  flags)
+{
+  g_return_val_if_fail (GTK_IS_ICON_THEME (icon_theme), NULL);
+  g_return_val_if_fail (icon_names != NULL, NULL);
+  g_return_val_if_fail ((flags & GTK_ICON_LOOKUP_NO_SVG) == 0 ||
+			(flags & GTK_ICON_LOOKUP_FORCE_SVG) == 0, NULL);
+  g_return_val_if_fail (scale >= 1, NULL);
+
+  return choose_icon (icon_theme, icon_names, size, scale, flags);
+}
+
+
 /* Error quark */
 GQuark
 gtk_icon_theme_error_quark (void)
@@ -1906,6 +2005,56 @@ gtk_icon_theme_load_icon (GtkIconTheme         *icon_theme,
 			  GtkIconLookupFlags    flags,
 			  GError              **error)
 {
+  g_return_val_if_fail (GTK_IS_ICON_THEME (icon_theme), NULL);
+  g_return_val_if_fail (icon_name != NULL, NULL);
+  g_return_val_if_fail ((flags & GTK_ICON_LOOKUP_NO_SVG) == 0 ||
+			(flags & GTK_ICON_LOOKUP_FORCE_SVG) == 0, NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  return gtk_icon_theme_load_icon_for_scale (icon_theme, icon_name,
+                                             size, 1, flags, error);
+}
+
+/**
+ * gtk_icon_theme_load_icon_for_scale:
+ * @icon_theme: a #GtkIconTheme
+ * @icon_name: the name of the icon to lookup
+ * @size: the desired icon size. The resulting icon may not be
+ *     exactly this size; see gtk_icon_info_load_icon().
+ * @scale: desired scale
+ * @flags: flags modifying the behavior of the icon lookup
+ * @error: (allow-none): Location to store error information on failure,
+ *     or %NULL.
+ *
+ * Looks up an icon in an icon theme for a particular window scale,
+ * scales it to the given size and renders it into a pixbuf. This is a
+ * convenience function; if more details about the icon are needed,
+ * use gtk_icon_theme_lookup_icon() followed by
+ * gtk_icon_info_load_icon().
+ *
+ * Note that you probably want to listen for icon theme changes and
+ * update the icon. This is usually done by connecting to the
+ * GtkWidget::style-set signal. If for some reason you do not want to
+ * update the icon when the icon theme changes, you should consider
+ * using gdk_pixbuf_copy() to make a private copy of the pixbuf
+ * returned by this function. Otherwise GTK+ may need to keep the old
+ * icon theme loaded, which would be a waste of memory.
+ *
+ * Return value: (transfer full): the rendered icon; this may be a
+ *     newly created icon or a new reference to an internal icon, so
+ *     you must not modify the icon. Use g_object_unref() to release
+ *     your reference to the icon. %NULL if the icon isn't found.
+ *
+ * Since: 3.10
+ **/
+GdkPixbuf *
+gtk_icon_theme_load_icon_for_scale (GtkIconTheme        *icon_theme,
+                                    const gchar         *icon_name,
+                                    gint                 size,
+                                    gint                 scale,
+                                    GtkIconLookupFlags   flags,
+                                    GError             **error)
+{
   GtkIconInfo *icon_info;
   GdkPixbuf *pixbuf = NULL;
   
@@ -1914,9 +2063,10 @@ gtk_icon_theme_load_icon (GtkIconTheme         *icon_theme,
   g_return_val_if_fail ((flags & GTK_ICON_LOOKUP_NO_SVG) == 0 ||
 			(flags & GTK_ICON_LOOKUP_FORCE_SVG) == 0, NULL);
   g_return_val_if_fail (error == NULL || *error == NULL, NULL);
-  
-  icon_info = gtk_icon_theme_lookup_icon (icon_theme, icon_name, size,
-				          flags | GTK_ICON_LOOKUP_USE_BUILTIN);
+  g_return_val_if_fail (scale >= 1, NULL);
+
+  icon_info = gtk_icon_theme_lookup_icon_for_scale (icon_theme, icon_name, size, scale,
+                                                    flags | GTK_ICON_LOOKUP_USE_BUILTIN);
   if (!icon_info)
     {
       g_set_error (error, GTK_ICON_THEME_ERROR,  GTK_ICON_THEME_NOT_FOUND,
@@ -2352,31 +2502,35 @@ theme_dir_destroy (IconThemeDir *dir)
 }
 
