Tests whether there is an editor that supports a given mime type or methods.
$arg = array(
'mime_type' => 'image/png',
'methods' => array(
'rotate',
'resize',
'save'
)
);
$img_editor_test = wp_image_editor_supports($arg);
if ($img_editor_test !== false) {
//mime_type and method(s) supported!
}
WP_Image_Editor_Supports() is located in wp-includes/media.php.