CALayer的应用

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CALayer

UIView VS CALayer

相对于UIView CALayer在更下面一层布局，view持有layer 所以都有view.layer 来对view设置其layer 关于layer有哪些属性及方法不再多说

CALayer旋转tranform是3D的，UIview是2D的

CALayer可以做显示（阴影、圆角、边框、遮罩、变换...) 动画

//CALayer展示

CALayer* layer1=[[CALayeralloc]init];

layer1.backgroundColor=[UIColor grayColor].CGColor;

layer1.frame=CGRectMake(100,100,150,150);

//layer的坐标系也是在左上角原点

//设置layer的边框

layer1.borderColor=[UIColor blackColor].CGColor;

layer1.borderWidth=2;

// 设置layer的圆角

layer1.cornerRadius=20;

//contents可以用来设置图片

layer1.contents=(id)[UIImage ImageNamed:@"..."]；

//不让子layer超出父layer的范围

layer1.masksToBounds=YES;

属性介绍position 与 anchorPoint

position相当于view的center ，但当anchorPoint改变时就不是center了而是锚点的坐标，anchorPoint相当于一张纸被一个图钉定住只可以绕着图钉转，这个图钉的位置就是anchorPoint这张纸就是layer,anchorPonit是CGPoint类型的取值范围是（0-1，0-1）

默认情况下锚点是（0.5，0.5）

如上述代码将layer1的锚点设置为（0，0），position的坐标就变成的（175，175） frame是（175，175，150，150）；

公式position.x=anchorPonit.x*frame.size.width+frame.origin.x     y值一样，把x换y

---

Mask Layer

    UIImageView* image=[[UIImageView alloc]initWithImage:[UIImage imageNamed:@"1.jpg"]];

    image.frame=CGRectMake(50,150,200,250);

    image.contentMode=UIViewContentModeScaleAspectFill;

    [self.viewaddSubview:image];

    UIImageView*imageMask=[[UIImageViewalloc]init];

    imageMask.image=[[UIImage imageNamed:@"imageMask.png"]stretchableImageWithLeftCapWidth:14 topCapHeight:28];

    imageMask.frame=image.bounds;

    image.layer.mask=imageMask.layer;

GAGrandient Layer

    //渐变颜色

    CAGradientLayer*layer=[[CAGradientLayer alloc]init];

    layer.frame=CGRectMake(100,100,150,150);

    [layersetColors:@[

                       (id)[UIColoryellowColor].CGColor,

                       (id)[UIColorgreenColor].CGColor,

                       (id)[UIColorblueColor].CGColor

                       ]];

    //默认为从上至下

    //使用渐变分割线

    [layersetLocations:@[@0.25,@0.5,@0.75]];

    //渐变方向 startpoint endpoint （0-1，0-1）;

    [layersetStartPoint:CGPointMake(0, 0)];

    [layersetEndPoint:CGPointMake(1, 0)];

    [self.view.layeraddSublayer:layer];

//作为mask

UIImageView *imageView=[[UIImageView alloc]init];  

imageView.image=[UIImage imageNamed:@"nature.jpg"];    

imageView.contentMode=UIViewContentModeScaleAspectFill;   

imageView.frame=CGRectMake(100, 260,150,100);    

 [self.view addSubview:imageView];          

//镜像效果    

UIImageView* mirrorImgView=[[UIImageView alloc]init];     

mirrorImgView.image=imageView.image;     

mirrorImgView.contentMode=UIViewContentModeScaleAspectFill;     

//翻转     

mirrorImgView.transform=CGAffineTransformMakeScale(1, -1);    

mirrorImgView.frame=CGRectMake(0, 0, 150, 100);     

mirrorImgView.center=CGPointMake(imageView.center.x, imageView.center.y+imageView.bounds.size.height);   

[self.view addSubview:mirrorImgView];          

CAGradientLayer* GDlayer=[CAGradientLayer layer];     

GDlayer.frame=CGRectMake(0, 0, 150, 100); 

[GDlayer setColors:@[(id)[UIColor clearColor].CGColor,  (id)[UIColor colorWithWhite:0 alpha:0.5].CGColor ]];    

[GDlayer setStartPoint:CGPointMake(0, 0.7)];    

[GDlayer setEndPoint:CGPointMake(0, 1)];     

mirrorImgView.layer.mask=GDlayer;

---

CAShaperLayer

用以绘制形状、CGPath

    CAShapeLayer *shapeLayer=[CAShapeLayer layer];

    shapeLayer.strokeColor=[UIColor redColor].CGColor;

    shapeLayer.fillColor=[UIColor clearColor].CGColor;

    [self.view.layeraddSublayer:shapeLayer];

    CGMutablePathRef path=CGPathCreateMutable();

    CGPathMoveToPoint(path,nil,50,200);

    CGPathAddCurveToPoint(path,nil,100,100,250,300,300,200);

    shapeLayer.path=path;

    CGPathRelease(path);

beizer曲线

    CAShapeLayer* slayer=[CAShapeLayer layer];

    CGPointstartPoint=CGPointMake(50,200);

    CGPointendPoint=CGPointMake(300,200);

    CGPointcontrolPoint1=CGPointMake(100,100);

    CGPointcontrolPoint2=CGPointMake(250,300);

    UIBezierPath* path=[UIBezierPath bezierPath];

    [pathmoveToPoint:startPoint];

    [pathaddCurveToPoint:endPointcontrolPoint1:controlPoint1controlPoint2:controlPoint2];

    slayer.path=path.CGPath;

    slayer.strokeColor=[UIColor redColor].CGColor;

    slayer.fillColor=[UIColor clearColor].CGColor;

    //矩形

    UIBezierPath* path2=[UIBezierPath bezierPathWithRect:CGRectMake(100, 100, 200, 200)];

    slayer.path=path2.CGPath;

    //[self.view.layer addSublayer:slayer];

    //带圆角的矩形 还有圆形等其他图形

    UIBezierPath* path3=[UIBezierPath bezierPathWithRoundedRect:CGRectMake(100, 100, 200, 200) cornerRadius:100];

    slayer.path=path3.CGPath;

    [self.view.layeraddSublayer:slayer];

//画图 ponit点我是随便写的主要想说明方法

UIBezierPath *bezierPath=[UIBezierPath bezierPath];

[bezierPath moveToPoint:CGPointMake(0, 0)];     

[bezierPath addLineToPoint:CGPointMake(10,20)];     

[bezierPath addCurveToPoint:CGPointMake(100, 200) controlPoint1:CGPointMake(50, 50) controlPoint2:CGPointMake(70, 120)];     

[bezierPath closePath];

自定义Layer 

调用时要将opaque置为0 当用法二时还要调用一下 setNeedDisplay ，法二的优先级高

//方法1

- (void)drawRect:(CGRect)rect {

    CGContextRef ctx=UIGraphicsGetCurrentContext();

    CGContextAddRect(ctx, CGRectMake(50, 50, 100, 100));

    CGContextSetRGBFillColor(ctx, 0, 0, 1, 1);

    CGContextFillPath(ctx);

}

//方法二

-(void)drawLayer:(CALayer*)layer inContext:(CGContextRef)ctx{

    CGContextAddRect(ctx, CGRectMake(50, 50, 100, 100));

    CGContextSetRGBFillColor(ctx, 1, 0, 0, 1);

    CGContextFillPath(ctx);

}