1 #import "ViewController.h"
2 #import "SecondVC.h"
3
4
5 #define WIDTH [UIScreen mainScreen].bounds.size.width
6 #define HEIGHT [UIScreen mainScreen].bounds.size.height
7
8 @interface ViewController ()
9 {
10 UIImageView *_canvasView;//画布
11 CGPoint _startPoint;//记录开始坐标
12
13 }
14 @end
15
16 @implementation ViewController
17
18 - (void)viewDidLoad {
19 [super viewDidLoad];
20
21 _canvasView = [[UIImageView alloc] initWithFrame:self.view.bounds];
22 [self.view addSubview:_canvasView];
23
24 UIButton *clearBtn = [UIButton buttonWithType:UIButtonTypeCustom];
25 clearBtn.frame = CGRectMake(50, 20, 100, 30);
26 [clearBtn addTarget:self action:@selector(clearBtnClick) forControlEvents:UIControlEventTouchUpInside];
27 [clearBtn setTitle:@"清空" forState:UIControlStateNormal];
28 clearBtn.backgroundColor = [UIColor orangeColor];
29 [self.view addSubview:clearBtn];
30
31 UIButton *cutPicBtn = [UIButton buttonWithType:UIButtonTypeCustom];
32 cutPicBtn.frame = CGRectMake(250, 20, 100, 30);
33 [cutPicBtn addTarget:self action:@selector(cutPicBtnClick) forControlEvents:UIControlEventTouchUpInside];
34 [cutPicBtn setTitle:@"截图" forState:UIControlStateNormal];
35 cutPicBtn.backgroundColor = [UIColor orangeColor];
36 [self.view addSubview:cutPicBtn];
37
38 }
39
40
41 - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
42 {
43 _startPoint = [[touches anyObject] locationInView:_canvasView];
44
45 }
46
47 - (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
48 {
49 CGPoint movePoint = [[touches anyObject] locationInView:_canvasView];
50
51 // 移动的点有很多，
52 @autoreleasepool {
53 UIGraphicsBeginImageContext(CGSizeMake(WIDTH, HEIGHT));//开始一个图片的绘图
54
55 [_canvasView drawRect:_canvasView.frame];//绘制原来已经存在的线条
56
57 CGContextRef context = UIGraphicsGetCurrentContext();//绘图缓存区，当前的是一张图片
58 CGContextSetLineWidth(context, 5);
59 CGContextSetRGBStrokeColor(context, 1, 0, 0, 1);
60 CGContextSetLineCap(context, kCGLineCapRound);//边帽
61 CGContextSetLineJoin(context, kCGLineJoinRound);//缝合
62
63 CGContextMoveToPoint(context, _startPoint.x, _startPoint.y);
64 CGContextAddLineToPoint(context, movePoint.x, movePoint.y);
65 CGContextStrokePath(context);
66 _canvasView.image = UIGraphicsGetImageFromCurrentImageContext();//获取当前图片绘制区域内的图片
67
68 UIGraphicsEndImageContext();//关闭图片绘制
69 }
70
71 _startPoint = movePoint;
72 }
73
74
75 #pragma mark - 清除按钮
76 - (void)clearBtnClick
77 {
78
79 _canvasView.image = nil;//这并不是一个好办法。
80
81 }
82
83 #pragma mark - 剪切按钮
84 - (void)cutPicBtnClick
85 {
86 UIGraphicsBeginImageContext(CGSizeMake(WIDTH, HEIGHT));//开始一个图片的绘图
87 // 在屏幕加载之后截图
88 [self.view drawViewHierarchyInRect:self.view.frame afterScreenUpdates:YES];
89
90 UIImage *image = UIGraphicsGetImageFromCurrentImageContext();//获取当前图片绘制区域内的图片
91
92 UIGraphicsEndImageContext();
93
94 SecondVC *vc = [[SecondVC alloc] init];
95 vc.image = image;
96 [self presentViewController:vc animated:YES completion:nil];
97 }
