An intial commit of a large set of changes attempting to clean up the way that saving images is processed in image_util.hpp and image_util.cpp.

* Changed the passing of rgba_palette to a shared_ptr in order to better facilitate the use of a visitor pattern.
 * Moved PNG util processing into its own set of files so that image_util_impl.hpp would not have to depend on HAVE_PNG.

.gitignore

@@ -5,6 +5,7 @@
 *.os
 *.so
 *.a
+*.swp
 *.dylib
 plugins/input/*.input
 plugins/input/templates/*.input

bindings/python/mapnik_image.cpp

@@ -83,7 +83,7 @@ PyObject* tostring2(image_32 const & im, std::string const& format)
         (s.data(),s.size());
 }
 
-PyObject* tostring3(image_32 const & im, std::string const& format, mapnik::rgba_palette const& pal)
+PyObject* tostring3(image_32 const & im, std::string const& format, mapnik::rgba_palette_ptr const& pal)
 {
     std::string s = save_to_string(im, format, pal);
     return
@@ -106,7 +106,7 @@ void save_to_file2(mapnik::image_32 const& im, std::string const& filename, std:
     save_to_file(im,filename,type);
 }
 
-void save_to_file3(mapnik::image_32 const& im, std::string const& filename, std::string const& type, mapnik::rgba_palette const& pal)
+void save_to_file3(mapnik::image_32 const& im, std::string const& filename, std::string const& type, mapnik::rgba_palette_ptr const& pal)
 {
     save_to_file(im,filename,type,pal);
 }

bindings/python/mapnik_image_view.cpp

@@ -77,7 +77,7 @@ PyObject* view_tostring2(image_view<image_data_rgba8> const & view, std::string
         (s.data(),s.size());
 }
 
-PyObject* view_tostring3(image_view<image_data_rgba8> const & view, std::string const& format, mapnik::rgba_palette const& pal)
+PyObject* view_tostring3(image_view<image_data_rgba8> const & view, std::string const& format, mapnik::rgba_palette_ptr const& pal)
 {
     std::string s = save_to_string(view, format, pal);
     return
@@ -126,7 +126,7 @@ void save_view2(image_view<image_data_rgba8> const& view,
 void save_view3(image_view<image_data_rgba8> const& view,
                 std::string const& filename,
                 std::string const& type,
-                mapnik::rgba_palette const& pal)
+                mapnik::rgba_palette_ptr const& pal)
 {
     save_to_file(view,filename,type,pal);
 }

bindings/python/mapnik_palette.cpp

@@ -55,7 +55,7 @@ void export_palette ()
 {
     using namespace boost::python;
 
-    class_<mapnik::rgba_palette,
+    class_<std::shared_ptr<mapnik::rgba_palette>,
         std::shared_ptr<mapnik::rgba_palette>,
         boost::noncopyable >("Palette",no_init)
         //, init<std::string,std::string>(

include/mapnik/image_util.hpp

@@ -46,6 +46,7 @@ namespace mapnik {
 class Map;
 class rgba_palette;
 class image_32;
+typedef std::shared_ptr<rgba_palette> rgba_palette_ptr;
 
 class ImageWriterException : public std::exception
 {
@@ -84,7 +85,7 @@ template <typename T>
 MAPNIK_DECL void save_to_file(T const& image,
                               std::string const& filename,
                               std::string const& type,
-                              rgba_palette const& palette);
+                              rgba_palette_ptr const& palette);
 
 // guess type from file extension
 template <typename T>
@@ -94,7 +95,7 @@ MAPNIK_DECL void save_to_file(T const& image,
 template <typename T>
 MAPNIK_DECL void save_to_file(T const& image,
                               std::string const& filename,
-                              rgba_palette const& palette);
+                              rgba_palette_ptr const& palette);
 
 template <typename T>
 MAPNIK_DECL std::string save_to_string(T const& image,
@@ -103,7 +104,7 @@ MAPNIK_DECL std::string save_to_string(T const& image,
 template <typename T>
 MAPNIK_DECL std::string save_to_string(T const& image,
                                        std::string const& type,
-                                       rgba_palette const& palette);
+                                       rgba_palette_ptr const& palette);
 
