add miniz support - closes #1554

CHANGELOG.md

@@ -8,6 +8,8 @@ For a complete change history, see the git log.
 
 ## Future
 
+- Added alternative PNG/ZLIB implementation (`miniz`) that can be enabled with `e=miniz` (#1554)
+
 - Added support for setting zlib `Z_FIXED` strategy with format string: `png:z=fixed`
 
 - Fixed handling of transparency level option in Octree-based PNG encoding (#1556)

include/mapnik/miniz_png.hpp

@@ -0,0 +1,82 @@
+/*****************************************************************************
+ *
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2012 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_MINIZ_PNG_HPP
+#define MAPNIK_MINIZ_PNG_HPP
+
+// mapnik
+#include <mapnik/palette.hpp>
+
+// stl
+#include <vector>
+#include <iostream>
+#include <stdexcept>
+
+/* miniz.c porting issues:
+  - duplicate symbols in python bindings require moving miniz.c include to just cpp file
+  - due to http://code.google.com/p/miniz/issues/detail?id=7
+  - avoiding including miniz.c here requires fwd declaring the two structs below
+  - being able to fwd declare requires removing typedef from struct declarations in miniz.c
+  - being able to fwd declare also requires using pointers to structs
+*/
+
+// TODO: try using #define MINIZ_HEADER_FILE_ONLY
+struct tdefl_output_buffer;
+struct tdefl_compressor;
+
+namespace mapnik { namespace MiniZ {
+
+using mapnik::rgb;
+
+class PNGWriter {
+
+public:
+    PNGWriter(int level, int strategy);
+    ~PNGWriter();
+private:
+    inline void writeUInt32BE(unsigned char *target, unsigned int value);
+    size_t startChunk(const unsigned char header[], size_t length);
+    void finishChunk(size_t start);
+public:
+    void writeIHDR(unsigned int width, unsigned int height, unsigned char pixel_depth);
+    void writePLTE(std::vector<rgb> const& palette);
+    void writetRNS(std::vector<unsigned> const& alpha);
+    template<typename T>
+    void writeIDAT(T const& image);
+    void writeIEND();
+    void toStream(std::ostream& stream);
+
+private:
+    unsigned int flags;
+    tdefl_compressor *compressor;
+    tdefl_output_buffer *buffer;
+    static const unsigned char preamble[];
+    static const unsigned char IHDR_tpl[];
+    static const unsigned char PLTE_tpl[];
+    static const unsigned char tRNS_tpl[];
+    static const unsigned char IDAT_tpl[];
+    static const unsigned char IEND_tpl[];
+};
+
+}}
+
+#endif // MAPNIK_MINIZ_PNG_HPP

include/mapnik/png_io.hpp

@@ -28,6 +28,7 @@
 #include <mapnik/palette.hpp>
 #include <mapnik/octree.hpp>
 #include <mapnik/hextree.hpp>
+#include <mapnik/miniz_png.hpp>
 #include <mapnik/image_data.hpp>
 // zlib
 #include <zlib.h>
@@ -56,8 +57,23 @@ void flush_data (png_structp png_ptr)
 }
 
