ios - 用 UIBezierPath 表示 CIRectangleFeature - Swift

Question

目前我正在使用 CIDetector 来检测 UIImage 中的矩形。我正在按照建议的方式将坐标传递给过滤器以取回 CIImage 以覆盖获取的 UIImage。它看起来像这样：

func performRectangleDetection(image: UIKit.CIImage) -> UIKit.CIImage? {
    var resultImage: UIKit.CIImage?
    let detector:CIDetector = CIDetector(ofType: CIDetectorTypeRectangle, context: nil, options: [CIDetectorAccuracy : CIDetectorAccuracyHigh])
        // Get the detections
        let features = detector.featuresInImage(image)
        for feature in features as! [CIRectangleFeature] {
            resultImage = self.drawHighlightOverlayForPoints(image, topLeft: feature.topLeft, topRight: feature.topRight,
                                                        bottomLeft: feature.bottomLeft, bottomRight: feature.bottomRight)
        }
    return resultImage

}


func drawHighlightOverlayForPoints(image: UIKit.CIImage, topLeft: CGPoint, topRight: CGPoint,
                                   bottomLeft: CGPoint, bottomRight: CGPoint) -> UIKit.CIImage {

    var overlay = UIKit.CIImage(color: CIColor(red: 1.0, green: 0.55, blue: 0.0, alpha: 0.45))
    overlay = overlay.imageByCroppingToRect(image.extent)
    overlay = overlay.imageByApplyingFilter("CIPerspectiveTransformWithExtent",
                                            withInputParameters: [
                                                "inputExtent": CIVector(CGRect: image.extent),
                                                "inputTopLeft": CIVector(CGPoint: topLeft),
                                                "inputTopRight": CIVector(CGPoint: topRight),
                                                "inputBottomLeft": CIVector(CGPoint: bottomLeft),
                                                "inputBottomRight": CIVector(CGPoint: bottomRight)
        ])
    return overlay.imageByCompositingOverImage(image)
}

调用 performRectangleDetection 通过 CIImage 显示检测到的矩形。

它看起来像上面的图片。我需要使用设置为笔划的 UIBezierPath 来显示这个相同的红色矩形。我需要这个，以便用户可以调整检测，以防它不是 100% 准确。我试图画一条路，但没有成功。这是我绘制路径的方式。我使用一个名为 rect 的自定义类来保存 4 个点。这是检测：

func detectRect() -> Rect{
    var rect:Rect?
    let detector:CIDetector = CIDetector(ofType: CIDetectorTypeRectangle, context: nil, options: [CIDetectorAccuracy : CIDetectorAccuracyHigh])
    // Get the detections
    let features = detector.featuresInImage(UIKit.CIImage(image: self)!)
    for feature in features as! [CIRectangleFeature] {
        rect = Rect(tL: feature.topLeft, tR: feature.topRight, bR: feature.bottomRight, bL: feature.bottomLeft)
    }
    return rect!
}

接下来，我必须缩放坐标。这是 Rect 类中执行此操作的函数：

func scaleRect(image:UIImage, imageView:UIImageView) ->Rect{

    let scaleX = imageView.bounds.width/image.size.width
    var tlx = topLeft.x * scaleX
    var tly = topLeft.y * scaleX
    tlx += (imageView.bounds.width - image.size.width * scaleX) / 2.0
    tly += (imageView.bounds.height - image.size.height * scaleX) / 2.0
    let tl = CGPointMake(tlx, tly)

    var trx = topRight.x * scaleX
    var trY = topRight.y * scaleX
    trx += (imageView.bounds.width - image.size.width * scaleX) / 2.0
    trY += (imageView.bounds.height - image.size.height * scaleX) / 2.0
    let tr = CGPointMake(trx, trY)

    var brx = bottomRight.x * scaleX
    var bry = bottomRight.y * scaleX
    brx += (imageView.bounds.width - image.size.width * scaleX) / 2.0
    bry += (imageView.bounds.height - image.size.height * scaleX) / 2.0
    let br = CGPointMake(brx, bry)

    var blx = bottomLeft.x * scaleX
    var bly = bottomLeft.y * scaleX
    blx += (imageView.bounds.width - image.size.width * scaleX) / 2.0
    bly += (imageView.bounds.height - image.size.height * scaleX) / 2.0
    let bl = CGPointMake(blx, bly)

    let rect = Rect(tL: tl, tR: tr, bR: br, bL: bl)
    return rect
}

最后我画了路径：

var tet = image.detectRect()
tet = tet.scaleRect(image, imageView: imageView)
let shapeLayer = CAShapeLayer()
let path = ViewController.drawPath(tet.topLeft, p2: tet.topRight, p3: tet.bottomRight, p4: tet.bottomLeft)
shapeLayer.path = path.CGPath
shapeLayer.lineWidth = 5
shapeLayer.fillColor = nil
shapeLayer.strokeColor = UIColor.orangeColor().CGColor
imageView.layer.addSublayer(shapeLayer)