 template <typename T>
 MAPNIK_DECL void save_to_stream
@@ -111,7 +112,7 @@ MAPNIK_DECL void save_to_stream
     T const& image,
     std::ostream & stream,
     std::string const& type,
-    rgba_palette const& palette
+    rgba_palette_ptr const& palette
 );
 
 template <typename T>
@@ -125,7 +126,7 @@ MAPNIK_DECL void save_to_stream
 template <typename T>
 void save_as_png(T const& image,
                  std::string const& filename,
-                 rgba_palette const& palette);
+                 rgba_palette_ptr const& palette);
 
 #if defined(HAVE_JPEG)
 template <typename T>
@@ -224,7 +225,7 @@ MAPNIK_DECL void save_to_file (image_32 const& image,
 MAPNIK_DECL void save_to_file (image_32 const& image,
                                std::string const& file,
                                std::string const& type,
-                               rgba_palette const& palette);
+                               rgba_palette_ptr const& palette);
 
 ///////////////////////////////////////////////////////////////////////////
 
@@ -234,14 +235,14 @@ MAPNIK_DECL std::string save_to_string(image_32 const& image,
 
 MAPNIK_DECL std::string save_to_string(image_32 const& image,
                                        std::string const& type,
-                                       rgba_palette const& palette);
+                                       rgba_palette_ptr const& palette);
 
 ///////////////////////////////////////////////////////////////////////////
 
 MAPNIK_DECL void save_to_stream(image_32 const& image,
                                 std::ostream & stream,
                                 std::string const& type,
-                                rgba_palette const& palette);
+                                rgba_palette_ptr const& palette);
 
 MAPNIK_DECL void save_to_stream(image_32 const& image,
                                 std::ostream & stream,
@@ -252,7 +253,7 @@ MAPNIK_DECL void save_to_stream(image_32 const& image,
 extern template MAPNIK_DECL void save_to_file<image_data_rgba8>(image_data_rgba8 const&,
                                                       std::string const&,
                                                       std::string const&,
-                                                      rgba_palette const&);
+                                                      rgba_palette_ptr const&);
 
 extern template MAPNIK_DECL void save_to_file<image_data_rgba8>(image_data_rgba8 const&,
                                                       std::string const&,
@@ -260,7 +261,7 @@ extern template MAPNIK_DECL void save_to_file<image_data_rgba8>(image_data_rgba8
 
 extern template MAPNIK_DECL void save_to_file<image_data_rgba8>(image_data_rgba8 const&,
                                                       std::string const&,
-                                                      rgba_palette const&);
+                                                      rgba_palette_ptr const&);
 
 extern template MAPNIK_DECL void save_to_file<image_data_rgba8>(image_data_rgba8 const&,
                                                       std::string const&);
@@ -269,7 +270,7 @@ extern template MAPNIK_DECL void save_to_file<image_data_rgba8>(image_data_rgba8
 extern template MAPNIK_DECL void save_to_file<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                                     std::string const&,
                                                                     std::string const&,
-                                                                    rgba_palette const&);
+                                                                    rgba_palette_ptr const&);
 
 extern template MAPNIK_DECL void save_to_file<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                                     std::string const&,
@@ -277,7 +278,7 @@ extern template MAPNIK_DECL void save_to_file<image_view<image_data_rgba8> > (im
 
 extern template MAPNIK_DECL void save_to_file<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                                     std::string const&,
-                                                                    rgba_palette const&);
+                                                                    rgba_palette_ptr const&);
 
 extern template MAPNIK_DECL void save_to_file<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                                     std::string const&);
@@ -287,21 +288,21 @@ extern template MAPNIK_DECL std::string save_to_string<image_data_rgba8>(image_d
 
 extern template MAPNIK_DECL std::string save_to_string<image_data_rgba8>(image_data_rgba8 const&,
                                                                std::string const&,
-                                                               rgba_palette const&);
+                                                               rgba_palette_ptr const&);
 
