Module to caculate max imagesize it could take in a box.

ImageFitBoundaries.module

<?php

/**
 * ProcessWire 'Image Fit Boundaries' module
 *
 * Module to calculate the max size a image can take in a boundary box.
 * © Martijn Geerts 2013
 * 
 * Usage:
 *
 * $image = $page->image; // image from $page, or any other ProcessWire image
 * 
 * // $x & $y are required
 * $x = 200; // width, the size of the box (max width an image can scale in width)
 * $y = 100; // height, the size of the box (max height an image can scale in height)
 * 
 * // $compress is optional
 * $compress = 30; // Makes heavier images procentual smaller then normal images, from (low) 1 to (high) 99 compression
 * 
 * // usage 1
 * $img = $modules->get("ImageFitBoundaries");
 * $img = $img->load($image, $x, $y, $compress);
 * echo $img->render();
 * 
 * // usage 2
 * $mod = $modules->get("ImageFitBoundaries");
 * $info = $mod->load($image, $x, $y, $compress)->info();
 * $thumb = $image->size($info['width'], $info['height']);
 * echo "<img src='$thumb->url'>";
 * 
 * ------------------------------------------------------
 *
 * ProcessWire 2.x 
 * Copyright (C) 2010 by Ryan Cramer 
 * Licensed under GNU/GPL v2, see LICENSE.TXT
 * 
 * http://www.processwire.com
 * http://www.ryancramer.com
 * 
 */

class ImageFitBoundaries extends WireData implements Module {



	// internal check to protect public methodes 'render' & 'info'
	protected $initialized = false;



	protected $settings = array(
		'image' => null,
		'box_x' => null,
		'box_y' => null,
		'new_size' => array(),
		'compress' => null,
		);



	/**
	 * Tell ProcessWire about this module
	 *
	 * @return array
	 *
	 */
	public static function getModuleInfo() {

		return array(
			'title' => 'ImageFitBoundaries',
			'version' => 001, 
			'summary' => __('Give in a box-size & and and Pageimage and it wil caculate the max image size the image can be.'),
			'href' => 'http://www.processwire.com',
			'singular' => false, 
			'autoload' => false, 
			);
	}



	/**
	 * Initialize the module, needed for ProcessWire
	 *
	 */
	public function init() {}



	/**
	 * Load a Pageimage and settings
	 * @param Pageimage $image	$images to calculate the new size for
	 * @param (int) $box_x The width of the box, max width an image can take.
	 * @param (int) $box_y The height of the box, max height an image can take.
	 * @param (int) $proc from 1 till 99
	 * @return $this For chaining only
	 */
	public function load( Pageimage $image, $box_x = 0, $box_y = 0, $proc = 0) {

		// return if no box-size given
		if(!$box_x && !$box_y) return false;

		// here to protect public 'render' & 'info'
		$this->initialized = true;

		// should we shrink ?
		$shrinkIt = (int) $proc > 0 && (int) $proc < 100 ? (int) round($proc) : null;

		// set settings
		$this->settings['image'] = $image;
		$this->settings['box_x'] = (int) $box_x;
		$this->settings['box_y'] = (int) $box_y;
		$this->settings['compress'] = $shrinkIt;
		
		// calculate the new sizes & set value in $settings array
		$this->calculateSize();
		//
		if ($shrinkIt) $this->shrinkIt();

		return $this;
	}



	/**
	 * Calculate new image size depending on box size
	 * 
	 * @return (array) Array with width & height
	 */
	protected function calculateSize() {

		// Related to Pageimage 
		$image = $this->settings['image'];

		// calculate ratio beween image & wanted size
		$rX = $this->settings['box_x'] / $image->width;
		$rY = $this->settings['box_y'] / $image->height;
		
		// the least expensive, is taken for size caculation
		$width = min($rX, $rY) * $image->width;
		$height = min($rX, $rY) * $image->height;

		// set new_size settings, array with width/height 
		$size = array('width' => $width, 'height' => $height);
		
		// cache it in the module
		$this->settings['new_size'] = $size;
		$this->info = $size;

		return $this;
	}



	/**
	 * Resize the resized sizes, depending on squared size of box.
	 * 
	 */
	protected function shrinkIt() {
		
		$i = 0;
		$array = array();
		$range = range(0, 100);	// create array
		$compress = $this->settings['compress'];
		$fraction = $compress / 100;
		$width = $this->settings['new_size']['width'];
		$height = $this->settings['new_size']['height'];

		// key of array, will be used by percentage value
		foreach ($range as $key) {
			$array[$key] = $i;
			$i = $i + $fraction;
		}

		// procent compare to box
		$proc = (int) ( $width * $height ) * 100 / ( $this->settings['box_x'] * $this->settings['box_y'] );

		$this->settings['new_size']['width'] = round($width - ($array[$proc] * $width / 100));
		$this->settings['new_size']['height'] = round($height - ($array[$proc] * $height / 100));
		// set the $info
		$this->info = $this->settings['new_size'];

		return $this;
	}



	/**
	 * Returns Markup for newly created image.
	 * 
	 * @return (string) <img src='...
	 */
	public function render() {

		// can't render when load is not called or data is insufficient.
		if(!$this->initialized) return $this->_("Only accessible if all data provided in the load methode.");

		// grab image
		$image = $this->settings['image'];

		// get new sizes (array)
		$size = $this->settings['new_size'];
		$width = $size['width'];
		$height = $size['height'];

		// create thumbnail
		$thumb = $image->size($width, $height);

		return "<img src='$thumb->url' alt='$thumb->description' width='$width' height='$height'>"; 
	}



	/**
	 * Returns an array containing with width & height info
	 * 
	 * @return (array) array('width' => ... , 'height' => ... );
	 */
	public function info() {

		// can't render when load is not called or data is insufficient.
		if(!$this->initialized) return $this->_("Only accessible if all data provided in the load methode.");

		// return size array
		return $this->settings['new_size'];
	}



	/**
	 * Same as info methode, here for convenience
	 * 
	 * @return (array) array('width' => ... , 'height' => ... );
	 */
	public $info = array();


	

}