The Headless Horseman rides!

On linux all worker processes/command line tools now use the headless QPA
plugin when using Qt based code. This means that they no longer require
a running X server or xvfb.

setup/qt5-migrate.py

@@ -6,11 +6,6 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
 
-# QT5XX: Implement a minimal QPA plugin to allow headless operation, see the
-# minimal example in the Qt source code and see
-# https://github.com/ariya/phantomjs/pull/173 for info on how to enable fonts
-# with fontconfig (probably needed for PDF output and SVG rendering)
-
 # QT5XX: Add a import checker that looks for all from PyQt5.* imports and runs
 # them to check that they work. This can probably be made part of python
 # setup.py check.

src/calibre/ebooks/oeb/transforms/rasterize.py

@@ -28,9 +28,8 @@ class Unavailable(Exception):
 
 class SVGRasterizer(object):
     def __init__(self):
-        from calibre.gui2 import is_ok_to_use_qt
-        if not is_ok_to_use_qt():
-            raise Unavailable('Not OK to use Qt')
+        from calibre.gui2 import must_use_qt
+        must_use_qt()
 
     @classmethod
     def config(cls, cfg):

src/calibre/ebooks/pdf/render/from_html.py

@@ -146,9 +146,8 @@ class PDFWriter(QObject):
         return self.current_section
 
     def __init__(self, opts, log, cover_data=None, toc=None):
-        from calibre.gui2 import is_ok_to_use_qt
-        if not is_ok_to_use_qt():
-            raise Exception('Not OK to use Qt')
+        from calibre.gui2 import must_use_qt
+        must_use_qt()
         QObject.__init__(self)
 
         self.logger = self.log = log

src/calibre/ebooks/pdf/writer.py

@@ -36,9 +36,8 @@ def get_custom_size(opts):
     return custom_size
 
 def get_pdf_printer(opts, for_comic=False, output_file_name=None):  # {{{
-    from calibre.gui2 import is_ok_to_use_qt
-    if not is_ok_to_use_qt():
-        raise Exception('Not OK to use Qt')
+    from calibre.gui2 import must_use_qt
+    must_use_qt()
 
     printer = QPrinter(QPrinter.HighResolution)
     custom_size = get_custom_size(opts)
@@ -137,10 +136,9 @@ class Page(QWebPage):  # {{{
 class PDFWriter(QObject):  # {{{
 
     def __init__(self, opts, log, cover_data=None, toc=None):
-        from calibre.gui2 import is_ok_to_use_qt
+        from calibre.gui2 import must_use_qt
         from calibre.utils.podofo import get_podofo
-        if not is_ok_to_use_qt():
-            raise Exception('Not OK to use Qt')
+        must_use_qt()
         QObject.__init__(self)
 
         self.logger = self.log = log

src/calibre/gui2/__init__.py

@@ -1039,12 +1039,16 @@ def open_local_file(path):
         open_url(url)
 
 def must_use_qt():
+    ''' This function should be called if you want to use Qt for some non-GUI
+    task like rendering HTML/SVG or using a headless browser. It will raise a
+    RuntimeError if using Qt is not possible, which will happen if the current
+    thread is not the main GUI thread. On linux, it uses a special QPA headless
+    plugin, so that the X server does not need to be running. '''
     global gui_thread, _store_app
-    if (islinux or isbsd) and ':' not in os.environ.get('DISPLAY', ''):
-        raise RuntimeError('X server required. If you are running on a'
-                ' headless machine, use xvfb')
     if _store_app is None and QApplication.instance() is None:
-        _store_app = QApplication([])
+        if islinux or isbsd:
+            args = sys.argv[:1] + ['-platformpluginpath', sys.extensions_location, '-platform', 'headless']
+        _store_app = QApplication(args)
     if gui_thread is None:
         gui_thread = QThread.currentThread()
     if gui_thread is not QThread.currentThread():

src/calibre/gui2/convert/font_key.py

@@ -94,7 +94,8 @@ class FontKeyChooser(QDialog, Ui_Dialog):
 
 
 if __name__ == '__main__':
-    from calibre.gui2 import is_ok_to_use_qt
-    is_ok_to_use_qt()
+    from PyQt5.Qt import QApplication
+    app = QApplication([])
     d = FontKeyChooser()
     d.exec_()
+    del app

src/calibre/gui2/dialogs/scheduler.py

@@ -197,8 +197,7 @@ class SchedulerDialog(QDialog, Ui_Dialog):
         self.recipe_model.do_refresh()
         self.count_label.setText(
             # NOTE: Number of news sources
-            _('%s news sources') %
-                self.recipe_model.showing_count)
+            _('%s news sources') % self.recipe_model.showing_count)
 
         self.schedule_widgets = []
         for key in reversed(self.SCHEDULE_TYPES):
@@ -583,8 +582,9 @@ class Scheduler(QObject):
                 break
 
