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如何从 UIBezierPath 获取点列表？

发布于 2024-09-05 11:42:21 字数 290 浏览 8 评论 0原文

我有一个 UIBezierPath 我需要获取以下列表点来自。

在Qt 中，有一个名为pointAtPercent 的函数可以满足我的需求，但我在Objective-C 中找不到任何等效的函数。

有谁知道该怎么做？

原文

I have a UIBezierPath that I need to take a list of points from.

In Qt there is a function called pointAtPercent that would fit my needs but I can't find anything equivalent in Objective-C.

Does anyone know how to do this?

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评论（7）

谁对谁错谁最难过 2024-09-12 11:42:21

您可以尝试这样做：

UIBezierPath *yourPath; // Assume this has some points in it
CGPath yourCGPath = yourPath.CGPath;
NSMutableArray *bezierPoints = [NSMutableArray array];
CGPathApply(yourCGPath, bezierPoints, MyCGPathApplierFunc);

路径应用程序函数将依次处理路径的每个路径元素。
查看 CGPathApplierFunction 和 CGPathApply。

路径应用程序函数可能看起来像这样

void MyCGPathApplierFunc (void *info, const CGPathElement *element) {
    NSMutableArray *bezierPoints = (NSMutableArray *)info;

    CGPoint *points = element->points;
    CGPathElementType type = element->type;

    switch(type) {
        case kCGPathElementMoveToPoint: // contains 1 point
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[0]]];
            break;
        
        case kCGPathElementAddLineToPoint: // contains 1 point
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[0]]];            
            break;
        
        case kCGPathElementAddQuadCurveToPoint: // contains 2 points
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[0]]];
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[1]]];            
            break;
        
        case kCGPathElementAddCurveToPoint: // contains 3 points
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[0]]];
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[1]]];
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[2]]];
            break;
        
        case kCGPathElementCloseSubpath: // contains no point
            break;
    }
}

You might try this:

UIBezierPath *yourPath; // Assume this has some points in it
CGPath yourCGPath = yourPath.CGPath;
NSMutableArray *bezierPoints = [NSMutableArray array];
CGPathApply(yourCGPath, bezierPoints, MyCGPathApplierFunc);

The path applier function will be handed each of the path's path elements in turn.
Check out CGPathApplierFunction and CGPathApply.

The path applier function might look something like this

void MyCGPathApplierFunc (void *info, const CGPathElement *element) {
    NSMutableArray *bezierPoints = (NSMutableArray *)info;

    CGPoint *points = element->points;
    CGPathElementType type = element->type;

    switch(type) {
        case kCGPathElementMoveToPoint: // contains 1 point
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[0]]];
            break;
        
        case kCGPathElementAddLineToPoint: // contains 1 point
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[0]]];            
            break;
        
        case kCGPathElementAddQuadCurveToPoint: // contains 2 points
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[0]]];
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[1]]];            
            break;
        
        case kCGPathElementAddCurveToPoint: // contains 3 points
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[0]]];
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[1]]];
            [bezierPoints addObject:[NSValue valueWithCGPoint:points[2]]];
            break;
        
        case kCGPathElementCloseSubpath: // contains no point
            break;
    }
}
回复 原文
不乱于心 2024-09-12 11:42:21

@莫里茨 很好的答案！为了找到类似 Swift 的解决方案，我在这篇文章中偶然发现了一种方法，并实现了一个像这样的 CGPath 扩展来获取要点路径：

extension CGPath {
    func points() -> [CGPoint]
    {
        var bezierPoints = [CGPoint]()
        forEach(body: { (element: CGPathElement) in
            let numberOfPoints: Int = {
                switch element.type {
                case .moveToPoint, .addLineToPoint: // contains 1 point
                    return 1
                case .addQuadCurveToPoint: // contains 2 points
                    return 2
                case .addCurveToPoint: // contains 3 points
                    return 3
                case .closeSubpath:
                    return 0
                }
            }()
            for index in 0..<numberOfPoints {
                let point = element.points[index]
                bezierPoints.append(point)
            }
        })
        return bezierPoints
    }
    
    func forEach(body: @escaping @convention(block) (CGPathElement) -> Void) {
        typealias Body = @convention(block) (CGPathElement) -> Void
        
        func callback(info: UnsafeMutableRawPointer?, element: UnsafePointer<CGPathElement>) {
            let body = unsafeBitCast(info, to: Body.self)
            body(element.pointee)
        }
        
        let unsafeBody = unsafeBitCast(body, to: UnsafeMutableRawPointer.self)
        apply(info: unsafeBody, function: callback)
    }
}

