# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1444480885 -7200
# Node ID 429cc2ef9b9f6025b616be866f5b145a1c07e556
# Parent  5b3e85002c1048fd41536b731b48c3a9b0bc63b4
Experiment with a simple alternative class to Image for pixel access.

diff -r 5b3e85002c10 -r 429cc2ef9b9f optimiser.py
--- a/optimiser.py	Fri Oct 09 22:16:49 2015 +0200
+++ b/optimiser.py	Sat Oct 10 14:41:25 2015 +0200
@@ -188,9 +188,9 @@
             else:
                 c[value] += f
 
-    c = [(n/width, value) for value, n in c.items()]
-    c.sort(reverse=True)
-    return c
+    d = [(n/width, value) for value, n in c.items()]
+    d.sort(reverse=True)
+    return d
 
 def get_combinations(c, n):
 
@@ -270,14 +270,15 @@
             return (y, l)
     return None
 
-def process_image(im, saturate, desaturate, darken, brighten):
+def process_image(pim, saturate, desaturate, darken, brighten):
 
     """
-    Process image 'im' using the given options: 'saturate', 'desaturate',
+    Process image 'pim' using the given options: 'saturate', 'desaturate',
     'darken', 'brighten'.
     """
 
-    width, height = im.size
+    width, height = pim.size
+    im = SimpleImage(list(pim.getdata()), pim.size)
 
     if saturate or desaturate or darken or brighten:
         for y in range(0, height):
@@ -289,30 +290,34 @@
                     rgb = amplify_rgb(rgb, brighten and 0.5 / brighten or 2 * darken)
                 im.putpixel((x, y), rgb)
 
-def preview_image(im, half_resolution_preview=False):
+    pim.putdata(im.getdata())
 
-    "Return a preview copy of image 'im'."
+def preview_image(pim, half_resolution_preview=False):
 
-    width, height = im.size
+    "Return a preview copy of image 'pim'."
 
-    imp = im.copy()
+    width, height = pim.size
+    imp = pim.copy()
+    im = SimpleImage(list(pim.getdata()), pim.size)
     step = half_resolution_preview and 2 or 1
 
     for y in range(0, height):
-        for x in range(0, width, step):
-            rgb = imp.getpixel((x, y))
+        for x in range(0, width):
+            rgb = im.getpixel((x, y))
             value = get_value(rgb)
-            imp.putpixel((x, y), value)
+            im.putpixel((x, y), value)
             if half_resolution_preview:
-                imp.putpixel((x+1, y), value)
+                im.putpixel((x+1, y), value)
 
+    imp.putdata(im.getdata())
     return imp
 
-def convert_image(im):
+def convert_image(pim):
 
-    "Convert image 'im' to an appropriate output representation."
+    "Convert image 'pim' to an appropriate output representation."
 
-    width, height = im.size
+    width, height = pim.size
+    im = SimpleImage(list(pim.getdata()), pim.size)
 
     for y in range(0, height):
         c = get_colours(im, y)
@@ -344,6 +349,8 @@
                 rgbn = tuple(map(lambda i: clip(i[0] + (i[1] - i[2]) / 2.0), zip(rgbn, rgb, value)))
                 im.putpixel((x, y+1), rgbn)
 
+    pim.putdata(im.getdata())
+
 def get_float(options, flag):
     try:
         i = options.index(flag)
@@ -354,6 +361,28 @@
     except ValueError:
         return 0.0
 
+class SimpleImage:
+
+    "An image behaving like PIL.Image."
+
+    def __init__(self, data, size):
+        self.data = data
+        self.width, self.height = self.size = size
+
+    def copy(self):
+        return SimpleImage(self.data[:], self.size)
+
+    def getpixel(self, xy):
+        x, y = xy
+        return self.data[y * self.width + x]
+
+    def putpixel(self, xy, value):
+        x, y = xy
+        self.data[y * self.width + x] = value
+
+    def getdata(self):
+        return self.data
+
 # Main program.
 
 if __name__ == "__main__":