 extern template MAPNIK_DECL std::string save_to_string<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                                              std::string const&);
 
 extern template MAPNIK_DECL std::string save_to_string<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                                              std::string const&,
-                                                                             rgba_palette const&);
+                                                                             rgba_palette_ptr const&);
 #ifdef _MSC_VER
 
 template MAPNIK_DECL void save_to_stream<image_data_rgba8>(
     image_data_rgba8 const& image,
     std::ostream & stream,
     std::string const& type,
-    rgba_palette const& palette
+    rgba_palette_ptr const& palette
 );
 
 template MAPNIK_DECL void save_to_stream<image_data_rgba8>(
@@ -314,7 +315,7 @@ template MAPNIK_DECL void save_to_stream<image_view<image_data_rgba8> > (
     image_view<image_data_rgba8> const& image,
     std::ostream & stream,
     std::string const& type,
-    rgba_palette const& palette
+    rgba_palette_ptr const& palette
 );
 
 template MAPNIK_DECL void save_to_stream<image_view<image_data_rgba8> > (

include/mapnik/image_util_png.hpp

@@ -0,0 +1,48 @@
+/*****************************************************************************
+ *
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2014 Artem Pavlenko
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ *****************************************************************************/
+
+#ifndef MAPNIK_IMAGE_UTIL_PNG_HPP
+#define MAPNIK_IMAGE_UTIL_PNG_HPP
+
+// mapnik
+#include <mapnik/util/variant.hpp>
+
+// stl
+#include <string>
+#include <iostream>
+
+namespace mapnik {
+
+struct png_saver : public mapnik::util::static_visitor<> 
+{
+    png_saver(std::ostream &, std::string &, rgba_palette_ptr const& = nullptr);
+    template <typename T>
+    void operator() (T const&) const;
+  private:
+    std::ostream _stream;
+    std::string _t;
+    rgba_palette_ptr _pal; 
+};
+
+} // end ns
+
+#endif // MAPNIK_IMAGE_UTIL_PNG_HPP

include/mapnik/palette.hpp

@@ -130,6 +130,8 @@ private:
     std::vector<unsigned> alpha_pal_;
 };
 
+typedef std::shared_ptr<rgba_palette> rgba_palette_ptr;
+
 } // namespace mapnik
 
 #endif // MAPNIK_PALETTE_HPP

include/mapnik/png_io.hpp

@@ -607,7 +607,7 @@ void save_as_png8(T1 & file,
             mapnik::image_data_gray8::pixel_type  * row_out = reduced_image.getRow(y);
             for (unsigned x = 0; x < width; ++x)
             {
-                row_out[x] = tree.quantize(row[x]);
+                row_out[x] = tree->quantize(row[x]);
             }
         }
         save_as_png(file, palette, reduced_image, width, height, 8, alphaTable, opts);
@@ -635,7 +635,7 @@ void save_as_png8(T1 & file,
             for (unsigned x = 0; x < width; ++x)
             {
 
-                index = tree.quantize(row[x]);
+                index = tree->quantize(row[x]);
                 if (x%2 == 0)
                 {
                     index = index<<4;
@@ -657,14 +657,14 @@ void save_as_png8_hex(T1 & file,
     if (width + height > 3) // at least 3 pixels (hextree implementation requirement)
     {
         // structure for color quantization
-        hextree<mapnik::rgba> tree(opts.colors);
+        std::shared_ptr<hextree<mapnik::rgba>> tree = std::make_shared<hextree<mapnik::rgba>>(opts.colors);
         if (opts.trans_mode >= 0)
         {
-            tree.setTransMode(opts.trans_mode);
+            tree->setTransMode(opts.trans_mode);
         }
         if (opts.gamma > 0)
         {
-            tree.setGamma(opts.gamma);
+            tree->setGamma(opts.gamma);
         }
 
         for (unsigned y = 0; y < height; ++y)
@@ -673,13 +673,13 @@ void save_as_png8_hex(T1 & file,
             for (unsigned x = 0; x < width; ++x)
             {
                 unsigned val = row[x];
-                tree.insert(mapnik::rgba(U2RED(val), U2GREEN(val), U2BLUE(val), U2ALPHA(val)));
+                tree->insert(mapnik::rgba(U2RED(val), U2GREEN(val), U2BLUE(val), U2ALPHA(val)));
             }
         }
 
