Check for the optimization programs at the start of execution.

This prevents the annoying case where MCO will fail hours into a run if
pngcrush and friends are missing.

optimizeimages.py

@@ -17,20 +17,33 @@ import os
 import subprocess
 import shlex
 
+pngcrush = "pngcrush"
+optipng = "optipng"
+advdef = "advdef"
+
+def check_programs(level):
+    path = os.environ.get("PATH").split(os.pathsep)
+
+    for prog,l in [(pngcrush,1), (optipng,2), (advdef,2)]:
+        if l <= level:
+            result = filter(lambda x: os.path.exists(os.path.join(x, prog)), path)
+            if len(result) == 0:
+                raise Exception("Optimization prog %s for level %d not found!" % (prog, l))
+
 def optimize_image(imgpath, imgformat, optimizeimg):
     if imgformat == 'png':
-        if optimizeimg == "1" or optimizeimg == "2":
+        if optimizeimg >= 1:
             # we can't do an atomic replace here because windows is terrible
             # so instead, we make temp files, delete the old ones, and rename
             # the temp files. go windows!
-            subprocess.Popen(shlex.split("pngcrush " + imgpath + " " + imgpath + ".tmp"),
+            subprocess.Popen(shlex.split(pngcrush +" " + imgpath + " " + imgpath + ".tmp"),
                 stderr=subprocess.STDOUT, stdout=subprocess.PIPE).communicate()[0]
             os.remove(imgpath)
             os.rename(imgpath+".tmp", imgpath)
 
-        if optimizeimg == "2":
-            subprocess.Popen(shlex.split("optipng " + imgpath), stderr=subprocess.STDOUT,
+        if optimizeimg >= 2:
+            subprocess.Popen(shlex.split(optipng + " " + imgpath), stderr=subprocess.STDOUT,
                 stdout=subprocess.PIPE).communicate()[0]
-            subprocess.Popen(shlex.split("advdef -z4 " + imgpath), stderr=subprocess.STDOUT,
+            subprocess.Popen(shlex.split(advdef + " -z4 " + imgpath), stderr=subprocess.STDOUT,
                 stdout=subprocess.PIPE).communicate()[0]