 template <typename T1, typename T2>
-void save_as_png(T1 & file , T2 const& image, int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY)
+void save_as_png(T1 & file,
+                T2 const& image,
+                int compression = Z_DEFAULT_COMPRESSION,
+                int strategy = Z_DEFAULT_STRATEGY,
+                bool use_miniz = false)
+
 {
+    if (use_miniz)
+    {
+        MiniZ::PNGWriter writer(compression,strategy);
+        writer.writeIHDR(image.width(), image.height(), 32);
+        writer.writeIDAT(image);
+        writer.writeIEND();
+        writer.toStream(file);
+        return;
+    }
+
     png_voidp error_ptr=0;
     png_structp png_ptr=png_create_write_struct(PNG_LIBPNG_VER_STRING,
                                                 error_ptr,0, 0);
@@ -127,8 +143,10 @@ void reduce_8  (T const& in, image_data_8 & out, octree<rgb> trees[], unsigned l
             mapnik::rgb c(U2RED(val), U2GREEN(val), U2BLUE(val));
             byte index = 0;
             int idx = -1;
-            for(int j=levels-1; j>0; j--){
+            for(int j=levels-1; j>0; j--)
-                if (U2ALPHA(val)>=limits[j] && trees[j].colors()>0) {
+            {
+                if (U2ALPHA(val)>=limits[j] && trees[j].colors()>0)
+                {
                     index = idx = trees[j].quantize(c);
                     break;
                 }
@@ -173,8 +191,10 @@ void reduce_4 (T const& in, image_data_8 & out, octree<rgb> trees[], unsigned li
             mapnik::rgb c(U2RED(val), U2GREEN(val), U2BLUE(val));
             byte index = 0;
             int idx=-1;
-            for(int j=levels-1; j>0; j--){
+            for(int j=levels-1; j>0; j--)
-                if (U2ALPHA(val)>=limits[j] && trees[j].colors()>0) {
+            {
+                if (U2ALPHA(val)>=limits[j] && trees[j].colors()>0)
+                {
                     index = idx = trees[j].quantize(c);
                     break;
                 }
@@ -210,8 +230,23 @@ void save_as_png(T & file, std::vector<mapnik::rgb> const& palette,
                  unsigned color_depth,
                  int compression,
                  int strategy,
-                 std::vector<unsigned> const&alpha)
+                 std::vector<unsigned> const&alpha,
+                 bool use_miniz)
 {
+    if (use_miniz)
+    {
+        MiniZ::PNGWriter writer(compression,strategy);
+        // image.width()/height() does not reflect the actual image dimensions; it
+        // refers to the quantized scanlines.
+        writer.writeIHDR(width, height, color_depth);
+        writer.writePLTE(palette);
+        writer.writetRNS(alpha);
+        writer.writeIDAT(image);
+        writer.writeIEND();
+        writer.toStream(file);
+        return;
+    }
+
     png_voidp error_ptr=0;
     png_structp png_ptr=png_create_write_struct(PNG_LIBPNG_VER_STRING,
                                                 error_ptr,0, 0);
@@ -277,8 +312,13 @@ void save_as_png(T & file, std::vector<mapnik::rgb> const& palette,
 }
 
 template <typename T1,typename T2>
-void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 256,
+void save_as_png8_oct(T1 & file,
-                      int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY, int trans_mode = -1)
+                      T2 const& image,
+                      const unsigned max_colors = 256,
+                      int compression = Z_DEFAULT_COMPRESSION,
+                      int strategy = Z_DEFAULT_STRATEGY,
+                      int trans_mode = -1,
+                      bool use_miniz = false)
 {
     // number of alpha ranges in png8 format; 2 results in smallest image with binary transparency
     // 3 is minimum for semitransparency, 4 is recommended, anything else is worse
@@ -288,11 +328,14 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
     unsigned alphaHist[256];//transparency histogram
     unsigned semiCount = 0;//sum of semitransparent pixels
     unsigned meanAlpha = 0;
-    for(int i=0; i<256; i++){
+    for(int i=0; i<256; i++)
+    {
         alphaHist[i] = 0;
     }
-    for (unsigned y = 0; y < height; ++y){
+    for (unsigned y = 0; y < height; ++y)
-        for (unsigned x = 0; x < width; ++x){
+    {
+        for (unsigned x = 0; x < width; ++x)
+        {
             unsigned val = U2ALPHA((unsigned)image.getRow(y)[x]);
             if (trans_mode==0)
                 val=255;
@@ -312,9 +355,11 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
     unsigned alphaHistSum = 0;
     for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
         limits[j] = limits[1];
-    for(unsigned i=1; i<256; i++){
+    for(unsigned i=1; i<256; i++)
+    {
         alphaHistSum += alphaHist[i];
-        for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++){
+        for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
+        {
             if (alphaHistSum<semiCount*(j)/4)
                 limits[j] = i;
         }
@@ -325,15 +370,18 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
     // avoid too wide full opaque range
     if (limits[TRANSPARENCY_LEVELS-1]<212)
         limits[TRANSPARENCY_LEVELS-1]=212;
-    if (TRANSPARENCY_LEVELS==2) {
+    if (TRANSPARENCY_LEVELS==2)
+    {
         limits[1]=127;
     }
     // estimated number of colors from palette assigned to chosen ranges
     unsigned cols[MAX_OCTREE_LEVELS];
     // count colors
-    for(unsigned j=1; j<=TRANSPARENCY_LEVELS; j++) {
+    for(unsigned j=1; j<=TRANSPARENCY_LEVELS; j++)
+    {
         cols[j-1] = 0;
-        for(unsigned i=limits[j-1]; i<limits[j]; i++){
+        for(unsigned i=limits[j-1]; i<limits[j]; i++)
+        {
             cols[j-1] += alphaHist[i];
         }
     }
@@ -342,16 +390,22 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
     if (divCoef==0) divCoef = 1;
     cols[0] = cols[0]>0?1:0; // fully transparent color (one or not at all)
 
