# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1444570098 -7200
# Node ID e5fce4442d7ea21c9b8fb376253794e21d71cba5
# Parent  065abc8520c57074949f63f6070bea4cc56a3259# Parent  abb04ac9cf8d5df2bda7ccb05ce5655462d98216
Combined the preview and conversion functions, added configuration of the number
of chosen colours and the output image width.
Fixed option descriptions.

diff -r 065abc8520c5 -r e5fce4442d7e optimiser.py
--- a/optimiser.py	Sat Oct 10 23:55:15 2015 +0200
+++ b/optimiser.py	Sun Oct 11 15:28:18 2015 +0200
@@ -297,27 +297,7 @@
 
     pim.putdata(im.getdata())
 
-def preview_image(pim, half_resolution_preview=False):
-
-    "Return a preview copy of image 'pim'."
-
-    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 = im.getpixel((x, y))
-            value = get_value(rgb)
-            im.putpixel((x, y), value)
-            if half_resolution_preview:
-                im.putpixel((x+1, y), value)
-
-    imp.putdata(im.getdata())
-    return imp
-
-def convert_image(pim):
+def convert_image(pim, colours):
 
     "Convert image 'pim' to an appropriate output representation."
 
@@ -327,7 +307,7 @@
     for y in range(0, height):
         c = get_colours(im, y)
 
-        for l in get_combinations(c, 4):
+        for l in get_combinations(c, colours):
             most = [value for f, value in l]
             for x in range(0, width):
                 rgb = im.getpixel((x, y))
@@ -337,7 +317,7 @@
             else:
                 break # use this combination
         else:
-            most = [value for f, value in c[:4]] # use the first four
+            most = [value for f, value in c[:colours]] # use the first colours
 
         for x in range(0, width):
             rgb = im.getpixel((x, y))
@@ -364,15 +344,23 @@
 
     pim.putdata(im.getdata())
 
-def get_float(options, flag):
+def get_parameter(options, flag, conversion, default, missing):
+
+    """
+    From 'options', return any parameter following the given 'flag', applying
+    the 'conversion' which has the given 'default' if no valid parameter is
+    found, or returning the given 'missing' value if the flag does not appear at
+    all.
+    """
+
     try:
         i = options.index(flag)
         try:
-            return float(options[i+1])
+            return conversion(options[i+1])
         except (IndexError, ValueError):
-            return 1.0
+            return default
     except ValueError:
-        return 0.0
+        return missing
 
 class SimpleImage:
 
@@ -414,10 +402,13 @@
 
 Options are...
 
--s - Saturate the input image (can be followed by a float, default 1.0)
--d - Desaturate the input image (can be followed by a float, default 1.0)
--D - Darken the input image (can be followed by a float, default 1.0)
--B - Brighten the input image (can be followed by a float, default 1.0)
+-W - Indicate the output width (default is 320)
+-C - Number of colours per scanline (default is 4)
+
+-s - Saturate the input image (optional float, 1.0 if unspecified)
+-d - Desaturate the input image (optional float, 1.0 if unspecified)
+-D - Darken the input image (optional float, 1.0 if unspecified)
+-B - Brighten the input image (optional float, 1.0 if unspecified)
 
 -r - Rotate the input image clockwise
 -p - Generate a separate preview image
@@ -427,7 +418,7 @@
 """ % split(sys.argv[0])[1]
         sys.exit(1)
 
-    width = 320
+    base_width = 320
     height = 256
 
     input_filename, output_filename = sys.argv[1:3]
@@ -436,12 +427,17 @@
 
     options = sys.argv[3:]
 
-    # Preprocessing options that can be repeated for extra effect.
+    # Basic image properties.
+
+    width = get_parameter(options, "-W", int, base_width, base_width)
+    number_of_colours = get_parameter(options, "-C", int, 4, 4)
 
-    saturate = get_float(options, "-s")
-    desaturate = get_float(options, "-d")
-    darken = get_float(options, "-D")
-    brighten = get_float(options, "-B")
+    # Preprocessing options that employ parameters.
+
+    saturate = get_parameter(options, "-s", float, 1.0, 0.0)
+    desaturate = get_parameter(options, "-d", float, 1.0, 0.0)
+    darken = get_parameter(options, "-D", float, 1.0, 0.0)
+    brighten = get_parameter(options, "-B", float, 1.0, 0.0)
 
     # General output options.
 
@@ -457,19 +453,30 @@
     if make_image or preview:
         exif = EXIF.process_file(open(input_filename))
         im = PIL.Image.open(input_filename).convert("RGB")
-        im = rotate_and_scale(exif, im, width, height, rotate)
+        im = rotate_and_scale(exif, im, base_width, height, rotate)
+
+        # Scale images to the appropriate width.
+
+        if width != base_width:
+            im = im.resize((width, height))
 
         process_image(im, saturate, desaturate, darken, brighten)
 
     # Generate a preview if requested.
 
     if preview:
-        preview_image(im, half_resolution_preview).save(preview_filename)
+        imp = im.copy()
+        if half_resolution_preview:
+            imp = imp.resize((width / 2, height))
+        convert_image(imp, 8)
+        if half_resolution_preview:
+            imp = imp.resize((width, height))
+        imp.save(preview_filename)
 
     # Generate an output image if requested.
 
     if make_image:
-        convert_image(im)
+        convert_image(im, number_of_colours)
         im.save(output_filename)
 
     # Verify the output image (which may be loaded) if requested.
@@ -478,7 +485,7 @@
         if no_normal_output:
             im = PIL.Image.open(output_filename).convert("RGB")
 
-        result = count_colours(im, 4)
+        result = count_colours(im, number_of_colours)
         if result is not None:
             y, colours = result
             print "Image %s: row %d has the following colours: %s" % (output_filename, y, "; ".join([repr(c) for c in colours]))