From 1ff83939d701dce230ea46fdf10d0834bbe9f8f7 Mon Sep 17 00:00:00 2001
From: Petr Viktorin <encukou@gmail.com>
Date: Mon, 28 Oct 2013 16:57:25 +0100
Subject: [PATCH] Add docs for trans

---
 tmxlib/image.py      | 10 ++++++++--
 tmxlib/image_base.py |  8 +++++++-
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/tmxlib/image.py b/tmxlib/image.py
index 067bfc2..e955ae1 100644
--- a/tmxlib/image.py
+++ b/tmxlib/image.py
@@ -30,8 +30,14 @@ def open(filename, trans=None, size=None):
 
     :param filename: Name of the file to load the image from
     :param trans:
-        Optional color that should be rendered as transparent
-        (this is not implemented yet)
+        Optional color that should be loaded as transparent
+
+        .. note::
+
+            Currently, loading images that use color-key transparency
+            is very inefficient.
+            If possible, use the alpha channel instead.
+
     :param size:
         Optional (width, height) tuple.
         If specified, the file will not be read from disk when the image size
diff --git a/tmxlib/image_base.py b/tmxlib/image_base.py
index e4156bb..663d1ac 100644
--- a/tmxlib/image_base.py
+++ b/tmxlib/image_base.py
@@ -106,7 +106,13 @@ class Image(ImageBase, fileio.ReadWriteBase):
 
         .. attribute:: trans
 
-            A color key used for transparency (currently not implemented)
+            A color key used for transparency
+
+            .. note::
+
+                Currently, loading images that use color-key transparency
+                is very inefficient.
+                If possible, use the alpha channel instead.
 
     Images support indexing (``img[x, y]``); see
     :meth:`tmxlib.image_base.ImageBase.__getitem__`