-    if (max_colors>=64) {
+    if (max_colors>=64)
+    {
         // give chance less populated but not empty cols to have at least few colors(12)
         unsigned minCols = (12+1)*divCoef/(max_colors-cols[0]);
-        for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++) if (cols[j]>12 && cols[j]<minCols) {
+        for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
+        {
+            if (cols[j]>12 && cols[j]<minCols)
+            {
                 divCoef += minCols-cols[j];
                 cols[j] = minCols;
             }
         }
+    }
     unsigned usedColors = cols[0];
-    for(unsigned j=1; j<TRANSPARENCY_LEVELS-1; j++){
+    for(unsigned j=1; j<TRANSPARENCY_LEVELS-1; j++)
+    {
         cols[j] = cols[j]*(max_colors-cols[0])/divCoef;
         usedColors += cols[j];
     }
@@ -378,8 +432,10 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
             unsigned val = row[x];
 
             // insert to proper tree based on alpha range
-            for(unsigned j=TRANSPARENCY_LEVELS-1; j>0; j--){
+            for(unsigned j=TRANSPARENCY_LEVELS-1; j>0; j--)
-                if (cols[j]>0 && U2ALPHA(val)>=limits[j]) {
+            {
+                if (cols[j]>0 && U2ALPHA(val)>=limits[j])
+                {
                     trees[j].insert(mapnik::rgb(U2RED(val), U2GREEN(val), U2BLUE(val)));
                     break;
                 }
@@ -390,11 +446,16 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
     std::vector<rgb> palette;
     palette.reserve(max_colors);
     if (cols[0])
+    {
         palette.push_back(rgb(0,0,0));
+    }
 
-    for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++) {
+    for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
-        if (cols[j]>0) {
+    {
-            if (leftovers>0) {
+        if (cols[j]>0)
+        {
+            if (leftovers>0)
+            {
                 cols[j] += leftovers;
                 trees[j].setMaxColors(cols[j]);
                 leftovers = 0;
@@ -405,7 +466,8 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
             assert(pal.size() <= max_colors);
             leftovers = cols[j]-pal.size();
             cols[j] = pal.size();
-            for(unsigned i=0; i<pal.size(); i++){
+            for(unsigned i=0; i<pal.size(); i++)
+            {
                 palette.push_back(pal[i]);
             }
             assert(palette.size() <= 256);
@@ -416,14 +478,16 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
     std::vector<unsigned> alphaTable;
     //alphaTable.resize(palette.size());//allow semitransparency also in almost opaque range
     if (trans_mode != 0)
+    {
         alphaTable.resize(palette.size() - cols[TRANSPARENCY_LEVELS-1]);
+    }
 
