PDF Output: Fix javascript dialog box popping up in the middle on converting very long documents. Fixes #1154948 (JavaScript Problem while generating PDF in 0.9.22)

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

@@ -12,7 +12,7 @@
 from math import floor
 
 from PyQt4.Qt import (QObject, QPainter, Qt, QSize, QString, QTimer,
-                      pyqtProperty, QEventLoop, QPixmap, QRect)
+                      pyqtProperty, QEventLoop, QPixmap, QRect, pyqtSlot)
 from PyQt4.QtWebKit import QWebView, QWebPage, QWebSettings
 
 from calibre import fit_image
@@ -82,6 +82,7 @@ def __init__(self, opts, log):
                     opts.pdf_sans_family)
         if opts.pdf_mono_family:
             settings.setFontFamily(QWebSettings.FixedFont, opts.pdf_mono_family)
+        self.longjs_counter = 0
 
     def javaScriptConsoleMessage(self, msg, lineno, msgid):
         self.log.debug(u'JS:', unicode(msg))
@@ -89,8 +90,14 @@ def javaScriptConsoleMessage(self, msg, lineno, msgid):
     def javaScriptAlert(self, frame, msg):
         self.log(unicode(msg))
 
+    @pyqtSlot(result=bool)
     def shouldInterruptJavaScript(self):
-        return False
+        if self.longjs_counter < 5:
+            self.log('Long running javascript, letting it proceed')
+            self.longjs_counter += 1
+            return False
+        self.log.warn('Long running javascript, aborting it')
+        return True
 
 # }}}
 
@@ -275,6 +282,7 @@ def do_paged_render(self):
             self.paged_js += cc('ebooks.oeb.display.mathjax')
 
         self.view.page().mainFrame().addToJavaScriptWindowObject("py_bridge", self)
+        self.view.page().longjs_counter = 0
         evaljs = self.view.page().mainFrame().evaluateJavaScript
         evaljs(self.paged_js)
         self.load_mathjax()