Hi Carlos,

I checked page 44 of the APIReferenceGuide you mention above and it seems we can't set the reference point to an exact x,y coordinate that we "touched". We only get to choose from the list quoted below. So the question I have then is how do we scroll something by touching and dragging without getting the glitchy "jump" effect that happens when setting the reference point to something other than the exact place where we touched the screen? Thanks in advance.

The argument referencePoint should be one of:
• display.CenterReferencePoint
• display.TopLeftReferencePoint
• display.TopCenterReferencePoint
• display.TopRightReferencePoint
• display.CenterRightReferencePoint
• display.BottomRightReferencePoint
• display.BottomCenterReferencePoint
• display.BottomLeftReferencePoint
• display.CenterLeftReferencePoint

local arguments =
{
	{ x=50, y=10, w=100, h=100, r=10, red=255, green=0, blue=128 },
	{ x=10, y=50, w=100, h=100, r=10, red=0, green=128, blue=255 },
	{ x=90, y=90, w=100, h=100, r=10, red=255, green=255, blue=0 }
}


local function printTouch( event )
 	if ( event.target ~= nil ) then
 		local bounds = event.target.stageBounds
		print( "event(" .. event.phase .. ") ("..event.x..","..event.y..") bounds: "..bounds.xMin..","..bounds.yMin..","..bounds.xMax..","..bounds.yMax )
	end
end


local function onTouch( event )
	local t = event.target

	local phase = event.phase
	if "began" == phase then
		-- Make target the top-most object
		local parent = t.parent
		parent:insert( t )
		display.getCurrentStage():setFocus( t )

		-- Spurious events can be sent to the target, e.g. the user presses
		-- elsewhere on the screen and then moves the finger over the target.
		-- To prevent this, we add this flag. Only when it's true will "move"
		-- events be sent to the target.
		t.isFocus = true

		-- Store initial position
		t.x0 = event.x - t.x
		t.y0 = event.y - t.y
	elseif t.isFocus then
		if "moved" == phase then
			-- Make object move (subtract t.x0,t.y0 so that moves are
			-- relative to initial grab point).
			t.x = event.x - t.x0
			t.y = event.y - t.y0
			printTouch(event)
		elseif "ended" == phase or "cancelled" == phase then
			display.getCurrentStage():setFocus( nil )
			t.isFocus = false
		end
	end


	-- Important to return true. This tells the system that the event
	-- should not be propagated to listeners of any objects underneath.
	return true
end

-- Iterate through arguments array and create rounded rects for each item
for _,item in ipairs( arguments ) do
	local button = display.newRoundedRect( item.x, item.y, item.w, item.h, item.r )
	button:setFillColor( item.red, item.green, item.blue )
	button.strokeWidth = 6
	button:setStrokeColor( 200,200,200,255 )

	-- Make the button instance respond to touch events
	button:addEventListener( "touch", onTouch )
end



Runtime:addEventListener( "touch", printTouch )

How would one put maximum bounds on an objects movement with this code if one wanted to restrict how much it could move. Thanks.

Just restrict what you allow to be in t.x and t.y at the move pahse to your allowed area would be suffice.

And about the reference point... you can't set a different one with the mentioned function.. but you can simply set object.xReference and object.yReference with the coordinates I guess.

The original routine in the video also has "acceleration" in it... which is also pretty easy to implement.

Don't move the object in the touch handler but set the position as target for a transform or your own "enterFrame" handler. Use the distance of the image position to your finger for setting the speed of the transform or for the movement distance per frame (count skipped frames using system.getTimer).

Maybe I write an example. Should be fun :)