 static int
-theme_dir_size_difference (IconThemeDir *dir, int size, gboolean *smaller)
+theme_dir_size_difference (IconThemeDir *dir,
+                           int           size,
+                           gint          scale)
 {
+  int scaled_size, scaled_dir_size;
   int min, max;
+
+  scaled_size = size * scale;
+  scaled_dir_size = dir->size * dir->scale;
+
   switch (dir->type)
     {
     case ICON_THEME_DIR_FIXED:
-      *smaller = size < dir->size;
-      return abs (size - dir->size);
+      return abs (scaled_size - scaled_dir_size);
       break;
     case ICON_THEME_DIR_SCALABLE:
-      *smaller = size < dir->min_size;
-      if (size < dir->min_size)
-	return dir->min_size - size;
-      if (size > dir->max_size)
-	return size - dir->max_size;
+      if (scaled_size < (dir->min_size * dir->scale))
+	return (dir->min_size * dir->scale) - scaled_size;
+      if (size > (dir->max_size * dir->scale))
+	return scaled_size - (dir->max_size * dir->scale);
       return 0;
       break;
     case ICON_THEME_DIR_THRESHOLD:
-      min = dir->size - dir->threshold;
-      max = dir->size + dir->threshold;
-      *smaller = size < min;
-      if (size < min)
-	return min - size;
-      if (size > max)
-	return size - max;
+      min = (dir->size - dir->threshold) * dir->scale;
+      max = (dir->size + dir->threshold) * dir->scale;
+      if (scaled_size < min)
+	return min - scaled_size;
+      if (scaled_size > max)
+	return scaled_size - max;
       return 0;
       break;
     case ICON_THEME_DIR_UNTHEMED:
@@ -2463,10 +2617,75 @@ theme_dir_get_icon_suffix (IconThemeDir *dir,
   return suffix;
 }
 
+/* returns TRUE if dir_a is a better match */
+static gboolean
+compare_dir_matches (IconThemeDir *dir_a, int difference_a,
+		     IconThemeDir *dir_b, int difference_b, 
+		     int requested_size, int requested_scale)
+{
+  int diff_a;
+  int diff_b;
+
+  if (difference_a == 0)
+    {
+      if (difference_b != 0)
+	return TRUE;
+      
+      /* a and b both exact matches */
+    }
+  else
+    {
+      /* If scaling, *always* prefer downscaling */
+      if (dir_a->size >= requested_size &&
+	  dir_b->size < requested_size)
+	return TRUE;
+
+      if (dir_a->size < requested_size &&
+	  dir_b->size >= requested_size)
+	return FALSE;
+ 
+      /* Otherwise prefer the closest match */
+
+      if (difference_a < difference_b)
+	return TRUE;
+
+      if (difference_a > difference_b)
+	return FALSE;
+
+      /* same pixel difference */
+    }
+
+  if (dir_a->scale == requested_scale &&
+      dir_b->scale != requested_scale)
+    return TRUE;
+
+  if (dir_a->scale != requested_scale &&
+      dir_b->scale == requested_scale)
+    return FALSE;
+
+  /* a and b both match the scale */
+
+  if (dir_a->type != ICON_THEME_DIR_SCALABLE &&
+      dir_b->type == ICON_THEME_DIR_SCALABLE)
+    return TRUE;
+
+  if (dir_a->type == ICON_THEME_DIR_SCALABLE &&
+      dir_b->type != ICON_THEME_DIR_SCALABLE)
+    return FALSE;
+      
+  /* a and b both are scalable */
+
+  diff_a = abs (requested_size * requested_scale - dir_a->size * dir_a->scale);
+  diff_b = abs (requested_size * requested_scale - dir_b->size * dir_b->scale);
+
+  return diff_a <= diff_b;
+}
+
 static GtkIconInfo *
 theme_lookup_icon (IconTheme          *theme,
 		   const char         *icon_name,
 		   int                 size,
+                   gint                scale,
 		   gboolean            allow_svg,
 		   gboolean            use_builtin)
 {
@@ -2475,13 +2694,10 @@ theme_lookup_icon (IconTheme          *theme,
   char *file;
   int min_difference, difference;
   BuiltinIcon *closest_builtin = NULL;
-  gboolean smaller, has_larger, match;
   IconSuffix suffix;
 
   min_difference = G_MAXINT;
   min_dir = NULL;
-  has_larger = FALSE;
-  match = FALSE;
 
