如何获取UIBezierPath的反向路径 [英] How to Get the reverse path of a UIBezierPath

问题描述

self.myPath=[UIBezierPath bezierPathWithArcCenter:center 
                                           radius:200 
                                       startAngle:0 
                                         endAngle:180 
                                        clockwise:YES];

（这一点我能够通过网络搜索开始运行）。

(This much I was able to get up running with some web searching).

我有这条路。现在我想填补这条路径的反面，所以留下这部分并填充其他所有内容。我怎样才能完成编码？我没有太多信息。

I have this path. Now I want to fill the reverse of this path, so leaving this portion and filling everything else. How can I finish the coding? I don't have much info on this.

使用Cemal后显示的区域以前只显示红色笔划的圆圈。

The area it is showing after using Cemal Answer previously it only showed a circle with red stroke.

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor whiteColor];
        self.punchedOutPath =  
         [UIBezierPath bezierPathWithOvalInRect:CGRectMake(50, 50, 400, 400)];
        self.fillColor = [UIColor redColor];
        self.alpha = 0.8;
    }
    return self;
}

- (void)drawRect:(CGRect)rect
{
    [[self fillColor] set];
    UIRectFill(rect);

    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextSetBlendMode(ctx, kCGBlendModeDestinationOut);

    [[self punchedOutPath] fill];

    CGContextSetBlendMode(ctx, kCGBlendModeNormal);
}

推荐答案

使用 bezierPathByReversingPath 。来自文档（仅限iOS 6.0+）：

Use bezierPathByReversingPath. From the docs (iOS 6.0+ only):

创建并返回一个新的贝塞尔曲线路径对象，其中包含当前路径的反转内容。 / p>

Creates and returns a new bezier path object with the reversed contents of the current path.

所以要改变你的路径，你只需：

so to reverse your path, you'd just:

UIBezierPath* aPath = [UIBezierPath bezierPathWithArcCenter:center
                                                     radius:200
                                                 startAngle:0
                                                   endAngle:180
                                                  clockwise:YES];
self.myPath = [aPath bezierPathByReversingPath];

这篇关于如何获取UIBezierPath的反向路径的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！