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File: GalleryToolkit.class
<?php
/*
 * Gallery - a web based photo album viewer and editor
 * Copyright (C) 2000-2007 Bharat Mediratta
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA  02110-1301, USA.
 */

/**
 * A toolkit for manipulating files.
 * This class defines the API for file manipulation toolkits.  It's designed such that we can
 * create many different toolkits, each providing its own unique functions for manipulating files.
 * Some of these toolkits may be centered around a particular technology (eg, NetPBPM, ImageMagick,
 * Jhead, etc) while others may be focussed on a specific type of file (eg JPEG).
 *
 * @package GalleryCore
 * @subpackage Classes
 * @author Ernesto Baschny <ernst@baschny.de>
 * @author Bharat Mediratta <bharat@menalto.com>
 * @version $Revision: 15513 $
 * @abstract
 */
class GalleryToolkit {

    /**
     * Get a certain property of a file
     *
     * @param string $mimeType
     * @param string $propertyName
     * @param string $sourceFilename
     * @return array object GalleryStatus a status code,
     *	       mixed the value of the property
     */
    function getProperty($mimeType, $propertyName, $sourceFilename) {
	return array(GalleryCoreApi::error(ERROR_UNIMPLEMENTED), null);
    }

    /**
     * Perform a certain operation
     *
     * Perform the wanted operation on sourceFilename and write the results in
     * destFilename.
     * Note: Rules for 'width' and 'height' keys in $context..
     *   If w/h are present in context and toolkit performs an operation that
     *   changes the w/h then it must update the context with the new values.
     *   (This is optional if the context previously had no w/h values)
     *
     * @param string $mimeType
     * @param string $operationName
     * @param string $sourceFilename the source file name
     * @param string $destFilename the destination file name (it will be overwritten if it exists)
     * @param array $parameters
     * @param array $context (optional) context data
     * @return array object GalleryStatus a status code
     *               string the output mime type
     *               array context data
     */
    function performOperation($mimeType, $operationName, $sourceFilename,
			      $destFilename, $parameters, $context=array()) {
	return array(GalleryCoreApi::error(ERROR_UNIMPLEMENTED), null, null);
    }

    /**
     * Apply the transform operation to the set of target operations.  The transform operation
     * will typically have happened upstream from the target operations, so we have to adjust
     * the target operations to take it into account.  For example, if the target operations
     * include a crop operation and upstream we rotate|90 it, then you'd want to rotate the
     * crop's parameters accordingly.
     *
     * @param string $transformOperation the upstream transform
     * @param string $targetOperations the current set of operations
     * @param boolean $reverse true if we should apply the transform in reverse
     * @return array boolean success or failure
     *               string the new set of operations
     */
    function applyTransform($transformOperation, $targetOperations, $reverse=false) {
	$transformedOperations = $targetOperations;

	/* Right now, only the rotate operation will cause issues */
	if (!strncmp($transformOperation, 'rotate', 6)) {
	    /* And it will only cause issues to the crop operation */
	    if (strstr($targetOperations, 'crop|') !== false) {
		$rotationAmount = substr($transformOperation, 7);
		if ($reverse) {
		    switch ($rotationAmount) {
		    case '90':
			$rotationAmount = '270';
			break;

		    case '-90':
		    case '270':
			$rotationAmount = '90';
			break;
		    }
		}

		$newOperations = array();
		foreach (split(';', $targetOperations) as $operation) {
		    if (!strncmp($operation, 'crop', 4)) {
			list ($x, $y, $width, $height) = split(',', substr($operation, 5));

			switch ($rotationAmount) {
			case '90':
			    $newX = GalleryUtilities::roundToString(
				100.0 - GalleryUtilities::castToFloat($y)
				      - GalleryUtilities::castToFloat($height), 3);
			    $newY = $x;
			    $newWidth = $height;
			    $newHeight = $width;
			    break;

			case '-90':
			case '270':
			    $newX = $y;
			    $newY = GalleryUtilities::roundToString(
				100.0 - GalleryUtilities::castToFloat($x)
				      - GalleryUtilities::castToFloat($width), 3);
			    $newWidth = $height;
			    $newHeight = $width;
			    break;