 if __name__ == '__main__':
-    from calibre.gui2 import is_ok_to_use_qt
-    is_ok_to_use_qt()
+    from PyQt5.Qt import QApplication
+    app = QApplication([])
     d = SchedulerDialog(RecipeModel())
     d.exec_()
+    del app
 

src/calibre/gui2/dialogs/user_profiles.py

@@ -440,9 +440,10 @@ class %(classname)s(%(base_class)s):
             ResizableDialog.reject(self)
 
 if __name__ == '__main__':
-    from calibre.gui2 import is_ok_to_use_qt
-    is_ok_to_use_qt()
+    from PyQt5.Qt import QApplication
+    app = QApplication([])
     from calibre.web.feeds.recipes.model import RecipeModel
     d=UserProfiles(None, RecipeModel())
     d.exec_()
+    del app
 

src/calibre/gui2/shortcuts.py

@@ -270,11 +270,10 @@ class ShortcutConfig(QWidget):
 
 
 if __name__ == '__main__':
-    from calibre.gui2 import is_ok_to_use_qt
+    app = QApplication([])
     from calibre.gui2.viewer.keys import SHORTCUTS
-    is_ok_to_use_qt()
     model = Shortcuts(SHORTCUTS, 'shortcuts/viewer')
     conf = ShortcutConfig(model)
     conf.resize(400, 500)
     conf.show()
-    QApplication.instance().exec_()
+    app.exec_()

src/calibre/utils/serve_coffee.py

@@ -22,54 +22,14 @@ import time, BaseHTTPServer, os, sys, re, SocketServer
 from threading import Lock
 from SimpleHTTPServer import SimpleHTTPRequestHandler
 
-
 # Compiler {{{
-try:
-    from PyQt5.Qt import QJSEngine, QJSValue
-
-    class Compiler(QJSEngine):
-
-        '''
-        You can use this class in any thread, but make sure you instantiate it in
-        the main thread. Alternatively, construct a QCoreApplication in the main
-        thread, after which you can instantiate this class and use it in any
-        thread.
-        '''
-
-        def __init__(self):
-            from PyQt5.Qt import QCoreApplication
-            if QCoreApplication.instance() is None:
-                self.__app_ = QCoreApplication([])
-
-            QJSEngine.__init__(self)
-            res = self.evaluate(CS_JS, 'coffee-script.js')
-            if res.isError():
-                raise Exception('Failed to run the coffee script compiler: %s'%
-                        res.toString())
-            self.lock = Lock()
-
-        def __call__(self, raw, filename=None):
-            with self.lock:
-                if not isinstance(raw, unicode):
-                    raw = raw.decode('utf-8')
-                if not filename:
-                    filename = '<string>'
-                go = self.globalObject()
-                go.setProperty('coffee_src', QJSValue(raw))
-                res = self.evaluate('this.CoffeeScript.compile(this.coffee_src)',
-                        filename)
-                if res.isError():
-                    return '', [res.toString()]
-                return res.toString(), []
-except ImportError:
-    pass
 
 def do_compile(raw, filename=None):
     from calibre.gui2 import must_use_qt
     must_use_qt()
     from PyQt5.Qt import QWebPage, QApplication
     import json
-    app = QApplication([])
+    app = QApplication.instance()
 
     class C(QWebPage):
 
@@ -95,19 +55,13 @@ def do_compile(raw, filename=None):
 # }}}
 
 def compile_coffeescript(raw, filename=None):
-    from calibre.gui2 import is_ok_to_use_qt
+    from calibre.utils.ipc.simple_worker import fork_job, WorkerError
     try:
-        if is_ok_to_use_qt():
-            raise NameError('The WebKit based compiler is much faster than QJSEngine')
-        return Compiler()(raw, filename)
-    except NameError:
-        from calibre.utils.ipc.simple_worker import fork_job, WorkerError
-        try:
-            return fork_job('calibre.utils.serve_coffee', 'do_compile',
-                    args=(raw,), no_output=True)['result']
-        except WorkerError as err:
-            print (err.orig_tb)
-            raise
+        return fork_job('calibre.utils.serve_coffee', 'do_compile',
+                args=(raw,), no_output=True)['result']
+    except WorkerError as err:
+        print (err.orig_tb)
+        raise
 
 def check_coffeescript(filename):
     with open(filename, 'rb') as f:
@@ -369,10 +323,8 @@ def main():
     cc.add_argument('--highlight', default=False, action='store_true',
             help='Syntax highlight the output (requires Pygments)')
 
-    cs.add_argument('--port', type=int, default=8000, help=
-            'The port on which to serve. Default: %default')
-    cs.add_argument('--host', default='0.0.0.0', help=
-            'The IP address on which to listen. Default is to listen on all'
+    cs.add_argument('--port', type=int, default=8000, help='The port on which to serve. Default: %default')
+    cs.add_argument('--host', default='0.0.0.0', help='The IP address on which to listen. Default is to listen on all'
             ' IPv4 addresses (0.0.0.0)')
     args = parser.parse_args()
     if args.which == 'compile':