png++ 0.2.9
consumer.hpp
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1/*
2 * Copyright (C) 2007,2008 Alex Shulgin
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31#ifndef PNGPP_CONSUMER_HPP_INCLUDED
32#define PNGPP_CONSUMER_HPP_INCLUDED
33
34#include <cassert>
35#include <stdexcept>
36#include <iostream>
37#include <istream>
38
39#include "config.hpp"
40#include "error.hpp"
41#include "streaming_base.hpp"
42#include "reader.hpp"
43#include "pixel_buffer.hpp"
44
45namespace png
46{
47
121 template< typename pixel,
122 class pixcon,
123 class info_holder = def_image_info_holder,
124 bool interlacing_supported = false >
126 : public streaming_base< pixel, info_holder >
127 {
128 public:
130
135 {
136 void operator()(io_base&) const {}
137 };
138
143 template< typename istream >
144 void read(istream& stream)
145 {
146 read(stream, transform_identity());
147 }
148
157 template< typename istream, class transformation >
158 void read(istream& stream, transformation const& transform)
159 {
160 reader< istream > rd(stream);
161 rd.read_info();
162 transform(rd);
163
164#if __BYTE_ORDER == __LITTLE_ENDIAN
166 {
167#ifdef PNG_READ_SWAP_SUPPORTED
168 rd.set_swap();
169#else
170 throw error("Cannot read 16-bit image: recompile with PNG_READ_SWAP_SUPPORTED.");
171#endif
172 }
173#endif
174
175 // interlace handling _must_ be set up prior to info update
176 size_t pass_count;
178 {
179#ifdef PNG_READ_INTERLACING_SUPPORTED
180 pass_count = rd.set_interlace_handling();
181#else
182 throw error("Cannot read interlaced image: interlace handling disabled.");
183#endif
184 }
185 else
186 {
187 pass_count = 1;
188 }
189
190 rd.update_info();
191 if (rd.get_color_type() != traits::get_color_type()
192 || rd.get_bit_depth() != traits::get_bit_depth())
193 {
194 throw std::logic_error("color type and/or bit depth mismatch"
195 " in png::consumer::read()");
196 }
197
198 this->get_info() = rd.get_image_info();
199
200 pixcon* pixel_con = static_cast< pixcon* >(this);
201 if (pass_count > 1 && !interlacing_supported)
202 {
203 skip_interlaced_rows(rd, pass_count);
204 pass_count = 1;
205 }
206 read_rows(rd, pass_count, pixel_con);
207
208 rd.read_end_info();
209 }
210
211 protected:
213
219 : base(info)
220 {
221 }
222
223 private:
224 template< typename istream >
225 void skip_interlaced_rows(reader< istream >& rd, size_t pass_count)
226 {
227 typedef std::vector< pixel > row;
228 typedef row_traits< row > row_traits_type;
229 row dummy_row(this->get_info().get_width());
230 for (size_t pass = 1; pass < pass_count; ++pass)
231 {
232 rd.read_row(reinterpret_cast< byte* >
233 (row_traits_type::get_data(dummy_row)));
234 }
235 }
236
237 template< typename istream >
238 void read_rows(reader< istream >& rd, size_t pass_count,
239 pixcon* pixel_con)
240 {
241 for (size_t pass = 0; pass < pass_count; ++pass)
242 {
243 pixel_con->reset(pass);
244
245 for (uint_32 pos = 0; pos < this->get_info().get_height(); ++pos)
246 {
247 rd.read_row(pixel_con->get_next_row(pos));
248 }
249 }
250 }
251 };
252
253} // namespace png
254
255#endif // PNGPP_CONSUMER_HPP_INCLUDED
Pixel consumer class template.
Definition: consumer.hpp:127
void read(istream &stream, transformation const &transform)
Reads an image from the stream using custom io transformation.
Definition: consumer.hpp:158
consumer(image_info &info)
Constructs a consumer object using passed image_info object to store image information.
Definition: consumer.hpp:218
void read(istream &stream)
Reads an image from the stream using default io transformation.
Definition: consumer.hpp:144
pixel_traits< pixel > traits
Definition: consumer.hpp:129
streaming_base< pixel, info_holder > base
Definition: consumer.hpp:212
Exception class to represent runtime errors related to png++ operation.
Definition: error.hpp:59
Holds information about PNG image.
Definition: image_info.hpp:48
uint_32 get_height() const
Definition: image_info.hpp:77
Holds information about PNG image. Adapter class for IO image operations.
Definition: info.hpp:48
Base class for PNG reader/writer classes.
Definition: io_base.hpp:63
int set_interlace_handling() const
Definition: io_base.hpp:376
int get_bit_depth() const
Definition: io_base.hpp:150
image_info const & get_image_info() const
Definition: io_base.hpp:97
color_type get_color_type() const
Definition: io_base.hpp:140
void set_swap() const
Definition: io_base.hpp:312
interlace_type get_interlace_type() const
Definition: io_base.hpp:160
The PNG reader class template. This is the low-level reading interface–use image class or consumer cl...
Definition: reader.hpp:67
void read_row(byte *bytes)
Reads a row of image data at a time.
Definition: reader.hpp:120
void read_end_info()
Reads ending info about PNG image.
Definition: reader.hpp:132
void read_info()
Reads info about PNG image.
Definition: reader.hpp:108
void update_info()
Definition: reader.hpp:141
The pixel row traits class template. Provides a common way to get starting address of the row for pac...
Definition: pixel_buffer.hpp:53
A base class template for consumer and generator classes. Provides default reset() method implementat...
Definition: streaming_base.hpp:91
image_info const & get_info() const
Definition: streaming_base.hpp:107
Definition: color.hpp:37
@ interlace_none
Definition: types.hpp:81
png_uint_32 uint_32
Definition: types.hpp:41
The default io transformation: does nothing.
Definition: consumer.hpp:135
void operator()(io_base &) const
Definition: consumer.hpp:136
Pixel traits class template.
Definition: pixel_traits.hpp:48