     if (palette.size() > 16 )
     {
         // >16 && <=256 colors -> write 8-bit color depth
         image_data_8 reduced_image(width,height);
         reduce_8(image, reduced_image, trees, limits, TRANSPARENCY_LEVELS, alphaTable);
-        save_as_png(file,palette,reduced_image,width,height,8,compression,strategy,alphaTable);
+        save_as_png(file,palette,reduced_image,width,height,8,compression,strategy,alphaTable,use_miniz);
     }
     else if (palette.size() == 1)
     {
@@ -432,11 +496,12 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
         unsigned image_height = height;
         image_data_8 reduced_image(image_width,image_height);
         reduce_1(image,reduced_image,trees, limits, alphaTable);
-        if (meanAlpha<255 && cols[0]==0) {
+        if (meanAlpha<255 && cols[0]==0)
+        {
             alphaTable.resize(1);
             alphaTable[0] = meanAlpha;
         }
-        save_as_png(file,palette,reduced_image,width,height,1,compression,strategy,alphaTable);
+        save_as_png(file,palette,reduced_image,width,height,1,compression,strategy,alphaTable,use_miniz);
     }
     else
     {
@@ -445,15 +510,20 @@ void save_as_png8_oct(T1 & file, T2 const& image, const unsigned max_colors = 25
         unsigned image_height = height;
         image_data_8 reduced_image(image_width,image_height);
         reduce_4(image, reduced_image, trees, limits, TRANSPARENCY_LEVELS, alphaTable);
-        save_as_png(file,palette,reduced_image,width,height,4,compression,strategy,alphaTable);
+        save_as_png(file,palette,reduced_image,width,height,4,compression,strategy,alphaTable,use_miniz);
     }
 }
 
 
 template <typename T1, typename T2, typename T3>
-void save_as_png8(T1 & file, T2 const& image, T3 const & tree,
+void save_as_png8(T1 & file,
-                  std::vector<mapnik::rgb> const& palette, std::vector<unsigned> const& alphaTable,
+                  T2 const& image,
-                  int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY)
+                  T3 const & tree,
+                  std::vector<mapnik::rgb> const& palette,
+                  std::vector<unsigned> const& alphaTable,
+                  int compression = Z_DEFAULT_COMPRESSION,
+                  int strategy = Z_DEFAULT_STRATEGY,
+                  bool use_miniz = false)
 {
     unsigned width = image.width();
     unsigned height = image.height();
@@ -462,18 +532,16 @@ void save_as_png8(T1 & file, T2 const& image, T3 const & tree,
     {
         // >16 && <=256 colors -> write 8-bit color depth
         image_data_8 reduced_image(width, height);
-
         for (unsigned y = 0; y < height; ++y)
         {
             mapnik::image_data_32::pixel_type const * row = image.getRow(y);
             mapnik::image_data_8::pixel_type  * row_out = reduced_image.getRow(y);
-
             for (unsigned x = 0; x < width; ++x)
             {
                 row_out[x] = tree.quantize(row[x]);
             }
         }
-        save_as_png(file, palette, reduced_image, width, height, 8, compression, strategy, alphaTable);
+        save_as_png(file, palette, reduced_image, width, height, 8, compression, strategy, alphaTable, use_miniz);
     }
     else if (palette.size() == 1)
     {
@@ -482,7 +550,7 @@ void save_as_png8(T1 & file, T2 const& image, T3 const & tree,
         unsigned image_height = height;
         image_data_8 reduced_image(image_width, image_height);
         reduced_image.set(0);
-        save_as_png(file, palette, reduced_image, width, height, 1, compression, strategy, alphaTable);
+        save_as_png(file, palette, reduced_image, width, height, 1, compression, strategy, alphaTable, use_miniz);
     }
     else
     {
@@ -504,14 +572,19 @@ void save_as_png8(T1 & file, T2 const& image, T3 const & tree,
                 row_out[x>>1] |= index;
             }
         }
-        save_as_png(file, palette, reduced_image, width, height, 4, compression, strategy, alphaTable);
+        save_as_png(file, palette, reduced_image, width, height, 4, compression, strategy, alphaTable, use_miniz);
     }
 }
 
 template <typename T1,typename T2>
-void save_as_png8_hex(T1 & file, T2 const& image, int colors = 256,
+void save_as_png8_hex(T1 & file,
-                      int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY,
+                      T2 const& image,
-                      int trans_mode = -1, double gamma = 2.0)
+                      int colors = 256,
+                      int compression = Z_DEFAULT_COMPRESSION,
+                      int strategy = Z_DEFAULT_STRATEGY,
+                      int trans_mode = -1,
+                      double gamma = 2.0,
+                      bool use_miniz = false)
 {
     unsigned width = image.width();
     unsigned height = image.height();
@@ -546,14 +619,18 @@ void save_as_png8_hex(T1 & file, T2 const& image, int colors = 256,
         alphaTable.push_back(pal[i].a);
     }
 