路径已脱离屏幕且不准确。我知道我必须将坐标从 CoreImage 坐标调整为 UIKit 坐标，然后为 UIImageView 缩放它们。不幸的是，我不知道如何正确地做到这一点。我知道我可以重用我的一些检测代码来完成此任务，但我不知道要采取的正确步骤。任何帮助，将不胜感激！谢谢。这是正在发生的事情的一个例子：

更新

为了测试我在 scaleRect() 中执行的缩放，我决定让我的 ImageView 大小与我的图像大小相同。然后我打印了缩放前后的坐标。我认为因为它们是相同的，所以我的缩放是正确的。这是代码：

var tet = image.detectRect()
//Before scaling
print(tet.topLeft)
print(tet.topRight)
print(tet.bottomRight)
print(tet.bottomLeft)
print("**************************************************")
//After scaling
tet = tet.scaleRect(image, imageView: imageView)
print(tet.topLeft)
print(tet.topRight)
print(tet.bottomRight)
print(tet.bottomLeft)

这是输出：

(742.386596679688, 927.240844726562)

(1514.93835449219, 994.811096191406)

(1514.29675292969, 155.2802734375)

(741.837524414062, 208.55403137207)

---

(742.386596679688, 927.240844726562)

(1514.93835449219, 994.811096191406)

(1514.29675292969, 155.2802734375)

(741.837524414062, 208.55403137207)

更新

为了尝试和缩放我的坐标，我又尝试了两件事。

数字 1：我尝试使用 UIView convertPoint 函数将点从图像转换为 UIImageView。这是我的编码方式：我将 scaleRect() 函数替换为

let view_image = UIView(frame: CGRectMake(0, 0, image.size.width, image.size.height))
let tL = view_image.convertPoint(self.topLeft, toView: imageView)
let tR = view_image.convertPoint(self.topRight, toView: imageView)
let bR = view_image.convertPoint(self.bottomRight, toView: imageView)
let bL = view_image.convertPoint(self.bottomLeft, toView: imageView)

然后我用这些点返回了一个新的矩形。

数字 2：我尝试根据图像和 imageView 的宽度和高度差异对坐标进行简单的转换。继承人的代码：

 let widthDiff = (image.size.width - imageView.frame.size.width)
 let highDiff = (image.size.height - imageView.frame.size.height)

 let tL = CGPointMake(self.topLeft.x-widthDiff, self.topLeft.y-highDiff)
 let tR = CGPointMake(self.topRight.x-widthDiff, self.topRight.y-highDiff)
 let bR = CGPointMake(self.bottomRight.x-widthDiff, self.bottomRight.y-highDiff)
 let bL = CGPointMake(self.bottomLeft.x-widthDiff, self.bottomLeft.y-highDiff)

更新 我也尝试过使用 CGAffineTransform。代码：

var transform = CGAffineTransformMakeScale(1, -1)
transform = CGAffineTransformTranslate(transform, 0, -imageView.bounds.size.height)
let tL = CGPointApplyAffineTransform(self.topLeft, transform)
let tR = CGPointApplyAffineTransform(self.topRight, transform)
let bR = CGPointApplyAffineTransform(self.bottomRight, transform)
let bL = CGPointApplyAffineTransform(self.bottomLeft, transform)

没有一个工作。我不知道我还能尝试什么。请帮忙。这将不胜感激。谢谢！

Answer 1

如果您只需要显示路径，那么在 CAShapeLayer 中绘制路径会更容易一些。

1. 将 CAShapeLayer 添加到预览图像。
2. 计算矩形。
3. 为该功能创建一个 UIBezierPath。
4. 转换路径以匹配源图像。
5. 设置 CAShapeLayer 的路径

如果您需要支持缩放图像或带有方向的图像（即来自用户相机的任何图像），第 4 步会出现一些复杂情况。

下面是一个例子。这支持此代码假定图像显示在 UIImageView 中，其 contentMode 为 AspectFit、AspectFill、ScaleToFill 或 Centre。它还支持向上、向下、向右和向左方向的图像。

