add PIL_mode_from_vips () and vips_from_PIL_mode () utility functions

ChangeLog

@@ -21,6 +21,7 @@
 - revise i18n configure, get rid of intltool 
 - command-line IMAGVEC input could segv with non-vips image output
 - added .tobuffer()/.frombuffer(), .tostring()/.fromstring() to Python binding
+- add PIL_mode_from_vips () and vips_from_PIL_mode () utility functions
 
 25/1/08 started 7.14.0
 - bump all version numbers for new stable

python/vipsCC/VImage.i

@@ -6,6 +6,8 @@
  * 3/8/08
  *      - add .tobuffer() / .frombuffer (), .tostring (), .fromstring ()
  *        methods
+ *      - add PIL_mode_from_vips () and vips_from_PIL_mode () utility
+ *        functions
  */
 
 %module VImage
@@ -142,6 +144,46 @@ public:
   }
 }
 
+%pythoncode %{
+# try to guess a PIL mode string from a VIPS image
+def PIL_mode_from_vips (vim):
+  if vim.Bands () == 3 and vim.BandFmt () == VImage.FMTUCHAR:
+    return 'RGB'
+  elif vim.Bands () == 4 and vim.BandFmt () == VImage.FMTUCHAR and vim.Type == VImage.VImage.RGB:
+    return 'RGBA'
+  elif vim.Bands () == 4 and vim.BandFmt () == VImage.FMTUCHAR and vim.Type == VImage.CMYK:
+    return 'CMYK'
+  elif vim.Bands () == 1 and vim.BandFmt () == VImage.FMTUCHAR:
+    return 'L'
+  elif vim.Bands () == 1 and vim.BandFmt () == VImage.FMTINT:
+    return 'I'
+  elif vim.Bands () == 1 and vim.BandFmt () == VImage.FMTFLOAT:
+    return 'F'
+  elif vim.Bands () == 2 and vim.BandFmt () == VImage.FMTUCHAR:
+    return 'LA'
+  else:
+    raise ValueError ('unsupported vips -> pil image')
+
+# return vips (bands, format, type) for a PIL mode
+def vips_from_PIL_mode (mode):
+  if mode == 'RGB':
+    return (3, VImage.FMTUCHAR, VImage.RGB)
+  elif mode == 'RGBA':
+    return (4, VImage.FMTUCHAR, VImage.RGB)
+  elif mode == 'CMYK':
+    return (4, VImage.FMTUCHAR, VImage.CMYK)
+  elif mode == 'L':
+    return (1, VImage.FMTUCHAR, VImage.B_W)
+  elif mode == 'I':
+    return (1, VImage.FMTINT, VImage.B_W)
+  elif mode == 'F':
+    return (1, VImage.FMTFLOAT, VImage.B_W)
+  elif mode == 'LA':
+    return (2, VImage.FMTUCHAR, VImage.B_W)
+  else:
+    raise ValueError ('unsupported pil -> vips image')
+%}
+
 /* Helper code for vips_init().
  */
 %{
@@ -211,14 +253,13 @@ args_new (void)
   if (!PyList_Check (av)) {
     PyErr_Warn (PyExc_Warning, "ignoring sys.argv: "
       "it must be a list of strings");
-                return (args);
+    return args;
   }
 
   n = PyList_Size (av);
   args->str = g_new (char *, n);
   for (i = 0; i < n; i++)
-		args->str[i] = g_strdup 
-			(PyString_AsString (PyList_GetItem (av, i)));
+    args->str[i] = g_strdup (PyString_AsString (PyList_GetItem (av, i)));
   args->n = n;
 
   /* +1 for NULL termination.
@@ -229,7 +270,7 @@ args_new (void)
     args->argv[i] = args->str[i];
   args->argv[i] = NULL;
 
-	return (args);
+  return args;
 }
 
 static void