gsk: Allow custom fonts in node files

This will let us store complete test fonts inside node files,
as data: urls. You can also use a file: url to refer to a local
file.

The syntax is as follows:

text {
  font: "FONT DESCRIPTION" url("data:font/ttf;base64,FONT DATA");
}

with the url being optional.

demos/node-editor/node-format.md

@@ -323,14 +323,22 @@ stroke bounds of the path.
 ### text
 
 | property | syntax              | default             | printed     |
-| -------- | ---------------- | ---------------------- | ----------- |
+| -------- | ------------------- | ------------------- | ----------- |
 | color    | `<color>`           | black               | non-default |
-| font     | `<string>`       | "Cantarell 11"         | always      |
+| font     | `<string>` `<url>`? | "Cantarell 11"      | always      |
 | glyphs   | `<glyphs>`          | "Hello"             | always      |
 | offset   | `<point>`           | 0 0                 | non-default |
 
 Creates a node like `gsk_text_node_new()` with the given properties.
 
+If a url is specified for the font, it must point to a font file for the
+font that is specified in the string. It can be either a data url containing
+a base64-encoded font file, or a regular url that points to a font file.
+
+Glyphs can be specified as an ASCII string, or as a comma-separated list of
+their glyph ID and advance width. Optionally, x and y offsets and flags can
+be specified as well, like this: 40 10 0 0 color.
+
 If the given font does not exist or the given glyphs are invalid for the given
 font, an error node will be returned.
 

gsk/gskrendernodeparser.c

@@ -46,12 +46,20 @@
 #include <cairo-script-interpreter.h>
 #endif
 
+#include <pango/pangocairo.h>
+#ifdef HAVE_PANGOFT
+#include <pango/pangofc-fontmap.h>
+#endif
+
+#include <glib/gstdio.h>
+
 typedef struct _Context Context;
 
 struct _Context
 {
   GHashTable *named_nodes;
   GHashTable *named_textures;
+  PangoFontMap *fontmap;
 };
 
 typedef struct _Declaration Declaration;
@@ -75,6 +83,7 @@ context_finish (Context *context)
 {
   g_clear_pointer (&context->named_nodes, g_hash_table_unref);
   g_clear_pointer (&context->named_textures, g_hash_table_unref);
+  g_clear_object (&context->fontmap);
 }
 
 static gboolean
@@ -844,20 +853,35 @@ parse_mask_mode (GtkCssParser *parser,
 }
 
 static PangoFont *
-font_from_string (const char *string)
+font_from_string (PangoFontMap *fontmap,
+                  const char   *string)
 {
   PangoFontDescription *desc;
-  PangoFontMap *font_map;
-  PangoContext *context;
+  PangoContext *ctx;
   PangoFont *font;
 
   desc = pango_font_description_from_string (string);
-  font_map = pango_cairo_font_map_get_default ();
-  context = pango_font_map_create_context (font_map);
-  font = pango_font_map_load_font (font_map, context, desc);
+  ctx = pango_font_map_create_context (fontmap);
+  font = pango_font_map_load_font (fontmap, ctx, desc);
+  g_object_unref (ctx);
+
+  if (font)
+    {
+      PangoFontDescription *desc2;
+      const char *family, *family2;
+
+      desc2 = pango_font_describe (font);
+
+      family = pango_font_description_get_family (desc);
+      family2 = pango_font_description_get_family (desc2);
+
+      if (g_strcmp0 (family, family2) != 0)
+        g_clear_object (&font);
+
+      pango_font_description_free (desc2);
+    }
 
   pango_font_description_free (desc);
-  g_object_unref (context);
 
   return font;
 }
@@ -926,22 +950,204 @@ create_ascii_glyphs (PangoFont *font)
   return result;
 }
 
+#ifdef HAVE_PANGOFT
+
+static void
+delete_file (gpointer data)
+{
+  char *path = data;
+
+  g_remove (path);
+  g_free (path);
+}
+
+static void
+ensure_fontmap (Context *context)
+{
+  FcConfig *config;
+  GPtrArray *files;
+
+  if (context->fontmap)
+    return;
+
+  context->fontmap = pango_cairo_font_map_new ();
+
+  config = FcInitLoadConfig ();
+  pango_fc_font_map_set_config (PANGO_FC_FONT_MAP (context->fontmap), config);
+  FcConfigDestroy (config);
+
+  files = g_ptr_array_new_with_free_func (delete_file);
+
+  g_object_set_data_full (G_OBJECT (context->fontmap), "font-files", files, (GDestroyNotify) g_ptr_array_unref);
+}
+
+static void
+add_font_from_file (Context     *context,
+                    const char  *path,
+                    GError     **error)
+{
+  FcConfig *config;
+  GPtrArray *files;
+
+  ensure_fontmap (context);
+
+  if (!PANGO_IS_FC_FONT_MAP (context->fontmap))
+    {
+      g_set_error (error,
+                   GTK_CSS_PARSER_ERROR,
+                   GTK_CSS_PARSER_ERROR_FAILED,
+                   "Custom fonts are not implemented for %s", G_OBJECT_TYPE_NAME (context->fontmap));
+      return;
+    }
+
+  config = pango_fc_font_map_get_config (PANGO_FC_FONT_MAP (context->fontmap));
+
+  if (!FcConfigAppFontAddFile (config, (FcChar8 *) path))
+    {
+      g_set_error (error,
+                   GTK_CSS_PARSER_ERROR,
+                   GTK_CSS_PARSER_ERROR_FAILED,
+                   "Failed to add %s to FcConfig", path);
+      return;
+    }
+
+  files = (GPtrArray *) g_object_get_data (G_OBJECT (context->fontmap), "font-files");
+  g_ptr_array_add (files, g_strdup (path));
+
+  pango_fc_font_map_config_changed (PANGO_FC_FONT_MAP (context->fontmap));
+}
+
+static void
+add_font_from_bytes (Context  *context,
+                     GBytes   *bytes,
+                     GError  **error)
+{
+  GFile *file;
+  GIOStream *iostream;
+  GOutputStream *ostream;
+
+  file = g_file_new_tmp ("gtk4-font-XXXXXX.ttf", (GFileIOStream **) &iostream, error);
+  if (!file)
+    return;
+
+  ostream = g_io_stream_get_output_stream (iostream);
+  if (g_output_stream_write_bytes (ostream, bytes, NULL, error) == -1)
+    {
+      g_object_unref (file);
+      g_object_unref (iostream);
+
+      return;
+    }
+
+  g_io_stream_close (iostream, NULL, NULL);
+  g_object_unref (iostream);
+
+  add_font_from_file (context, g_file_peek_path (file), error);
+
+  g_object_unref (file);
+}
+
+#else /* !HAVE_PANGOFT */
+
+static void
+add_font_from_bytes (Context  *context,
+                     GBytes   *bytes,
+                     GError  **error)
+{
+  g_set_error (error,
+               GTK_CSS_PARSER_ERROR,
+               GTK_CSS_PARSER_ERROR_FAILED,
+               "Not implemented");
+}
+
+#endif
+
 static gboolean
 parse_font (GtkCssParser *parser,
             Context      *context,
             gpointer      out_font)
 {
-  PangoFont *font;
+  PangoFont *font = NULL;
   char *s;
+  GtkCssLocation start_location;
+  PangoFontMap *fontmap;
+
+  fontmap = pango_cairo_font_map_get_default ();
 
