Iphone画笔功能

iphone灵敏的触摸功能在应用开发中有很多的用处，你可以用它来开发一个手绘软件。在此我将探讨一下iphone手绘功能的实现， 很简单，创建一个base-view的工程， 然后所有的工作都是在触摸事件中, 实现touchesBegan， touchesMoved, touchesEnded三个方法。

在屏上移动就能实现手绘，点击画个点，双击清空绘制。

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { mouseSwiped = NO; UITouch *touch = [touches anyObject]; if ([touch tapCount] == 2) { drawImage.image = nil; return; } lastPoint = [touch locationInView:self.view]; lastPoint.y -= 20; } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { mouseSwiped = YES; UITouch *touch = [touches anyObject]; CGPoint currentPoint = [touch locationInView:self.view]; currentPoint.y -= 20; UIGraphicsBeginImageContext(self.view.frame.size); [drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)]; CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0); CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0); CGContextBeginPath(UIGraphicsGetCurrentContext()); CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y); CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y); CGContextStrokePath(UIGraphicsGetCurrentContext()); drawImage.image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); lastPoint = currentPoint; mouseMoved++; if (mouseMoved == 10) { mouseMoved = 0; } } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; if ([touch tapCount] == 2) { drawImage.image = nil; return; } if(!mouseSwiped) { UIGraphicsBeginImageContext(self.view.frame.size); [drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)]; CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0); CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0); CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y); CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y); CGContextStrokePath(UIGraphicsGetCurrentContext()); CGContextFlush(UIGraphicsGetCurrentContext()); drawImage.image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); } }

参考：http://www.ipodtouchfans.com/forums/showthread.php?t=132024

里面有源码下载。