         //transparency values per palette index
         std::vector<mapnik::rgba> pal;
-        tree.create_palette(pal);
+        tree->create_palette(pal);
         std::vector<mapnik::rgb> palette;
         std::vector<unsigned> alphaTable;
         for (unsigned i=0; i<pal.size(); ++i)
@@ -687,7 +687,7 @@ void save_as_png8_hex(T1 & file,
             palette.push_back(rgb(pal[i].r, pal[i].g, pal[i].b));
             alphaTable.push_back(pal[i].a);
         }
-        save_as_png8<T1, T2, hextree<mapnik::rgba> >(file, image, tree, palette, alphaTable, opts);
+        save_as_png8<T1, T2, std::shared_ptr<hextree<mapnik::rgba>> >(file, image, tree, palette, alphaTable, opts);
     }
     else
     {
@@ -698,10 +698,10 @@ void save_as_png8_hex(T1 & file,
 template <typename T1, typename T2>
 void save_as_png8_pal(T1 & file,
                       T2 const& image,
-                      rgba_palette const& pal,
+                      rgba_palette_ptr const& pal,
                       png_options const& opts)
 {
-    save_as_png8<T1, T2, rgba_palette>(file, image, pal, pal.palette(), pal.alphaTable(), opts);
+    save_as_png8<T1, T2, rgba_palette_ptr>(file, image, pal, pal->palette(), pal->alphaTable(), opts);
 }
 
 }

src/image_util.cpp

@@ -20,18 +20,7 @@
  *
  *****************************************************************************/
 
-#if defined(HAVE_PNG)
-extern "C"
-{
-#include <png.h>
-}
-#endif
-
 // mapnik
-#if defined(HAVE_PNG)
-#include <mapnik/png_io.hpp>
-#endif
-
 #if defined(HAVE_TIFF)
 #include <mapnik/tiff_io.hpp>
 #endif
@@ -45,6 +34,7 @@ extern "C"
 #endif
 
 #include <mapnik/image_util.hpp>
+#include <mapnik/image_util_png.hpp>
 #include <mapnik/image_data.hpp>
 #include <mapnik/graphics.hpp>
 #include <mapnik/memory.hpp>
@@ -52,6 +42,7 @@ extern "C"
 #include <mapnik/palette.hpp>
 #include <mapnik/map.hpp>
 #include <mapnik/util/conversions.hpp>
+#include <mapnik/util/variant.hpp>
 
 #ifdef HAVE_CAIRO
 #include <mapnik/cairo/cairo_renderer.hpp>
@@ -84,7 +75,7 @@ namespace mapnik
 template <typename T>
 std::string save_to_string(T const& image,
                            std::string const& type,
-                           rgba_palette const& palette)
+                           rgba_palette_ptr const& palette)
 {
     std::ostringstream ss(std::ios::out|std::ios::binary);
     save_to_stream(image, ss, type, palette);
@@ -104,7 +95,7 @@ template <typename T>
 void save_to_file(T const& image,
                   std::string const& filename,
                   std::string const& type,
-                  rgba_palette const& palette)
+                  rgba_palette_ptr const& palette)
 {
     std::ofstream file (filename.c_str(), std::ios::out| std::ios::trunc|std::ios::binary);
     if (file)
@@ -127,134 +118,6 @@ void save_to_file(T const& image,
     else throw ImageWriterException("Could not write file to " + filename );
 }
 
