Hello, I'm trying to implement "hand draw tool". At the moment algorythm looks like that (I don't insert any code because methods are quite big, will try to explain an idea):

Drawing

1. In touchesStarted: method I create NSMutableArray *pointsArray and add point into it. Call setNeedsDisplay: method.
2. In touchesMoved: method I calculate points between last added point from the pointsArray and current point. Add all points to the pointsArray. Call setNeedsDisplay: method.
3. In touchesFinished: event I calculate points between last added point from the array and current point. Set flag touchesWereFinished. Call setNeedsDisplay:.

Render:

drawRect: method checks is pointsArray != nil and is there any data in it. If there is - it starts to traw circles in each point of this array. If flag touchesWereFinished is set - save current context to the UIImage, release pointsArray, set it to nil and reset the flag.

There are a lot disadvantages of this method:

• It is slow
• It becomes extremely slow when user touches and move finger for long time. Array becomes enormous
• "Lines" composed by circles are ugly

I would like to change my algorithm to make it bit faster and line smoother. In result I would like to have lines like on the picture at following URL (sorry, not enough reputation to insert an image): http://2.bp.blogspot.com/_r5VzEAUYXJ4/SrOYp8tJCPI/AAAAAAAAAMw/ZwDKXiHlhV0/s320/SketchBook+Mobile(4).png

Can you advice me, ho I can draw lines this way (smooth and slim on the edges)? I thought to draw circles with alpha gradient on the edges (to make lines smoother), but it will be extremely slowly IMHO.

Thanks for help