add support for reading jpeg images - closes #518

CHANGELOG

@@ -14,11 +14,13 @@ For a complete change history, see the SVN log.
 Mapnik Trunk
 ------------
 
+- Added support for reading jpeg images (in addition to png/tiff) for image symbolizers (#518)
+
 - Made libjpeg dependency optional at compile time and added mapnik2.has_jpeg() method to check for support in python (#545).
 
 - Fixed reading of PostGIS data on Big Endian systems (#515)
 
-- PostGIS: Added better support for alterative schemas (#500)
+- PostGIS: Added better support for alternative schemas (#500)
 
 - AGG Renderer - Enforced default gamma function on all symbolizers to ensure proper antialiasing
   even when gamma is modified on the PolygonSymbolizer. (#512)

src/SConscript

@@ -113,7 +113,12 @@ source = Split(
     """   
     )
 
-
+if env['JPEG']:
+    source += Split(
+        """
+        jpeg_reader.cpp
+        """)
+        
 if True : # agg backend
     source += Split(
         """

src/jpeg_reader.cpp

@@ -0,0 +1,174 @@
+/*****************************************************************************
+ * 
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2010 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
+ *
+ *****************************************************************************/
+
+//$Id: jpeg_reader.cpp 33 2005-04-04 13:01:03Z dane $
+
+// mapnik
+#include <mapnik/image_reader.hpp>
+#include <mapnik/color.hpp>
+
+// jpeg
+extern "C"
+{
+#include <jpeglib.h>
+}
+
+// mapnik
+
+#include <boost/scoped_array.hpp>
+#include <boost/utility.hpp>
+
+#ifdef MAPNIK_DEBUG
+#include <iostream>
+#endif
+
+namespace mapnik
+{
+    class JpegReader : public image_reader, boost::noncopyable
+    {
+    private:
+        std::string fileName_;
+        unsigned width_;
+        unsigned height_;
+    public:
+        explicit JpegReader(const std::string& fileName);
+        ~JpegReader();
+        unsigned width() const;
+        unsigned height() const;
+        void read(unsigned x,unsigned y,image_data_32& image);	
+    private:
+        void init();
+    };
+  
+    namespace 
+    {
+        image_reader* createJpegReader(const std::string& file)
+        {
+            return new JpegReader(file);
+        }
+        const bool registered = register_image_reader("jpeg",createJpegReader);
+    }
+
+    JpegReader::JpegReader(const std::string& fileName) 
+        : fileName_(fileName),
+          width_(0),
+          height_(0)
+    {
+        init();
+    }
+
+    JpegReader::~JpegReader() {}
+
+    void JpegReader::init()
+    {
+        FILE *fp = fopen(fileName_.c_str(),"rb");
+        if (!fp) throw image_reader_exception("JPEG Reader: cannot open image file " + fileName_);
+
+        struct jpeg_decompress_struct cinfo;
+        struct jpeg_error_mgr jerr;
+                
+        cinfo.err = jpeg_std_error(&jerr);
+
+        jpeg_create_decompress(&cinfo);
+        jpeg_stdio_src(&cinfo, fp);
+        jpeg_read_header(&cinfo, TRUE);
+
+        jpeg_start_decompress(&cinfo);        
+        width_ = cinfo.output_width;
+        height_ = cinfo.output_height;
+        //jpeg_finish_decompress(&cinfo);
+        jpeg_destroy_decompress(&cinfo);
+        fclose(fp);
+    }
+
+    unsigned JpegReader::width() const 
+    {
+        return width_;
+    }
+
+    unsigned JpegReader::height() const 
+    {
+        return height_;
+    }
+    
+    void JpegReader::read(unsigned x0, unsigned y0,image_data_32& image) 
+    {
+        struct jpeg_decompress_struct cinfo;
+
+        FILE *fp = fopen(fileName_.c_str(),"rb");
+        if (!fp) throw image_reader_exception("JPEG Reader: cannot open image file " + fileName_);
+
+        struct jpeg_error_mgr jerr;
+        cinfo.err = jpeg_std_error(&jerr);
+
+        jpeg_create_decompress(&cinfo);
+        jpeg_stdio_src(&cinfo, fp);
+
+        jpeg_read_header(&cinfo, TRUE);
+        if (cinfo.out_color_space == JCS_UNKNOWN)
+            throw image_reader_exception("JPEG Reader: failed to read unknown color space in " + fileName_);
+        
+        jpeg_start_decompress(&cinfo);
+
+        if (cinfo.output_width == 0) {
+          jpeg_destroy_decompress (&cinfo);
+          fclose(fp);
+          throw image_reader_exception("JPEG Reader: failed to read image size of " + fileName_);
+        }
+
+        JSAMPARRAY buffer;
+        int row_stride;
+        unsigned char a,r,g,b;
+        row_stride = cinfo.output_width * cinfo.output_components;
+        buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);
+
+        unsigned w = std::min(unsigned(image.width()),width_);
+        unsigned h = std::min(unsigned(image.height()),height_);
+        
+        unsigned int out_row[w];
+        for (unsigned i=0;i<h;++i)
+        {
+            jpeg_read_scanlines(&cinfo, buffer, 1);
+            if (i>=y0 && i<h) 
+            {
+                for (unsigned int x=0; x<w; x++)
+                {
+                    a = 255; // alpha not supported in jpg
+                    r = buffer[0][cinfo.output_components * x];
+                    if (cinfo.output_components > 2)
+                    {
+                        g = buffer[0][cinfo.output_components*x+1];
+                        b = buffer[0][cinfo.output_components*x+2];
+                    } else {
+                        g = r;
+                        b = r;
+                    }
+                    out_row[x] = color(r, g, b, a).rgba();
+                }
+                image.setRow(i-y0, out_row, w);
+            } 
+        }
+        //jpeg_finish_decompress(&cinfo);
+        jpeg_destroy_decompress(&cinfo);
+        fclose(fp);
+    }
+}