-#if defined(HAVE_PNG)
-
-void handle_png_options(std::string const& type,
-                        png_options & opts)
-{
-    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;
-    for (std::string const& t : tokens)
-    {
-        if (t == "png8" || t == "png256")
-        {
-            opts.paletted = true;
-        }
-        else if (t == "png" || t == "png24" || t == "png32")
-        {
-            opts.paletted = false;
-        }
-        else if (t == "m=o")
-        {
-            opts.use_hextree = false;
-        }
-        else if (t == "m=h")
-        {
-            opts.use_hextree = true;
-        }
-        else if (t == "e=miniz")
-        {
-            opts.use_miniz = true;
-        }
-        else if (boost::algorithm::starts_with(t, "c="))
-        {
-            set_colors = true;
-            if (!mapnik::util::string2int(t.substr(2),opts.colors) || opts.colors < 1 || opts.colors > 256)
-            {
-                throw ImageWriterException("invalid color parameter: " + t.substr(2));
-            }
-        }
-        else if (boost::algorithm::starts_with(t, "t="))
-        {
-            if (!mapnik::util::string2int(t.substr(2),opts.trans_mode) || opts.trans_mode < 0 || opts.trans_mode > 2)
-            {
-                throw ImageWriterException("invalid trans_mode parameter: " + t.substr(2));
-            }
-        }
-        else if (boost::algorithm::starts_with(t, "g="))
-        {
-            set_gamma = true;
-            if (!mapnik::util::string2double(t.substr(2),opts.gamma) || opts.gamma < 0)
-            {
-                throw ImageWriterException("invalid gamma parameter: " + t.substr(2));
-            }
-        }
-        else if (boost::algorithm::starts_with(t, "z="))
-        {
-            /*
-              #define Z_NO_COMPRESSION         0
-              #define Z_BEST_SPEED             1
-              #define Z_BEST_COMPRESSION       9
-              #define Z_DEFAULT_COMPRESSION  (-1)
-            */
-            if (!mapnik::util::string2int(t.substr(2),opts.compression)
-                || opts.compression < Z_DEFAULT_COMPRESSION
-                || opts.compression > 10) // use 10 here rather than Z_BEST_COMPRESSION (9) to allow for MZ_UBER_COMPRESSION
-            {
-                throw ImageWriterException("invalid compression parameter: " + t.substr(2) + " (only -1 through 10 are valid)");
-            }
-        }
-        else if (boost::algorithm::starts_with(t, "s="))
-        {
-            std::string s = t.substr(2);
-            if (s == "default")
-            {
-                opts.strategy = Z_DEFAULT_STRATEGY;
-            }
-            else if (s == "filtered")
-            {
-                opts.strategy = Z_FILTERED;
-            }
-            else if (s == "huff")
-            {
-                opts.strategy = Z_HUFFMAN_ONLY;
-            }
-            else if (s == "rle")
-            {
-                opts.strategy = Z_RLE;
-            }
-            else if (s == "fixed")
-            {
-                opts.strategy = Z_FIXED;
-            }
-            else
-            {
-                throw ImageWriterException("invalid compression strategy parameter: " + s);
-            }
-        }
-        else
-        {
-            throw ImageWriterException("unhandled png option: " + t);
-        }
-    }
-    // validation
-    if (!opts.paletted && set_colors)
-    {
-        throw ImageWriterException("invalid color parameter: unavailable for true color (non-paletted) images");
-    }
-    if (!opts.paletted && set_gamma)
-    {
-        throw ImageWriterException("invalid gamma parameter: unavailable for true color (non-paletted) images");
-    }
-    if ((opts.use_miniz == false) && opts.compression > Z_BEST_COMPRESSION)
-    {
-        throw ImageWriterException("invalid compression value: (only -1 through 9 are valid)");
-    }
-}
-#endif
-
 #if defined(HAVE_TIFF)
 void handle_tiff_options(std::string const& type,
                         tiff_config & config)
@@ -666,10 +529,26 @@ void handle_webp_options(std::string const& type,
 #endif
 