   /* Builtin icons are logically part of the default theme and
    * are searched before other subdirectories of the default theme.
@@ -2489,9 +2705,8 @@ theme_lookup_icon (IconTheme          *theme,
   if (use_builtin && strcmp (theme->name, DEFAULT_THEME_NAME) == 0)
     {
       closest_builtin = find_builtin_icon (icon_name, 
-					   size,
-					   &min_difference,
-					   &has_larger);
+					   size, scale,
+					   &min_difference);
 
       if (min_difference == 0)
 	return icon_info_new_builtin (closest_builtin);
@@ -2511,57 +2726,14 @@ theme_lookup_icon (IconTheme          *theme,
       suffix = theme_dir_get_icon_suffix (dir, icon_name, NULL);
       if (best_suffix (suffix, allow_svg) != ICON_SUFFIX_NONE)
 	{
-	  difference = theme_dir_size_difference (dir, size, &smaller);
-
-	  if (difference == 0)
+	  difference = theme_dir_size_difference (dir, size, scale);
+	  if (min_dir == NULL ||
+	      compare_dir_matches (dir, difference,
+				   min_dir, min_difference,
+				   size, scale))
 	    {
-              if (dir->type == ICON_THEME_DIR_SCALABLE)
-                {
-                  /* don't pick scalable if we already found
-                   * a matching non-scalable dir
-                   */
-                  if (!match)
-                    {
-	              min_dir = dir;
-	              break;
-                    }
-                }
-              else
-                {
-                  /* for a matching non-scalable dir keep
-                   * going and look for a closer match
-                   */             
-                  difference = abs (size - dir->size);
-                  if (!match || difference < min_difference)
-                    {
-                      match = TRUE;
-                      min_difference = difference;
-	              min_dir = dir;
-                    }
-                  if (difference == 0)
-                    break;
-                }
-	    } 
-  
-          if (!match)
-            {
-	      if (!has_larger)
-	        {
-	          if (difference < min_difference || smaller)
-	  	    {
-		      min_difference = difference;
-		      min_dir = dir;
-		      has_larger = smaller;
-	 	    }
-	        }
-	      else
-	        {
-	          if (difference < min_difference && smaller)
-		    {
-		      min_difference = difference;
-		      min_dir = dir;
-		    }
-	        }
+	      min_dir = dir;
+	      min_difference = difference;
 	    }
         }
 
@@ -2640,6 +2812,7 @@ theme_lookup_icon (IconTheme          *theme,
 
       icon_info->dir_type = min_dir->type;
       icon_info->dir_size = min_dir->size;
+      icon_info->dir_scale = min_dir->scale;
       icon_info->threshold = min_dir->threshold;
       
       return icon_info;
@@ -2858,6 +3031,7 @@ theme_subdir_load (GtkIconTheme *icon_theme,
   char *full_dir;
   GError *error = NULL;
   IconThemeDirMtime *dir_mtime;
+  int scale;
 
   size = g_key_file_get_integer (theme_file, subdir, "Size", &error);
   if (error)
@@ -2905,6 +3079,11 @@ theme_subdir_load (GtkIconTheme *icon_theme,
   else
     threshold = 2;
 