			case '180':
			    $newX = GalleryUtilities::roundToString(
				100.0 - GalleryUtilities::castToFloat($x)
				      - GalleryUtilities::castToFloat($width), 3);
			    $newY = GalleryUtilities::roundToString(
				100.0 - GalleryUtilities::castToFloat($y)
				      - GalleryUtilities::castToFloat($height), 3);
			    $newWidth = $width;
			    $newHeight = $height;
			    break;

			default:
			    /* What do we do now?  Do nothing. */
			    $newX = $x;
			    $newY = $y;
			    $newWidth = $width;
			    $newHeight = $height;
			}

			$newOperations[] = sprintf('crop|%s,%s,%s,%s',
						   $newX, $newY, $newWidth, $newHeight);
		    } else {
			$newOperations[] = $operation;
		    }
		}
		$transformedOperations = join(';', $newOperations);
	    }
	}

	return array(true, $transformedOperations);
    }


    /**
     * Merge two operations together in an intelligent way.  The end result of
     * the merge should be a new operation and arguments that would result if
     * you applied the operations in sequence.  For example, if the operations
     * are 'rotate|90' and 'rotate|180', then the result would be 'rotate|270'
     * (or 'rotate|-90').  The toolkit should only merge the operations if it
     * can do so cleanly.
     *
     * @param string $operation1 the first operation
     * @param array $args1 the first operation's arguments
     * @param string $operation2 the second operation
     * @param array $args2 the second operation's arguments
     * @return array (true if the operation was success,
     *                $mergedOperation,
     *                $mergedArgs)
     */
    function mergeOperations($operation1, $args1, $operation2, $args2) {
	/* We can only merge like operations */
	if ($operation1 != $operation2) {
	    /* But not all like operations have the same name */
	    $likeOperations = array('resize', 'scale', 'thumbnail');
	    if (!(in_array($operation1, $likeOperations)
		    && in_array($operation2, $likeOperations))) {
		return array(false, null, null);
	    }
	}

	switch ($operation1) {
	case 'crop':
	case 'resize':
	case 'scale':
	case 'thumbnail':
	    /* For like operations, the second operation takes precedence */
	    return array(true, $operation2, $args2);
	    break;

	case 'rotate':
	    /* Rotation is additive */
	    $rotation = (360 + $args1[0] + $args2[0]) % 360;

	    /* 0 rotation means the operation goes away */
	    if ($rotation == 0) {
		return array(true, null, null);
	    }

	    if (abs($rotation) > 180) {
		$rotation = $rotation - 360;
	    }
	    return array(true, $operation2, array($rotation));

	default:
	    return array(false, null, null);
	}
    }

    /**
     * Estimate the dimensions of a GalleryDerivativeImage from its operations and its source.
     *
     * @param object GalleryDerivativeImage $derivative
     * @param object GalleryEntity $source (probably a GalleryPhotoItem or GalleryMovieItem)
     * @static
     */
    function estimateDimensions(&$derivative, $source) {
	if (method_exists($source, 'getwidth') && method_exists($source, 'getheight')) {
	    $width = $source->getWidth();
	    $height = $source->getHeight();
	    if ($width && $height) {
		$operations = $derivative->getDerivativeOperations();
		if (preg_match('/^(?:thumbnail|scale)\|(\d+)$/', $operations, $matches)) {
		    $target = $matches[1];
		    if (!empty($target)) {
			if (GalleryUtilities::isA($source, 'GalleryDerivativeImage')) {
			    /*
			     * If the source is also a derivative then assume the real source
			     * is larger and allow upscaling in this estimate.  It's possible
			     * the real source is actually smaller than our $target size, but
			     * it will be corrected once the derivative is actually built.
			     */
			    list ($newWidth, $newHeight) =
				GalleryUtilities::scaleDimensionsToFit($width, $height, $target);
			} else {
			    list ($newWidth, $newHeight) =
				GalleryUtilities::shrinkDimensionsToFit($width, $height, $target);
			}
			$derivative->setWidth($newWidth);
			$derivative->setHeight($newHeight);
		    }
		}
	    }
	}
    }
}
?>