@Moritz Great answer! To find a Swift like solution I strumbled across an approach in this post and implemented a CGPath extension like this to get the points from the path:

extension CGPath {
    func points() -> [CGPoint]
    {
        var bezierPoints = [CGPoint]()
        forEach(body: { (element: CGPathElement) in
            let numberOfPoints: Int = {
                switch element.type {
                case .moveToPoint, .addLineToPoint: // contains 1 point
                    return 1
                case .addQuadCurveToPoint: // contains 2 points
                    return 2
                case .addCurveToPoint: // contains 3 points
                    return 3
                case .closeSubpath:
                    return 0
                }
            }()
            for index in 0..<numberOfPoints {
                let point = element.points[index]
                bezierPoints.append(point)
            }
        })
        return bezierPoints
    }
    
    func forEach(body: @escaping @convention(block) (CGPathElement) -> Void) {
        typealias Body = @convention(block) (CGPathElement) -> Void
        
        func callback(info: UnsafeMutableRawPointer?, element: UnsafePointer<CGPathElement>) {
            let body = unsafeBitCast(info, to: Body.self)
            body(element.pointee)
        }
        
        let unsafeBody = unsafeBitCast(body, to: UnsafeMutableRawPointer.self)
        apply(info: unsafeBody, function: callback)
    }
}
回复 原文
你如我软肋 2024-09-12 11:42:21

我认为你试图做这样的事情：

https://math.stackexchange.com/questions/26846/is-there-an-explicit-form-for-cubic-bézier-curves

y=u0(1−x^3)+3u1(1−x^2)x+3u2(1−x)x^2+u3x^3< /code>

这是我打印该函数的所有值的方法。

- (void)logXY {

    float u0 = 0;
    float u1 = 0.05;
    float u2 = 0.25;
    float u3 = 1;

    for (float x = 0; x <= 10.0; x = x + 0.1) {
        float y = u0 * (1 - x * x * x) + 3 * u1 * (1 - x * x) * x + 3 * u2 * (1 - x) * x * x + u3 * x * x * x;

        NSLog(@"x: %f\ty: %f", x, y);
    }
}

输出是：

x: 0.000000 y: 0.000000
x: 0.100000 y: 0.022600
x: 0.200000 y: 0.060800
x: 0.300000 y: 0.115200
x: 0.400000 y: 0.186400
x: 0.500000 y: 0.275000
x: 0.600000 y: 0.381600
x: 0.700000 y: 0.506800
x: 0.800000 y: 0.651200
x: 0.900000 y: 0.815400
x: 1.000000 y: 1.000000
x: 1.100000 y: 1.205600
x: 1.200000 y: 1.432800
x: 1.300000 y: 1.682200
x: 1.400000 y: 1.954401
x: 1.500000 y: 2.250001
x: 1.600000 y: 2.569601
x: 1.700000 y: 2.913801
x: 1.800000 y: 3.283201
x: 1.900000 y: 3.678401
x: 2.000000 y: 4.100001
x: 2.100000 y: 4.548601
x: 2.200000 y: 5.024800
x: 2.300000 y: 5.529200
x: 2.400000 y: 6.062399
x: 2.500000 y: 6.625000
x: 2.600000 y: 7.217597
x: 2.700000 y: 7.840797
x: 2.799999 y: 8.495197
x: 2.899999 y: 9.181394
x: 2.999999 y: 9.899996

I think you were trying to do something like this:

https://math.stackexchange.com/questions/26846/is-there-an-explicit-form-for-cubic-bézier-curves

y=u0(1−x^3)+3u1(1−x^2)x+3u2(1−x)x^2+u3x^3

This is my method for printing all values of that function.

- (void)logXY {

    float u0 = 0;
    float u1 = 0.05;
    float u2 = 0.25;
    float u3 = 1;

    for (float x = 0; x <= 10.0; x = x + 0.1) {
        float y = u0 * (1 - x * x * x) + 3 * u1 * (1 - x * x) * x + 3 * u2 * (1 - x) * x * x + u3 * x * x * x;