-    save_as_png8<T1, T2, hextree<mapnik::rgba> >(file, image, tree, palette, alphaTable, compression, strategy);
+    save_as_png8<T1, T2, hextree<mapnik::rgba> >(file, image, tree, palette, alphaTable, compression, strategy, use_miniz);
 }
 
 template <typename T1, typename T2>
-void save_as_png8_pal(T1 & file, T2 const& image, rgba_palette const& pal,
+void save_as_png8_pal(T1 & file,
-                      int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY)
+                      T2 const& image,
+                      rgba_palette const& pal,
+                      int compression = Z_DEFAULT_COMPRESSION,
+                      int strategy = Z_DEFAULT_STRATEGY,
+                      bool use_miniz = false)
 {
-    save_as_png8<T1, T2, rgba_palette>(file, image, pal, pal.palette(), pal.alphaTable(), compression, strategy);
+    save_as_png8<T1, T2, rgba_palette>(file, image, pal, pal.palette(), pal.alphaTable(), compression, strategy, use_miniz);
 }
 
 }

src/build.py

@@ -100,6 +100,7 @@ else: # unix, non-macos
 
 source = Split(
     """
+    miniz_png.cpp
     color.cpp
     css_color_grammar.cpp
     conversions.cpp

src/image_util.cpp

@@ -112,7 +112,8 @@ void handle_png_options(std::string const& type,
                         int * strategy,
                         int * trans_mode,
                         double * gamma,
-                        bool * use_octree)
+                        bool * use_octree,
+                        bool * use_miniz)
 {
     if (type == "png" || type == "png24" || type == "png32")
     {
@@ -139,6 +140,10 @@ void handle_png_options(std::string const& type,
             {
                 *use_octree = true;
             }
+            else if (t == "e=miniz")
+            {
+                *use_miniz = true;
+            }
             else if (boost::algorithm::starts_with(t, "c="))
             {
                 if (*colors < 0)
@@ -174,9 +179,9 @@ void handle_png_options(std::string const& type,
                 */
                 if (!mapnik::util::string2int(t.substr(2),*compression)
                     || *compression < Z_DEFAULT_COMPRESSION
-                    || *compression > Z_BEST_COMPRESSION)
+                    || *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 9 are valid)");
+                    throw ImageWriterException("invalid compression parameter: " + t.substr(2) + " (only -1 through 10 are valid)");
                 }
             }
             else if (boost::algorithm::starts_with(t, "s="))
@@ -208,6 +213,10 @@ void handle_png_options(std::string const& type,
                 }
             }
         }
+        if ((*use_miniz == false) && *compression > Z_BEST_COMPRESSION)
+        {
+            throw ImageWriterException("invalid compression value: (only -1 through 9 are valid)");
+        }
     }
 }
 
@@ -229,6 +238,7 @@ void save_to_stream(T const& image,
             int trans_mode = -1;
             double gamma = -1;
             bool use_octree = true;
+            bool use_miniz = false;
 
             handle_png_options(t,
                                &colors,
@@ -236,16 +246,25 @@ void save_to_stream(T const& image,
                                &strategy,
                                &trans_mode,
                                &gamma,
-                               &use_octree);
+                               &use_octree,
+                               &use_miniz);
 
             if (palette.valid())
-                save_as_png8_pal(stream, image, palette, compression, strategy);
+            {
+                save_as_png8_pal(stream, image, palette, compression, strategy, use_miniz);
+            }
             else if (colors < 0)
-                save_as_png(stream, image, compression, strategy);
+            {
+                save_as_png(stream, image, compression, strategy, use_miniz);
+            }
             else if (use_octree)
-                save_as_png8_oct(stream, image, colors, compression, strategy, trans_mode);
+            {
+                save_as_png8_oct(stream, image, colors, compression, strategy, trans_mode, use_miniz);
+            }
             else
-                save_as_png8_hex(stream, image, colors, compression, strategy, trans_mode, gamma);
+            {
+                save_as_png8_hex(stream, image, colors, compression, strategy, trans_mode, gamma, use_miniz);
+            }
         }
         else if (boost::algorithm::starts_with(t, "tif"))
         {
@@ -280,6 +299,7 @@ void save_to_stream(T const& image,
             int trans_mode = -1;
             double gamma = -1;
             bool use_octree = true;
+            bool use_miniz = false;
 
