Dictionary Entry For TouchMove

Brian Milby brian at milby7.com
Mon Mar 12 23:43:15 EDT 2018


PR submitted to clarify the touchMove dictionary entry:
https://github.com/livecode/livecode/pull/6413

On Mon, Mar 12, 2018 at 5:24 PM, Brian Milby <brian at milby7.com> wrote:

> Short answer, you need to track the location of each touch yourself and do
> the math.
>
> Check out this piece of code:
> https://raw.githubusercontent.com/bwmilby/lc-misc/master/
> PinchZoom/pinchzoom.livecodescript
>
> That is a piece of code that I translated into LCS that deals with
> tracking two touch points to zoom an object.  Depending on what you want to
> accomplish, you won't need anything that complicated.
>
> Looking at the Netflix app, you can either go vertical or horizontal.
> First movement direction locks it until all touches are released.  So you
> would need to capture the touchStart to get the ID and then 2 touchMove
> messages to establish direction (I didn't try using mouseloc to get the
> touchStart location).  You may want to pair the direction detection with a
> minimum to ensure you capture the correct direction.
>
> Hope this helps,
> Brian
>
> On Mon, Mar 12, 2018 at 4:39 PM, Sannyasin Brahmanathaswami via
> use-livecode <use-livecode at lists.runrev.com> wrote:
>
>> I have a group control (made up smaller groups) they I want users to
>> scroll vertically. And the sub-groups, which want the user to scroller
>> horizontally. My current thinking is to turn off scrollers until we get
>> swipe direction, and turn them on, "mid-swipe"
>>
>> simply: how do you know if touchMove is a horizontal or vertical swipe?
>>
>> in the dictionary, it says (another cryptic entry!)
>>
>> touchMove pTouchID, pTouchX, pTouchY
>>
>> Summary
>>
>> Sent when the point at which the user is touching the screen changes.
>> Example
>>
>> on touchMove pTouchID, pX, pY
>>      if pX > lastX then
>>      -- user has moved to the right
>>      end if
>> end touchMove
>>
>> where does "lastX"  come from? It is not localized as a variable.
>>
>> Other touch handlers do not record the X,Y coords of touchRelease.
>>
>> should we
>>
>> local sLastMouseUp
>>
>> end touchRelease
>>   put the mouseloc to sLastMouseUp
>> end touchRelease
>>
>> on touchMove pTouchID, pX, pY
>>      if pX > (item 1 of sLastMouseUp) then
>>      -- user has moved to the right
>>      end if
>> end touchMove
>>
>> But this relative to the last swipe -  this is not "runtime" as the
>> dictionary says:
>>
>> "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."
>>
>> BR
>>
>>
>>
>>
>>
>>
>>
>>
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>
>



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