 template <typename T>
-void save_to_stream(T const& image,
+void save_to_stream(image_view<T> const& image,
                     std::ostream & stream,
                     std::string const& type,
-                    rgba_palette const& palette)
+                    rgba_palette_ptr const& palette)
+{
+    save_to_stream(image.data(), stream, type, palette);
+}
+
+void save_to_stream(image_32 const& image,
+                    std::ostream & stream,
+                    std::string const& type,
+                    rgba_palette_ptr const& palette)
+{
+    save_to_stream(image.data(), stream, type, palette);
+}
+
+void save_to_stream(image_data_any const& image,
+                    std::ostream & stream,
+                    std::string const& type,
+                    rgba_palette_ptr const& palette)
 {
     if (stream && image.width() > 0 && image.height() > 0)
     {
@@ -677,20 +556,7 @@ void save_to_stream(T const& image,
         std::transform(t.begin(), t.end(), t.begin(), ::tolower);
         if (t == "png" || boost::algorithm::starts_with(t, "png"))
         {
-#if defined(HAVE_PNG)
+            mapnik::util::apply_visitor(png_saver(stream, t, palette), image);
-            if (palette.valid())
-            {
-                png_options opts;
-                handle_png_options(t,opts);
-                save_as_png8_pal(stream, image, palette, opts);
-            }
-            else
-            {
-                save_to_stream(image,stream,type);
-            }
-#else
-            throw ImageWriterException("png output is not enabled in your build of Mapnik");
-#endif
         }
         else if (boost::algorithm::starts_with(t, "tif"))
         {
@@ -705,9 +571,22 @@ void save_to_stream(T const& image,
     else throw ImageWriterException("Could not write to empty stream" );
 }
 
-
 template <typename T>
-void save_to_stream(T const& image,
+void save_to_stream(image_view<T> const& image,
+                    std::ostream & stream,
+                    std::string const& type)
+{
+    save_to_stream(image.data(), stream, type);
+}
+
+void save_to_stream(image_32 const& image,
+                    std::ostream & stream,
+                    std::string const& type)
+{
+    save_to_stream(image.data(), stream, type);
+}
+
+void save_to_stream(image_data_any const& image,
                     std::ostream & stream,
                     std::string const& type)
 {
@@ -717,27 +596,7 @@ void save_to_stream(T const& image,
         std::transform(t.begin(), t.end(), t.begin(), ::tolower);
         if (t == "png" || boost::algorithm::starts_with(t, "png"))
         {
-#if defined(HAVE_PNG)
+            mapnik::util::apply_visitor(png_saver(stream, t), image);
-            png_options opts;
-            handle_png_options(t,opts);
-            if (opts.paletted)
-            {
-                if (opts.use_hextree)
-                {
-                    save_as_png8_hex(stream, image, opts);
-                }
-                else
-                {
-                    save_as_png8_oct(stream, image, opts);
-                }
-            }
-            else
-            {
-                save_as_png(stream, image, opts);
-            }
-#else
-            throw ImageWriterException("png output is not enabled in your build of Mapnik");
-#endif
         }
         else if (boost::algorithm::starts_with(t, "tif"))
         {
@@ -800,7 +659,7 @@ void save_to_file(T const& image, std::string const& filename)
 }
 
 template <typename T>
-void save_to_file(T const& image, std::string const& filename, rgba_palette const& palette)
+void save_to_file(T const& image, std::string const& filename, rgba_palette_ptr const& palette)
 {
     boost::optional<std::string> type = type_from_filename(filename);
     if (type)
@@ -899,21 +758,21 @@ template void save_to_file<image_data_rgba8>(image_data_rgba8 const&,
 template void save_to_file<image_data_rgba8>(image_data_rgba8 const&,
                                           std::string const&,
                                           std::string const&,
-                                          rgba_palette const& palette);
+                                          rgba_palette_ptr const& palette);
 
 template void save_to_file<image_data_rgba8>(image_data_rgba8 const&,
                                           std::string const&);
 
 template void save_to_file<image_data_rgba8>(image_data_rgba8 const&,
                                           std::string const&,
-                                          rgba_palette const& palette);
+                                          rgba_palette_ptr const& palette);
 
 template std::string save_to_string<image_data_rgba8>(image_data_rgba8 const&,
                                                    std::string const&);
 
 template std::string save_to_string<image_data_rgba8>(image_data_rgba8 const&,
                                                    std::string const&,
-                                                   rgba_palette const& palette);
+                                                   rgba_palette_ptr const& palette);
 
