Thanks Rob,
Getting the number of points was dead easy thanks to great sample code!
But I noticed that if I have three( or any number but at least 2 ) fingers touching screen then lift one off the code set touches to 0 points. If I then press a finger again the fingers left on screen does not get detected. Should I have some sort of listener in the moved phase for keeping track if there are still fingers touching?
[lua]
system.activate(“multitouch”)
local group = display.newGroup()
local background = display.newRect(group, 0, 0, display.contentWidth, display.contentHeight)
background:setFillColor(223, 223, 156, 255)
local touchText = display.newText(group, “0”, 0, 0, 0, 0, “Helvetica”, 80)
touchText:setReferencePoint(display.CenterReferencePoint)
touchText.x = display.contentWidth - 50
touchText.y = 60
touchText:setTextColor(0)
local function calculateDelta( previousTouches, event )
local id,touch = next( previousTouches )
if event.id == id then
id,touch = next( previousTouches, id )
assert( id ~= event.id )
end
local dx = touch.x - event.x
local dy = touch.y - event.y
return dx, dy
end
local function onObjectTouch(self, event )
local previousTouches = self.previousTouches
local numTotalTouches = 1
if ( previousTouches ) then
– add in total from previousTouches, subtract one if event is already in the array
numTotalTouches = numTotalTouches + self.numPreviousTouches
if previousTouches[event.id] then
numTotalTouches = numTotalTouches - 1
end
end
if event.phase == “began” then
if ( not self.isFocus ) then
– Subsequent touch events will target button even if they are outside the contentBounds of button
display.getCurrentStage():setFocus( self )
self.isFocus = true
previousTouches = {}
self.previousTouches = previousTouches
self.numPreviousTouches = 0
elseif ( not self.distance ) then
local dx,dy
if previousTouches and ( numTotalTouches ) >= 2 then
dx,dy = calculateDelta( previousTouches, event )
end
– initialize to distance between two touches
if ( dx and dy ) then
local d = math.sqrt( dx*dx + dy*dy )
if ( d > 0 ) then
self.distance = d
--self.xScaleOriginal = self.xScale
--self.yScaleOriginal = self.yScale
print( "distance = " … self.distance )
end
end
end
if not previousTouches[event.id] then
self.numPreviousTouches = self.numPreviousTouches + 1
end
previousTouches[event.id] = event
– touchText update
touchText.text = self.numPreviousTouches
elseif self.isFocus then
– do something here; or not
if event.phase == “moved” then
print("—> Touch moved")
if ( self.distance ) then
local dx,dy
if previousTouches and ( numTotalTouches ) >= 2 then
dx,dy = calculateDelta( previousTouches, event )
end
if ( dx and dy ) then
local newDistance = math.sqrt( dx*dx + dy*dy )
local scale = newDistance / self.distance
print( “newDistance(” …newDistance … “) / distance(” … self.distance … “) = scale(”… scale …")" )
if ( scale > 0 ) then
--self.xScale = self.xScaleOriginal * scale
--self.yScale = self.yScaleOriginal * scale
end
end
end
if not previousTouches[event.id] then
self.numPreviousTouches = self.numPreviousTouches + 1
end
previousTouches[event.id] = event
– touchText update
touchText.text = self.numPreviousTouches
elseif event.phase == “ended” or event.phase == “cancelled” then
print("—> Touch ended or cancelled")
if previousTouches[event.id] then
self.numPreviousTouches = self.numPreviousTouches - 1
previousTouches[event.id] = nil
end
if ( #previousTouches > 0 ) then
– must be at least 2 touches remaining to pinch/zoom
self.distance = nil
else
– previousTouches is empty so no more fingers are touching the screen
– Allow touch events to be sent normally to the objects they “hit”
display.getCurrentStage():setFocus( nil )
self.isFocus = false
self.distance = nil
self.xScaleOriginal = nil
self.yScaleOriginal = nil
– Reset touchText
touchText.text = 0
– reset array
self.previousTouches = nil
self.numPreviousTouches = nil
end
end
end
return true
end
background.touch = onObjectTouch
background:addEventListener(“touch”, background)
[/lua]
