fix: fix svg c code extern problem

src/subset/hb-glyph-to-svg-path.cc

@@ -110,24 +110,26 @@ close_path(hb_draw_funcs_t *dfuncs, user_data_t *draw_data, hb_draw_state_t *, v
 
 static hb_draw_funcs_t *funcs = 0;
 
-
-int hb_glyph_to_svg_path(hb_font_t *font, hb_codepoint_t glyph, char *buf, unsigned buf_size)
+extern "C"
 {
-  if (funcs == 0) /* not the best pattern for multi-threaded apps which is not a concern here */
+  int hb_glyph_to_svg_path(hb_font_t *font, hb_codepoint_t glyph, char *buf, unsigned buf_size)
   {
-    funcs = hb_draw_funcs_create(); /* will be leaked */
-    hb_draw_funcs_set_move_to_func(funcs, (hb_draw_move_to_func_t)move_to, nullptr, nullptr);
-    hb_draw_funcs_set_line_to_func(funcs, (hb_draw_line_to_func_t)line_to, nullptr, nullptr);
-    hb_draw_funcs_set_quadratic_to_func(funcs, (hb_draw_quadratic_to_func_t)quadratic_to, nullptr, nullptr);
-    hb_draw_funcs_set_cubic_to_func(funcs, (hb_draw_cubic_to_func_t)cubic_to, nullptr, nullptr);
-    hb_draw_funcs_set_close_path_func(funcs, (hb_draw_close_path_func_t)close_path, nullptr, nullptr);
+    if (funcs == 0) /* not the best pattern for multi-threaded apps which is not a concern here */
+    {
+      funcs = hb_draw_funcs_create(); /* will be leaked */
+      hb_draw_funcs_set_move_to_func(funcs, (hb_draw_move_to_func_t)move_to, nullptr, nullptr);
+      hb_draw_funcs_set_line_to_func(funcs, (hb_draw_line_to_func_t)line_to, nullptr, nullptr);
+      hb_draw_funcs_set_quadratic_to_func(funcs, (hb_draw_quadratic_to_func_t)quadratic_to, nullptr, nullptr);
+      hb_draw_funcs_set_cubic_to_func(funcs, (hb_draw_cubic_to_func_t)cubic_to, nullptr, nullptr);
+      hb_draw_funcs_set_close_path_func(funcs, (hb_draw_close_path_func_t)close_path, nullptr, nullptr);
+    }
+
+    user_data_t draw_data(buf, buf_size);
+    hb_font_draw_glyph(font, glyph, funcs, &draw_data);
+    if (draw_data.failure)
+      return -1;
+
+    buf[draw_data.consumed] = '\0';
+    return draw_data.consumed;
   }
-
-  user_data_t draw_data(buf, buf_size);
-  hb_font_draw_glyph(font, glyph, funcs, &draw_data);
-  if (draw_data.failure)
-    return -1;
-
-  buf[draw_data.consumed] = '\0';
-  return draw_data.consumed;
 }

src/subset/hb-glyph-to-svg-path.h

@@ -1,3 +1,6 @@
 #include "../../harfbuzz/src/hb.h"
 
-int hb_glyph_to_svg_path(hb_font_t *font, hb_codepoint_t glyph, char *buf, unsigned buf_size);
+extern "C"
+{
+    int hb_glyph_to_svg_path(hb_font_t *font, hb_codepoint_t glyph, char *buf, unsigned buf_size);
+}