Simulating Feedback

Touch devices provide feedback when users interact with the touch screen. Feedback consists of small signs (audio, vibration) that accompany touch events. These signs provide immediate physical confirmation that a touch event has been registered. Feedback thus enables a more responsive interaction experience by eliminating the passive feeling of touch UIs.

The technology available today usually only provides haptic effects, which deal with the sense of touch, and audio effects.

Providing Haptic Feedback

Providing haptic feedback reduces the number of mistakes made by the user. It also improves user performance in terms of speed and accuracy, because haptic feedback is perceived more quickly than visual or audio feedback, which can be difficult for users to perceive when they are distracted or on the move.

Furthermore, haptic feedback is silent, nonvisual, and individually communicated; it can be used for communicating information privately.

Haptic feedback provides intuitive confirmation of an action. This is especially useful in case of gestures and strokes, where real-time confirmation of a successful action is essential.

When creating custom components, consider using haptic feedback in:

• Buttons and sliders
• Strokes and gestures
• Notifications

Providing real-time feedback is essential for confirming successful action. Lack of feedback is usually the best option for indicating that the user lost control of an object and an action was not completed. Users prefer short and gentle vibrations as gesture confirmation. Audio feedback can also be used, but it should be configurable by the user.

• Use soft feedback for successful actions.
• Use sharper, more disruptive feedback for unsuccessful actions.

Haptic feedback is applied in order to increase usability. To achieve this goal, the triggering actions, feedback duration, patterns, and sequences must be planned carefully.

When using haptic feedback, consider the following:

• Providing haptic feedback increases power consumption. Thus, excessive use of haptic feedback will drain the battery.
• If haptic feedback is used for every possible UI event, the device vibrates all the time and the vibration will no longer be meaningful for the user. Additionally, continuous haptic feedback may become irritating.
• When using different vibration patterns, they should be easy to differentiate; at maximum, use seven different patterns. Rhythmic patterns are easier to remember.
• Vibration sequences should be short in order to keep the feedback pleasant. Avoid sequences longer than 50 ms.
• If audio feedback is used, vibration sequences and audio should be synchronised.
• Haptic feedback should also be supported by a change in the visual style of the element, especially in case of buttons.

Testing Feedback Effects

You can use Qt Simulator to test applications that use Qt Feedback API to manage device vibration and audio feedback.

The Vibration Actuator is used to control a mobile device's vibrator and the Audio Actuator to play audio feedback. Usually, you do not have to change the settings. However, you can disable an actuator to check that the application behaves correctly if another application is using all actuators, for example.

If you use feedback effects, such as haptic data files or audio files in your application, you can view their name, state, and duration in Qt Simulator while they run (some MIME types may not support duration information). This allows you to test that the application runs and terminates effects correctly.

Note: Qt Simulator only displays feedback effects that are triggered explicitly by using the Qt Feedback API. The default feedback effects are not displayed.