创建一个圆形颜色选择器

Question

我试图创建一个圆形颜色选择器。我的方法是插入一个图像并使用pixelColors函数来获取该点的颜色。问题是每次点击都会返回错误的颜色。我不知道出了什么问题。

这是图片：

这是我的代码

extension UIImage {
    func getPixelColor(x: CGFloat, y: CGFloat) -> UIColor? {        
        let pixelData = self.cgImage!.dataProvider!.data
        let data: UnsafePointer<UInt8> = CFDataGetBytePtr(pixelData)

        let pixelIndex: Int = ((Int(self.size.width) * Int(y)) + Int(x)) * 4

        let r = CGFloat(data[pixelIndex]) / CGFloat(255.0)
        let g = CGFloat(data[pixelIndex+1]) / CGFloat(255.0)
        let b = CGFloat(data[pixelIndex+2]) / CGFloat(255.0)
        let a = CGFloat(data[pixelIndex+3]) / CGFloat(255.0)

        return UIColor(red: r, green: g, blue: b, alpha: a)
    }

以下是我使用此功能的方法

    func imageTapped(recognizer: UITapGestureRecognizer) {
        let thePoint = recognizer.location(in: view)
        let color = imageView.image?.getPixelColor(x: thePoint.x, y: thePoint.y)
        print(color)

Answer 1

尝试使用以下功能获取颜色触摸这个对我来说很好用

//MARK: Get Pixel color on touch
    /**
     This function is Read data from CSV File
     - parameter point: CGPoint Touch Point
     - parameter sourceView: View to Detect in
     - returns: UIColor
     */
    class func getPixelColorAtPoint(point:CGPoint, sourceView: UIView) -> UIColor
    {
        let pixel = UnsafeMutablePointer<CUnsignedChar>.allocate(capacity: 4)
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue)
        let context = CGContext(data: pixel, width: 1, height: 1, bitsPerComponent: 8, bytesPerRow: 4, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)

        context!.translateBy(x: -point.x, y: -point.y)
        sourceView.layer.render(in: context!)
        let color:UIColor = UIColor(red: CGFloat(pixel[0])/255.0,
                                    green: CGFloat(pixel[1])/255.0,
                                    blue: CGFloat(pixel[2])/255.0,
                                    alpha: CGFloat(pixel[3])/255.0)
        pixel.deallocate(capacity: 4)
        return color
    }

用法：

        //here get location as CGPoint and just pass it in function 
        let point = sender.location(in: sender.view)

        //For example take reference Color 
        let color  = self.getPixelColorAtPoint(point: point, sourceView: self.GramPieChart)

        //self.gramPieChart is my View created from which I need to get the color at touch pass your ImageView here 

现在比较

 if (color.isEqual(UIColor.init(red: 230/255, green: 53/255, blue: 42/255, alpha: 1.0)))
    {
                        //Required Operation here 
    }

Or directly 

if (color.isEqual(UIColor.init(red: 230/255, green: 53/255, blue: 42/255, alpha: 1.0)))
    {
                        //Required Operation here 
    }

    if (color == UIColor.red)
    {
                        //Required Operation here
     }