+  if (g_key_file_has_key (theme_file, subdir, "OutputScale", NULL))
+    scale = g_key_file_get_integer (theme_file, subdir, "OutputScale", NULL);
+  else
+    scale = 1;
+
   for (d = icon_theme->priv->dir_mtimes; d; d = d->next)
     {
       dir_mtime = (IconThemeDirMtime *)d->data;
@@ -2933,6 +3112,8 @@ theme_subdir_load (GtkIconTheme *icon_theme,
 	  dir->dir = full_dir;
 	  dir->icon_data = NULL;
 	  dir->subdir = g_strdup (subdir);
+          dir->scale = scale;
+
 	  if (dir_mtime->cache != NULL)
             {
 	      dir->cache = _gtk_icon_cache_ref (dir_mtime->cache);
@@ -3048,8 +3229,10 @@ icon_info_dup (GtkIconInfo *icon_info)
   dup->data = icon_data_dup (icon_info->data);
   dup->dir_type = icon_info->dir_type;
   dup->dir_size = icon_info->dir_size;
+  dup->dir_scale = icon_info->dir_scale;
   dup->threshold = icon_info->threshold;
   dup->desired_size = icon_info->desired_size;
+  dup->desired_scale = icon_info->desired_scale;
   dup->raw_coordinates = icon_info->raw_coordinates;
   dup->forced_size = icon_info->forced_size;
   dup->emblems_applied = icon_info->emblems_applied;
@@ -3065,6 +3248,7 @@ icon_info_new_builtin (BuiltinIcon *icon)
   icon_info->cache_pixbuf = g_object_ref (icon->pixbuf);
   icon_info->dir_type = ICON_THEME_DIR_THRESHOLD;
   icon_info->dir_size = icon->size;
+  icon_info->dir_scale = 1;
   icon_info->threshold = 2;
 
   return icon_info;
@@ -3158,7 +3342,10 @@ gtk_icon_info_class_init (GtkIconInfoClass *klass)
  * to a larger icon. These icons will be given
  * the same base size as the larger icons to which
  * they are attached.
- * 
+ *
+ * Note that for scaled icons the base size does
+ * not include the base scale.
+ *
  * Return value: the base size, or 0, if no base
  *  size is known for the icon.
  *
@@ -3173,6 +3360,27 @@ gtk_icon_info_get_base_size (GtkIconInfo *icon_info)
 }
 
 /**
+ * gtk_icon_info_get_base_scale:
+ * @icon_info: a #GtkIconInfo
+ *
+ * Gets the base scale for the icon. The base scale is a scale for the
+ * icon that was specified by the icon theme creator. For instance an
+ * icon drawn for a high-dpi screen with window-scale 2 for a base
+ * size of 32 will be 64 pixels tall and have a base_scale of 2.
+ *
+ * Return value: the base scale.
+ *
+ * Since: 3.10
+ **/
+gint
+gtk_icon_info_get_base_scale (GtkIconInfo *icon_info)
+{
+  g_return_val_if_fail (icon_info != NULL, 0);
+
+  return icon_info->dir_scale;
+}
+
+/**
  * gtk_icon_info_get_filename:
  * @icon_info: a #GtkIconInfo
  * 
@@ -3332,6 +3540,7 @@ icon_info_ensure_scale_and_pixbuf (GtkIconInfo  *icon_info,
 				   gboolean      scale_only)
 {
   int image_width, image_height;
+  int scaled_desired_size;
   GdkPixbuf *source_pixbuf;
   gboolean is_svg;
 
@@ -3356,6 +3565,8 @@ icon_info_ensure_scale_and_pixbuf (GtkIconInfo  *icon_info,
   if (icon_info->icon_file && !icon_info->loadable)
     icon_info->loadable = G_LOADABLE_ICON (g_file_icon_new (icon_info->icon_file));
 
+  scaled_desired_size = icon_info->desired_size * icon_info->desired_scale;
+
   is_svg = FALSE;
   if (G_IS_FILE_ICON (icon_info->loadable))
     {
@@ -3383,20 +3594,21 @@ icon_info_ensure_scale_and_pixbuf (GtkIconInfo  *icon_info,
     {
       GInputStream *stream;
 
-      icon_info->scale = icon_info->desired_size / 1000.;
+      icon_info->scale = scaled_desired_size / 1000.;
 
