图形上下文状态栈

Posted on 2016-07-12 16:57  柠檬片  阅读(179)  评论(0)    收藏  举报 
 1 - (void)drawRect:(CGRect)rect {
 2     // Drawing code
 3     
 4     
 5     //1.获取跟View相关联的上下文
 6    CGContextRef ctx = UIGraphicsGetCurrentContext();
 7     //2.描述路径
 8     UIBezierPath *path = [UIBezierPath bezierPath];
 9     
10     //添加横线
11     [path moveToPoint:CGPointMake(10, 150)];
12     [path addLineToPoint:CGPointMake(290, 150)];
13 
14     //把当前的状态保存到图片上下文状态栈里.
15     CGContextSaveGState(ctx);
16 
17     
18     [[UIColor redColor] set];
19     CGContextSetLineWidth(ctx, 10);
20     
21     
22     //3.把路径添加到上下文
23     CGContextAddPath(ctx, path.CGPath);
24 
25     //4.把上下文的内容渲染出来.
26     CGContextStrokePath(ctx);
27     
28     
29     path = [UIBezierPath bezierPath];
30     [path moveToPoint:CGPointMake(150, 10)];
31     [path addLineToPoint:CGPointMake(150, 290)];
32 
33     
34     //恢复上下文状态栈
35     CGContextRestoreGState(ctx);
36     
37     
38     //3.把路径添加到上下文
39     CGContextAddPath(ctx, path.CGPath);
40     
41     //4.把上下文的内容渲染出来.
42     CGContextStrokePath(ctx);
43     
44     
45 }
图形上下文状态栈