# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1444666253 -7200
# Node ID e51a3f1dd41316e1bb06d69221622ca726548b22
# Parent  e9be7371523129f0ba7983b479eb1375c3b09b22# Parent  fcd8939da191eb0931fb3f221e2a22edc3adf193
Made the verify-only mode more usable, improving the documentation.

diff -r e9be73715231 -r e51a3f1dd413 optimiser.py
--- a/optimiser.py	Mon Oct 12 12:05:24 2015 +0200
+++ b/optimiser.py	Mon Oct 12 18:10:53 2015 +0200
@@ -100,9 +100,14 @@
     elif "--test-flat" in sys.argv:
         test_flat((120, 40, 60))
         sys.exit(0)
-    elif "--help" in sys.argv:
+    elif "--help" in sys.argv or len(sys.argv) < 3:
+        basename = split(sys.argv[0])[1]
         print >>sys.stderr, """\
-Usage: %s <input filename> <output filename> [ <options> ]
+Usage:
+
+%s <input filename> <output filename> [ <options> ]
+
+%s -v <filename> [ -C <number of colours> ]
 
 Options are...
 
@@ -126,9 +131,10 @@
 -v - Verify the output image (loaded if -n is given)
 -n - Generate no output image
 
-An input filename of - implies the -n option, and is useful for verifying
-previously generated images.
-""" % split(sys.argv[0])[1]
+Specifying -v instead of input filename permits the verification of
+previously-generated images. Doing so causes all other options except for -C
+to be ignored.
+""" % (basename, basename)
         sys.exit(1)
 
     base_width = width = 320
@@ -138,6 +144,7 @@
     basename, ext = splitext(output_filename)
     preview_filename = "".join([basename + "_preview", ext])
 
+    verify_only = input_filename == "-v"
     options = sys.argv[3:]
 
     # Basic image properties.
@@ -158,12 +165,15 @@
 
     # General output options.
 
+    no_normal_output = "-n" in options or verify_only
+    verify = "-v" in options or verify_only
+
+    rotate = "-r" in options and not verify_only
+    preview = "-p" in options and not verify_only
+
+    half_resolution_preview = "-h" in options
     least_error = "-l" in options
-    rotate = "-r" in options
-    preview = "-p" in options
-    half_resolution_preview = "-h" in options
-    verify = "-v" in options
-    no_normal_output = "-n" in options or input_filename == "-"
+
     make_image = not no_normal_output
 
     # Load the input image if requested.