From f8b82a2309bc55f7a216669038dccacf650c6878 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Wed, 14 Nov 2012 15:00:13 +0100
Subject: [PATCH] allow to select frontend via command-line; add a GUI-less
 frontend for scripted actions

---
 dsl.py | 13 ++++++--
 gui.py | 97 ++++++++++++++++++++++++++++++++++++++++------------------
 2 files changed, 78 insertions(+), 32 deletions(-)

diff --git a/dsl.py b/dsl.py
index d13d0a0..b4f77bf 100755
--- a/dsl.py
+++ b/dsl.py
@@ -17,7 +17,8 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 
 import argparse, sys, os, re, subprocess
-import gui
+from gui import getFrontend
+frontend = getFrontend("cli") # the fallback, until we got a proper frontend. This is guaranteed to be available.
 
 # for auto-config: common names of internal connectors
 commonInternalConnectorNames = ['LVDS', 'LVDS0', 'LVDS1', 'LVDS-0', 'LVDS-1']
@@ -182,11 +183,17 @@ if __name__ == "__main__":
 	try:
 		# parse command-line arguments
 		parser = argparse.ArgumentParser(description='easy Display Setup for Laptops')
+		parser.add_argument("-f, --frontend",
+							dest="frontend",
+							help="The frontend to be used for user interaction")
 		parser.add_argument("-r, --relative-position",
 							dest="rel_position", choices=('left', 'right', 'external-only'),
 							help="Position of external screen relative to internal one")
 		cmdArgs = parser.parse_args()
 		
+		# load frontend
+		frontend = getFrontend(cmdArgs.frontend)
+		
 		# load connectors and classify them
 		connectors = getXrandrInformation()
 		(internalConnector, externalConnectors) = classifyConnectors(connectors)
@@ -212,7 +219,7 @@ if __name__ == "__main__":
 				setup = ScreenSetup(relPosition, connectors[internalConnector][0], connectors[usedExternalConnector][0]) # use default resolutions
 			else:
 				# use GUI
-				setup = gui.setup(connectors[internalConnector], connectors[usedExternalConnector])
+				setup = frontend.setup(connectors[internalConnector], connectors[usedExternalConnector])
 			if setup is None: sys.exit(1) # the user canceled
 			# apply it
 			connectorArgs[internalConnector] = setup.getInternalArgs()
@@ -228,5 +235,5 @@ if __name__ == "__main__":
 		print "Call that will be made:",call
 		subprocess.check_call(call)
 	except Exception as e:
-		gui.error(str(e))
+		frontend.error(str(e))
 		raise
diff --git a/gui.py b/gui.py
index 6dabe0f..a87b82f 100644
--- a/gui.py
+++ b/gui.py
@@ -29,42 +29,81 @@ def setup(internalResolutions, externalResolutions):
 	The user should be asked about his display setup preferences.
 	The function returns None if the user cancelled, and an instance of dsl.ScreenSetup otherwise.
 '''
+import subprocess, collections
 
-# frontend detectors
-def qtAvailable():
-	try:
-		import PyQt4
-		return True
-	except ImportError:
-		return False
-
-def zenityAvailable():
-	try:
-		from dsl import processOutputIt
-		processOutputIt("zenity", "--version")
-		return True
-	except Exception:
-		return False
-
-# actual frontends
-if qtAvailable():
-	from PyQt4 import QtGui
-	from qt_dialogue import PositionSelection
-	app = QtGui.QApplication(sys.argv)
+# Qt frontend
+class QtFrontend:
+	def __init__(self):
+		from PyQt4 import QtGui
+		self.app = QtGui.QApplication(sys.argv)
+		print "Qt loaded"
 	
-	def error(message):
+	def error(self, message):
+		from PyQt4 import QtGui
 		QtGui.QMessageBox.critical(None, 'Fatal error', message)
 	
-	def setup(internalResolutions, externalResolutions):
+	def setup(self, internalResolutions, externalResolutions):
+		from qt_dialogue import PositionSelection
 		return PositionSelection(internalResolutions, externalResolutions).run()
-
-elif zenityAvailable():
-	import subprocess
-	from zenity_dialogue import run as setup # this provides the setup function
 	
+	@staticmethod
+	def isAvailable():
+		try:
+			import PyQt4
+			return True
+		except ImportError:
+			return False
+
+
+# Zenity frontend
+class ZenityFrontend:
 	def error(message):
 		'''Displays a fatal error to the user'''
 		subprocess.check_call(["zenity", "--error", "--text="+message])
+	
+	def setup(self, internalResolutions, externalResolutions):
+		from zenity_dialogue import run
+		run(internalResolutions, externalResolutions)
+	
+	@staticmethod
+	def isAvailable():
+		try:
+			from dsl import processOutputIt
+			processOutputIt("zenity", "--version")
+			return True
+		except Exception:
+			return False
+
+
+# CLI frontend
+class CLIFrontend:
+	def error(self, message):
+		print >> sys.stderr, message
+	
+	def setup(self, internalResolutions, externalResolutions):
+		raise Exception("Choosing the setup interactively is not supported with the CLI frontend")
+	
+	@staticmethod
+	def isAvailable():
+		return True
+
+# list of available frontends
+frontends = collections.OrderedDict()
+frontends["qt"] = QtFrontend
+frontends["zenity"] = ZenityFrontend
+frontends["cli"] = CLIFrontend
 
-else:
-	print >> sys.stderr, 'No GUI frontend available, please make sure PyQt4 or Zenity is installed'
+# get a frontend
+def getFrontend(name = None):
+	# by name
+	if name is not None:
+		if name in frontends:
+			if frontends[name].isAvailable():
+				return frontends[name]() # call constructor
+		# frontend not found or not available
+		raise Exception("Frontend %s not found or not available" % name)
+	# auto-detect
+	for frontend in frontends.values():
+		if frontend.isAvailable():
+			return frontend() # call constructor
+	raise Exception("No frontend is available - this should not happen")
-- 
2.30.2