在Swift中是否等效于CGPathApply?
在预发布文档中,似乎没有Swift版本的CGPathApply。是否有同等的或替代的?我正在尝试获取CGPath的所有子路径,以便可以从其他起点重绘它。
回答:
斯威夫特3.0
在Swift 3.0中,您可以这样使用CGPath.apply
:
let path: CGPath = ...// or let path: CGMutablePath
path.apply(info: nil) { (_, elementPointer) in
let element = elementPointer.pointee
let command: String
let pointCount: Int
switch element.type {
case .moveToPoint: command = "moveTo"; pointCount = 1
case .addLineToPoint: command = "lineTo"; pointCount = 1
case .addQuadCurveToPoint: command = "quadCurveTo"; pointCount = 2
case .addCurveToPoint: command = "curveTo"; pointCount = 3
case .closeSubpath: command = "close"; pointCount = 0
}
let points = Array(UnsafeBufferPointer(start: element.points, count: pointCount))
Swift.print("\(command) \(points)")
}
斯威夫特2.2
通过添加@convention(c)
,您现在可以CGPathApply
直接从Swift进行调用。这是做必要魔术的包装器:
extension CGPath { func forEach(@noescape body: @convention(block) (CGPathElement) -> Void) {
typealias Body = @convention(block) (CGPathElement) -> Void
func callback(info: UnsafeMutablePointer<Void>, element: UnsafePointer<CGPathElement>) {
let body = unsafeBitCast(info, Body.self)
body(element.memory)
}
print(sizeofValue(body))
let unsafeBody = unsafeBitCast(body, UnsafeMutablePointer<Void>.self)
CGPathApply(self, unsafeBody, callback)
}
}
(请注意,@convention(c)
我的代码中没有提到,但是CGPathApply
在Core Graphics模块的声明中使用了它。)
用法示例:
let path = UIBezierPath(roundedRect: CGRectMake(0, 0, 200, 100), cornerRadius: 15)path.CGPath.forEach { element in
switch (element.type) {
case CGPathElementType.MoveToPoint:
print("move(\(element.points[0]))")
case .AddLineToPoint:
print("line(\(element.points[0]))")
case .AddQuadCurveToPoint:
print("quadCurve(\(element.points[0]), \(element.points[1]))")
case .AddCurveToPoint:
print("curve(\(element.points[0]), \(element.points[1]), \(element.points[2]))")
case .CloseSubpath:
print("close()")
}
}
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