CoreAnimation----CAShapeLayer

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先说说使用CAShapeLayer的优点: GPU执行, GPU执行, GPU执行

CAShapeLayer

1. CAShapeLayer的优点

• 渲染迅速，硬件加速GPU执行 。
• 内存利用率高，不需要寄宿图，所以比CALayer的内存占用还低。 。
• 图层边界不会被裁减掉，CAShapeLayer可在边界外进行绘制
• 不会 像素化

2. 使用CGPath

1. CAShapeLayer可绘制所有通过CGPath表示的形状
2. 这个形状不一定要闭合
3. 可控制属性如：lineWidth(线宽)，lineCap(线条结尾的样式)，lineJoin(线条之间结合点的样式)

使用CAShapeLayer画“火柴人”：

- (void)viewDidLoad {

 [super  viewDidLoad];

  UIBezierPath *path = [UIBezierPath  bezierPath];

 [path moveToPoint:CGPointMake(175, 100)];

 [path addArcWithCenter:CGPointMake(150, 100) radius:25  startAngle:0  endAngle:M_PI * 2  clockwise:YES];

 [path moveToPoint:CGPointMake(150, 125)];

 [path addLineToPoint:CGPointMake(150, 175)];

 [path addLineToPoint:CGPointMake(125, 225)];

 [path moveToPoint:CGPointMake(150, 175)];

 [path addLineToPoint:CGPointMake(175, 225)];

 [path moveToPoint:CGPointMake(100, 150)];

 [path addLineToPoint:CGPointMake(200, 150)];

  CAShapeLayer *shapeLayer = [CAShapeLayer  layer];

 shapeLayer.strokeColor = [UIColor  redColor].CGColor;

 shapeLayer.fillColor = [UIColor  clearColor].CGColor;

 shapeLayer.lineWidth = 5.0f;

 shapeLayer.lineJoin = @"round";

 shapeLayer.lineCap = @"round";

 shapeLayer.path = path.CGPath;

 [self.view.layer addSublayer:shapeLayer];

  NSLog(@"-------viewDidlod-------");

}

3. 圆角

• 除了设置CALayer的cornerRadius，还可以单独设置一个角的圆角
  设置矩形的三个角为圆角

- (void)viewDidLoad {

 [super  viewDidLoad];

 CGRect tect = CGRectMake(50, 50, 100, 100);

 CGSize radii = CGSizeMake(20, 20);

  UIRectCorner corner = UIRectCornerTopRight | UIRectCornerBottomLeft | UIRectCornerBottomRight;

  UIBezierPath *path = [UIBezierPath  bezierPathWithRoundedRect:tect byRoundingCorners:corner cornerRadii:radii];

  CAShapeLayer *shapeLayer = [CAShapeLayer  layer];

 shapeLayer.path = path.CGPath;

 [self.view.layer addSublayer:shapeLayer];

  NSLog(@"-------viewDidlod-------");

}