rework GUI frontend selection

diff --git a/gui.py b/gui.py
index 83099e884b0bbd50cef5700fd26f6da5d4902f96..155226b3939fff4598786870baa61b3aedf13396 100644 (file)
--- a/gui.py
+++ b/gui.py
@@ -18,26 +18,36 @@
 # This file abstracts GUI stuff away, so that the actual dsl.py does not have to deal with it
 import sys
 
-qt_available = True
-try:
+# frontend detectors
+def qtAvailable():
+       try:
+               import PyQt4
+               return True
+       except ImportError:
+               return False
+
+def zenityAvailable():
+       return True # FIXME
+
+# actual frontend
+if qtAvailable():
        from PyQt4 import QtGui
        from qt_dialogue import PositionSelection
        app = QtGui.QApplication(sys.argv)
-except Exception, e:
-       import subprocess
-       from zenity_dialogue import run as zenity_run
-       qt_available = False
-
-def error(message):
-       '''Displays a fatal error to the user'''
-       if qt_available:
+       
+       def error(message):
+               '''Displays a fatal error to the user'''
                QtGui.QMessageBox.critical(None, 'Fatal error', message)
-       else:
-               subprocess.check_call(["zenity", "--error", "--text="+message])
-
-def setup(internalResolutions, externalResolutions):
-       '''Returns a ScreenSetup instance, or None if the user canceled'''
-       if qt_available:
+       
+       def setup(internalResolutions, externalResolutions):
+               '''Returns a ScreenSetup instance, or None if the user canceled'''
                return PositionSelection(internalResolutions, externalResolutions).run()
-       else:
-               return zenity_run(internalResolutions, externalResolutions)
+elif zenityAvailable():
+       import subprocess
+       from zenity_dialogue import run as setup # this provides the setup function
+       
+       def error(message):
+               '''Displays a fatal error to the user'''
+               subprocess.check_call(["zenity", "--error", "--text="+message])
+else:
+       print >> sys.stderr, 'No GUI frontend available, please make sure PyQt4 or Zenity is installed'