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2.5.2 Pointer Cancellation (A)

Understanding 2.5.2 Pointer Cancellation (A)

For mobile devices or tablets where if there is functionality triggered by a single pointer, at least one of the following is true:

No Down-Event
The down-event of the pointer is not used to ‘fire’ the function;

Stop the action or Undo
The function is triggered on the up-event, and a method is available to stop completion or undo the function;;

Up Reversal
The up-event reverses what happens on the down-event;

Completing the function on the down-event is essential.

Why is this a problem?

This aims to reduce accidentally triggering things on a page. Any interaction were a control fires as soon as it is touched is problematic for a range of users (and not just disabled users). It is better when there is a way to ‘undo’ or change your mind. This is what the success criterion aims to address and will help people with visual disabilities, cognitive disabilities, and motor impairments.

However, it can present problems for users with dexterity issues.

Requirements / What to do?

  • Simply make activation of any function occur on the up-event. This is where the control is released by the user. This can be by the users finger or a mouse for example. Using the click event by default will only trigger the event on release.
  • To ‘Cancel’ or ‘Undo’ a function. You can add a ‘confirmation dialog’ or an ‘undo button’. This asks the user to confirm the interaction and by doing so, you give them time to reflect and choose one way or another.
  • Up Reversal: You can design a control where the down-event trigger an action that can be reversed when the up-event is ended. Examples of this include press-and-hold actions such which make a popup appear and on release it disappears.
  • Some just things will need to fire on the ‘down-event’ such as games or on screen keyboards.

What are down-events?

A down-event is when an action is caused to ‘fire’ when the trigger stimulus of a pointer (like a finger) is pressed.

The down-event may have different names, such as “touchstart” or “mousedown”.

What are up-events?

A up-event is when an action is caused to ‘fire’ when the trigger stimulus of a pointer (like a finger) is released.

The up-event may have different names, such as “touchend” or “mouseup”.

Common mistakes

  • Allowing controls or user interface components to fire as soon as they are touched.
  • After a user has made a selection of a user interface component, there is no way to dismiss the selection or undo the function.