Port ancient LRF viewer settings not serializable to JSON

Also just ignore non-serializable settings, making them None
when migrating .py files. Such settings are very rare and likely
in unused/rarely used corners of calibre so better to hav those fail
than the entire migration process.

src/calibre/gui2/lrf_renderer/main.py

@@ -7,10 +7,12 @@ from PyQt5.Qt import (
     QKeySequence, QPainter, QDialog, QSpinBox, QSlider, QIcon, Qt, QCoreApplication, QThread, QScrollBar)
 
 from calibre import __appname__, setup_cli_handlers, islinux, isbsd, as_unicode
+from calibre.gui2 import gprefs
 from calibre.ebooks.lrf.lrfparser import LRFDocument
 
-from calibre.gui2 import error_dialog, \
-                         config, choose_files, Application
+from calibre.gui2 import (
+        error_dialog, choose_files, Application
+        )
 from calibre.gui2.dialogs.conversion_error import ConversionErrorDialog
 from calibre.gui2.lrf_renderer.main_ui import Ui_MainWindow
 from calibre.gui2.lrf_renderer.config_ui import Ui_ViewerConfig
@@ -107,15 +109,12 @@ class Main(MainWindow, Ui_MainWindow):
         self.closed = False
 
     def configure(self, triggered):
-        opts = config['LRF_ebook_viewer_options']
-        if not opts:
-            opts = self.opts
+        opts = self.opts
         d = Config(self, opts)
         d.exec_()
         if d.result() == QDialog.Accepted:
-            opts.white_background = bool(d.white_background.isChecked())
-            opts.hyphenate = bool(d.hyphenate.isChecked())
-            config['LRF_ebook_viewer_options'] = opts
+            gprefs['lrf_viewer_white_background'] = opts.white_background = bool(d.white_background.isChecked())
+            gprefs['lrf_viewer_hyphenate'] = opts.hyphenate = bool(d.hyphenate.isChecked())
 
     def set_ebook(self, stream):
         self.progress_bar.setMinimum(0)
@@ -289,15 +288,13 @@ Read the LRF e-book book.lrf
 
 
 def normalize_settings(parser, opts):
-    saved_opts = config['LRF_ebook_viewer_options']
-    if not saved_opts:
-        saved_opts = opts
-    for opt in parser.option_list:
-        if not opt.dest:
-            continue
-        if getattr(opts, opt.dest) == opt.default and hasattr(saved_opts, opt.dest):
-            continue
-        setattr(saved_opts, opt.dest, getattr(opts, opt.dest))
+    saved_opts = opts
+    dh = gprefs.get('lrf_viewer_hyphenate', None)
+    if dh is not None:
+        opts.hyphenate = bool(dh)
+    wb = gprefs.get('lrf_viewer_white_background', None)
+    if wb is not None:
+        opts.white_background = bool(wb)
     return saved_opts
 
 

src/calibre/utils/config_base.py

@@ -38,6 +38,13 @@ def to_json(obj):
     raise TypeError(repr(obj) + ' is not JSON serializable')
 
 
+def safe_to_json(obj):
+    try:
+        return to_json(obj)
+    except Exception:
+        pass
+
+
 def from_json(obj):
     custom = obj.get('__class__')
     if custom is not None:
@@ -52,9 +59,9 @@ def from_json(obj):
     return obj
 
 
-def json_dumps(obj):
+def json_dumps(obj, ignore_unserializable=False):
     import json
-    ans = json.dumps(obj, indent=2, default=to_json, sort_keys=True, ensure_ascii=False)
+    ans = json.dumps(obj, indent=2, default=safe_to_json if ignore_unserializable else to_json, sort_keys=True, ensure_ascii=False)
     if not isinstance(ans, bytes):
         ans = ans.encode('utf-8')
     return ans
@@ -288,9 +295,9 @@ class OptionSet(object):
 
         return opts
 
-    def serialize(self, opts):
+    def serialize(self, opts, ignore_unserializable=False):
         data = {pref.name: getattr(opts, pref.name, pref.default) for pref in self.preferences}
-        return json_dumps(data)
+        return json_dumps(data, ignore_unserializable=ignore_unserializable)
 
 
 class ConfigInterface(object):
@@ -351,7 +358,7 @@ class Config(ConfigInterface):
                 migrate = bool(src)
         ans = self.option_set.parse_string(src)
         if migrate:
-            new_src = self.option_set.serialize(ans)
+            new_src = self.option_set.serialize(ans, ignore_unserializable=True)
             with ExclusiveFile(self.config_file_path) as f:
                 f.seek(0), f.truncate()
                 f.write(new_src)