Implement font-variation-settings

This is a CSS font level 4 property that lets us
use font variation settings from css.

docs/reference/gtk/css-properties.xml

@@ -322,6 +322,15 @@ We use <literallayout> for syntax productions, and each line is put in a <code>
               <entry><ulink url="https://www.w3.org/TR/css3-fonts/#font-feature-settings-prop">CSS3</ulink></entry>
               <entry></entry>
             </row>
+            <row>
+              <entry><phrase role="nowrap">font-variation-settings</phrase></entry>
+              <entry><code>normal | [ 〈string〉〈number〉]&num;</code></entry>
+              <entry>normal</entry>
+              <entry>✓</entry>
+              <entry>✓</entry>
+              <entry><ulink url="https://www.w3.org/TR/css-fonts-4/#font-variation-settings-def">CSS4</ulink></entry>
+              <entry></entry>
+            </row>
           </tbody>
         </tgroup>
         <tgroup cols="5">

gtk/gtkcssfontvariationsvalue.c

@@ -0,0 +1,294 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Matthias Clasen
+ */
+
+#include "config.h"
+
+#include "gtkcssparserprivate.h"
+#include "gtkcssnumbervalueprivate.h"
+#include "gtkcssfontvariationsvalueprivate.h"
+
+struct _GtkCssValue {
+  GTK_CSS_VALUE_BASE
+  GHashTable *axes;
+};
+
+static GtkCssValue *default_font_variations;
+
+static GtkCssValue *gtk_css_font_variations_value_new_empty (void);
+
+static void
+gtk_css_font_variations_value_add_axis (GtkCssValue *value,
+                                        const char  *name,
+                                        GtkCssValue *coord)
+{
+  g_hash_table_insert (value->axes, g_strdup (name), coord);
+}
+
+
+static void
+gtk_css_value_font_variations_free (GtkCssValue *value)
+{
+  g_hash_table_unref (value->axes);
+
+  g_slice_free (GtkCssValue, value);
+}
+
+static GtkCssValue *
+gtk_css_value_font_variations_compute (GtkCssValue      *specified,
+                                       guint             property_id,
+                                       GtkStyleProvider *provider,
+                                       GtkCssStyle      *style,
+                                       GtkCssStyle      *parent_style)
+{
+  GHashTableIter iter;
+  gpointer name, coord;
+  GtkCssValue *computed_coord;
+  GtkCssValue *result;
+  gboolean changes = FALSE;
+
+  result = gtk_css_font_variations_value_new_empty ();
+
+  g_hash_table_iter_init (&iter, specified->axes);
+  while (g_hash_table_iter_next (&iter, &name, &coord))
+    {
+      computed_coord = _gtk_css_value_compute (coord, property_id, provider, style, parent_style);
+      changes |= computed_coord != coord;
+      gtk_css_font_variations_value_add_axis (result, name, computed_coord);
+    }
+
+  if (!changes)
+    {
+      _gtk_css_value_unref (result);
+      result = _gtk_css_value_ref (specified);
+    }
+
+  return result;
+}
+
+static gboolean
+gtk_css_value_font_variations_equal (const GtkCssValue *value1,
+                                     const GtkCssValue *value2)
+{
+  gpointer name, coord1, coord2;
+  GHashTableIter iter;
+
+  if (g_hash_table_size (value1->axes) != g_hash_table_size (value2->axes))
+    return FALSE;
+
+  g_hash_table_iter_init (&iter, value1->axes);
+  while (g_hash_table_iter_next (&iter, &name, &coord1))
+    {
+      coord2 = g_hash_table_lookup (value2->axes, name);
+      if (coord2 == NULL)
+        return FALSE;
+
+      if (!_gtk_css_value_equal (coord1, coord2))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+static GtkCssValue *
+gtk_css_value_font_variations_transition (GtkCssValue *start,
+                                          GtkCssValue *end,
+                                          guint        property_id,
+                                          double       progress)
+{
+  const char *name;
+  GtkCssValue *start_coord, *end_coord;
+  GHashTableIter iter;
+  GtkCssValue *result, *transition;
+
+  /* XXX: For value that are only in start or end but not both,
+   * we don't transition but just keep the value.
+   * That causes an abrupt transition to the new value at the end.
+   */
+
+  result = gtk_css_font_variations_value_new_empty ();
+
+  g_hash_table_iter_init (&iter, start->axes);
+  while (g_hash_table_iter_next (&iter, (gpointer *)&name, (gpointer *)&start_coord))
+    {
+      end_coord = g_hash_table_lookup (end->axes, name);
+      if (end_coord == NULL)
