0
我正在探索制作一个涂鸦应用程序，用户在其中用手指绘制图片，并且我遇到了几种不同的将线条绘制到屏幕上的方法。iOS屏幕绘图的最佳实践
- (void)drawRect:(CGRect)rect // (5)
{
[[UIColor blackColor] setStroke];
[path stroke];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[path moveToPoint:p];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[path addLineToPoint:p]; // (4)
[self setNeedsDisplay];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[self touchesMoved:touches withEvent:event];
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
[self touchesEnded:touches withEvent:event];
}
到：我从看到代码的任何地方
mouseSwiped = YES; UITouch * touch = [touch anyObject]; CGPoint currentPoint = [touch locationInView：self.view];
UIGraphicsBeginImageContext(self.view.frame.size);
[self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brush);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal);
CGContextStrokePath(UIGraphicsGetCurrentContext());
self.tempDrawImage.image = UIGraphicsGetImageFromCurrentImageContext();
[self.tempDrawImage setAlpha:opacity];
UIGraphicsEndImageContext();
lastPoint = currentPoint;
和最后一个方法（一个我想出了至少最有意义对我来说）
- (void) viewDidLoad{
UIPanGestureRecognizer* pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(drawImage:)];
[self.view addGestureRecognizer:pan];
pan.delegate = self;
paths = [[NSMutableArray alloc]init];
}
- (void) drawImage:(UIPanGestureRecognizer*)pan{
CGPoint point = [pan translationInView:self.view];
[paths addObject:[NSValue valueWithCGPoint:point]];
}
在最后实现，我会存储用户沿拖动点和画一条线。我觉得这样会有很多开销，但由于在用户与应用程序进行交互时有很多绘图正在进行。
所以我的问题是，有最佳做法/最好的方式来绘图？苹果公司是否比其他公司更喜欢这种方式，每种方式都有哪些优点/缺点？