# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1444421809 -7200
# Node ID 5b3e85002c1048fd41536b731b48c3a9b0bc63b4
# Parent  92dade31295323c9972c62a1de810d7123730c74
Moved various activities to their own functions.

diff -r 92dade312953 -r 5b3e85002c10 optimiser.py
--- a/optimiser.py	Fri Oct 09 21:58:23 2015 +0200
+++ b/optimiser.py	Fri Oct 09 22:16:49 2015 +0200
@@ -261,6 +261,7 @@
     """
 
     width, height = im.size
+
     for y in range(0, height):
         l = set()
         for x in range(0, width):
@@ -269,6 +270,80 @@
             return (y, l)
     return None
 
+def process_image(im, saturate, desaturate, darken, brighten):
+
+    """
+    Process image 'im' using the given options: 'saturate', 'desaturate',
+    'darken', 'brighten'.
+    """
+
+    width, height = im.size
+
+    if saturate or desaturate or darken or brighten:
+        for y in range(0, height):
+            for x in range(0, width):
+                rgb = im.getpixel((x, y))
+                if saturate or desaturate:
+                    rgb = saturate_rgb(rgb, saturate and 0.5 / saturate or 2 * desaturate)
+                if darken or brighten:
+                    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):
+
+    "Return a preview copy of image 'im'."
+
+    width, height = im.size
+
+    imp = im.copy()
+    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))
+            value = get_value(rgb)
+            imp.putpixel((x, y), value)
+            if half_resolution_preview:
+                imp.putpixel((x+1, y), value)
+
+    return imp
+
+def convert_image(im):
+
+    "Convert image 'im' to an appropriate output representation."
+
+    width, height = im.size
+
+    for y in range(0, height):
+        c = get_colours(im, y)
+
+        for l in get_combinations(c, 4):
+            most = [value for f, value in l]
+            for x in range(0, width):
+                rgb = im.getpixel((x, y))
+                value = get_value(rgb, most, True)
+                if value is None:
+                    break # try next combination
+            else:
+                break # use this combination
+        else:
+            most = [value for f, value in c[:4]] # use the first four
+
+        for x in range(0, width):
+            rgb = im.getpixel((x, y))
+            value = get_value(rgb, most)
+            im.putpixel((x, y), value)
+
+            if x < width - 1:
+                rgbn = im.getpixel((x+1, y))
+                rgbn = tuple(map(lambda i: clip(i[0] + (i[1] - i[2]) / 4.0), zip(rgbn, rgb, value)))
+                im.putpixel((x+1, y), rgbn)
+
+            if y < height - 1:
+                rgbn = im.getpixel((x, y+1))
+                rgbn = tuple(map(lambda i: clip(i[0] + (i[1] - i[2]) / 2.0), zip(rgbn, rgb, value)))
+                im.putpixel((x, y+1), rgbn)
+
 def get_float(options, flag):
     try:
         i = options.index(flag)
@@ -342,66 +417,17 @@
         im = PIL.Image.open(input_filename).convert("RGB")
         im = rotate_and_scale(exif, im, width, height, rotate)
 
-        width, height = im.size
-
-        if saturate or desaturate or darken or brighten:
-            for y in range(0, height):
-                for x in range(0, width):
-                    rgb = im.getpixel((x, y))
-                    if saturate or desaturate:
-                        rgb = saturate_rgb(rgb, saturate and 0.5 / saturate or 2 * desaturate)
-                    if darken or brighten:
-                        rgb = amplify_rgb(rgb, brighten and 0.5 / brighten or 2 * darken)
-                    im.putpixel((x, y), rgb)
+        process_image(im, saturate, desaturate, darken, brighten)
 
     # Generate a preview if requested.
 
     if preview:
-        imp = im.copy()
-        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))
-                value = get_value(rgb)
-                imp.putpixel((x, y), value)
-                if half_resolution_preview:
-                    imp.putpixel((x+1, y), value)
-
-        imp.save(preview_filename)
+        preview_image(im, half_resolution_preview).save(preview_filename)
 
     # Generate an output image if requested.
 
     if make_image:
-        for y in range(0, height):
-            c = get_colours(im, y)
-
-            for l in get_combinations(c, 4):
-                most = [value for f, value in l]
-                for x in range(0, width):
-                    rgb = im.getpixel((x, y))
-                    value = get_value(rgb, most, True)
-                    if value is None:
-                        break # try next combination
-                else:
-                    break # use this combination
-            else:
-                most = [value for f, value in c[:4]] # use the first four
-
-            for x in range(0, width):
-                rgb = im.getpixel((x, y))
-                value = get_value(rgb, most)
-                im.putpixel((x, y), value)
-
-                if x < width - 1:
-                    rgbn = im.getpixel((x+1, y))
-                    rgbn = tuple(map(lambda i: clip(i[0] + (i[1] - i[2]) / 4.0), zip(rgbn, rgb, value)))
-                    im.putpixel((x+1, y), rgbn)
-
-                if y < height - 1:
-                    rgbn = im.getpixel((x, y+1))
-                    rgbn = tuple(map(lambda i: clip(i[0] + (i[1] - i[2]) / 2.0), zip(rgbn, rgb, value)))
-                    im.putpixel((x, y+1), rgbn)
-
+        convert_image(im)
         im.save(output_filename)
 
     # Verify the output image (which may be loaded) if requested.