             handle_png_options(t,
                                &colors,
@@ -287,14 +307,21 @@ void save_to_stream(T const& image,
                                &strategy,
                                &trans_mode,
                                &gamma,
-                               &use_octree);
+                               &use_octree,
+                               &use_miniz);
 
             if (colors < 0)
-                save_as_png(stream, image, compression, strategy);
+            {
+                save_as_png(stream, image, compression, strategy, use_miniz);
+            }
             else if (use_octree)
-                save_as_png8_oct(stream, image, colors, compression, strategy, trans_mode);
+            {
+                save_as_png8_oct(stream, image, colors, compression, strategy, trans_mode, use_miniz);
+            }
             else
-                save_as_png8_hex(stream, image, colors, compression, strategy, trans_mode, gamma);
+            {
+                save_as_png8_hex(stream, image, colors, compression, strategy, trans_mode, gamma, use_miniz);
+            }
         }
         else if (boost::algorithm::starts_with(t, "tif"))
         {

src/miniz_png.cpp

@@ -0,0 +1,313 @@
+/*****************************************************************************
+ *
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2012 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
+ *
+ *****************************************************************************/
+
+// mapnik
+#include <mapnik/palette.hpp>
+#include <mapnik/miniz_png.hpp>
+#include <mapnik/image_data.hpp>
+#include <mapnik/image_view.hpp>
+
+// miniz
+#define MINIZ_NO_ARCHIVE_APIS
+#define MINIZ_NO_STDIO
+#define MINIZ_NO_ZLIB_COMPATIBLE_NAMES
+#include "miniz.c"
+
+// zlib
+#include <zlib.h>
+
+// stl
+#include <vector>
+#include <iostream>
+#include <stdexcept>
+
+namespace mapnik { namespace MiniZ {
+
+PNGWriter::PNGWriter(int level, int strategy)
+{
+    buffer = NULL;
+    compressor = NULL;
+
+    if (level == -1)
+    {
+        level = MZ_DEFAULT_LEVEL; // 6
+    }
+    else if (level < 0 || level > 10)
+    {
+        throw std::runtime_error("compression level must be between 0 and 10");
+    }
+    flags = s_tdefl_num_probes[level]| (level <= 3) ? TDEFL_GREEDY_PARSING_FLAG : 0 | TDEFL_WRITE_ZLIB_HEADER;
+
+    if (strategy == Z_FILTERED) flags |= TDEFL_FILTER_MATCHES;
+    else if (strategy == Z_HUFFMAN_ONLY) flags &= ~TDEFL_MAX_PROBES_MASK;
+    else if (strategy == Z_RLE) flags |= TDEFL_RLE_MATCHES;
+    else if (strategy == Z_FIXED) flags |= TDEFL_FORCE_ALL_STATIC_BLOCKS;
+
+    buffer = (tdefl_output_buffer *)MZ_MALLOC(sizeof(tdefl_output_buffer));
+    if (buffer == NULL)
+    {
+        throw std::bad_alloc();
+    }
+
+    buffer->m_pBuf = NULL;
+    buffer->m_capacity = 8192;
+    buffer->m_expandable = MZ_TRUE;
+    buffer->m_pBuf = (mz_uint8 *)MZ_MALLOC(buffer->m_capacity);
+    if (buffer->m_pBuf == NULL)
+    {
+        throw std::bad_alloc();
+    }
+
+    compressor = (tdefl_compressor *)MZ_MALLOC(sizeof(tdefl_compressor));
+    if (compressor == NULL)
+    {
+        throw std::bad_alloc();
+    }
+
+    // Reset output buffer.
+    buffer->m_size = 0;
+    tdefl_init(compressor, tdefl_output_buffer_putter, buffer, flags);
+
+    // Write preamble.