       if (scale_only)
 	return TRUE;
-      
+
+      /* TODO: We should have a load_at_scale */
       stream = g_loadable_icon_load (icon_info->loadable,
-                                     icon_info->desired_size,
+                                     scaled_desired_size,
                                      NULL, NULL,
                                      &icon_info->load_error);
       if (stream)
         {
           icon_info->pixbuf = gdk_pixbuf_new_from_stream_at_scale (stream,
-                                                                   icon_info->desired_size,
-                                                                   icon_info->desired_size,
+                                                                   scaled_desired_size,
+                                                                   scaled_desired_size,
                                                                    TRUE,
                                                                    NULL,
                                                                    &icon_info->load_error);
@@ -3419,19 +3631,19 @@ icon_info_ensure_scale_and_pixbuf (GtkIconInfo  *icon_info,
   if (icon_info->forced_size)
     icon_info->scale = -1;
   else if (icon_info->dir_type == ICON_THEME_DIR_FIXED)
-    icon_info->scale = 1.0;
+    icon_info->scale = round((gdouble) scaled_desired_size / (icon_info->dir_size * icon_info->dir_scale));
   else if (icon_info->dir_type == ICON_THEME_DIR_THRESHOLD)
     {
-      if (icon_info->desired_size >= icon_info->dir_size - icon_info->threshold &&
-	  icon_info->desired_size <= icon_info->dir_size + icon_info->threshold)
-	icon_info->scale = 1.0;
+      if (scaled_desired_size  >= (icon_info->dir_size - icon_info->threshold) * icon_info->dir_scale &&
+	  scaled_desired_size <= (icon_info->dir_size + icon_info->threshold) * icon_info->dir_scale)
+	icon_info->scale = round((gdouble) scaled_desired_size / (icon_info->dir_size * icon_info->dir_scale));
       else if (icon_info->dir_size > 0)
-	icon_info->scale =(gdouble) icon_info->desired_size / icon_info->dir_size;
+	icon_info->scale =(gdouble) scaled_desired_size / (icon_info->dir_size * icon_info->dir_scale);
     }
   else if (icon_info->dir_type == ICON_THEME_DIR_SCALABLE)
     {
       if (icon_info->dir_size > 0)
-	icon_info->scale = (gdouble) icon_info->desired_size / icon_info->dir_size;
+	icon_info->scale = (gdouble) scaled_desired_size / (icon_info->dir_size * icon_info->dir_scale);
     }
 
   if (icon_info->scale >= 0. && scale_only)
@@ -3447,8 +3659,9 @@ icon_info_ensure_scale_and_pixbuf (GtkIconInfo  *icon_info,
     {
       GInputStream *stream;
 
+      /* TODO: We should have a load_at_scale */
       stream = g_loadable_icon_load (icon_info->loadable,
-                                     icon_info->desired_size,
+                                     scaled_desired_size,
                                      NULL, NULL,
                                      &icon_info->load_error);
       if (stream)
@@ -3472,7 +3685,7 @@ icon_info_ensure_scale_and_pixbuf (GtkIconInfo  *icon_info,
     {
       gint image_size = MAX (image_width, image_height);
       if (image_size > 0)
-	icon_info->scale = (gdouble)icon_info->desired_size / (gdouble)image_size;
+	icon_info->scale = (gdouble)scaled_desired_size / (gdouble)image_size;
       else
 	icon_info->scale = 1.0;
       
@@ -3887,8 +4100,8 @@ _gtk_icon_info_load_symbolic_internal (GtkIconInfo  *icon_info,
 
   stream = g_memory_input_stream_new_from_data (data, -1, g_free);
   pixbuf = gdk_pixbuf_new_from_stream_at_scale (stream,
-                                                icon_info->desired_size,
-                                                icon_info->desired_size,
+                                                icon_info->desired_size * icon_info->desired_scale,
+                                                icon_info->desired_size * icon_info->desired_scale,
                                                 TRUE,
                                                 NULL,
                                                 error);
@@ -4740,8 +4953,8 @@ gtk_icon_theme_add_builtin_icon (const gchar *icon_name,
 static BuiltinIcon *
 find_builtin_icon (const gchar *icon_name,
 		   gint         size,
-		   gint        *min_difference_p,
-		   gboolean    *has_larger_p)
+		   gint         scale,
+		   gint        *min_difference_p)
 {
   GSList *icons = NULL;
   gint min_difference = G_MAXINT;
@@ -4751,6 +4964,8 @@ find_builtin_icon (const gchar *icon_name,
   if (!icon_theme_builtin_icons)
     return NULL;
 
