How can I speed up line drawing?

ondesic

I am drawing a line where one end is fixed and the other end is where I am touching the screen. Though the code works, the line has a lag while I am moving my finger. while moving my finger on the screen, it seems to take a 1/3 of a second to catch up. Here is the code:

local theLine= Shape   function Main() theLine= DrawLine(10,10,application:getDeviceWidth()/2,10,5,1,0xffffff) stage:addChild(theLine) end   function onTouchMove(event) theLine:clear() ChangeLine( theLine,10,10,event.touch.x,event.touch.y,5,1,0xffffff) end   function DrawLine(x1, y1, x2, y2, width, alpha, rgbcolor) local line = Shape.new() line:setLineStyle(width, rgbcolor, alpha) line:beginPath() line:moveTo(x1,y1) line:lineTo(x2, y2) line:endPath() return line end   function ChangeLine(which, x1, y1, x2, y2, width, alpha, rgbcolor) if which == theLine then theLine:setLineStyle(width, rgbcolor, alpha) theLine:beginPath() theLine:moveTo(x1,y1) theLine:lineTo(x2, y2) theLine:endPath() end end   Main() stage:addEventListener(Event.TOUCHES_MOVE, onTouchMove) application:setBackgroundColor(0x000000)

Any thoughts?

techdojo

Even at 60fps you'll get lag as the latency of the touchscreen is about 100ms, some guy at MS did some tests and you need latency in the order of 10ms for accurate tracking.

ondesic

Thanks techdojo. That's very interesting information.
I don't think I would have thought twice about this, except before Gideros, I was using a different environment and had near 0 lag doing the same thing on the phone.