ios - 在 Swift 中获取 UIImage 的主要颜色

Question

我试图在 Swift 中获取 UIImage 的主要颜色，并尝试移植 this code .不幸的是，代码一直返回相同的颜色。我看到了the answer provided here也不断返回相同的颜色。我避免使用 CIFilter，因为它只返回我研究中的平均颜色。

在移植的代码下方。我已将 CGContext 数据设置为 nil，因为 Swift 可以处理它的内存，并且在我的测试中它给出了很多内存错误。

func mainColors(image:UIImage, detail: Int) -> [UIColor] {
            //COLOR PROCESS STEP 1:
            //Determine the detail.
                var dimension = 10
                var flexibility = 2
                var range = 60

        //Low detail.
            if detail == 0 {
                dimension = 4
                flexibility = 1
                range = 100
            }
        //High detail.
            else if detail == 2 {
                dimension = 100
                flexibility = 10
                range = 20
            }

        //COLOR PROCESS STEP 2:
        //Determine the colors in the image.

        //Create an array to store the colors.
            var colors = Array<Array<CGFloat>>()

        //Get the bitmap data of the image.
            let imageRef = image.cgImage
        //Variable to store the color space, RGB in this case.
            let colorSpace = CGColorSpaceCreateDeviceRGB()
        //Additional CGContext data.
            let bytesPerPixel = 4
            let bytesPerRow = bytesPerPixel * dimension
            let bitsPerComponent = 8
        //Create the context. Data uses the memory pointer created above, the width and height determine the dimensions of the bitmap, the space is for the colorspace, the bitmap specifies the alpha channel.
            let context = CGContext(data: nil, width: dimension, height: dimension, bitsPerComponent: bitsPerComponent, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue | CGBitmapInfo.byteOrder32Big.rawValue)!
        //Draw the image.
            let rect = CGRect(x: 0, y: 0, width: dimension, height: dimension)
            context.draw(imageRef!, in: rect)

        //Iterate through the raw data in order to create a UIColor.
            var x = 0
            var y = 0

            for _ in 0..<(dimension * dimension) {
                let index = (bytesPerRow * y) + x * bytesPerPixel
                let red = CGFloat(index)
                let green = CGFloat(index + 1)
                let blue = CGFloat(index + 2)
                let alpha = CGFloat(index + 3)

                let color = [red, green, blue, alpha]
                colors.append(color)

                y += 1
                if y == dimension {
                    y = 0
                    x += 1
                }
            }

        //Deallocate the mutable pointer.
            //free(rawData)

        //COLOR PROCESS STEP 3:
        //Add some color flexibility.

        //Create an array containing the previous colored items and create another one for the flexible colors.
            var copiedColors = colors
            var flexibleColors = Array<String>()

        //Iterate through the copied colors in order to create an improved UIColor.
            let flexFactor = flexibility * 2 + 1
            let factor = flexFactor * flexFactor * 3

            for n in 0..<(dimension * dimension) {
                let pixelColors = copiedColors[n]

                var reds = Array<CGFloat>()
                var greens = Array<CGFloat>()
                var blues = Array<CGFloat>()

                for p in 0..<3 {
                    let rgb = pixelColors[p]

                    for f in -flexibility...flexibility {
                        var newRGB = rgb + CGFloat(f)

                        if newRGB < 0 {
                            newRGB = 0
                        }

                        switch p {
                            case 0:
                                reds.append(newRGB)
                            case 1:
                                greens.append(newRGB)
                            case 2:
                                blues.append(newRGB)
                            default:
                                print("Error! Loop out of range! \(p)")
                        }
                    }
                }

                var r = 0
                var g = 0
                var b = 0

                for _ in 0..<factor {
                    let red = reds[r]
                    let green = greens[g]
                    let blue = blues[b]

                    let rgbString = "\(red),\(green),\(blue)"
                    flexibleColors.append(rgbString)

                    b += 1
                    if b == flexFactor {
                        b = 0
                        g += 1
                    }
                    if g == flexFactor {
                        g = 0
                        r += 1
                    }
                }
            }

        //COLOR PROCESS STEP 4:
        //Distinguish the colors. Orders the flexible colors by their occurence and then keeps them if they are sufficiently disimilar.