 template void save_to_file<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                         std::string const&,
@@ -922,21 +781,21 @@ template void save_to_file<image_view<image_data_rgba8> > (image_view<image_data
 template void save_to_file<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                         std::string const&,
                                                         std::string const&,
-                                                        rgba_palette const& palette);
+                                                        rgba_palette_ptr const& palette);
 
 template void save_to_file<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                         std::string const&);
 
 template void save_to_file<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                         std::string const&,
-                                                        rgba_palette const& palette);
+                                                        rgba_palette_ptr const& palette);
 
 template std::string save_to_string<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                                  std::string const&);
 
 template std::string save_to_string<image_view<image_data_rgba8> > (image_view<image_data_rgba8> const&,
                                                                  std::string const&,
-                                                                 rgba_palette const& palette);
+                                                                 rgba_palette_ptr const& palette);
 
 void save_to_file(image_32 const& image,std::string const& file)
 {
@@ -953,7 +812,7 @@ void save_to_file (image_32 const& image,
 void save_to_file (image_32 const& image,
                    std::string const& file,
                    std::string const& type,
-                   rgba_palette const& palette)
+                   rgba_palette_ptr const& palette)
 {
     save_to_file<image_data_rgba8>(image.data(), file, type, palette);
 }
@@ -966,7 +825,7 @@ std::string save_to_string(image_32 const& image,
 
 std::string save_to_string(image_32 const& image,
                            std::string const& type,
-                           rgba_palette const& palette)
+                           rgba_palette_ptr const& palette)
 {
     return save_to_string<image_data_rgba8>(image.data(), type, palette);
 }