// Extension for calculating the image scale in an image view.
// See: http://stackoverflow.com/questions/6856879/iphone-getting-the-size-of-an-image-after-aspectft
extension UIImageView {

    var imageScale: CGSize? {

        guard let image = image else {
            return nil
        }

        let sx = Double(self.frame.size.width / image.size.width)
        let sy = Double(self.frame.size.height / image.size.height)
        var s = 1.0
        switch (self.contentMode) {
        case .ScaleAspectFit:
            s = fmin(sx, sy)
            return CGSize (width: s, height: s)

        case .ScaleAspectFill:
            s = fmax(sx, sy)
            return CGSize(width:s, height:s)

        case .ScaleToFill:
            return CGSize(width:sx, height:sy)

        default:
            return CGSize(width:s, height:s)
        }
    }
}

// Extension which provides a transform to rotate the image based on it's orientation metadata. 
extension UIImageView {

    var normalizedTransformForOrientation: CGAffineTransform? {

        guard let image = image else {
            return nil
        }

        let r: CGFloat

        switch image.imageOrientation {

        case .Up:
            r = 0

        case .Down:
            r = +1.0

        case .Left:
            r = -0.5

        case .Right:
            r = +0.5

        default:
            fatalError()
        }

        let cx = CGRectGetMidX(bounds)
        let cy = CGRectGetMidY(bounds)

        var transform = CGAffineTransformIdentity
        transform = CGAffineTransformTranslate(transform, cx, cy)
        transform = CGAffineTransformRotate(transform, CGFloat(M_PI) * r)
        transform = CGAffineTransformTranslate(transform, -cx, -cy)
        return transform
    }
}

class ViewController: UIViewController {

    // Shape layer for displaying the path.
    let pathLayer: CAShapeLayer = {
        let layer = CAShapeLayer()
        layer.fillColor = UIColor.greenColor().colorWithAlphaComponent(0.3).CGColor
        layer.strokeColor = UIColor.greenColor().colorWithAlphaComponent(0.9).CGColor
        layer.lineWidth = 2.0
        return layer
    }()

    // Image view where the preview and path overlay will be displayed.
    @IBOutlet var imageView: UIImageView?

    override func viewDidLoad() {

        super.viewDidLoad()

        // Add the path overlay to the image view.
        imageView?.layer.addSublayer(pathLayer)

        // Load a sample image from the assets.
        selectImage(UIImage(named: "sample"))
    }

    func selectImage(image: UIImage?) {

        imageView?.image = image

        if let image = image {
            processImage(image)
        }
    }

    // Detect rectangles in image, and draw the path on the screen.
    func processImage(input: UIImage) {

        let path = pathsForRectanglesInImage(input)

        let transform = pathTransformForImageView(imageView!)
        path?.applyTransform(transform)

        pathLayer.path = path?.CGPath
    }

    // Detect rectangles in an image and return a UIBezierPath.
    func pathsForRectanglesInImage(input: UIImage) -> UIBezierPath? {

        guard let sourceImage = CIImage(image: input) else {
            return nil
        }

        let features = performRectangleDetection(sourceImage)

        return pathForFeatures(features)
    }

    // Detect rectangles in image.
    func performRectangleDetection(image: CIImage) -> [CIFeature] {

        let detector:CIDetector = CIDetector(
            ofType: CIDetectorTypeRectangle,
            context: nil,
            options: [CIDetectorAccuracy : CIDetectorAccuracyHigh]
        )

        let features = detector.featuresInImage(image)

        return features
    }

    // Compose a UIBezierPath from CIRectangleFeatures. 
    func pathForFeatures(features: [CIFeature]) -> UIBezierPath {

        let path = UIBezierPath()

        for feature in features {

            guard let rect = feature as? CIRectangleFeature else {
                continue
            }

            path.moveToPoint(rect.topLeft)
            path.addLineToPoint(rect.topRight)
            path.addLineToPoint(rect.bottomRight)
            path.addLineToPoint(rect.bottomLeft)
            path.closePath()
        }

        return path
    }

    // Calculate the transform to orient the preview path to the image shown inside the image view.
    func pathTransformForImageView(imageView: UIImageView) -> CGAffineTransform {

        guard let image = imageView.image else {
            return CGAffineTransformIdentity
        }

        guard let imageScale = imageView.imageScale else {
            return CGAffineTransformIdentity
        }

        guard let imageTransform = imageView.normalizedTransformForOrientation else {
            return CGAffineTransformIdentity
        }

        let frame = imageView.frame

        let imageWidth = image.size.width * imageScale.width
        let imageHeight = image.size.height * imageScale.height

        var transform = CGAffineTransformIdentity

        // Rotate to match the image orientation.
        transform = CGAffineTransformConcat(imageTransform, transform)

        // Flip vertically (flipped in CIDetector).
        transform = CGAffineTransformTranslate(transform, 0, CGRectGetHeight(frame))
        transform = CGAffineTransformScale(transform, 1.0, -1.0)

        // Centre align.
        let tx: CGFloat = (CGRectGetWidth(frame) - imageWidth) * 0.5
        let ty: CGFloat = (CGRectGetHeight(frame) - imageHeight) * 0.5
        transform = CGAffineTransformTranslate(transform, tx, ty)

