add image_reader abstraction layer to hanfle multiple image formats
(work-in-progress)
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artemp
279
platform/default/png_reader.cpp
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279
platform/default/png_reader.cpp
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#include "mbgl/util/image_reader.hpp"
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#include <iostream>
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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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// boost
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#pragma GCC diagnostic push
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//#pragma GCC diagnostic ignored "-Wunused-local-typedef"
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#include <boost/iostreams/device/file.hpp>
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#include <boost/iostreams/device/array.hpp>
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#include <boost/iostreams/stream.hpp>
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#pragma GCC diagnostic pop
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// stl
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#include <cstring>
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#include <memory>
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namespace mbgl { namespace util {
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template <typename T>
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class png_reader : public image_reader
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{
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using source_type = T;
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using input_stream = boost::iostreams::stream<source_type>;
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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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source_type source_;
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input_stream stream_;
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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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bool has_alpha_;
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public:
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explicit png_reader(std::string const& file_name);
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png_reader(char const* data, std::size_t size);
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~png_reader();
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unsigned width() const;
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unsigned height() const;
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inline bool has_alpha() const { return has_alpha_; }
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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, unsigned width, unsigned height, char * image);
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private:
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void init();
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static void png_read_data(png_structp png_ptr, png_bytep data, png_size_t length);
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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<boost::iostreams::file_source>(file);
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}
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image_reader* create_png_reader2(char const * data, std::size_t size)
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{
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return new png_reader<boost::iostreams::array_source>(data, size);
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}
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const bool registered = register_image_reader("png",create_png_reader);
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const bool registered2 = register_image_reader("png", create_png_reader2);
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}
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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(std::string("failed to read invalid png: '") + error_msg + "'");
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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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fprintf(stderr, "ImageReader (PNG): %s\n", warning_msg);
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}
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template <typename T>
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void png_reader<T>::png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
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{
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input_stream * fin = reinterpret_cast<input_stream*>(png_get_io_ptr(png_ptr));
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fin->read(reinterpret_cast<char*>(data), length);
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std::streamsize read_count = fin->gcount();
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if (read_count < 0 || static_cast<png_size_t>(read_count) != 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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template <typename T>
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png_reader<T>::png_reader(std::string const& file_name)
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: source_(file_name,std::ios_base::in | std::ios_base::binary),
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stream_(source_),
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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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has_alpha_(false)
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{
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if (!source_.is_open()) throw image_reader_exception("PNG reader: cannot open file '"+ file_name + "'");
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if (!stream_) throw image_reader_exception("PNG reader: cannot open file '"+ file_name + "'");
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init();
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}
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template <typename T>
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png_reader<T>::png_reader(char const* data, std::size_t size)
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: source_(data,size),
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stream_(source_),
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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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has_alpha_(false)
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{
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if (!stream_) throw image_reader_exception("PNG reader: cannot open image stream");
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init();
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}
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template <typename T>
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png_reader<T>::~png_reader() {}
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template <typename T>
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void png_reader<T>::init()
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{
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png_byte header[8];
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std::memset(header,0,8);
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stream_.read(reinterpret_cast<char*>(header),8);
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if ( stream_.gcount() != 8)
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{
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throw image_reader_exception("PNG reader: Could not read image");
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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("File or stream is not a png");
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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)&stream_, 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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has_alpha_ = (color_type_ & PNG_COLOR_MASK_ALPHA) || png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS);
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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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template <typename T>
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unsigned png_reader<T>::width() const
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{
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return width_;
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}
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template <typename T>
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unsigned png_reader<T>::height() const
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{
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return height_;
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}
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template <typename T>
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void png_reader<T>::read(unsigned x0, unsigned y0, unsigned width, unsigned height, char * image)
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{
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stream_.clear();
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stream_.seekg(0, std::ios_base::beg);
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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)&stream_, 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 && width >= width_ && 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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const std::unique_ptr<png_bytep[]> rows(new png_bytep[height_]);
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for (unsigned row = 0; row < height_; ++row)
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rows[row] = (png_bytep)image + row * width_ ;
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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(width, width_ - x0);
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unsigned h=std::min(height, height_ - y0);
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unsigned rowbytes=png_get_rowbytes(png_ptr, info_ptr);
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const std::unique_ptr<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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//std::copy(image, buf + size, pData_ + i * width);
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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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