Definition for WCAG 2.1 success criterion 2.5.2
2.5.2 Pointer Cancellation: For functionality that can be operated using a single pointer, at least one of the following is true:
- No Down-Event
- The down-event of the pointer is not used to execute any part of the function;
- Abort or Undo
- Completion of the function is on the up-event, and a mechanism is available to abort the function before completion or undo the function after completion;
- Up Reversal
- The up-event reverses any outcome of the preceding down-event;
- Essential
- Completing the function on the down-event is essential.
The intent of this success criterion is to make it easier for all users to recover from hitting the wrong target, reducing the chance that a control will be accidentally activated or an action will occur unexpectedly.
People with various disabilities can inadvertently initiate touch or mouse events with unwanted results. Up-Event activation refers to the activation of a component when the trigger stimulus is released. For example, for touchscreen interaction the event would be triggered when a finger is lifted from the touchscreen at the end of a tap. There is a distinction between when someone touches a screen and when they remove their finger. On a mouse there is a difference between mouse down (initiating a click) and mouse up (releasing the finger). Authors can reduce the problem of users inadvertently triggering an action, by making activation on the up-event. This gives users the opportunity to move their finger or other pointer (e.g. mouse) away from the wrong target once they hit it. If touch down activation is necessary, there are several options:
- A confirmation alert allows the user to change their mind.
- An undo button or other mechanism allows the user to reverse the action.
- A setting in preferences allows the user to choose whether activation happens on the down or up event.
Note: Generic platform activation/click events generally trigger on up and when they do, they are also allowed. For example, in the case of mouse interactions, the "click" event in JavaScript triggers on release of the primary mouse button, and is an example of an implicit up-event.
Testing success criterion 2.5.2
Input into spreadsheet
- Fail
- Pointer events cannot be canceled. Record the nature of the failure:
- The activation occurs on the down-event.
- A mechanism is not available to abort the function before completion.
- A mechanism is not available to undo the function after completion.
- The up-event does not reverse the outcome of the down-event.
- Completing the function on the down event is not essential.
- Pass
-
- The activation only occurs on the up-event.
- A mechanism is available to abort the function before completion.
- A mechanism is available to undo the function after completion.
- The up-event reverses the outcome of the down-event.
- Completing the function on the down event is essential.
How to test
- Identify all pointer activation triggers.
-
For each trigger, ensure:
- The activation only occurs on the up-event, OR
- A mechanism is available to abort the function before completion, OR
- A mechanism is available to undo the function after completion, OR
- The up-event reverses the outcome of the down-event, OR
- Completing the function on the down event is essential (such as a piano program).