/**
* Builds the requested subfield image.
*
* Normalizing request & native image scales:
*
* When comparing the requested or "desired" image scale for the subfield
* image to the native or "actual" image scale of the source image, it is
* convenient to create a variable called "desiredToActual" which
* represents the ratio of the desired scale to the actual scale.
*
* There are three possible cases which may occur:
*
* 1) desiredToActual = 1
*
* In this case the subfield requested is at the natural image
* scale. No resizing is necessary.
*
* 2) desiredToActual < 1
*
* The subfield requested is at a lower image scale (HIGHER
* quality) than the source JP2.
*
* 3) desiredToActual > 1
*
* The subfield requested is at a higher image scale (LOWER
* quality) than the source JP2.
*
* @TODO: Normalize quality scale.
* @TODO: Create a cleanup array with names of files to be wiped after
* processing is complete?
* @TODO: Move generation of intermediate file to separate method
*
* @return void
*/
protected function build()
{
/*
* Need to extend the time limit that writeImage() can use so it
* doesn't throw fatal errors when movie frames are being made.
* It seems that even if this particular instance of writeImage
* doesn't take the full time frame, if several instances of it are
* running PHP will complain.
*/
set_time_limit(600);
try {
// Choose extension to convert source image to
if ($this->options['palettedJP2']) {
$extension = '.bmp';
} else {
$extension = '.pgm';
}
$input = substr($this->outputFile, 0, -4) . rand() . $extension;
// Extract region (PGM)
$this->jp2->extractRegion($input, $this->imageSubRegion, $this->reduce);
// Apply colormap if needed
if (!$this->options['palettedJP2']) {
// Convert to GD-readable format
$grayscale = new IMagick($input);
if (isset($this->options['verifyGrayscale']) && $this->options['verifyGrayscale'] && $grayscale->getImageType() != imagick::IMGTYPE_GRAYSCALE) {
$this->colorTable = false;
}
$grayscale->setImageFormat('PNG');
$grayscale->setImageDepth(8);
// Fastest PNG compression setting
$grayscale->setImageCompressionQuality(10);
// Assume that no color table is needed
$coloredImage = $grayscale;
// Apply color table if one exists
if ($this->colorTable) {
$clut = new IMagick($this->colorTable);
$coloredImage->clutImage($clut);
}
} else {
$coloredImage = new IMagick($input);
}
// Set alpha channel for images with transparent components
$this->setAlphaChannel($coloredImage);
// Apply compression and interlacing
$this->compressImage($coloredImage);
// Resize extracted image to correct size before padding.
$rescaleBlurFactor = 0.6;
$coloredImage->resizeImage(round($this->subfieldRelWidth), round($this->subfieldRelHeight), $this->imageOptions['rescale'], $rescaleBlurFactor);
$coloredImage->setImageBackgroundColor('transparent');
// Places the current image on a larger field of black if the final
// image is larger than this one
$imagickVersion = $coloredImage->getVersion();
if ($imagickVersion['versionNumber'] > IMAGE_MAGICK_662_VERSION_NUM) {
// ImageMagick 6.6.2-6 and higher
// Problematic change occurred in revision 6.6.4-2
// See: http://www.imagemagick.org/script/changelog.php
$coloredImage->extentImage($this->padding['width'], $this->padding['height'], $this->padding['offsetX'], $this->padding['offsetY']);
} else {
// Imagick 3.0 and lower
$coloredImage->extentImage($this->padding['width'], $this->padding['height'], -$this->padding['offsetX'], -$this->padding['offsetY']);
}
$this->image = $coloredImage;
// Check for PGM before deleting just in case another process
// already removed it
if (@file_exists($input)) {
@unlink($input);
}
} catch (Exception $e) {
// Clean-up intermediate files
$this->_abort($this->outputFile);
throw $e;
}
}
