Add a new Debug option that will allow you to debug the different stages of the conversion pipeline. Available when converting a single book at a time.

src/calibre/gui2/convert/debug.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import with_statement
+
+__license__   = 'GPL v3'
+__copyright__ = '2009, Kovid Goyal <kovid@kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+import os
+
+from PyQt4.Qt import SIGNAL
+
+from calibre.gui2.convert.debug_ui import Ui_Form
+from calibre.gui2.convert import Widget
+from calibre.gui2 import error_dialog, choose_dir
+
+class DebugWidget(Widget, Ui_Form):
+
+    TITLE = _('Debug')
+    ICON  = ':/images/debug.svg'
+    HELP  = _('Debug the conversion process.')
+
+    def __init__(self, parent, get_option, get_help, db=None, book_id=None):
+        Widget.__init__(self, parent, 'debug',
+                ['debug_pipeline']
+                )
+        self.db, self.book_id = db, book_id
+        self.initialize_options(get_option, get_help, db, book_id)
+        self.connect(self.button_debug_dir, SIGNAL('clicked()'),
+                self.set_debug_dir)
+        self.connect(self.button_clear, SIGNAL('clicked()'),
+                self.clear_debug_dir)
+
+    def clear_debug_dir(self):
+        self.opt_debug_pipeline.setText('')
+
+    def set_debug_dir(self):
+        x = choose_dir(self, 'conversion debug dir', _('Choose debug folder'))
+        if x:
+            self.opt_debug_pipeline.setText(x)
+
+    def pre_commit_check(self):
+        try:
+            x = unicode(self.opt_debug_pipeline.text()).strip()
+            x = os.path.abspath(x)
+            if x:
+                if not os.path.exists(x):
+                    os.makedirs(x)
+                test = os.path.join(x, 'test')
+                open(test, 'wb').close()
+                os.remove(test)
+        except:
+            import traceback
+            det_msg = traceback.format_exc()
+            error_dialog(self, _('Invalid debug directory'),
+                    _('Failed to create debug directory')+': '+
+                        unicode(self.opt_debug_pipeline.text()),
+                        det_msg=det_msg, show=True)
+            return False
+        return True
+

src/calibre/gui2/convert/debug.ui

@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>Form</class>
+ <widget class="QWidget" name="Form">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>436</width>
+    <height>382</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Form</string>
+  </property>
+  <layout class="QGridLayout" name="gridLayout">
+   <item row="0" column="0" colspan="3">
+    <widget class="QLabel" name="label">
+     <property name="text">
+      <string>Choose a folder to put the debug output into. If you specify a folder, calibre will place a lot of debug output into it. This will be useful in understanding the conversion process and figuring out the correct values for conversion parameters like Table of Contents and Chapter Detection.</string>
+     </property>
+     <property name="wordWrap">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
+   <item row="1" column="0">
+    <widget class="QLineEdit" name="opt_debug_pipeline">
+     <property name="readOnly">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
+   <item row="1" column="2">
+    <widget class="QToolButton" name="button_debug_dir">
+     <property name="toolTip">
+      <string>Choose debug folder</string>
+     </property>
+     <property name="text">
+      <string>...</string>
+     </property>
+     <property name="icon">
+      <iconset resource="../images.qrc">
+       <normaloff>:/images/document_open.svg</normaloff>:/images/document_open.svg</iconset>
+     </property>
+    </widget>
+   </item>
+   <item row="2" column="0">
+    <spacer name="verticalSpacer">
+     <property name="orientation">
+      <enum>Qt::Vertical</enum>
+     </property>
+     <property name="sizeHint" stdset="0">
+      <size>
+       <width>20</width>
+       <height>40</height>
+      </size>
+     </property>
+    </spacer>
+   </item>
+   <item row="1" column="1">
+    <widget class="QToolButton" name="button_clear">
+     <property name="text">
+      <string>...</string>
+     </property>
+     <property name="icon">
+      <iconset resource="../images.qrc">
+       <normaloff>:/images/clear_left.svg</normaloff>:/images/clear_left.svg</iconset>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources>
+  <include location="../images.qrc"/>
+ </resources>
+ <connections/>
+</ui>

src/calibre/gui2/convert/single.py

@@ -19,6 +19,8 @@ from calibre.gui2.convert.look_and_feel import LookAndFeelWidget
 from calibre.gui2.convert.page_setup import PageSetupWidget
 from calibre.gui2.convert.structure_detection import StructureDetectionWidget
 from calibre.gui2.convert.toc import TOCWidget
+from calibre.gui2.convert.debug import DebugWidget
+
 
 from calibre.ebooks.conversion.plumber import Plumber, supported_input_formats
 from calibre.customize.ui import available_output_formats
@@ -139,6 +141,7 @@ class Config(ResizableDialog, Ui_Dialog):
         ps = widget_factory(PageSetupWidget)
         sd = widget_factory(StructureDetectionWidget)
         toc = widget_factory(TOCWidget)
+        debug = widget_factory(DebugWidget)
 
         output_widget = None
         name = self.plumber.output_plugin.name.lower().replace(' ', '_')
@@ -173,6 +176,7 @@ class Config(ResizableDialog, Ui_Dialog):
             widgets.append(input_widget)
         if output_widget is not None:
             widgets.append(output_widget)
+        widgets.append(debug)
         for w in widgets:
             self.stack.addWidget(w)
             self.connect(w, SIGNAL('set_help(PyQt_PyObject)'),

src/calibre/gui2/tools.py

@@ -126,6 +126,10 @@ def convert_bulk_ebook(parent, db, book_ids, out_format=None):
                     OptionRecommendation.HIGH))
                 temp_files.append(d.cover_file)
 
+            for x in list(lrecs):
+                if x[0] == 'debug_pipeline':
+                    lrecs.remove(x)
+
             desc = _('Convert book %d of %d (%s)') % (i + 1, total, repr(mi.title))
 
             args = [in_file, out_file.name, lrecs]