GestureHandler

GestureHandler[expr,{"gesture1"fun1,"gesture2"fun2,…}]

displays as expr, evaluating funi[value,velocity] whenever "gesturei" occurs within the screen space occupied by expr.

GestureHandler[expr,{"gesture"{fun,funend},…}]

evaluates fun as updates are received for "gesture", followed by funend[value,velocity] when the gesture ends.

GestureHandler[expr,{"gesture"{funstart,fun,funend},…}]

also evaluates fstart[value,velocity] when "gesture" begins.

Details

  • GestureHandler is only active on touchscreen devices. Otherwise, it acts as an inert wrapper.
  • Functions take arguments that are associated with the specific gesture. Typically, the argument is a value in scaled coordinates that represents the magnitude of the gesture.
  • Standard gestures include:
  • "Pinch"two-fingered gesture where the fingers pinch together or apart; typically used for resizing
    "Drag"one-fingered dragging gesture
    {"Drag",n}dragging gesture using touches
  • GestureHandler passes two arguments to funi. The first argument represents the magnitude of the gesture, while the second represents the velocity of the gesture.
  • "Pinch"valuescale of the pinch as a fraction of the starting distance between the touches
    "Drag"{valx,valy}drag distance as a fraction of the horizontal and vertical sizes of expr
  • When GestureHandler expressions are nested, events are by default shared by all the expressions, with the innermost expression operating first on a particular event.

Examples

open allclose all

Basic Examples  (2)

Print when a pinch gesture happens:

Dynamically print the distance of the last drag gesture:

Scope  (6)

Types of Gestures  (5)

Drag gesture:

Pinch gesture:

Tap gesture:

Spin gesture:

Long press gesture:

Combining Gesture Handlers  (1)

A single gesture may be simultaneously recognized by multiple gesture handlers:

Wolfram Research (2012), GestureHandler, Wolfram Language function, https://reference.wolfram.com/language/ref/GestureHandler.html.

Text

Wolfram Research (2012), GestureHandler, Wolfram Language function, https://reference.wolfram.com/language/ref/GestureHandler.html.

CMS

Wolfram Language. 2012. "GestureHandler." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/GestureHandler.html.

APA

Wolfram Language. (2012). GestureHandler. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/GestureHandler.html

BibTeX

@misc{reference.wolfram_2024_gesturehandler, author="Wolfram Research", title="{GestureHandler}", year="2012", howpublished="\url{https://reference.wolfram.com/language/ref/GestureHandler.html}", note=[Accessed: 22-December-2024 ]}

BibLaTeX

@online{reference.wolfram_2024_gesturehandler, organization={Wolfram Research}, title={GestureHandler}, year={2012}, url={https://reference.wolfram.com/language/ref/GestureHandler.html}, note=[Accessed: 22-December-2024 ]}