        NSLog(@"x: %f\ty: %f", x, y);
    }
}

And output is:

x: 0.000000 y: 0.000000
x: 0.100000 y: 0.022600
x: 0.200000 y: 0.060800
x: 0.300000 y: 0.115200
x: 0.400000 y: 0.186400
x: 0.500000 y: 0.275000
x: 0.600000 y: 0.381600
x: 0.700000 y: 0.506800
x: 0.800000 y: 0.651200
x: 0.900000 y: 0.815400
x: 1.000000 y: 1.000000
x: 1.100000 y: 1.205600
x: 1.200000 y: 1.432800
x: 1.300000 y: 1.682200
x: 1.400000 y: 1.954401
x: 1.500000 y: 2.250001
x: 1.600000 y: 2.569601
x: 1.700000 y: 2.913801
x: 1.800000 y: 3.283201
x: 1.900000 y: 3.678401
x: 2.000000 y: 4.100001
x: 2.100000 y: 4.548601
x: 2.200000 y: 5.024800
x: 2.300000 y: 5.529200
x: 2.400000 y: 6.062399
x: 2.500000 y: 6.625000
x: 2.600000 y: 7.217597
x: 2.700000 y: 7.840797
x: 2.799999 y: 8.495197
x: 2.899999 y: 9.181394
x: 2.999999 y: 9.899996
回复 原文
眉黛浅 2024-09-12 11:42:21

我写了一篇关于查找 UIBezierPath 上最近的点的文章，其中与OP正在寻找的非常相似。我还在 Swift 上创建了一个演示项目： https://github.com/agordeev/BezierPathClosestPoint

I wrote an article about finding the closest point on UIBezierPath, which is very similar to what the OP is looking for. I've also created a demo project on Swift: https://github.com/agordeev/BezierPathClosestPoint

回复 原文
若水微香 2024-09-12 11:42:21

我已经修改了 @FBente 帖子以与 swift 3 一起使用

extension CGPath {
func points() -> [CGPoint]
{
    var bezierPoints = [CGPoint]()
    self.forEach(body: { (element: CGPathElement) in
        let numberOfPoints: Int = {
            switch element.type {
            case .moveToPoint, .addLineToPoint: // contains 1 point
                return 1
            case .addQuadCurveToPoint: // contains 2 points
                return 2
            case .addCurveToPoint: // contains 3 points
                return 3
            case .closeSubpath:
                return 0
            }
        }()
        for index in 0..<numberOfPoints {
            let point = element.points[index]
            bezierPoints.append(point)
        }
    })
    return bezierPoints
}

func forEach( body: @convention(block) (CGPathElement) -> Void) {
    typealias Body = @convention(block) (CGPathElement) -> Void
    func callback(info: UnsafeMutableRawPointer, element: UnsafePointer<CGPathElement>) {
        let body = unsafeBitCast(info, to: Body.self)
        body(element.pointee)
    }
    let unsafeBody = unsafeBitCast(body, to: UnsafeMutableRawPointer.self)
    self.apply(info: unsafeBody, function: callback as! CGPathApplierFunction)
}
}

i have modified @FBente post to work with swift 3

extension CGPath {
func points() -> [CGPoint]
{
    var bezierPoints = [CGPoint]()
    self.forEach(body: { (element: CGPathElement) in
        let numberOfPoints: Int = {
            switch element.type {
            case .moveToPoint, .addLineToPoint: // contains 1 point
                return 1
            case .addQuadCurveToPoint: // contains 2 points
                return 2
            case .addCurveToPoint: // contains 3 points
                return 3
            case .closeSubpath:
                return 0
            }
        }()
        for index in 0..<numberOfPoints {
            let point = element.points[index]
            bezierPoints.append(point)
        }
    })
    return bezierPoints
}

func forEach( body: @convention(block) (CGPathElement) -> Void) {
    typealias Body = @convention(block) (CGPathElement) -> Void
    func callback(info: UnsafeMutableRawPointer, element: UnsafePointer<CGPathElement>) {
        let body = unsafeBitCast(info, to: Body.self)
        body(element.pointee)
    }
    let unsafeBody = unsafeBitCast(body, to: UnsafeMutableRawPointer.self)
    self.apply(info: unsafeBody, function: callback as! CGPathApplierFunction)
}
}
回复 原文
错爱 2024-09-12 11:42:21

迅速4.0：

    var bezierPoints = NSMutableArray()
    yourPath.apply(info: &bezierPoints, function: { info, element in

        guard let resultingPoints = info?.assumingMemoryBound(to: NSMutableArray.self) else {
            return
        }

        let points = element.pointee.points
        let type = element.pointee.type

        switch type {
        case .moveToPoint:
            resultingPoints.pointee.add([NSNumber(value: Float(points[0].x)), NSNumber(value: Float(points[0].y))])

        case .addLineToPoint:
            resultingPoints.pointee.add([NSNumber(value: Float(points[0].x)), NSNumber(value: Float(points[0].y))])