+        transition = _gtk_css_value_ref (start_coord);
+      else
+        transition = _gtk_css_value_transition (start_coord, end_coord, property_id, progress);
+
+      gtk_css_font_variations_value_add_axis (result, name, transition);
+    }
+
+  g_hash_table_iter_init (&iter, end->axes);
+  while (g_hash_table_iter_next (&iter, (gpointer *)&name, (gpointer *)&end_coord))
+    {
+      start_coord = g_hash_table_lookup (start->axes, name);
+      if (start_coord != NULL)
+        continue;
+
+      gtk_css_font_variations_value_add_axis (result, name, _gtk_css_value_ref (end_coord));
+    }
+
+  return result;
+}
+
+static void
+gtk_css_value_font_variations_print (const GtkCssValue *value,
+                                     GString           *string)
+{
+  GHashTableIter iter;
+  const char *name;
+  GtkCssValue *coord;
+  gboolean first = TRUE;
+
+  if (value == default_font_variations)
+    {
+      g_string_append (string, "normal");
+      return;
+    }
+
+  g_hash_table_iter_init (&iter, value->axes);
+  while (g_hash_table_iter_next (&iter, (gpointer *)&name, (gpointer *)&coord))
+    {
+      if (first)
+        first = FALSE;
+      else
+        g_string_append (string, ", ");
+      g_string_append_printf (string, "\"%s\" ", name);
+      _gtk_css_value_print (coord, string);
+    }
+}
+
+static const GtkCssValueClass GTK_CSS_VALUE_FONT_VARIATIONS = {
+  gtk_css_value_font_variations_free,
+  gtk_css_value_font_variations_compute,
+  gtk_css_value_font_variations_equal,
+  gtk_css_value_font_variations_transition,
+  gtk_css_value_font_variations_print
+};
+
+static GtkCssValue *
+gtk_css_font_variations_value_new_empty (void)
+{
+  GtkCssValue *result;
+
+  result = _gtk_css_value_new (GtkCssValue, &GTK_CSS_VALUE_FONT_VARIATIONS);
+  result->axes = g_hash_table_new_full (g_str_hash, g_str_equal,
+                                        g_free,
+                                        (GDestroyNotify) _gtk_css_value_unref);
+
+  return result;
+}
+
+GtkCssValue *
+gtk_css_font_variations_value_new_default (void)
+{
+  if (default_font_variations == NULL)
+    default_font_variations = gtk_css_font_variations_value_new_empty ();
+
+  return _gtk_css_value_ref (default_font_variations);
+}
+
+static gboolean
+is_valid_opentype_tag (const char *s)
+{
+  if (strlen (s) != 4)
+    return FALSE;
+
+  if (s[0] < 0x20 || s[0] > 0x7e ||
+      s[1] < 0x20 || s[1] > 0x7e ||
+      s[2] < 0x20 || s[2] > 0x7e ||
+      s[3] < 0x20 || s[3] > 0x7e)
+    return FALSE;
+
+  return TRUE;
+}
+
+GtkCssValue *
+gtk_css_font_variations_value_parse (GtkCssParser *parser)
+{
+  GtkCssValue *result, *coord;
+  char *name;
+
+  if (_gtk_css_parser_try (parser, "normal", TRUE))
+    return gtk_css_font_variations_value_new_default ();
+
+  result = gtk_css_font_variations_value_new_empty ();
+
+  do {
+    _gtk_css_parser_skip_whitespace (parser);
+    name = _gtk_css_parser_read_string (parser);
+    if (name == NULL)
+      {
+        _gtk_css_value_unref (result);
+        return NULL;
+      }
+
+    if (!is_valid_opentype_tag (name))
+      {
+        _gtk_css_parser_error (parser, "Not a valid OpenType tag.");
+        g_free (name);
+        _gtk_css_value_unref (result);
+        return NULL;
+      }
+
+    coord = _gtk_css_number_value_parse (parser, GTK_CSS_PARSE_NUMBER);
+    if (coord == NULL)
+      {
+        g_free (name);
+        _gtk_css_value_unref (result);
+        return NULL;
+      }
+
+    gtk_css_font_variations_value_add_axis (result, name, coord);
+    g_free (name);
+  } while (_gtk_css_parser_try (parser, ",", TRUE));
+
+  return result;
+}
+
+char *
+gtk_css_font_variations_value_get_variations (GtkCssValue *value)
+{
+  GtkCssValue *coord;
+  GHashTableIter iter;
+  gboolean first = TRUE;
+  const char *name;
+  GString *string;
+
+  g_return_val_if_fail (value->class == &GTK_CSS_VALUE_FONT_VARIATIONS, NULL);
+
+  if (value == default_font_variations)
+    return NULL;
+
+  string = g_string_new ("");
+
+  g_hash_table_iter_init (&iter, value->axes);
+  while (g_hash_table_iter_next (&iter, (gpointer *)&name, (gpointer *)&coord))
+    {
+      if (first)
+        first = FALSE;
+      else
+        g_string_append (string, ",");
+      g_string_append_printf (string, "%s=%g", name,
+                              _gtk_css_number_value_get (coord, 100));
+    }
+
+  return g_string_free (string, FALSE);
+}