+  size *= scale;
+
   icons = g_hash_table_lookup (icon_theme_builtin_icons, icon_name);
 
   while (icons)
@@ -4798,8 +5013,6 @@ find_builtin_icon (const gchar *icon_name,
 
   if (min_difference_p)
     *min_difference_p = min_difference;
-  if (has_larger_p)
-    *has_larger_p = has_larger;
 
   return min_icon;
 }
@@ -4828,6 +5041,37 @@ gtk_icon_theme_lookup_by_gicon (GtkIconTheme       *icon_theme,
                                 gint                size,
                                 GtkIconLookupFlags  flags)
 {
+  return gtk_icon_theme_lookup_by_gicon_for_scale (icon_theme, icon,
+                                                   size, 1, flags);
+}
+
+
+/**
+ * gtk_icon_theme_lookup_by_gicon_for_scale:
+ * @icon_theme: a #GtkIconTheme
+ * @icon: the #GIcon to look up
+ * @size: desired icon size
+ * @scale: the desired scale
+ * @flags: flags modifying the behavior of the icon lookup
+ *
+ * Looks up an icon and returns a structure containing
+ * information such as the filename of the icon.
+ * The icon can then be rendered into a pixbuf using
+ * gtk_icon_info_load_icon_for_scale ().
+ *
+ * Return value: (transfer full): a #GtkIconInfo structure containing 
+ *     information about the icon, or %NULL if the icon 
+ *     wasn't found. Unref with g_object_unref()
+ *
+ * Since: 2.14
+ */
+GtkIconInfo *
+gtk_icon_theme_lookup_by_gicon_for_scale (GtkIconTheme       *icon_theme,
+                                          GIcon              *icon,
+                                          gint                size,
+                                          gint                scale,
+                                          GtkIconLookupFlags  flags)
+{
   GtkIconInfo *info;
 
   g_return_val_if_fail (GTK_IS_ICON_THEME (icon_theme), NULL);
@@ -4851,6 +5095,7 @@ gtk_icon_theme_lookup_by_gicon (GtkIconTheme       *icon_theme,
       info->dir_type = ICON_THEME_DIR_UNTHEMED;
       info->dir_size = size;
       info->desired_size = size;
+      info->desired_scale = scale;
       info->threshold = 2;
       info->forced_size = (flags & GTK_ICON_LOOKUP_FORCE_SIZE) != 0;
 
@@ -4861,7 +5106,7 @@ gtk_icon_theme_lookup_by_gicon (GtkIconTheme       *icon_theme,
       const gchar **names;
 
       names = (const gchar **)g_themed_icon_get_names (G_THEMED_ICON (icon));
-      info = gtk_icon_theme_choose_icon (icon_theme, names, size, flags);
+      info = gtk_icon_theme_choose_icon_for_scale (icon_theme, names, size, scale, flags);
 
       return info;
     }
@@ -4875,7 +5120,7 @@ gtk_icon_theme_lookup_by_gicon (GtkIconTheme       *icon_theme,
         _gtk_numerable_icon_set_background_icon_size (GTK_NUMERABLE_ICON (icon), size / 2);
 
       base = g_emblemed_icon_get_icon (G_EMBLEMED_ICON (icon));
-      base_info = gtk_icon_theme_lookup_by_gicon (icon_theme, base, size, flags);
+      base_info = gtk_icon_theme_lookup_by_gicon_for_scale (icon_theme, base, size, scale, flags);
       if (base_info)
         {
           info = icon_info_dup (base_info);
@@ -4886,7 +5131,7 @@ gtk_icon_theme_lookup_by_gicon (GtkIconTheme       *icon_theme,
             {
               emblem = g_emblem_get_icon (G_EMBLEM (l->data));
 	      /* always force size for emblems */
-              emblem_info = gtk_icon_theme_lookup_by_gicon (icon_theme, emblem, size / 2, flags | GTK_ICON_LOOKUP_FORCE_SIZE);
+              emblem_info = gtk_icon_theme_lookup_by_gicon_for_scale (icon_theme, emblem, size / 2, scale, flags | GTK_ICON_LOOKUP_FORCE_SIZE);
               if (emblem_info)
                 info->emblem_infos = g_slist_prepend (info->emblem_infos, emblem_info);
             }
@@ -4905,17 +5150,17 @@ gtk_icon_theme_lookup_by_gicon (GtkIconTheme       *icon_theme,
       if ((flags & GTK_ICON_LOOKUP_FORCE_SIZE) != 0)
 	{
 	  gint width, height, max;
-	  gdouble scale;
+	  gdouble pixbuf_scale;
 	  GdkPixbuf *scaled;
 
