Description
This event is reported when the user touches two fingers on an object and twists them clockwise or anticlockwise.
The event message reported as the result of ⎕DQ, or supplied as the right argument to your callback function, is a 5-element vector as follows :
| [1] | Object | ref or character vector |
| [2] | Event | 'GestureRotate' or 495 |
| [3] | Flags | integer which reports the state of the gesture |
| [4] | Location | 2-element integer vector containing the y and x-position respectively of the point midway between the two fingers. These are reported in pixel coordinates relative to the origin of the screen. |
| [5] | Angle | a scalar number which represents the angle of rotation of the twist measured in radians (0 → ○2) from the x-axis in a counter-clockwise direction. |
The Flags parameter [3] which reports the state of the Gesture, is an integer with the value 0, 1 (GF_BEGIN),or 4 (GF_END) with the following meanings:
| Name | Value | Description |
| 0 | A gesture is in progress | |
| GF_BEGIN | 1 | A gesture is starting. |
| GF_END | 4 | A gesture has finished. |
When the user first touches two fingers on an object and begins to twist, the object generates a GestureRotate event with a Flags parameter of 1 (GF_BEGIN). As the user continues to twist his fingers, the object generates a series of GestureRotate events with a Flags parameter of 0. When the user lifts one or both fingers away, the object generates a final GestureRotate event, with a Flags parameter of 4 (GF_END).
No other event will be reported between the start and end of a series of GestureRotate events.
The associated callback is run immediately while the windows notification is still on the stack. See High-Priority Callback Functions.
Returning zero from the callback disables any default handling by the operating system.