+    mz_bool status = tdefl_output_buffer_putter(preamble, 8, buffer);
+    if (status != MZ_TRUE)
+    {
+        throw std::bad_alloc();
+    }
+}
+
+PNGWriter::~PNGWriter()
+{
+    if (compressor)
+    {
+        MZ_FREE(compressor);
+    }
+    if (buffer)
+    {
+        if (buffer->m_pBuf)
+        {
+            MZ_FREE(buffer->m_pBuf);
+        }
+        MZ_FREE(buffer);
+    }
+}
+
+inline void PNGWriter::writeUInt32BE(mz_uint8 *target, mz_uint32 value)
+{
+    target[0] = (value >> 24) & 0xFF;
+    target[1] = (value >> 16) & 0xFF;
+    target[2] = (value >> 8) & 0xFF;
+    target[3] = value & 0xFF;
+}
+
+size_t PNGWriter::startChunk(const mz_uint8 header[], size_t length)
+{
+    size_t start = buffer->m_size;
+    mz_bool status = tdefl_output_buffer_putter(header, length, buffer);
+    if (status != MZ_TRUE)
+    {
+        throw std::bad_alloc();
+    }
+    return start;
+}
+
+void PNGWriter::finishChunk(size_t start)
+{
+    // Write chunk length at the beginning of the chunk.
+    size_t payloadLength = buffer->m_size - start - 4 - 4;
+    writeUInt32BE(buffer->m_pBuf + start, payloadLength);
+
+    // Write CRC32 checksum. Don't include the 4-byte length, but /do/ include
+    // the 4-byte chunk name.
+    mz_uint32 crc = mz_crc32(MZ_CRC32_INIT, buffer->m_pBuf + start + 4, payloadLength + 4);
+    mz_uint8 checksum[] = { crc >> 24, crc >> 16, crc >> 8, crc };
+    mz_bool status = tdefl_output_buffer_putter(checksum, 4, buffer);
+    if (status != MZ_TRUE)
+    {
+        throw std::bad_alloc();
+    }
+}
+
+void PNGWriter::writeIHDR(mz_uint32 width, mz_uint32 height, mz_uint8 pixel_depth)
+{
+    // Write IHDR chunk.
+    size_t IHDR = startChunk(IHDR_tpl, 21);
+    writeUInt32BE(buffer->m_pBuf + IHDR + 8, width);
+    writeUInt32BE(buffer->m_pBuf + IHDR + 12, height);
+
+    if (pixel_depth == 32)
+    {
+        // Alpha full color image.
+        buffer->m_pBuf[IHDR + 16] = 8; // bit depth
+        buffer->m_pBuf[IHDR + 17] = 6; // color type (6 == true color with alpha)
+    }
+    else if (pixel_depth == 24)
+    {
+        // Full color image.
+        buffer->m_pBuf[IHDR + 16] = 8; // bit depth
+        buffer->m_pBuf[IHDR + 17] = 2; // color type (2 == true color without alpha)
+    }
+    else
+    {
+        // Paletted image.
+        buffer->m_pBuf[IHDR + 16] = pixel_depth; // bit depth
+        buffer->m_pBuf[IHDR + 17] = 3; // color type (3 == indexed color)
+    }
+
+    buffer->m_pBuf[IHDR + 18] = 0; // compression method
+    buffer->m_pBuf[IHDR + 19] = 0; // filter method
+    buffer->m_pBuf[IHDR + 20] = 0; // interlace method
+    finishChunk(IHDR);
+}
+
+void PNGWriter::writePLTE(std::vector<rgb> const& palette)
+{
+    // Write PLTE chunk.
+    size_t PLTE = startChunk(PLTE_tpl, 8);
+    const mz_uint8 *colors = reinterpret_cast<const mz_uint8 *>(&palette[0]);
+    mz_bool status = tdefl_output_buffer_putter(colors, palette.size() * 3, buffer);
+    if (status != MZ_TRUE)
+    {
+        throw std::bad_alloc();
+    }
+    finishChunk(PLTE);
+}
+
+void PNGWriter::writetRNS(std::vector<unsigned> const& alpha)
+{
+    if (alpha.size() == 0) return;
+
+    std::vector<unsigned char> transparency(alpha.size());
+    unsigned char transparencySize = 0; // Stores position of biggest to nonopaque value.
+    for(unsigned i = 0; i < alpha.size(); i++)
+    {
+        transparency[i] = alpha[i];
