From 171a55bf567607430cabaef7965690eeac85d2ce Mon Sep 17 00:00:00 2001
From: Jack Jansen <jack.jansen@cwi.nl>
Date: Fri, 19 Feb 1993 15:52:30 +0000
Subject: Will now generate converters that go thru intermedeate formats

---
 Demo/sgi/video/imgconv.py | 84 +++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 81 insertions(+), 3 deletions(-)

diff --git a/Demo/sgi/video/imgconv.py b/Demo/sgi/video/imgconv.py
index a3a5d19..3990ae1 100755
--- a/Demo/sgi/video/imgconv.py
+++ b/Demo/sgi/video/imgconv.py
@@ -18,8 +18,14 @@ converters = [ \
 	  ('mono',  'grey',  mono2grey,            NOT_LOSSY), \
 	  ('grey2', 'grey',  imageop.grey22grey,   NOT_LOSSY), \
 	  ('grey4', 'grey',  imageop.grey42grey,   NOT_LOSSY), \
+	  ('rgb',   'rgb8',  imageop.rgb2rgb8,     LOSSY), \
+	  ('rgb8',  'rgb',   imageop.rgb82rgb,     NOT_LOSSY), \
+	  ('rgb',   'grey',  imageop.rgb2grey,     LOSSY), \
+	  ('grey',  'rgb',   imageop.grey2rgb,     NOT_LOSSY) \
 ]
 
+built = {}
+
 def addconverter(fcs, tcs, lossy, func):
 	for i in range(len(converters)):
 		ifcs, itcs, irtn, ilossy = converters[i]
@@ -29,10 +35,82 @@ def addconverter(fcs, tcs, lossy, func):
 	converters.append((fcs,tcs,lossy,func))
 
 def getconverter(fcs, tcs):
+	#
+	# If formats are the same return the dummy converter
+	#
 	if fcs == tcs: return null
-	
+	#
+	# Otherwise, if we have a converter return that one
+	#
 	for ifcs, itcs, irtn, ilossy in converters:
 		if (fcs, tcs) == (ifcs, itcs):
 			return irtn
-	raise error, 'Sorry, that conversion is not implemented'
-	  
+	#
+	# Finally, we try to create a converter
+	#
+	if not built.has_key(fcs):
+		built[fcs] = enumerate_converters(fcs)
+	if not built[fcs].has_key(tcs):
+		raise error, 'Sorry, conversion from '+fcs+' to '+tcs+ \
+			  ' is not implemented'
+	if len(built[fcs][tcs]) == 3:
+		#
+		# Converter not instantiated yet
+		#
+		built[fcs][tcs].append(instantiate_converter(built[fcs][tcs]))
+	cf = built[fcs][tcs][3]
+	return cf
+
+def enumerate_converters(fcs):
+	cvs = {}
+	formats = [fcs]
+	steps = 0
+	while 1:
+		workdone = 0
+		for ifcs, itcs, irtn, ilossy in converters:
+			if ifcs == fcs:
+				template = [ilossy, 1, [irtn]]
+			elif cvs.has_key(ifcs):
+				template = cvs[ifcs][:]
+				template[2] = template[2][:]
+				if ilossy:
+					template[0] = ilossy
+				template[1] = template[1] + 1
+				template[2].append(irtn)
+			else:
+				continue
+			if not cvs.has_key(itcs):
+				cvs[itcs] = template
+				workdone = 1
+			else:
+				previous = cvs[itcs]
+				if template < previous:
+					cvs[itcs] = template
+					workdone = 1
+		if not workdone:
+			break
+		steps = steps + 1
+		if steps > len(converters):
+			print '------------------loop in emunerate_converters--------'
+			print 'CONVERTERS:'
+			print converters
+			print 'RESULTS:'
+			print cvs
+			raise error, 'Internal error - loop'
+	return cvs
+
+def instantiate_converter(args):
+	list = args[2]
+	cl = RtConverters().init(list)
+	args.append(cl.convert)
+	return args
+
+class RtConverters():
+	def init(self, list):
+		self.list = list
+		return self
+
+	def convert(self, img, w, h):
+		for cv in self.list:
+			img = cv(img, w, h)
+		return img
-- 
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