CALayer知识：创建带阴影效果的圆角图片图层和创建自定义绘画内容图层

1 #import <UIKit/UIKit.h>2 3 @interface KMLayerDelegate : NSObject4 5 @end

 1 #import "KMLayerDelegate.h" 2  3 @implementation KMLayerDelegate 4  5 /** 6  *  根据角度，获取对应的弧度 7  * 8  *  @param degree 角度 9  *10  *  @return 对应的弧度11  */12 static inline double radian(double degree) {13     return degree * M_PI/180;14 }15 16 /**17  *  绘画着色模式内容；绘画预定宽高大小的单元格，每个单元格包含两个半圆，分别为『左上角的上半圆』和『右下边的下半圆』18  *19  *  @param info    信息20  *  @param context 上下文21  */22 void drawColoredPattern(void *info, CGContextRef context) {23     CGColorRef dotColor = [UIColor colorWithHue:0.0 saturation:0.0 brightness:0.0 alpha:0.8].CGColor; //圆点颜色；以色彩、饱和度、亮度和不透明度组合的颜色24     CGColorRef dotShadowColor = [UIColor orangeColor].CGColor; //圆点阴影颜色25     26     CGContextSetFillColorWithColor(context, dotColor); //设置填充色27     CGContextSetShadowWithColor(context, CGSizeMake(2.0, 2.0), 1, dotShadowColor); //设置阴影颜色；以阴影位置偏差为(2.0, 2.0)、模糊效果的 dotShadowColor 作为阴影颜色28     29     CGContextAddArc(context, 10.0, 10.0, 10.0, 0.0, radian(180.0), 1); //添加圆点；以居中点为(10.0, 10.0)、半径为10.0、顺时针画0.0到180.0弧度的圆点（即为上半圆），注意0.0弧度为水平线左边位置开始30     CGContextFillPath(context);31     32     CGContextAddArc(context, 30.0, 20.0, 10.0, 0.0, radian(180.0), 0); //添加圆点；以居中点为(30.0, 20.0)、半径为10.0、逆时针画0.0到180.0弧度的圆点（即为下半圆），注意0.0弧度为水平线左边位置开始33     CGContextFillPath(context);34 }35 36 /**37  *  绘画内容图层38  *39  *  @param layer   当前图层40  *  @param context 上下文41  */42 - (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)context {43     //图层背景颜色44     CGColorRef backgroundColor = [UIColor lightGrayColor].CGColor;45     CGContextSetFillColorWithColor(context, backgroundColor);46     CGContextFillRect(context, layer.bounds);47     48     static const CGPatternCallbacks callbacks = { 0, &drawColoredPattern, NULL };49     //绘画连续的单元格，每个单元格的内容由 drawColoredPattern 方法决定50     CGContextSaveGState(context);51     CGColorSpaceRef patternSpace = CGColorSpaceCreatePattern(NULL);52     CGContextSetFillColorSpace(context, patternSpace);53     CGColorSpaceRelease(patternSpace);54     55     CGPatternRef pattern = CGPatternCreate(NULL,56                                            layer.bounds,57                                            CGAffineTransformIdentity,58                                            40.0, //单元格的宽度59                                            40.0, //单元格的高度60                                            kCGPatternTilingConstantSpacing,61                                            true,62                                            &callbacks);63     CGFloat alpha = 1.0; //着色模式内容的不透明度64     CGContextSetFillPattern(context, pattern, &alpha);65     CGPatternRelease(pattern);66     CGContextFillRect(context, layer.bounds);67     CGContextRestoreGState(context);68 }69 70 @end

1 #import <UIKit/UIKit.h>2 #import "KMLayerDelegate.h"3 4 @interface ViewController : UIViewController5 @PRoperty (strong, nonatomic) KMLayerDelegate *layerDelegate;6 7 @end

