Multitouch

When you have a touch devices, like mobile phones and tablets, it is useful to manage the touch of multiple fingers simultaneously. Many programs, in fact, are easier to use with the touch of more fingers, such as zoom effects.

Livecode has also incorporated a system to manage multitouch without limit to the number of fingers that can be used simultaneously. This system works on Android and iOS.

The messages to be intercepted are: touchStart, touchMove and touchEnd.

For each of us we have a disposition a unique identifier (tID) of the finger a contact with the screen, which is presented by a number.

• touchStart is sent as soon as a finger touches the screen
• touchMove is sent when a finger scrolls across the screen, including the position (X, Y) of the finger
• touchEnd is sent as soon as a finger comes off the screen

For example, the following code show the position, the instant by instant, of the fingers on the screen.

on touchstart tID
   lock screen
   create field ("finger" & tID)
   set the width of the field ("dito" & tID) to 250
   put "1," & (22 * tID) into temp #posizione
   set the topleft of the field ("dito" & tID) to temp
   create graphic ("finger" & tID)
   set the opaque of graphic ("finger" & tID) to True
   set the style of graphic ("finger" & tID) to oval
   put (25 * tID) & comma & (25 * tID) & comma & (25 * tID) into temp #colore
   set the backgroundcolor of graphic ("finger" & tID) to temp
   set the width of graphic ("finger" & tID) to 30
   set the height of graphic ("finger" & tID) to 30
   unlock screen
end touchstart

on touchend tID
   delete field ("finger" & tID)
   delete graphic ("finger" & tID)
end touchend

on touchmove tID, tX, tY
   set the text of field ("dito" & tID) to ("il dito " & tID & " si trova in " & tX & comma & tY)
   set the loc of graphic ("dito" & tID) to (tX & comma & tY)
end touchmove

This is the result on a Android device: