OS X: Do not hang the UI waiting for fontconfig to finish scanning on first start. Instead present a blank list of available fonts

src/calibre/gui2/font_family_chooser.py

@@ -118,7 +118,7 @@ class FontFamilyChooser(QComboBox):
         QComboBox.__init__(self, parent)
         from calibre.utils.fonts import fontconfig
         try:
-            self.families = fontconfig.find_font_families()
+            ok, self.families = fontconfig.find_font_families_no_delay()
         except:
             self.families = []
             print ('WARNING: Could not load fonts')

src/calibre/utils/fonts/__init__.py

@@ -6,7 +6,7 @@ __license__   = 'GPL v3'
 __copyright__ = '2009, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-from calibre.constants import iswindows
+from calibre.constants import iswindows, isosx
 
 class Fonts(object):
 
@@ -23,6 +23,12 @@ class Fonts(object):
             return self.backend.font_families()
         return self.backend.find_font_families(allowed_extensions=allowed_extensions)
 
+    def find_font_families_no_delay(self, allowed_extensions={'ttf', 'otf'}):
+        if isosx:
+            if self.backend.is_scanning():
+                return False, []
+        return True, self.find_font_families(allowed_extensions=allowed_extensions)
+
     def files_for_family(self, family, normalize=True):
         '''
         Find all the variants in the font family `family`.

src/calibre/utils/fonts/fc.py

@@ -8,7 +8,7 @@ __docformat__ = 'restructuredtext en'
 
 import os, sys
 
-from calibre.constants import plugins, islinux, isbsd
+from calibre.constants import plugins, islinux, isbsd, isosx
 
 _fc, _fc_err = plugins['fontconfig']
 
@@ -44,6 +44,11 @@ class FontConfig(Thread):
         if not self.failed and hasattr(_fc, 'add_font_dir'):
             _fc.add_font_dir(P('fonts/liberation'))
 
+    def is_scanning(self):
+        if isosx:
+            return self.is_alive()
+        return False
+
     def wait(self):
         if not (islinux or isbsd):
             self.join()