iOS 绘图-UIBezierPath

Posted 2023-05-17

参考技术A

即UIBezierPath在drawRect中的使用，在实际中，我们多使用UIBezierPath来自定义视图。

效果

UIBezierPath与CAShapeLayer的结合，是我们开发中最常见的，功能很强大。

CAShapeLayer与UIBezierPath的关系 ：

CAShapeLayer中shape代表形状的意思，所以需要形状才能生效
贝塞尔曲线可以创建基于矢量的路径，而UIBezierPath类是对CGPathRef的封装
贝塞尔曲线给CAShapeLayer提供路径，CAShapeLayer在提供的路径中进行渲染。路径会闭环，所以绘制出了Shape
用于CAShapeLayer的贝塞尔曲线作为path，其path是一个首尾相接的闭环的曲线，即使该贝塞尔曲线不是一个闭环的曲线

例如设置圆角：

自定义视图

效果

iOS---实现在屏幕上实时绘图的简单效果---CAShaperLayer和UIBezierPath的简单运用

首先，声明几个属性

@property(nonatomic,strong)UIBezierPath * beizer;
@property(nonatomic,assign)CGPoint startPoint;
@property(nonatomic,assign)CGPoint movePoint;
@property(nonatomic,strong)CAShapeLayer * shapelayer;

然后注册屏幕上的拖拽事件，并初始化贝塞尔曲线和CAShapeLayer

- (void)viewDidLoad {
    [super viewDidLoad];
    UIPanGestureRecognizer * pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panTouch:)];
    [self.view addGestureRecognizer:pan];
    self.beizer = [UIBezierPath bezierPath];
    [self initCAShaper];

}
-(void)initCAShaper
{
    self.shapelayer = [CAShapeLayer new];
    self.shapelayer.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
    self.shapelayer.fillColor = nil;
    self.shapelayer.lineCap = kCALineCapRound;
    self.shapelayer.strokeColor = [UIColor cyanColor].CGColor;
    self.shapelayer.lineWidth =2;
    [self.view.layer addSublayer:self.shapelayer];

}

紧接着处理拖拽事件

-(void)panTouch:(UIPanGestureRecognizer *)pan
{
    _startPoint = [pan locationInView:self.view];
    if(pan.state == UIGestureRecognizerStateBegan)
    {
        [self.beizer moveToPoint:_startPoint];
    }
    if(pan.state == UIGestureRecognizerStateChanged)
    {
        _movePoint = [pan locationInView:self.view];
        [_beizer addLineToPoint:_movePoint];
        self.shapelayer.path = _beizer.CGPath;
    }
}

大功告成。如图