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@srsbiz srsbiz/pgm.p5.php
Last active Dec 12, 2015

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Read and write PGM P5 images in php
<?php
class PGM{
public
$magicNumber = '',
$pixelArray = array(),
$width = 0,
$height = 0,
$grayMax = 0,
$createdBy = '';
public function loadPGM($filename){
$this->grayMax = $this->height = $this->width = $this->magicNumber = 0;
$this->pixelArray = array();
$fh = fopen($filename, 'rb');
while($line = fgets($fh)){
if(strpos($line, '#') === 0){
continue;
}
if(!$this->grayMax){
$arr = preg_split('/\s+/', trim($line));
if($arr && !$this->magicNumber){
$this->magicNumber = array_shift($arr);
if($this->magicNumber != 'P5'){
throw new Exception("Unsupported PGM version");
}
}
if($arr && !$this->width)
$this->width = array_shift($arr);
if($arr && !$this->height)
$this->height = array_shift($arr);
if($arr && !$this->grayMax)
$this->grayMax = array_shift($arr);
}else{
$unpackMethod = ($this->grayMax > 255)?'n*':'C*';
foreach(unpack($unpackMethod, $line) as $pixel){
$this->pixelArray[] = $pixel;
}
}
}
fclose($fh);
}
public function savePGM($filename){
$fh = fopen($filename, 'wb');
$this->magicNumber = 'P5';
fwrite($fh, "{$this->magicNumber}\n");
if($this->createdBy){
fwrite($fh, "# {$this->createdBy}\n");
}
fwrite($fh, "{$this->width} {$this->height}\n");
fwrite($fh, "{$this->grayMax}\n");
$packMethod = ($this->grayMax > 255)?'n*':'C*';
fwrite($fh, call_user_func_array('pack', array_merge(array($packMethod), $this->pixelArray)));
fclose($fh);
}
}
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