 1 #import "ViewController.h" 2  3 static const CGFloat cornerRadius = 10.0; 4 @interface ViewController () 5 - (void)createShadowCornerImage:(UIImage *)image withRootLayer:(CALayer *)rootLayer; 6 - (void)createCustomDrawingLayer:(CALayer *)rootLayer; 7 - (void)layoutUI; 8 @end 9 10 @implementation ViewController11 12 - (void)viewDidLoad {13     [super viewDidLoad];14     15     [self layoutUI];16 }17 18 - (void)didReceiveMemoryWarning {19     [super didReceiveMemoryWarning];20     // Dispose of any resources that can be recreated.21 }22 23 /**24  *  创建带阴影效果的圆角图片图层25  *26  *  @param image     图片27  *  @param rootLayer 根图层28  */29 - (void)createShadowCornerImage:(UIImage *)image withRootLayer:(CALayer *)rootLayer {30     //子图层（图片的阴影图层）31     CALayer *subLayer = [CALayer layer];32     subLayer.frame = CGRectMake(40.0, 40.0, 240.0, 240.0);33     subLayer.backgroundColor = [UIColor lightGrayColor].CGColor;34     subLayer.cornerRadius = cornerRadius;35     subLayer.borderColor = [UIColor blackColor].CGColor;36     subLayer.borderWidth = 2.0;37     subLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影颜色38     subLayer.shadowOpacity = 0.7; //设置阴影不透明度39     subLayer.shadowOffset = CGSizeMake(4.0, 3.0); //设置阴影位置偏差40     subLayer.shadowRadius = 5.0; //设置阴影圆角半径41     [rootLayer addSublayer:subLayer];42     43     //子图层的子图层（图片的内容图层）44     CALayer *imageLayer = [CALayer layer];45     imageLayer.frame = subLayer.bounds;46     imageLayer.contents = (id)image.CGImage;47     imageLayer.masksToBounds = YES; //设置标示剪切界限；内容图层需设置为 YES，才能有圆角效果48     imageLayer.cornerRadius = cornerRadius;49     CGAffineTransform affineTransform = CGAffineTransformConcat(CGAffineTransformMakeScale(0.8, 0.8), CGAffineTransformMakeRotation(M_PI_4/9)); //合并缩放和旋转效果；以0.8比例居中缩放，以45度/9=5度的角度顺时针旋转50     imageLayer.affineTransform = affineTransform;51     [subLayer addSublayer:imageLayer];52 }53 54 /**55  *  创建自定义绘画内容图层56  *57  *  @param rootLayer 根图层58  */59 - (void)createCustomDrawingLayer:(CALayer *)rootLayer {60     CALayer *drawingLayer = [CALayer layer];61     drawingLayer.frame = CGRectMake(40.0, 320.0, 240.0, 240.0);62     drawingLayer.backgroundColor = [UIColor orangeColor].CGColor; //背景颜色会被内容图层遮住，所以最终呈现的以内容图层为准63     drawingLayer.masksToBounds = YES; //设置标示剪切界限；内容图层需设置为 YES，才能有圆角效果64     drawingLayer.cornerRadius = cornerRadius;65     drawingLayer.borderColor = [UIColor blackColor].CGColor;66     drawingLayer.borderWidth = 2.0;67     drawingLayer.shadowColor = [UIColor darkGrayColor].CGColor; //设置阴影颜色68     drawingLayer.shadowOpacity = 0.8; //设置阴影不透明度69     drawingLayer.shadowOffset = CGSizeMake(8.0, 6.0); //设置阴影位置偏差70     drawingLayer.shadowRadius = 5.0; //设置阴影圆角半径71     72     _layerDelegate = [KMLayerDelegate new];73     drawingLayer.delegate = _layerDelegate;74     [drawingLayer setNeedsDisplay]; //这里必须调用方法 setNeedsDisplay，才会触发委托代理方法 drawLayer:75     [rootLayer addSublayer:drawingLayer];76 }77 78 - (void)layoutUI {79     //根图层80     CALayer *rootLayer = self.view.layer;81     rootLayer.backgroundColor = [UIColor cyanColor].CGColor;82     rootLayer.cornerRadius = 40.0;83     84     [self createShadowCornerImage:[UIImage imageNamed:@"Emoticon_tusiji_icon2"]85                     withRootLayer:rootLayer];86     [self createCustomDrawingLayer:rootLayer];87 }88 89 @end