264 lines
7.6 KiB
C++
264 lines
7.6 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2011 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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#include <mapnik/debug.hpp>
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#include <mapnik/image_reader.hpp>
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#include <mapnik/noncopyable.hpp>
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extern "C"
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{
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#include <png.h>
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}
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#include <boost/scoped_array.hpp>
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namespace mapnik
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{
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class png_reader : public image_reader
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{
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struct png_file_guard
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{
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png_file_guard(FILE * fd)
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: fd_(fd) {}
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~png_file_guard()
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{
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if (fd_) fclose(fd_);
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}
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FILE * fd_;
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};
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struct png_struct_guard
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{
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png_struct_guard(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
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: p_(png_ptr_ptr),
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i_(info_ptr_ptr) {}
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~png_struct_guard()
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{
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png_destroy_read_struct(p_,i_,0);
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}
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png_structpp p_;
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png_infopp i_;
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};
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private:
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std::string fileName_;
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unsigned width_;
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unsigned height_;
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int bit_depth_;
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int color_type_;
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public:
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explicit png_reader(std::string const& fileName);
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~png_reader();
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unsigned width() const;
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unsigned height() const;
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bool premultiplied_alpha() const { return false; } //http://www.libpng.org/pub/png/spec/1.1/PNG-Rationale.html
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void read(unsigned x,unsigned y,image_data_32& image);
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private:
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void init();
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};
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namespace
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{
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image_reader* create_png_reader(std::string const& file)
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{
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return new png_reader(file);
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}
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const bool registered = register_image_reader("png",create_png_reader);
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}
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png_reader::png_reader(std::string const& fileName)
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: fileName_(fileName),
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width_(0),
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height_(0),
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bit_depth_(0),
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color_type_(0)
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{
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init();
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}
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png_reader::~png_reader() {}
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void user_error_fn(png_structp png_ptr, png_const_charp error_msg)
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{
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throw image_reader_exception("failed to read invalid png");
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}
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void user_warning_fn(png_structp png_ptr, png_const_charp warning_msg)
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{
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MAPNIK_LOG_DEBUG(png_reader) << "libpng warning: '" << warning_msg << "'";
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}
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static void
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png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
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{
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png_size_t check;
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check = (png_size_t)fread(data, (png_size_t)1, length,
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(FILE *)png_get_io_ptr(png_ptr));
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if (check != length)
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{
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png_error(png_ptr, "Read Error");
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}
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}
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void png_reader::init()
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{
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FILE *fp=fopen(fileName_.c_str(),"rb");
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if (!fp) throw image_reader_exception("cannot open image file "+fileName_);
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png_file_guard guard(fp);
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png_byte header[8];
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memset(header,0,8);
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if ( fread(header,1,8,fp) != 8)
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{
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throw image_reader_exception("Could not read " + fileName_);
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}
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int is_png=!png_sig_cmp(header,0,8);
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if (!is_png)
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{
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throw image_reader_exception(fileName_ + " is not a png file");
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}
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png_structp png_ptr = png_create_read_struct
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(PNG_LIBPNG_VER_STRING,0,0,0);
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if (!png_ptr)
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{
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throw image_reader_exception("failed to allocate png_ptr");
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}
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// catch errors in a custom way to avoid the need for setjmp
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png_set_error_fn(png_ptr, png_get_error_ptr(png_ptr), user_error_fn, user_warning_fn);
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png_infop info_ptr;
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png_struct_guard sguard(&png_ptr,&info_ptr);
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info_ptr = png_create_info_struct(png_ptr);
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if (!info_ptr) throw image_reader_exception("failed to create info_ptr");
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png_set_read_fn(png_ptr, (png_voidp)fp, png_read_data);
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png_set_sig_bytes(png_ptr,8);
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png_read_info(png_ptr, info_ptr);
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png_uint_32 width, height;
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png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth_, &color_type_,0,0,0);
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width_=width;
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height_=height;
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MAPNIK_LOG_DEBUG(png_reader) << "png_reader: bit_depth=" << bit_depth_ << ",color_type=" << color_type_;
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}
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unsigned png_reader::width() const
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{
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return width_;
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}
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unsigned png_reader::height() const
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{
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return height_;
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}
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void png_reader::read(unsigned x0, unsigned y0,image_data_32& image)
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{
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FILE *fp=fopen(fileName_.c_str(),"rb");
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if (!fp) throw image_reader_exception("cannot open image file "+fileName_);
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png_file_guard guard(fp);
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png_structp png_ptr = png_create_read_struct
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(PNG_LIBPNG_VER_STRING,0,0,0);
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if (!png_ptr)
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{
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throw image_reader_exception("failed to allocate png_ptr");
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}
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// catch errors in a custom way to avoid the need for setjmp
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png_set_error_fn(png_ptr, png_get_error_ptr(png_ptr), user_error_fn, user_warning_fn);
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png_infop info_ptr;
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png_struct_guard sguard(&png_ptr,&info_ptr);
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info_ptr = png_create_info_struct(png_ptr);
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if (!info_ptr) throw image_reader_exception("failed to create info_ptr");
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png_set_read_fn(png_ptr, (png_voidp)fp, png_read_data);
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png_read_info(png_ptr, info_ptr);
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if (color_type_ == PNG_COLOR_TYPE_PALETTE)
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png_set_expand(png_ptr);
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if (color_type_ == PNG_COLOR_TYPE_GRAY && bit_depth_ < 8)
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png_set_expand(png_ptr);
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if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
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png_set_expand(png_ptr);
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if (bit_depth_ == 16)
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png_set_strip_16(png_ptr);
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if (color_type_ == PNG_COLOR_TYPE_GRAY ||
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color_type_ == PNG_COLOR_TYPE_GRAY_ALPHA)
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png_set_gray_to_rgb(png_ptr);
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// quick hack -- only work in >=libpng 1.2.7
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png_set_add_alpha(png_ptr,0xff,PNG_FILLER_AFTER); //rgba
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double gamma;
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if (png_get_gAMA(png_ptr, info_ptr, &gamma))
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png_set_gamma(png_ptr, 2.2, gamma);
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if (x0 == 0 && y0 == 0 && image.width() >= width_ && image.height() >= height_)
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{
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if (png_get_interlace_type(png_ptr,info_ptr) == PNG_INTERLACE_ADAM7)
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{
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png_set_interlace_handling(png_ptr); // FIXME: libpng bug?
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// according to docs png_read_image
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// "..automatically handles interlacing,
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// so you don't need to call png_set_interlace_handling()"
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}
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png_read_update_info(png_ptr, info_ptr);
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// we can read whole image at once
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// alloc row pointers
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boost::scoped_array<png_byte*> rows(new png_bytep[height_]);
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for (unsigned i=0; i<height_; ++i)
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rows[i] = (png_bytep)image.getRow(i);
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png_read_image(png_ptr, rows.get());
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}
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else
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{
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png_read_update_info(png_ptr, info_ptr);
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unsigned w=std::min(unsigned(image.width()),width_ - x0);
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unsigned h=std::min(unsigned(image.height()),height_ - y0);
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unsigned rowbytes=png_get_rowbytes(png_ptr, info_ptr);
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boost::scoped_array<png_byte> row(new png_byte[rowbytes]);
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//START read image rows
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for (unsigned i = 0;i < height_; ++i)
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{
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png_read_row(png_ptr,row.get(),0);
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if (i >= y0 && i < (y0 + h))
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{
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image.setRow(i-y0,reinterpret_cast<unsigned*>(&row[x0 * 4]),w);
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}
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}
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//END
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}
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png_read_end(png_ptr,0);
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}
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}
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