GestureEvent Class Reference

Inherits from	UIEvent : Event
Companion guide	Safari Web Content Guide
Availability	Available in iOS 2.0 and later.

Overview

The GestureEvent class encapsulates information about a multi-touch gesture.

GestureEvent objects are high-level events that encapsulate the low-level TouchEvent objects. Both GestureEvent and TouchEvent events are sent during a multi-touch sequence. Gesture events contain scaling and rotation information allowing gestures to be combined, if supported by the platform. If not supported, one gesture ends before another starts. Listen for GestureEvent events if you want to respond to gestures only, not process the low-level TouchEvent objects.

The different types of GestureEvent objects that can occur are:

gesturestart: Sent when two or more fingers touch the surface.
gesturechange: Sent when fingers are moved during a gesture.
gestureend: Sent when the gesture ends (when there are 1 or 0 fingers touching the surface).

For example, for a two finger multi-touch gesture, the events occur in the following sequence:

touchstart for finger 1. Sent when the first finger touches the surface.
gesturestart. Sent when the second finger touches the surface.
touchstart for finger 2. Sent immediately after gesturestart when the second finger touches the surface.
gesturechange for current gesture. Sent when both fingers move while still touching the surface.
gestureend. Sent when the second finger lifts from the surface.
touchend for finger 2. Sent immediately after gestureend when the second finger lifts from the surface.
touchend for finger 1. Sent when the first finger lifts from the surface.

See TouchEvent Class Reference if you want to process just low-level TouchEvent objects.

Tasks

Accessing Properties

Initializing

Properties

altKey

A Boolean value indicating whether the alt key is pressed.

readonly attribute boolean altKey

Discussion

If true, the alt key is pressed; otherwise, it is not. If there is no keyboard, this value is false.

Availability

Available in iOS 2.0 and later.

ctrlKey

A Boolean value indicating whether the control key is pressed.

readonly attribute boolean ctrlKey

Discussion

If true, the control key is pressed; otherwise, it is not. If there is no keyboard, this value is false.

Availability

Available in iOS 2.0 and later.

metaKey

A Boolean value indicating whether the meta key is pressed.

readonly attribute boolean metaKey

Discussion

If true, the meta key is pressed; otherwise, it is not. If there is no keyboard, this value is false.

Availability

Available in iOS 2.0 and later.

rotation

The delta rotation since the start of an event, in degrees, where clockwise is positive and counter-clockwise is negative.

readonly attribute float rotation

Discussion

The initial value is 0.0.

Availability

Available in iOS 2.0 and later.

scale

The distance between two fingers since the start of an event, as a multiplier of the initial distance.

readonly attribute float scale

Discussion

The initial value is 1.0. If less than 1.0, the gesture is pinch close (to zoom out). If greater than 1.0, the gesture is pinch open (to zoom in).

Availability

Available in iOS 2.0 and later.

shiftKey

A Boolean value indicating whether the shift key is pressed.

readonly attribute boolean shiftKey

Discussion

If true, the Shift key is pressed; otherwise, it is not. If there is no keyboard, this value is false.

Availability

Available in iOS 2.0 and later.

target

The target of this gesture.

readonly attribute EventTarget target

Availability

Available in iOS 2.0 and later.

Methods

initGestureEvent

Initializes a newly created GestureEvent object.

void initGestureEvent (in DOMString type, in boolean canBubble, in boolean cancelable, in DOMWindow view, in long detail, in long screenX, in long screenY, in long clientX, in long clientY, in boolean ctrlKey, in boolean altKey, in boolean shiftKey, in boolean metaKey, in EventTarget target, in float scale, in float rotation);

Parameters

type: The type of event that occurred.
canBubble: Indicates whether an event can bubble. If true, the event can bubble; otherwise, it cannot.
cancelable: Indicates whether an event can have its default action prevented. If true, the default action can be prevented; otherwise, it cannot.
view: The view (DOM window) where the event occurred.
detail: Specifies some detail information about the event depending on the type of event.
screenX: The x-coordinate of the event’s location in screen coordinates.
screenY: The y-coordinate of the event’s location in screen coordinates.
clientX: The x-coordinate of the event’s location relative to the window's viewport.
clientY: The y-coordinate of the event’s location relative to the window's viewport.
ctrlKey: If true, the control key is pressed; otherwise, it is not.
altKey: If true, the alt key is pressed; otherwise, it is not.
shiftKey: If true, the Shift key is pressed; otherwise, it is not.
metaKey: If true, the meta key is pressed; otherwise, it is not.
target: The target of this gesture.
scale: The distance between two fingers since the start of an event as a multiplier of the initial distance. The initial value is 1.0. If less than 1.0, the gesture is pinch close (to zoom out). If greater than 1.0, the gesture is pinch open (to zoom in).
rotation: The delta rotation since the start of an event, in degrees, where clockwise is positive and counter-clockwise is negative. The initial value is 0.0.

Discussion

Use this method to programmatically create a GestureEvent object.

Availability

Available in iOS 2.0 and later.

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