        //Dictionary to store all the colors.
            let colorCounter = NSMutableDictionary()

        //Check the number of times item is in array.
            let countedSet = NSCountedSet(array: flexibleColors)

            for item in countedSet {
                let item = item as! String

                let count = countedSet.count(for: item)
                let value = NSNumber(integerLiteral: count)
                colorCounter.setValue(value, forKey: item)
            }

        //Sort keys from highest occurence to lowest.
            let orderedKeys = colorCounter.keysSortedByValue(comparator: {
                (obj1, obj2) in
                let x = obj1 as! NSNumber
                let y = obj2 as! NSNumber
                return x.compare(y)
            })

        //Check if the color is similar to another one already included.
            var ranges = Array<String>()

            for key in orderedKeys as! [String] {
                let rgb = key.components(separatedBy: ",")
                let r = NSString(string: rgb[0]).integerValue
                let g = NSString(string: rgb[1]).integerValue
                let b = NSString(string: rgb[2]).integerValue

                var exclude = false

                for rangedkey in ranges {
                    let rangedRGB = rangedkey.components(separatedBy: ",")

                    let ranged_r = NSString(string: rangedRGB[0]).integerValue
                    let ranged_g = NSString(string: rangedRGB[1]).integerValue
                    let ranged_b = NSString(string: rangedRGB[2]).integerValue

                    if r >= ranged_r - range && r <= ranged_r + range {
                        if g >= ranged_g - range && g <= ranged_g + range {
                            if b >= ranged_b - range && b <= ranged_b + range {
                                exclude = true
                            }
                        }
                    }
                }

                if exclude == false {
                    ranges.append(key)
                }
            }

        //Create the colors and fill them.
            var mainColors = Array<UIColor>()

            for key in ranges {
                let rgb = key.components(separatedBy: ",")
                let r = NSString(string: rgb[0]).floatValue
                let g = NSString(string: rgb[1]).floatValue
                let b = NSString(string: rgb[2]).floatValue

                let finalColor = UIColor(red: CGFloat((r / 255)), green: CGFloat((g / 255)), blue: CGFloat((b / 255)), alpha: CGFloat(1.0))

                mainColors.append(finalColor)
            }

            return mainColors
    }

Answer 1

这个很棒的开源类似乎运行良好:https://github.com/jathu/UIImageColors

将下面的此类导入到您的项目中。

//
//  UIImageColors.swift
//  https://github.com/jathu/UIImageColors
//
//  Created by Jathu Satkunarajah (@jathu) on 2015-06-11 - Toronto
//

import UIKit

public struct UIImageColors {
    public var background: UIColor!
    public var primary: UIColor!
    public var secondary: UIColor!
    public var detail: UIColor!

    public init(background: UIColor, primary: UIColor, secondary: UIColor, detail: UIColor) {
      self.background = background
      self.primary = primary
      self.secondary = secondary
      self.detail = detail
    }
}

public enum UIImageColorsQuality: CGFloat {
    case lowest = 50 // 50px
    case low = 100 // 100px
    case high = 250 // 250px
    case highest = 0 // No scale
}

fileprivate struct UIImageColorsCounter {
    let color: Double
    let count: Int
    init(color: Double, count: Int) {
        self.color = color
        self.count = count
    }
}

/*
    Extension on double that replicates UIColor methods. We DO NOT want these
    exposed outside of the library because they don't make sense outside of the
    context of UIImageColors.
*/
fileprivate extension Double {

    private var r: Double {
        return fmod(floor(self/1000000),1000000)
    }

    private var g: Double {
        return fmod(floor(self/1000),1000)
    }

    private var b: Double {
        return fmod(self,1000)
    }

    fileprivate var isDarkColor: Bool {
        return (r*0.2126) + (g*0.7152) + (b*0.0722) < 127.5
    }

    fileprivate var isBlackOrWhite: Bool {
        return (r > 232 && g > 232 && b > 232) || (r < 23 && g < 23 && b < 23)
    }