+        if (alpha[i] < 255)
+        {
+            transparencySize = i + 1;
+        }
+    }
+    if (transparencySize > 0)
+    {
+        // Write tRNS chunk.
+        size_t tRNS = startChunk(tRNS_tpl, 8);
+        mz_bool status = tdefl_output_buffer_putter(&transparency[0], transparencySize, buffer);
+        if (status != MZ_TRUE)
+        {
+            throw std::bad_alloc();
+        }
+        finishChunk(tRNS);
+    }
+}
+
+template<typename T>
+void PNGWriter::writeIDAT(T const& image)
+{
+    // Write IDAT chunk.
+    size_t IDAT = startChunk(IDAT_tpl, 8);
+    mz_uint8 filter_type = 0;
+    tdefl_status status;
+
+    int bytes_per_pixel = sizeof(typename T::pixel_type);
+    int stride = image.width() * bytes_per_pixel;
+
+    for (unsigned int y = 0; y < image.height(); y++)
+    {
+        // Write filter_type
+        status = tdefl_compress_buffer(compressor, &filter_type, 1, TDEFL_NO_FLUSH);
+        if (status != TDEFL_STATUS_OKAY)
+        {
+            throw std::runtime_error("failed to compress image");
+        }
+
+        // Write scanline
+        status = tdefl_compress_buffer(compressor, (mz_uint8 *)image.getRow(y), stride, TDEFL_NO_FLUSH);
+        if (status != TDEFL_STATUS_OKAY)
+        {
+            throw std::runtime_error("failed to compress image");
+        }
+    }
+
+    status = tdefl_compress_buffer(compressor, NULL, 0, TDEFL_FINISH);
+    if (status != TDEFL_STATUS_DONE)
+    {
+        throw std::runtime_error("failed to compress image");
+    }
+
+    finishChunk(IDAT);
+}
+
+void PNGWriter::writeIEND()
+{
+    // Write IEND chunk.
+    size_t IEND = startChunk(IEND_tpl, 8);
+    finishChunk(IEND);
+}
+
+void PNGWriter::toStream(std::ostream& stream)
+{
+    stream.write((char *)buffer->m_pBuf, buffer->m_size);
+}
+
+const mz_uint8 PNGWriter::preamble[] = {
+    0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a
+};
+
+const mz_uint8 PNGWriter::IHDR_tpl[] = {
+    0x00, 0x00, 0x00, 0x0D, // chunk length
+    'I', 'H', 'D', 'R',     // "IHDR"
+    0x00, 0x00, 0x00, 0x00, // image width (4 bytes)
+    0x00, 0x00, 0x00, 0x00, // image height (4 bytes)
+    0x00,                   // bit depth (1 byte)
+    0x00,                   // color type (1 byte)
+    0x00,                   // compression method (1 byte), has to be 0
+    0x00,                   // filter method (1 byte)
+    0x00                    // interlace method (1 byte)
+};
+
+const mz_uint8 PNGWriter::PLTE_tpl[] = {
+    0x00, 0x00, 0x00, 0x00, // chunk length
+    'P', 'L', 'T', 'E'      // "IDAT"
+};
+
+const mz_uint8 PNGWriter::tRNS_tpl[] = {
+    0x00, 0x00, 0x00, 0x00, // chunk length
+    't', 'R', 'N', 'S'      // "IDAT"
+};
+
+const mz_uint8 PNGWriter::IDAT_tpl[] = {
+    0x00, 0x00, 0x00, 0x00, // chunk length
+    'I', 'D', 'A', 'T'      // "IDAT"
+};
+
+const mz_uint8 PNGWriter::IEND_tpl[] = {
+    0x00, 0x00, 0x00, 0x00, // chunk length
+    'I', 'E', 'N', 'D'      // "IEND"
+};
+
+template void PNGWriter::writeIDAT<image_data_8>(image_data_8 const& image);
+template void PNGWriter::writeIDAT<image_view<image_data_8> >(image_view<image_data_8> const& image);
+template void PNGWriter::writeIDAT<image_data_32>(image_data_32 const& image);
+template void PNGWriter::writeIDAT<image_view<image_data_32> >(image_view<image_data_32> const& image);
+
+}}
+