touchMove

Type

message

Summary

Sent when the point at which the user is touching the screen changes.

Syntax

touchMove <pTouchID>, <pTouchX>, <pTouchY>

Description

Handle the touchMove message if you want to perform some action when the user changes the touch position without ending the touch or if you want to keep continuous track of the touch position.

The touchMove message is sent to the control which received the touchStart message to begin the touch sequence.

The pTouchID parameter is a number which uniquely identifies a sequence of touch messages corresponding to an individual, physical touch action. All such sequences start with a touchStart message, have one or more touchMove messages and finish with either a touchEnd or a touchRelease message.

No two touch sequences will have the same id, and it is possible to have multiple (interleaving) such sequences occurring at once. This allows handling of more than one physical touch at once and, for example, allows you to track two fingers moving on the device screen.

The sequence of touch messages is tied to the control in which the touch started, in much the same way mouse messages are tied to the object a mouse down starts in. The test used to determine what object a touch starts in is identical to that used to determine whether the pointer is inside a control. In particular, invisible and disabled controls will not considered viable candidates.

Since the current touch position is reported for each move message, the previous position will need to be tracked to calculate direction and/or distance moved.

Parameters

Name	Type	Description
pTouchID		A number which uniquely identifies a sequence of touch messages corresponding to an individual, physical touch action. This is the same id as the touchStart message which started the sequence.
pTouchX		The horizontal coordinate of the touchPosition
pTouchY		The vertical coordinate of the touchPosition

Examples

local sLastX
on touchMove pTouchID, pTouchX, pTouchY
   -- sLastX[pTouchID] will be empty when the first move
   -- message for pTouchID is sent
   if sLastX[pTouchID] is not empty and \
         pTouchX > sLastX[pTouchID] then
      -- user has moved to the right
   end if
   put pTouchX into sLastX[pTouchID]
end touchMove

Related

message: touchRelease, touchStart, touchEnd

Compatibility and Support

Introduced

LiveCode 4.5.2

OS

ios

android

Platforms

mobile