png++ 0.2.10

reader.hpp
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1/*
2 * Copyright (C) 2007,2008 Alex Shulgin
3 *
4 * This file is part of png++ the C++ wrapper for libpng. PNG++ is free
5 * software; the exact copying conditions are as follows:
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
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10 * 1. Redistributions of source code must retain the above copyright notice,
11 * this list of conditions and the following disclaimer.
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18 * derived from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
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25 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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30 */
31#ifndef PNGPP_READER_HPP_INCLUDED
32#define PNGPP_READER_HPP_INCLUDED
33
34#include <cassert>
35#include "io_base.hpp"
36
37 namespace png
38{
39
64 template< class istream >
65 class reader
66 : public io_base
67 {
68 public:
73 explicit reader(istream& stream)
74 : io_base(png_create_read_struct(PNG_LIBPNG_VER_STRING,
75 static_cast< io_base* >(this),
76 raise_error,
77 0))
78 {
79 png_set_read_fn(m_png, & stream, read_data);
80 }
81
82 ~reader()
83 {
84 png_destroy_read_struct(& m_png,
85 m_info.get_png_info_ptr(),
86 m_end_info.get_png_info_ptr());
87 }
88
93 void read_png()
94 {
95 if (setjmp(png_jmpbuf(m_png)))
96 {
97 throw error(m_error);
98 }
99 png_read_png(m_png,
100 m_info.get_png_info(),
101 /* transforms = */ 0,
102 /* params = */ 0);
103 }
104
108 void read_info()
109 {
110 if (setjmp(png_jmpbuf(m_png)))
111 {
112 throw error(m_error);
113 }
114 m_info.read();
115 }
116
120 void read_row(byte* bytes)
121 {
122 if (setjmp(png_jmpbuf(m_png)))
123 {
124 throw error(m_error);
125 }
126 png_read_row(m_png, bytes, 0);
127 }
128
132 void read_end_info()
133 {
134 if (setjmp(png_jmpbuf(m_png)))
135 {
136 throw error(m_error);
137 }
138 m_end_info.read();
139 }
140
141 void update_info()
142 {
143 m_info.update();
144 }
145
146 private:
147 static void read_data(png_struct* png, byte* data, png_size_t length)
148 {
149 io_base* io = static_cast< io_base* >(png_get_error_ptr(png));
150 reader* rd = static_cast< reader* >(io);
151 rd->reset_error();
152 istream* stream = reinterpret_cast< istream* >(png_get_io_ptr(png));
153 try
154 {
155 stream->read(reinterpret_cast< char* >(data), length);
156 if (!stream->good())
157 {
158 rd->set_error("istream::read() failed");
159 }
160 }
161 catch (std::exception const& error)
162 {
163 rd->set_error(error.what());
164 }
165 catch (...)
166 {
167 assert(!"read_data: caught something wrong");
168 rd->set_error("read_data: caught something wrong");
169 }
170 if (rd->is_error())
171 {
172 rd->raise_error();
173 }
174 }
175 };
176
177} // namespace png
178
179#endif // PNGPP_READER_HPP_INCLUDED
png::error
Exception class to represent runtime errors related to png++ operation.
Definition error.hpp:59
png::io_base
Base class for PNG reader/writer classes.
Definition io_base.hpp:63
png::io_base::m_error
std::string m_error
Definition io_base.hpp:462
png::io_base::m_info
info m_info
Definition io_base.hpp:460
png::io_base::m_png
png_struct * m_png
Definition io_base.hpp:459
png::io_base::set_error
void set_error(char const *message)
Definition io_base.hpp:424
png::io_base::m_end_info
end_info m_end_info
Definition io_base.hpp:461
png::io_base::is_error
bool is_error() const
Definition io_base.hpp:442
png::io_base::raise_error
void raise_error()
Definition io_base.hpp:447
png::io_base::reset_error
void reset_error()
Definition io_base.hpp:430
png::reader
The PNG reader class template. This is the low-level reading interface–use image class or consumer cl...
Definition reader.hpp:67
png::reader::read_row
void read_row(byte *bytes)
Reads a row of image data at a time.
Definition reader.hpp:120
png::reader::read_end_info
void read_end_info()
Reads ending info about PNG image.
Definition reader.hpp:132
png::reader::read_png
void read_png()
Reads the whole PNG data stream into memory. Not particularly useful.
Definition reader.hpp:93
png::reader::read_info
void read_info()
Reads info about PNG image.
Definition reader.hpp:108
png::reader::~reader
~reader()
Definition reader.hpp:82
png::reader::reader
reader(istream &stream)
Constructs a reader prepared to read PNG image from a stream.
Definition reader.hpp:73
png::reader::update_info
void update_info()
Definition reader.hpp:141
io_base.hpp
png
Definition color.hpp:37