gtk/gtkcssfontvariationsvalueprivate.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright © 2017 Red Hat Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#ifndef __GTK_CSS_FONT_VARIATIONS_VALUE_PRIVATE_H__
+#define __GTK_CSS_FONT_VARIATIONS_PRIVATE_H__
+
+#include "gtkcssparserprivate.h"
+#include "gtkcssvalueprivate.h"
+
+G_BEGIN_DECLS
+
+GtkCssValue *   gtk_css_font_variations_value_new_default    (void);
+
+GtkCssValue *   gtk_css_font_variations_value_parse          (GtkCssParser *parser);
+
+char *          gtk_css_font_variations_value_get_variations (GtkCssValue  *value);
+
+G_END_DECLS
+
+#endif /* __GTK_CSS_FONT_VARIATIONS_VALUE_PRIVATE_H__ */

gtk/gtkcssstylepropertyimpl.c

@@ -59,6 +59,7 @@
 #include "gtkcssshadowsvalueprivate.h"
 #include "gtkcssstringvalueprivate.h"
 #include "gtkcsstransformvalueprivate.h"
+#include "gtkcssfontvariationsvalueprivate.h"
 #include "gtktypebuiltins.h"
 
 /*** REGISTRATION ***/
@@ -664,6 +665,13 @@ parse_font_feature_settings (GtkCssStyleProperty *property,
   return gtk_css_font_features_value_parse (parser);
 }
 
+static GtkCssValue *
+parse_font_variation_settings (GtkCssStyleProperty *property,
+                               GtkCssParser        *parser)
+{
+  return gtk_css_font_variations_value_parse (parser);
+}
+
 static GtkCssValue *
 box_shadow_value_parse (GtkCssStyleProperty *property,
                         GtkCssParser        *parser)
@@ -1816,4 +1824,12 @@ _gtk_css_style_property_init_properties (void)
                                           parse_font_feature_settings,
                                           NULL,
                                           gtk_css_font_features_value_new_default ());
+  gtk_css_style_property_register        ("font-variation-settings",
+                                          GTK_CSS_PROPERTY_FONT_VARIATION_SETTINGS,
+                                          G_TYPE_NONE,
+                                          GTK_STYLE_PROPERTY_INHERIT | GTK_STYLE_PROPERTY_ANIMATED,
+                                          GTK_CSS_AFFECTS_TEXT_ATTRS | GTK_CSS_AFFECTS_TEXT_SIZE,
+                                          parse_font_variation_settings,
+                                          NULL,
+                                          gtk_css_font_variations_value_new_default ());
 }

gtk/gtkcsstypesprivate.h

@@ -245,6 +245,7 @@ enum { /*< skip >*/
   GTK_CSS_PROPERTY_CARET_COLOR,
   GTK_CSS_PROPERTY_SECONDARY_CARET_COLOR,
   GTK_CSS_PROPERTY_FONT_FEATURE_SETTINGS,
+  GTK_CSS_PROPERTY_FONT_VARIATION_SETTINGS,
   /* add more */
   GTK_CSS_PROPERTY_N_PROPERTIES
 };

gtk/gtkwidget.c

@@ -76,6 +76,7 @@
 #include "gtkdebugupdatesprivate.h"
 #include "gsk/gskdebugprivate.h"
 #include "gtkeventcontrollerlegacyprivate.h"
+#include "gtkcssfontvariationsvalueprivate.h"
 
 #include "inspector/window.h"
 
@@ -8580,15 +8581,23 @@ update_pango_context (GtkWidget    *widget,
   GtkStyleContext *style_context;
   GtkSettings *settings;
   cairo_font_options_t *font_options;
+  GtkCssValue *value;
+  char *variations;
 
   style_context = _gtk_widget_get_style_context (widget);
   gtk_style_context_get (style_context,
                          "font", &font_desc,
                          NULL);
 
+  value = _gtk_style_context_peek_property (_gtk_widget_get_style_context (widget), GTK_CSS_PROPERTY_FONT_VARIATION_SETTINGS);
+  variations = gtk_css_font_variations_value_get_variations (value);
+
+  pango_font_description_set_variations (font_desc, variations);
+
   pango_context_set_font_description (context, font_desc);
 
   pango_font_description_free (font_desc);
+  g_free (variations);
 
   pango_context_set_base_dir (context,
 			      _gtk_widget_get_direction (widget) == GTK_TEXT_DIR_LTR ?

gtk/meson.build

@@ -88,6 +88,7 @@ gtk_public_sources = files([
   'gtkcssenumvalue.c',
   'gtkcssfiltervalue.c',
   'gtkcssfontfeaturesvalue.c',
+  'gtkcssfontvariationsvalue.c',
   'gtkcssiconthemevalue.c',
   'gtkcssimage.c',
   'gtkcssimagebuiltin.c',