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/******************************************************************/
/* This file is part of the homework assignments for CSCI-427/527 */
/* at The College of William & Mary and authored by Pieter Peers. */
/* No part of this file, whether altered or in original form, can */
/* be distributed or used outside the context of CSCI-427/527 */
/* without consent of either the College of William & Mary or */
/* Pieter Peers. */
/******************************************************************/
#include "imageIO.ppm.h"
#include "errorMessage.h"
#include <memory>
#include <cassert>
#include <cstdint>
#include <fstream>
#include <algorithm>
//////////////////////
// Helper functions //
//////////////////////
static void skipToNewline(std::ifstream& ifs)
{
while(ifs.get() != '\n' && ifs.good());
}
static void skipComments(std::ifstream& ifs)
{
while(!ifs.eof() && ifs.peek() == '#') skipToNewline(ifs);
}
////////////////
// Import PPM //
////////////////
void importPPM(const std::string& name, image& img)
{
// open file
std::ifstream ifs(name.c_str());
if(!ifs.is_open()) errorMessage("Unable to open file: '%s'.", name.c_str());
// read header
std::string magicMark;
ifs >> magicMark;
skipToNewline(ifs);
if(magicMark != "P6") errorMessage("Unsupported PPM format (%s).", magicMark.c_str());
// read width & height
image::size_type width, height;
skipComments(ifs);
ifs >> width >> height;
skipToNewline(ifs);
// allocate
img = image(width, height);
// check magic number (again)
skipComments(ifs);
ifs >> magicMark;
skipToNewline(ifs);
if(magicMark != "255") errorMessage("Unsupported bit-depth in PPM file (%s).", magicMark.c_str());
// read char buffer
std::unique_ptr<uint8_t[]> tempBuffer(new uint8_t[img.size() * 3]);
ifs.read((char *)(tempBuffer.get()), img.size() * 3);
// convert to image
std::transform(tempBuffer.get(), tempBuffer.get() + (img.size()*3), img.begin()->begin(), [](uint8_t val)
{
return (float)(val) / 255.0f;
});
// Done.
}
////////////////
// Export PPM //
////////////////
void exportPPM(const std::string& name, const image& img)
{
// sanity check
assert(img.width() != 0 && img.height() != 0);
// open file
std::ofstream ofs(name.c_str());
if(!ofs.is_open()) errorMessage("Unable to open file: '%s'.", name.c_str());
// write header
ofs << "P6\n" << img.width() << " " << img.height() << "\n" << "255\n";
// convert to char buffer
std::unique_ptr<uint8_t[]> tempBuffer(new uint8_t[img.size() * 3]);
std::transform(img.begin()->begin(), img.end()->begin(), tempBuffer.get(), [](float val)
{
return (val < 0.0f) ? 0 :
(val > 1.0f) ? 255 :
uint8_t(val*255);
});
// write body
ofs.write((const char*)(tempBuffer.get()), img.size() * 3);
// Done.
}
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