Xcode - 在中心周围画圆
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Xcode - Draw Circle Around Centre
提问by dgee4
I was wondering how to draw a circle around a point taken from a control's positioning.
我想知道如何围绕从控件定位中获取的点画一个圆圈。
This is not working as hoped
这不像预期的那样工作
CGContextRef contextRef = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(contextRef, 2.0);
CGContextSetRGBFillColor(contextRef, 0, 0, 1.0, 1.0);
CGContextSetRGBStrokeColor(contextRef, 0, 0, 1.0, 1.0);
CGRect circlePoint = (CGRectMake(self.frame.size.width / 2, self.frame.size.height / 2, 10.0, 10.0));
CGContextFillEllipseInRect(contextRef, circlePoint);
回答by Naga Mallesh Maddali
I think its pretty easy to draw a circle using UIBezierPath. All you need to do is subclass UIView and create UIBezierPath. I have created a example using UIBezierPath :
我认为使用 UIBezierPath 画一个圆很容易。您需要做的就是继承 UIView 并创建 UIBezierPath。我使用 UIBezierPath 创建了一个示例：
Create a subclass of UIView called CirecleView. Add following code :
创建一个名为 CirecleView 的 UIView 子类。添加以下代码：
#import "CircleView.h"
@implementation CircleView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
- (void)drawRect:(CGRect)rect
{
CGFloat rectX = self.frame.size.width / 2;
CGFloat rectY = self.frame.size.height / 2;
CGFloat width = 100;
CGFloat height = 100;
CGFloat centerX = rectX - width/2;
CGFloat centerY = rectY - height/2;
UIBezierPath *bezierPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(centerX, centerY, width, height)];
[[UIColor blackColor] set];
[bezierPath stroke];
}
@end
Change your controller's view class to CircleView. Please see below picture.
将控制器的视图类更改为 CircleView。请看下图。
Thats it. Run your code to present your controller's view. Following is the output :
就是这样。运行您的代码以显示控制器的视图。以下是输出：
You can down code example from here
您可以从这里下载代码示例
回答by Knight0fDragon
You just need to translate to the point first
你只需要先翻译到重点
cgContextRef.translateBy(x:circlePoint.x, y:circlePoint.y)
Note this is Swift 3, it may be different in other languages, just search "translate cgcontext"
请注意，这是 Swift 3，在其他语言中可能有所不同，只需搜索“translate cgcontext”
