rollback png8 default in 2.3.x - closes #2110

CHANGELOG.md

@@ -40,9 +40,6 @@ Summary: TODO
 
 - Moved `label-position-tolerance` from unsigned type to double
 
-- Default PNG encoding method when `png` is supplied is now `png8:m=h`, so paletted png using hextree color quantization (#2028)
-  Use `png32` now for full color png. More details at https://github.com/mapnik/mapnik/wiki/Image-IO.
-
 - Added support for more seamless blurring by rendering to a larger internal image to avoid edge effects (#1478)
 
 - Fixed rendering of large shapes at high zoom levels, which might dissapear due to integer overflow. This

src/image_util.cpp

@@ -133,27 +133,27 @@ void save_to_file(T const& image,
 void handle_png_options(std::string const& type,
                         png_options & opts)
 {
-    if (type == "png" || type == "png8" || type == "png256")
-    {
-        // stick with defaults
-        return;
-    }
-    else if (type == "png24" || type == "png32")
+    if (type == "png" || type == "png24" || type == "png32")
     {
         opts.paletted = false;
         return;
     }
+    else if (type == "png8" || type == "png256")
+    {
+        opts.paletted = true;
+        return;
+    }
     boost::char_separator<char> sep(":");
     boost::tokenizer< boost::char_separator<char> > tokens(type, sep);
     bool set_colors = false;
     bool set_gamma = false;
     BOOST_FOREACH(std::string const& t, tokens)
     {
-        if (t == "png" || t == "png8")
+        if (t == "png8" || t == "png256")
         {
             opts.paletted = true;
         }
-        else if (t == "png24" || t == "png32")
+        else if (t == "png" || t == "png24" || t == "png32")
         {
             opts.paletted = false;
         }

tests/python_tests/png_encoding_test.py

@@ -18,8 +18,8 @@ if mapnik.has_png():
        os.makedirs(tmp_dir)
 
     opts = [
-    'png',
-    'png:t=0',
+    'png32',
+    'png32:t=0',
     'png8:m=o',
     'png8:m=o:c=1',
     'png8:m=o:t=0',
@@ -32,7 +32,7 @@ if mapnik.has_png():
     'png8:m=h:c=1:t=0',
     'png8:m=h:t=1',
     'png8:m=h:t=2',
-    'png:e=miniz',
+    'png32:e=miniz',
     'png8:e=miniz'
     ]