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 : NSObject
4 
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 : UIViewController
5 @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 ViewController
11 
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