        case .addQuadCurveToPoint:
            resultingPoints.pointee.add([NSNumber(value: Float(points[0].x)), NSNumber(value: Float(points[0].y))])
            resultingPoints.pointee.add([NSNumber(value: Float(points[1].x)), NSNumber(value: Float(points[1].y))])

        case .addCurveToPoint:
            resultingPoints.pointee.add([NSNumber(value: Float(points[0].x)), NSNumber(value: Float(points[0].y))])
            resultingPoints.pointee.add([NSNumber(value: Float(points[1].x)), NSNumber(value: Float(points[1].y))])
            resultingPoints.pointee.add([NSNumber(value: Float(points[2].x)), NSNumber(value: Float(points[2].y))])

        case .closeSubpath:
            break
        }
    })

swift 4.0:

    var bezierPoints = NSMutableArray()
    yourPath.apply(info: &bezierPoints, function: { info, element in

        guard let resultingPoints = info?.assumingMemoryBound(to: NSMutableArray.self) else {
            return
        }

        let points = element.pointee.points
        let type = element.pointee.type

        switch type {
        case .moveToPoint:
            resultingPoints.pointee.add([NSNumber(value: Float(points[0].x)), NSNumber(value: Float(points[0].y))])

        case .addLineToPoint:
            resultingPoints.pointee.add([NSNumber(value: Float(points[0].x)), NSNumber(value: Float(points[0].y))])

        case .addQuadCurveToPoint:
            resultingPoints.pointee.add([NSNumber(value: Float(points[0].x)), NSNumber(value: Float(points[0].y))])
            resultingPoints.pointee.add([NSNumber(value: Float(points[1].x)), NSNumber(value: Float(points[1].y))])

        case .addCurveToPoint:
            resultingPoints.pointee.add([NSNumber(value: Float(points[0].x)), NSNumber(value: Float(points[0].y))])
            resultingPoints.pointee.add([NSNumber(value: Float(points[1].x)), NSNumber(value: Float(points[1].y))])
            resultingPoints.pointee.add([NSNumber(value: Float(points[2].x)), NSNumber(value: Float(points[2].y))])

        case .closeSubpath:
            break
        }
    })
回复 原文
昇り龍 2024-09-12 11:42:21

更新了 FBente 的 Swift 3 扩展：

extension CGPath {
  func points() -> [CGPoint]
  {
    var bezierPoints = [CGPoint]()
    self.forEach({ (element: CGPathElement) in
      let numberOfPoints: Int = {
        switch element.type {
        case .moveToPoint, .addLineToPoint: // contains 1 point
          return 1
        case .addQuadCurveToPoint: // contains 2 points
          return 2
        case .addCurveToPoint: // contains 3 points
          return 3
        case .closeSubpath:
          return 0
        }
      }()
      for index in 0..<numberOfPoints {
        let point = element.points[index]
        bezierPoints.append(point)
      }
    })
    return bezierPoints
  }

  func forEach(_ body: @convention(block) (CGPathElement) -> Void) {
    typealias Body = @convention(block) (CGPathElement) -> Void
    func callback(info: UnsafeMutableRawPointer, element: UnsafePointer<CGPathElement>) {
      let body = unsafeBitCast(info, to: Body.self)
      body(element.pointee)
    }
    let unsafeBody = unsafeBitCast(body, to: UnsafeMutableRawPointer.self)
    self.apply(info: unsafeBody, function: callback as! CGPathApplierFunction)
  }
}

Updated FBente's extension for Swift 3:

extension CGPath {
  func points() -> [CGPoint]
  {
    var bezierPoints = [CGPoint]()
    self.forEach({ (element: CGPathElement) in
      let numberOfPoints: Int = {
        switch element.type {
        case .moveToPoint, .addLineToPoint: // contains 1 point
          return 1
        case .addQuadCurveToPoint: // contains 2 points
          return 2
        case .addCurveToPoint: // contains 3 points
          return 3
        case .closeSubpath:
          return 0
        }
      }()
      for index in 0..<numberOfPoints {
        let point = element.points[index]
        bezierPoints.append(point)
      }
    })
    return bezierPoints
  }

  func forEach(_ body: @convention(block) (CGPathElement) -> Void) {
    typealias Body = @convention(block) (CGPathElement) -> Void
    func callback(info: UnsafeMutableRawPointer, element: UnsafePointer<CGPathElement>) {
      let body = unsafeBitCast(info, to: Body.self)
      body(element.pointee)
    }
    let unsafeBody = unsafeBitCast(body, to: UnsafeMutableRawPointer.self)
    self.apply(info: unsafeBody, function: callback as! CGPathApplierFunction)
  }
}
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