    fileprivate func isDistinct(_ other: Double) -> Bool {
        let _r = self.r
        let _g = self.g
        let _b = self.b
        let o_r = other.r
        let o_g = other.g
        let o_b = other.b

        return (fabs(_r-o_r) > 63.75 || fabs(_g-o_g) > 63.75 || fabs(_b-o_b) > 63.75)
            && !(fabs(_r-_g) < 7.65 && fabs(_r-_b) < 7.65 && fabs(o_r-o_g) < 7.65 && fabs(o_r-o_b) < 7.65)
    }

    fileprivate func with(minSaturation: Double) -> Double {
        // Ref: https://en.wikipedia.org/wiki/HSL_and_HSV

        // Convert RGB to HSV

        let _r = r/255
        let _g = g/255
        let _b = b/255
        var H, S, V: Double
        let M = fmax(_r,fmax(_g, _b))
        var C = M-fmin(_r,fmin(_g, _b))

        V = M
        S = V == 0 ? 0:C/V

        if minSaturation <= S {
            return self
        }

        if C == 0 {
            H = 0
        } else if _r == M {
            H = fmod((_g-_b)/C, 6)
        } else if _g == M {
            H = 2+((_b-_r)/C)
        } else {
            H = 4+((_r-_g)/C)
        }

        if H < 0 {
            H += 6
        }

        // Back to RGB

        C = V*minSaturation
        let X = C*(1-fabs(fmod(H,2)-1))
        var R, G, B: Double

        switch H {
        case 0...1:
            R = C
            G = X
            B = 0
        case 1...2:
            R = X
            G = C
            B = 0
        case 2...3:
            R = 0
            G = C
            B = X
        case 3...4:
            R = 0
            G = X
            B = C
        case 4...5:
            R = X
            G = 0
            B = C
        case 5..<6:
            R = C
            G = 0
            B = X
        default:
            R = 0
            G = 0
            B = 0
        }

        let m = V-C

        return (floor((R + m)*255)*1000000)+(floor((G + m)*255)*1000)+floor((B + m)*255)
    }

    fileprivate func isContrasting(_ color: Double) -> Bool {
        let bgLum = (0.2126*r)+(0.7152*g)+(0.0722*b)+12.75
        let fgLum = (0.2126*color.r)+(0.7152*color.g)+(0.0722*color.b)+12.75
        if bgLum > fgLum {
            return 1.6 < bgLum/fgLum
        } else {
            return 1.6 < fgLum/bgLum
        }
    }

    fileprivate var uicolor: UIColor {
        return UIColor(red: CGFloat(r)/255, green: CGFloat(g)/255, blue: CGFloat(b)/255, alpha: 1)
    }

    fileprivate var pretty: String {
        return "\(Int(self.r)), \(Int(self.g)), \(Int(self.b))"
    }
}

extension UIImage {
    private func resizeForUIImageColors(newSize: CGSize) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(newSize, false, 0)
        defer {
            UIGraphicsEndImageContext()
        }
        self.draw(in: CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height))
        guard let result = UIGraphicsGetImageFromCurrentImageContext() else {
            fatalError("UIImageColors.resizeForUIImageColors failed: UIGraphicsGetImageFromCurrentImageContext returned nil.")
        }

        return result
    }


    public func getColors(quality: UIImageColorsQuality = .high, _ completion: @escaping (UIImageColors) -> Void) {
        DispatchQueue.global().async {
            let result = self.getColors(quality: quality)
            DispatchQueue.main.async {
                completion(result)
            }
        }
    }


    public func getColors(quality: UIImageColorsQuality = .high) -> UIImageColors {
        var scaleDownSize: CGSize = self.size
        if quality != .highest {
            if self.size.width < self.size.height {
                let ratio = self.size.height/self.size.width
                scaleDownSize = CGSize(width: quality.rawValue/ratio, height: quality.rawValue)
            } else {
                let ratio = self.size.width/self.size.height
                scaleDownSize = CGSize(width: quality.rawValue, height: quality.rawValue/ratio)
            }
        }

