Altering & handling default and custom wordpress image sizes and related stuff

image-sizes-extd.php

<?php
defined( 'ABSPATH' ) OR exit;

add_action( 'init', array( 'oxoImageSizesExtd', 'init' ), 0 );

class oxoImageSizesExtd extends oxoImageSizes
{
	/**
	 * The Class Object
	 * @var 
	 */
	static private $class = null;

	/**
	 * The array of custom size definitions.
	 * If overriding of defaults is needed,
	 * then 'large', 'medium', 'thumbnail' should be added here.
	 * If custom sizes are needed, then each sizes name.
	 * @var array 
	 */
	protected $sizes      = null;


	/**
	 * Handler for the action 'init'. Instantiates this class.
	 * 
	 * @return void
	 */
	public static function init()
	{
		if ( null === self::$class ) 
			self :: $class = new self;

		return self :: $class;
	}


	public function __construct()
	{
		$this->sizes = array(
			 'large'     => array(
			 	 'h'    => 960
			 	,'w'    => 640
			 	,'crop' => false
			 	,'attr' => array(
				 )
			 )
			,'medium'    => array(
			 	 'h'	=> 114
			 	,'w'	=> 114
			 	,'crop'	=> false
			 	,'attr' => array(
				 )
			 )
			,'thumbnail' => array(
			 	 'h'    => 57
			 	,'w'    => 57
			 	,'crop' => true
			 	,'attr' => array(
				 )
			 )
		);

		parent::__construct();
	}
} // END Class oxoImageSizesExtd

image-sizes.php

<?php
defined( 'ABSPATH' ) OR exit;

class oxoImageSizes
{
	/**
	 * Whether post thumbnails should be used or not
	 * @var boolean
	 */
	protected $post_thumbnail = true;


	/**
	 * The default sizes. 
	 * Can be overridden in the extending class
	 * by defining the $sizes array
	 * @var array
	 */
	private $default_sizes = array(
		 'large'     => array(
		 	 'h'    => 740
		 	,'w'    => 500
		 	,'crop' => false
		 )
		,'medium'    => array(
		 	 'h'    => 320
		 	,'w'    => 250
		 	,'crop' => false
		 )
		,'thumbnail' => array(
		 	 'h'    => 74
		 	,'w'    => 50
		 	,'crop' => true
		 )
	);


	/**
	 * Construct
	 * 
	 * @return void
	 */
	public function __construct()
	{
		// Merge extd class sizes with default sizes
		$this->sizes = wp_parse_args( $this->sizes, $this->default_sizes );

		add_action( 'init', array( $this, 'image_sizes_init' ) );
		add_action( 'init', array( $this, 'image_sizes' ) );

		// Image attr filter
		add_filter( 'wp_get_attachment_image_attributes', array( $this, 'img_attr' ), 10, 2 );
	}


	public function image_sizes_init()
	{
		if ( 
			$this->post_thumbnail 
			AND isset( $this->sizes['post-thumbnail'] ) 
			)
		{
			add_theme_support( 'post-thumbnails' );
			extract( $this->sizes['post-thumbnail'], EXTR_SKIP );
			set_post_thumbnail_size( $w, $h, $crop );
		}
	}


	/**
	 * Rework built in image sizes
	 * 
	 * @since 0.3
	 * 
	 * @return void
	 */
	public function image_sizes()
	{
		foreach ( array_keys( $this->sizes ) as $size )
		{
			$filter_array[] = "{$size}_size_w";
			$filter_array[] = "{$size}_size_h";
			$filter_array[] = "{$size}_crop";
		}

		foreach ( $filter_array as $hook )
			add_filter( "pre_option_$hook", array( $this, 'image_filter_cb' ), 10, 1 );
	}


	/**
	 * Callback for image filter return values
	 * 
	 * @since 0.3
	 * @param mixed $val
	 * 
	 * @return mixed $value
	 */
	public function image_filter_cb( $val )
	{
		$filter = current_filter();
		$size	= str_replace( 
			 array( 'pre_option_', '_size', '_crop', '_h', '_w' )
			,''
			,$filter 
		);

		switch ( $filter )
		{
			case "pre_option_{$size}_size_w" :
				$val = $this->sizes[ $size ]['h'];
				break;

			case "pre_option_{$size}_size_h" :
				$val = $this->sizes[ $size ]['h'];
				break;

			case "pre_option_{$size}_crop" :
				$val = $this->sizes[ $size ]['crop'];
				break;
		}

		return $val;
	}


	/**
	 * Alter attributes for images
	 * filters the output of `wp_get_attachment_image()`
	 * 
	 * @param array $attr
	 * Gets merged with Defaults 
	 * @see /wp-includes/media.php wp_get_attachment_image()
		'src'	=> $path,
		'class'	=> " class",
		'alt'	=> trim( strip_tags( # ) )
		'title'	=> trim( strip_tags( # ) )
	 * @param unknown_type $attachment
	 * 
	 * @return string $html
	 */
	public function img_attr( $attr, $attachment )
	{
		// current size - only works as long as core doesn't change the default class
		$size = trim( str_replace( 'attachment-', '', $attr['class'] ) );

		if ( 
			! isset( $this->sizes[ $size ]['attr'] )
			OR empty( $this->sizes[ $size ]['attr'] ) 
		)
			return $attr;

		$curr_attr = $this->sizes[ $size ]['attr'];

		# >>>> Prepare attributes
			// Get rid of empty attributes
			$curr_attr = array_filter( $curr_attr );

			// trim, strip tags & esc_html - mapped as custom attributes could get added
			foreach ( array( 'strip_tags', 'trim', 'esc_html' ) as $cb )
				$curr_attr = array_map( $cb, $curr_attr );

			// Prevent missing empty spaces for added classes
			$curr_attr['class']	= " {$curr_attr['class']}";
			// esc_attr() gets mapped inside wp_get_attachment_image()
		# <<<<

		return wp_parse_args( $curr_attr, $attr );
	}
} // END Class oxoImageSizes