Use decimals for path data and limit to 6 digits of precision

scour.py

@@ -37,7 +37,6 @@
 #  * Eliminate empty path segments
 #  * Eliminate last segment in a polygon
 #  * Collapse straight curves.
-#  * Convert absolute path segments to relative ones.
 # * Process Transformations
 #  * Process quadratic Bezier curves
 #  * Collapse all group based transformations
@@ -50,6 +49,7 @@
 # + Sanitize path data (remove unnecessary whitespace
 # + Move from absolute to relative path data
 # + Remove trailing zeroes from path data
+# + Limit to no more than 6 digits of precision
 # - Remove unnecessary units of precision on attributes (use decimal: http://docs.python.org/library/decimal.html)
 # - Remove unnecessary units of precision on path coordinates
 # - Convert all colors to #RRGGBB format
@@ -69,6 +69,10 @@ import base64
 import os.path
 import urllib
 from svg_regex import svg_parser
+from decimal import *
+
+# set precision to 6 decimal places
+getcontext().prec = 6
 
 APP = 'scour'
 VER = '0.10'
@@ -619,15 +623,16 @@ def cleanPath(element) :
 			# one or more tuples, each containing two numbers
 			nums = []
 			for t in dataset:
-				nums.append(t[0])
-				nums.append(t[1])
+				# convert to a Decimal and ensure precision
+				nums.append(Decimal(str(t[0])) * Decimal(1))
+				nums.append(Decimal(str(t[1])) * Decimal(1))
 			path.append( (cmd, nums) )
 			
 		elif cmd in ['V','v','H','h']:
 			# one or more numbers
 			nums = []
 			for n in dataset:
-				nums.append(n)
+				nums.append(Decimal(str(n)))
 			path.append( (cmd, nums) )
 			
 		elif cmd in ['C','c']:
@@ -635,8 +640,8 @@ def cleanPath(element) :
 			nums = []
 			for t in dataset:
 				for pair in t:
-					nums.append(pair[0])
-					nums.append(pair[1])
+					nums.append(Decimal(str(pair[0])) * Decimal(1))
+					nums.append(Decimal(str(pair[1])) * Decimal(1))
 			path.append( (cmd, nums) )
 			
 		elif cmd in ['S','s','Q','q']:
@@ -644,8 +649,8 @@ def cleanPath(element) :
 			nums = []
 			for t in dataset:
 				for pair in t:
-					nums.append(pair[0])
-					nums.append(pair[1])
+					nums.append(Decimal(str(pair[0])) * Decimal(1))
+					nums.append(Decimal(str(pair[1])) * Decimal(1))
 			path.append( (cmd, nums) )
 			
 		elif cmd in ['A','a']:
@@ -653,18 +658,18 @@ def cleanPath(element) :
 			# another boolean, and a tuple of two numbers
 			nums = []
 			for t in dataset:
-				nums.append( t[0][0] )
-				nums.append( t[0][1] )
-				nums.append( t[1] )
+				nums.append( Decimal(str(t[0][0])) * Decimal(1) )
+				nums.append( Decimal(str(t[0][1])) * Decimal(1) )
+				nums.append( Decimal(str(t[1])) * Decimal(1))
 				
-				if t[2]: nums.append( 1 )
-				else: nums.append( 0 )
+				if t[2]: nums.append( Decimal(1) )
+				else: nums.append( Decimal(0) )
 
-				if t[3]: nums.append( 1 )
-				else: nums.append( 0 )
+				if t[3]: nums.append( Decimal(1) )
+				else: nums.append( Decimal(0) )
 				
-				nums.append( t[4][0] )
-				nums.append( t[4][1] )
+				nums.append( Decimal(str(t[4][0])) * Decimal(1) )
+				nums.append( Decimal(str(t[4][1])) * Decimal(1) )
 			path.append( (cmd, nums) )
 		
 		elif cmd in ['Z','z']:
@@ -741,7 +746,7 @@ def cleanPath(element) :
 
 # - reserialize the path data with some cleanups:
 #   - removes scientific notation (exponents)
-#   - removes trailing zeros after the decimal
+#   - removes all trailing zeros after the decimal
 #   - removes extraneous whitespace
 #   - adds commas between all values in a subcommand
 def serializePath(pathObj):

testscour.py

@@ -444,5 +444,21 @@ class ConvertAbsoluteToRelativePathCommands(unittest.TestCase):
 		self.assertEquals(path[1][1][0], -20.0,
 			'Absolute V value not converted to relative v value')
 
+class RoundPathData(unittest.TestCase):
+	def runTest(self):
+		doc = scour.scourXmlFile('unittests/path-precision.svg')
+		path = svg_parser.parse(doc.getElementsByTagNameNS(SVGNS, 'path')[0].getAttribute('d'))
+		self.assertEquals(path[0][1][0][0], 100.0,
+			'Not rounding down' )
+		self.assertEquals(path[0][1][0][1], 100.0,
+			'Not rounding up' )
+			
+class LimitPrecisionInPathData(unittest.TestCase):
+	def runTest(self):
+		doc = scour.scourXmlFile('unittests/path-precision.svg')
+		path = svg_parser.parse(doc.getElementsByTagNameNS(SVGNS, 'path')[0].getAttribute('d'))
+		self.assertEquals(path[1][1][0], 100.001,
+			'Not correctly limiting precision on path data' )
+			
 if __name__ == '__main__':
     unittest.main()

unittests/path-abs-to-rel.svg

@@ -1,3 +1,3 @@
 <svg xmlns="http://www.w3.org/2000/svg">
-      <path d="M 385.88362,201.47812 V181.47812 l100,-50 h20 C 505.43501,223.44223 659.42238,164.82405 714.32160,-0.0015300000 C 649.90356,227.13187 497.48814,312.46353 371.30643,277.40123 C 245.12472,242.33893 157.17674,250.88268 121.69357,12.440270 C 211.69357,149.44027 323.87473,190.08578 385.88362,201.47812 z " fill="blue"/>
+      <path d="M 385,201 V181 l100,-50 h20 C 505.43501,223.44223 659.42238,164.82405 714.32160,-0.0015300000 C 649.90356,227.13187 497.48814,312.46353 371.30643,277.40123 C 245.12472,242.33893 157.17674,250.88268 121.69357,12.440270 C 211.69357,149.44027 323.87473,190.08578 385.88362,201.47812 z " fill="blue"/>
 </svg>

unittests/path-precision.svg

@@ -0,0 +1,3 @@
+<svg viewBox="0 0 400 400" xmlns="http://www.w3.org/2000/svg" version="1.1">
+  <path d="M 100.0000001 99.9999999 h100.001 v100 h-100 z" fill="red" />
+</svg>