src/image_util_png.cpp

@@ -0,0 +1,241 @@
+/*****************************************************************************
+ *
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2014 Artem Pavlenko
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ *****************************************************************************/
+
+#if defined(HAVE_PNG)
+extern "C"
+{
+#include <png.h>
+}
+#endif
+
+// mapnik
+#if defined(HAVE_PNG)
+#include <mapnik/png_io.hpp>
+#endif
+
+#include <mapnik/image_util_png.hpp>
+#include <mapnik/image_data.hpp>
+
+// boost
+#include <boost/tokenizer.hpp>
+
+// stl
+#include <string>
+#include <iostream>
+
+namespace mapnik
+{
+
+#if defined(HAVE_PNG)
+
+void handle_png_options(std::string const& type,
+                        png_options & opts)
+{
+    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;
+    for (std::string const& t : tokens)
+    {
+        if (t == "png8" || t == "png256")
+        {
+            opts.paletted = true;
+        }
+        else if (t == "png" || t == "png24" || t == "png32")
+        {
+            opts.paletted = false;
+        }
+        else if (t == "m=o")
+        {
+            opts.use_hextree = false;
+        }
+        else if (t == "m=h")
+        {
+            opts.use_hextree = true;
+        }
+        else if (t == "e=miniz")
+        {
+            opts.use_miniz = true;
+        }
+        else if (boost::algorithm::starts_with(t, "c="))
+        {
+            set_colors = true;
+            if (!mapnik::util::string2int(t.substr(2),opts.colors) || opts.colors < 1 || opts.colors > 256)
+            {
+                throw ImageWriterException("invalid color parameter: " + t.substr(2));
+            }
+        }
+        else if (boost::algorithm::starts_with(t, "t="))
+        {
+            if (!mapnik::util::string2int(t.substr(2),opts.trans_mode) || opts.trans_mode < 0 || opts.trans_mode > 2)
+            {
+                throw ImageWriterException("invalid trans_mode parameter: " + t.substr(2));
+            }
+        }
+        else if (boost::algorithm::starts_with(t, "g="))
+        {
+            set_gamma = true;
+            if (!mapnik::util::string2double(t.substr(2),opts.gamma) || opts.gamma < 0)
+            {
+                throw ImageWriterException("invalid gamma parameter: " + t.substr(2));
+            }
+        }
+        else if (boost::algorithm::starts_with(t, "z="))
+        {
+            /*
+              #define Z_NO_COMPRESSION         0
+              #define Z_BEST_SPEED             1
+              #define Z_BEST_COMPRESSION       9
+              #define Z_DEFAULT_COMPRESSION  (-1)
+            */
+            if (!mapnik::util::string2int(t.substr(2),opts.compression)
+                || opts.compression < Z_DEFAULT_COMPRESSION
+                || opts.compression > 10) // use 10 here rather than Z_BEST_COMPRESSION (9) to allow for MZ_UBER_COMPRESSION
+            {
+                throw ImageWriterException("invalid compression parameter: " + t.substr(2) + " (only -1 through 10 are valid)");
+            }
+        }
+        else if (boost::algorithm::starts_with(t, "s="))
+        {
+            std::string s = t.substr(2);
+            if (s == "default")
+            {
+                opts.strategy = Z_DEFAULT_STRATEGY;
+            }
+            else if (s == "filtered")
+            {
+                opts.strategy = Z_FILTERED;
+            }
+            else if (s == "huff")
+            {
+                opts.strategy = Z_HUFFMAN_ONLY;
+            }
+            else if (s == "rle")
+            {
+                opts.strategy = Z_RLE;
+            }
+            else if (s == "fixed")
+            {
+                opts.strategy = Z_FIXED;
+            }
+            else
+            {
+                throw ImageWriterException("invalid compression strategy parameter: " + s);
+            }
+        }
+        else
+        {
+            throw ImageWriterException("unhandled png option: " + t);
+        }
+    }
+    // validation
+    if (!opts.paletted && set_colors)
+    {
+        throw ImageWriterException("invalid color parameter: unavailable for true color (non-paletted) images");
+    }
+    if (!opts.paletted && set_gamma)
+    {
+        throw ImageWriterException("invalid gamma parameter: unavailable for true color (non-paletted) images");
+    }
+    if ((opts.use_miniz == false) && opts.compression > Z_BEST_COMPRESSION)
+    {
+        throw ImageWriterException("invalid compression value: (only -1 through 9 are valid)");
+    }
+}
+#endif
+
+png_saver::png_saver(std::ostream & stream, std::string const& t, rgba_palette_ptr const& pal):
+    _stream(stream), _t(t), _pal(pal) {}
+
+void png_saver::operator() (mapnik::image_data_rgba8 const& image) const
+{
+#if defined(HAVE_PNG)
+    png_options opts;
+    handle_png_options(_t, opts);
+    if (_pal && _pal->valid())
+    {
+        png_options opts;
+        handle_png_options(t,opts);
+        save_as_png8_pal(stream, image, _pal, opts);
+    }
+    else if (opts.paletted)
+    {
+        if (opts.use_hextree)
+        {
+            save_as_png8_hex(_stream, image, opts);
+        }
+        else
+        {
+            save_as_png8_oct(_stream, image, opts);
+        }
+    }
+    else
+    {
+        save_as_png(_stream, image, opts);
+    }
+#else
+    throw ImageWriterException("png output is not enabled in your build of Mapnik");
+#endif
+}
+
+void png_saver::operator() (mapnik::image_data_gray8 const& image) const
+{
+#if defined(HAVE_PNG)
+    png_options opts;
+    handle_png_options(_t, opts);
+    save_as_png(_stream, image, opts);
+#else
+    throw ImageWriterException("png output is not enabled in your build of Mapnik");
+#endif
+}
+
+void png_saver::operator() (mapnik::image_data_gray16 const& image) const
+{
+#if defined(HAVE_PNG)
+    png_options opts;
+    handle_png_options(_t, opts);
+    save_as_png(_stream, image, opts);
+#else
+    throw ImageWriterException("png output is not enabled in your build of Mapnik");
+#endif
+}
+
+void png_saver::operator() (mapnik::image_data_gray32f const& image) const
+{
+#if defined(HAVE_PNG)
+    png_options opts;
+    handle_png_options(_t, opts);
+    save_as_png(_stream, image, opts);
+#else
+    throw ImageWriterException("png output is not enabled in your build of Mapnik");
+#endif
+}