Full Example

full_example.php

$thumb_sizes = array(
	'breaking' => array( 'breaking', 80, 80, true ),
	'slider1' => array( 'slider1', 390, 280, true ),
	'slider1-wide' => array( 'slider1-wide', 450, 320, true ),
	'slider1-thumbnail' => array( 'slider1-thumbnail', 120, 72, true ),
	'slider2' => array( 'slider2', 710, 385, true ),
	'slider2-wide' => array( 'slider2-wide', 880, 385, true ),
	'slider3' => array( 'slider3', 455, 430, true ),
	'slider3-wide' => array( 'slider3-wide', 630, 430, true ),
	'slider3-small' => array( 'slider3-small', 80, 64, true ),
	'latest' => array( 'latest', 200, 120, true ),
	'feed' => array( 'feed', 260, 152, true ),
	'feed-latest' => array( 'feed-latest', 290, 170, true ),
	'feed-vertical' => array( 'feed-vertical', 200, 200, true ),
	'single' => array( 'single', 602, 602, false ),
	'single-medium' => array( 'single-medium', 300, 300, false ),
	'single-small' => array( 'single-small', 180, 180, false ),
	'archive' => array( 'archive', 120, 120, true ),
	'review' => array( 'review', 300, 300, false )
);

//add thumbnail support
if ( function_exists( 'add_theme_support' ) ) { // Added in 2.9
	add_theme_support( 'post-thumbnails' );
	set_post_thumbnail_size( 160, 160, true ); // default post thumbnails
	foreach($thumb_sizes as $thumb_size){
		$name = $thumb_size[0];
		$width = get_option('con_'.$name.'_width', $thumb_size[1]);
		$height = get_option('con_'.$name.'_height', $thumb_size[2]);
		$crop = get_option('con_'.$name.'_crop', $thumb_size[3]);
		add_image_size($name, $width, $height, $crop);
	}
}

function con_global_callback($field){
	global $thumb_sizes;

	if($field["part"] == "width"){
		$part = 1;
	}else if($field["part"] == "height"){
		$part = 2;
	}else if($field["part"] == "crop"){
		$part = 3;
	}
 	$selected = get_option($field["id"], $thumb_sizes[$field['desc']][$part]);

 	if($field["type"] == "text"){
 	?>
		<input type="text" name="<?php echo $field["id"]; ?>" id="<?php echo $field["id"]; ?>" value="<?php echo $selected ?>">
	<?php
 	}else if($field["type"] == "checkbox"){
 		if($selected){
 			$selText = ' checked="checked" ';
 		}else{
 			$selText = ' ';
 		}
 	?>
 		<input type="checkbox" name="<?php echo $field["id"]; ?>" id="<?php echo $field["id"]; ?>" <?php echo $selText; ?>>
 	<?php
 	}

}

add_action('admin_init', 'con_thumbnails_init');

function con_thumbnails_init(){
	global $thumb_sizes;

	$parts = array(array("width", "text"), array("height", "text"), array("crop", "checkbox"));
	$section = "thumb_settings";
	con_register_section($section, 'Custom Thumbnail Settings');
	////////////////////////////////////////////////
	// THUMB SETTINGS
	foreach($thumb_sizes as $thumb_size){
		foreach($parts as $part){
			$id = 'con_' . $thumb_size[0] . '_' . $part[0];
			con_register_field($id, $thumb_size[0], $part[0], $section, $part[1]);
		}
	}
	////////////////////////////////////////////////
}

function con_register_field($id, $desc, $part, $section, $type, $filter = NULL){
	$safeCallback = preg_replace("/\-/", "_", $id);

	add_settings_field($id,
		$desc . " $part",
		"con_global_callback",
		'media',
		'con_setting_' . $section,
		array("id" => $id,
				"desc" => $desc,
				"part" => $part,
				"type" => $type)
	);
	register_setting('con_settings_group', $id, $filter);
}

function con_register_section($section, $title){
	add_settings_section('con_setting_' . $section,
		$title,
		'con_setting_'.$section.'_callback_function',
		'media');
}

function con_setting_thumb_settings_callback_function(){
	settings_fields("con_settings_group");
	echo "<p>Thumbnail sizes custom to continuum</p>";
}