 	  width = gdk_pixbuf_get_width (pixbuf);
 	  height = gdk_pixbuf_get_height (pixbuf);
 	  max = MAX (width, height);
-	  scale = (gdouble) size / (gdouble) max;
+	  pixbuf_scale = (gdouble) size * scale / (gdouble) max;
 
 	  scaled = gdk_pixbuf_scale_simple (pixbuf,
-					    0.5 + width * scale,
-					    0.5 + height * scale,
+					    0.5 + width * pixbuf_scale,
+					    0.5 + height * pixbuf_scale,
 					    GDK_INTERP_BILINEAR);
 
 	  info = gtk_icon_info_new_for_pixbuf (icon_theme, scaled);
diff --git a/gtk/gtkicontheme.h b/gtk/gtkicontheme.h
index 443457dbf3..0902909459 100644
--- a/gtk/gtkicontheme.h
+++ b/gtk/gtkicontheme.h
@@ -179,23 +179,49 @@ GtkIconInfo * gtk_icon_theme_lookup_icon           (GtkIconTheme
 						    const gchar                 *icon_name,
 						    gint                         size,
 						    GtkIconLookupFlags           flags);
+GDK_AVAILABLE_IN_3_10
+GtkIconInfo * gtk_icon_theme_lookup_icon_for_scale (GtkIconTheme                *icon_theme,
+                                                    const gchar                 *icon_name,
+                                                    gint                         size,
+                                                    gint                         scale,
+                                                    GtkIconLookupFlags           flags);
+
 GDK_AVAILABLE_IN_ALL
 GtkIconInfo * gtk_icon_theme_choose_icon           (GtkIconTheme                *icon_theme,
 						    const gchar                 *icon_names[],
 						    gint                         size,
 						    GtkIconLookupFlags           flags);
+GDK_AVAILABLE_IN_3_10
+GtkIconInfo * gtk_icon_theme_choose_icon_for_scale (GtkIconTheme                *icon_theme,
+						    const gchar                 *icon_names[],
+						    gint                         size,
+                                                    gint                         scale,
+						    GtkIconLookupFlags           flags);
 GDK_AVAILABLE_IN_ALL
 GdkPixbuf *   gtk_icon_theme_load_icon             (GtkIconTheme                *icon_theme,
 						    const gchar                 *icon_name,
 						    gint                         size,
 						    GtkIconLookupFlags           flags,
 						    GError                     **error);
+GDK_AVAILABLE_IN_3_10
+GdkPixbuf *   gtk_icon_theme_load_icon_for_scale   (GtkIconTheme                *icon_theme,
+                                                    const gchar                 *icon_name,
+                                                    gint                         size,
+                                                    gint                         scale,
+                                                    GtkIconLookupFlags           flags,
+                                                    GError                     **error);
 
 GDK_AVAILABLE_IN_ALL
 GtkIconInfo * gtk_icon_theme_lookup_by_gicon       (GtkIconTheme                *icon_theme,
                                                     GIcon                       *icon,
                                                     gint                         size,
                                                     GtkIconLookupFlags           flags);
+GtkIconInfo * gtk_icon_theme_lookup_by_gicon_for_scale (GtkIconTheme             *icon_theme,
+                                                        GIcon                    *icon,
+                                                        gint                      size,
+                                                        gint                      scale,
+                                                        GtkIconLookupFlags        flags);
+
 
 GDK_AVAILABLE_IN_ALL
 GList *       gtk_icon_theme_list_icons            (GtkIconTheme                *icon_theme,
@@ -226,6 +252,8 @@ GtkIconInfo *         gtk_icon_info_new_for_pixbuf     (GtkIconTheme  *icon_them
 
 GDK_AVAILABLE_IN_ALL
 gint                  gtk_icon_info_get_base_size      (GtkIconInfo   *icon_info);
+GDK_AVAILABLE_IN_3_10
+gint                  gtk_icon_info_get_base_scale     (GtkIconInfo   *icon_info);
 GDK_AVAILABLE_IN_ALL
 const gchar *         gtk_icon_info_get_filename       (GtkIconInfo   *icon_info);
 GDK_AVAILABLE_IN_ALL