        let cgImage = self.resizeForUIImageColors(newSize: scaleDownSize).cgImage!
        let width: Int = cgImage.width
        let height: Int = cgImage.height

        let threshold = Int(CGFloat(height)*0.01)
        var proposed: [Double] = [-1,-1,-1,-1]

        guard let data = CFDataGetBytePtr(cgImage.dataProvider!.data) else {
            fatalError("UIImageColors.getColors failed: could not get cgImage data.")
        }

        let imageColors = NSCountedSet(capacity: width*height)
        for x in 0..<width {
            for y in 0..<height {
                let pixel: Int = ((width * y) + x) * 4
                if 127 <= data[pixel+3] {
                    imageColors.add((Double(data[pixel+2])*1000000)+(Double(data[pixel+1])*1000)+(Double(data[pixel])))
                }
            }
        }

        let sortedColorComparator: Comparator = { (main, other) -> ComparisonResult in
            let m = main as! UIImageColorsCounter, o = other as! UIImageColorsCounter
            if m.count < o.count {
                return .orderedDescending
            } else if m.count == o.count {
                return .orderedSame
            } else {
                return .orderedAscending
            }
        }

        var enumerator = imageColors.objectEnumerator()
        var sortedColors = NSMutableArray(capacity: imageColors.count)
        while let K = enumerator.nextObject() as? Double {
            let C = imageColors.count(for: K)
            if threshold < C {
                sortedColors.add(UIImageColorsCounter(color: K, count: C))
            }
        }
        sortedColors.sort(comparator: sortedColorComparator)

        var proposedEdgeColor: UIImageColorsCounter
        if 0 < sortedColors.count {
            proposedEdgeColor = sortedColors.object(at: 0) as! UIImageColorsCounter
        } else {
            proposedEdgeColor = UIImageColorsCounter(color: 0, count: 1)
        }

        if proposedEdgeColor.color.isBlackOrWhite && 0 < sortedColors.count {
            for i in 1..<sortedColors.count {
                let nextProposedEdgeColor = sortedColors.object(at: i) as! UIImageColorsCounter
                if Double(nextProposedEdgeColor.count)/Double(proposedEdgeColor.count) > 0.3 {
                    if !nextProposedEdgeColor.color.isBlackOrWhite {
                        proposedEdgeColor = nextProposedEdgeColor
                        break
                    }
                } else {
                    break
                }
            }
        }
        proposed[0] = proposedEdgeColor.color

        enumerator = imageColors.objectEnumerator()
        sortedColors.removeAllObjects()
        sortedColors = NSMutableArray(capacity: imageColors.count)
        let findDarkTextColor = !proposed[0].isDarkColor

        while var K = enumerator.nextObject() as? Double {
            K = K.with(minSaturation: 0.15)
            if K.isDarkColor == findDarkTextColor {
                let C = imageColors.count(for: K)
                sortedColors.add(UIImageColorsCounter(color: K, count: C))
            }
        }
        sortedColors.sort(comparator: sortedColorComparator)

        for color in sortedColors {
            let color = (color as! UIImageColorsCounter).color

            if proposed[1] == -1 {
                if color.isContrasting(proposed[0]) {
                    proposed[1] = color
                }
            } else if proposed[2] == -1 {
                if !color.isContrasting(proposed[0]) || !proposed[1].isDistinct(color) {
                    continue
                }
                proposed[2] = color
            } else if proposed[3] == -1 {
                if !color.isContrasting(proposed[0]) || !proposed[2].isDistinct(color) || !proposed[1].isDistinct(color) {
                    continue
                }
                proposed[3] = color
                break
            }
        }

        let isDarkBackground = proposed[0].isDarkColor
        for i in 1...3 {
            if proposed[i] == -1 {
                proposed[i] = isDarkBackground ? 255255255:0
            }
        }

        return UIImageColors(
            background: proposed[0].uicolor,
            primary: proposed[1].uicolor,
            secondary: proposed[2].uicolor,
            detail: proposed[3].uicolor
        )
    }
}