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  • 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

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  • 原文地址:https://www.cnblogs.com/zhendiao/p/5164910.html
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