        // Scale to match UIImageView scaling.
        transform = CGAffineTransformScale(transform, imageScale.width, imageScale.height)

        return transform
    }
}

Answer 2

几天来我一直在努力解决同样的问题，这就是我克服问题的方法：

我制作了一个自定义类来存储点并添加一些辅助函数：

//
//  ObyRectangleFeature.swift
//
//  Created by 4oby on 5/20/16.
//  Copyright © 2016 cvv. All rights reserved.
//

import Foundation
import UIKit

extension CGPoint {
    func scalePointByCeficient(ƒ_x: CGFloat, ƒ_y: CGFloat) -> CGPoint {
        return CGPoint(x: self.x/ƒ_x, y: self.y/ƒ_y) //original image
    }

    func reversePointCoordinates() -> CGPoint {
        return CGPoint(x: self.y, y: self.x)
    }

    func sumPointCoordinates(add: CGPoint) -> CGPoint {
        return CGPoint(x: self.x + add.x, y: self.y + add.y)
    }

    func substractPointCoordinates(sub: CGPoint) -> CGPoint {
        return CGPoint(x: self.x - sub.x, y: self.y - sub.y)
    }
}

class ObyRectangleFeature : NSObject {

    var topLeft: CGPoint!
    var topRight: CGPoint!
    var bottomLeft: CGPoint!
    var bottomRight: CGPoint!

    var centerPoint : CGPoint{
        get {
            let centerX = ((topLeft.x + bottomLeft.x)/2 + (topRight.x + bottomRight.x)/2)/2
            let centerY = ((topRight.y + topLeft.y)/2 + (bottomRight.y + bottomLeft.y)/2)/2
            return CGPoint(x: centerX, y: centerY)
        }

    }

    convenience init(_ rectangleFeature: CIRectangleFeature) {
        self.init()
        topLeft = rectangleFeature.topLeft
        topRight = rectangleFeature.topRight
        bottomLeft = rectangleFeature.bottomLeft
        bottomRight = rectangleFeature.bottomRight
    }

    override init() {
        super.init()
    }


    func rotate90Degree() -> Void {

        let centerPoint =  self.centerPoint

//        /rotate cos(90)=0, sin(90)=1
        topLeft = CGPoint(x: centerPoint.x + (topLeft.y - centerPoint.y), y: centerPoint.y + (topLeft.x - centerPoint.x))
        topRight = CGPoint(x: centerPoint.x + (topRight.y - centerPoint.y), y: centerPoint.y + (topRight.x - centerPoint.x))
        bottomLeft = CGPoint(x: centerPoint.x + (bottomLeft.y - centerPoint.y), y: centerPoint.y + (bottomLeft.x - centerPoint.x))
        bottomRight = CGPoint(x: centerPoint.x + (bottomRight.y - centerPoint.y), y: centerPoint.y + (bottomRight.x - centerPoint.x))
    }

    func  scaleRectWithCoeficient(ƒ_x: CGFloat, ƒ_y: CGFloat) -> Void {
        topLeft =  topLeft.scalePointByCeficient(ƒ_x, ƒ_y: ƒ_y)
        topRight = topRight.scalePointByCeficient(ƒ_x, ƒ_y: ƒ_y)
        bottomLeft = bottomLeft.scalePointByCeficient(ƒ_x, ƒ_y: ƒ_y)
        bottomRight = bottomRight.scalePointByCeficient(ƒ_x, ƒ_y: ƒ_y)
    }

    func correctOriginPoints() -> Void {

        let deltaCenter = self.centerPoint.reversePointCoordinates().substractPointCoordinates(self.centerPoint)

        let TL = topLeft
        let TR = topRight
        let BL = bottomLeft
        let BR = bottomRight

        topLeft = BL.sumPointCoordinates(deltaCenter)
        topRight = TL.sumPointCoordinates(deltaCenter)
        bottomLeft = BR.sumPointCoordinates(deltaCenter)
        bottomRight = TR.sumPointCoordinates(deltaCenter)
    }
}

这是初始化代码：

let scalatedRect : ObyRectangleFeature = ObyRectangleFeature(rectangleFeature)
        // fromSize -> Initial size of the CIImage
        // toSize -> the size of the scaled Image
        let ƒ_x = (fromSize.width/toSize.width)
        let ƒ_y = (fromSize.height/toSize.height)

        /*the coeficients are interchange intentionally cause of the different
        coordinate system used by CIImage and UIImage, you could rotate before 
        scaling, to preserve the order, but if you do, the result will be offCenter*/

        scalatedRect.scaleRectWithCoeficient(ƒ_y, ƒ_y: ƒ_x)
        scalatedRect.rotate90Degree()
        scalatedRect.correctOriginPoints()

此时scaleRect已准备好以您喜欢的任何方式绘制。