Element image_button

image_button =>

array:18 [
  "class" => "Drupal\Core\Render\Element\ImageButton"
  "provider" => "core"
  "id" => "image_button"
  "#return_value" => true
  "#has_garbage_value" => true
  "#src" => null
  "#theme_wrappers" => array:1 [
    0 => "input__image_button"
  ]
  "#executes_submit_callback" => true
  "#input" => true
  "#name" => "op"
  "#is_button" => true
  "#submit_button" => true
  "#limit_validation_errors" => false
  "#process" => array:2 [
    0 => array:2 [
      0 => "Drupal\Core\Render\Element\ImageButton"
      1 => "processButton"
    ]
    1 => array:2 [
      0 => "Drupal\Core\Render\Element\ImageButton"
      1 => "processAjaxForm"
    ]
  ]
  "#pre_render" => array:1 [
    0 => array:2 [
      0 => "Drupal\Core\Render\Element\ImageButton"
      1 => "preRenderButton"
    ]
  ]
  "#value_callback" => array:2 [
    0 => "Drupal\Core\Render\Element\ImageButton"
    1 => "valueCallback"
  ]
  "#type" => "image_button"
  "#defaults_loaded" => true
]