   s = gtk_css_parser_consume_string (parser);
   if (s == NULL)
     return FALSE;
 
-  font = font_from_string (s);
-  if (font == NULL)
+  start_location = *gtk_css_parser_get_start_location (parser);
+
+  if (gtk_css_parser_try_token (parser, GTK_CSS_TOKEN_URL) ||
+      gtk_css_parser_has_function (parser, "url"))
     {
-      gtk_css_parser_error_syntax (parser, "This font does not exist.");
+      char *url;
+      char *scheme;
+      GBytes *bytes = NULL;
+      GError *error = NULL;
+
+      /* If we have a url, it is a bug if the font already exists in our custom fontmap */
+      if (context->fontmap)
+        {
+          font = font_from_string (context->fontmap, s);
+          if (font)
+            {
+              g_object_unref (font);
+              gtk_css_parser_error_value (parser, "This font already exists.");
+              return FALSE;
+            }
+        }
+
+      url = gtk_css_parser_consume_url (parser);
+
+      scheme = g_uri_parse_scheme (url);
+      if (scheme && g_ascii_strcasecmp (scheme, "data") == 0)
+        {
+          bytes = gtk_css_data_url_parse (url, NULL, &error);
+        }
+      else
+        {
+          GFile *file;
+
+          file = g_file_new_for_uri (url);
+          bytes = g_file_load_bytes (file, NULL, NULL, &error);
+          g_object_unref (file);
+        }
+
+      g_free (scheme);
+      g_free (url);
+
+      if (bytes)
+        {
+          add_font_from_bytes (context, bytes, &error);
+          g_bytes_unref (bytes);
+
+          fontmap = context->fontmap;
+        }
+      else
+        {
+          g_assert (error != NULL);
+
+          gtk_css_parser_emit_error (parser,
+                                     &start_location,
+                                     gtk_css_parser_get_end_location (parser),
+                                     error);
+          g_clear_error (&error);
+
+          return FALSE;
+        }
+    }
+
+  font = font_from_string (fontmap, s);
+
+  if (!font && context->fontmap && fontmap != context->fontmap)
+    font = font_from_string (context->fontmap, s);
+
+  if (!font)
+    {
+      gtk_css_parser_error_value (parser, "This font does not exist.");
       return FALSE;
     }
 
@@ -2013,7 +2219,7 @@ parse_text_node (GtkCssParser *parser,
 
   if (font == NULL)
     {
-      font = font_from_string ("Cantarell 11");
+      font = font_from_string (pango_cairo_font_map_get_default (), "Cantarell 11");
       g_assert (font);
     }
 

gsk/gskrendernodeparserprivate.h

@@ -6,4 +6,3 @@
 GskRenderNode * gsk_render_node_deserialize_from_bytes  (GBytes            *bytes,
                                                          GskParseErrorFunc  error_func,
                                                          gpointer           user_data);
-

testsuite/gsk/nodeparser/text-fail.errors

@@ -1,3 +1,3 @@
-<data>:4:3-7: error: GTK_CSS_PARSER_WARNING_SYNTAX
+<data>:3:11-12: error: GTK_CSS_PARSER_ERROR_UNKNOWN_VALUE
+<data>:4:11-12: error: GTK_CSS_PARSER_ERROR_UNKNOWN_VALUE
 <data>:6:3-9: error: GTK_CSS_PARSER_WARNING_SYNTAX
-<data>:8:1-2: error: GTK_CSS_PARSER_ERROR_UNKNOWN_VALUE

testsuite/gsk/nodeparser/text-fail.ref.node

@@ -1,4 +1,6 @@
-color {
-  bounds: 0 0 50 50;
-  color: rgb(255,0,204);
+text {
+  color: rgb(50,50,50);
+  font: "Cantarell 11";
+  glyphs: "N";
+  offset: 0 32.0186;
 }