iPhone smooth sketch drawing algorithm
drawing, ios, iphone, quartz-graphics
Solution
The easiest way to smooth a curve like this is to use a Bezier curve instead of straight line segments. For the math behind this, see this article (pointed to in this answer), which describes how to calculate the curves required to smooth a curve that passes through multiple points.
I believe that the Core Plot framework now has the ability to smooth the curves of plots, so you could look at the code used there to implement this kind of smoothing.
There's no magic to any of this, as these smoothing routines are fast and relatively easy to implement.
Problem
I am working on a sketching app on the iPhone. I got it working but not pretty as seen here And I am looking for any suggestion to smooth the drawing Basically, what I did is when user places a finger on the screen I called ``` - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event ``` then I collect a single touch in an array with ``` - (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event ``` and when the user lefts a finger from the screen, I called ``` - (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event ``` then I draw all the points in the array using ``` NSMutableArray *points = [collectedArray points]; CGPoint firstPoint; [[points objectAtIndex:0] getValue:&firstPoint]; CGContextMoveToPoint(context, firstPoint.x, firstPoint.y); CGContextSetLineCap(context, kCGLineCapRound); CGContextSetLineJoin(context, kCGLineJoinRound); for (int i=1; i < [points count]; i++) { NSValue *value = [points objectAtIndex:i]; CGPoint point; [value getValue:&point]; CGContextAddLineToPoint(context, point.x, point.y); } CGContextStrokePath(context); UIGraphicsPushContext(context); ``` And now I want to improve the drawing tobe more like "Sketch Book" App I think there is something to do with signal processing algorithm to rearrange all the points in the array but I am not sure. Any Help would be much appreciated. Thankz in advance :)