从 UIColor 中提取 RGB 值 [英] Extract RGB Values From UIColor
问题描述
我见过人们在 Objective-c 中这样做,但我在 swift 中遇到了麻烦.我已经从图片中获取了像素的颜色,但现在我需要获取单独的红色、绿色和蓝色值.这是我所拥有的(h、w 和 rgb 是整数,而 image.getPixelColor(CGPoint) 返回一个 UIColor):
I have seen people do this in objective-c, but I am having trouble with this in swift. I have gotten the color of a pixel from a picture, but now I need to take the individual red, green, and blue values. Here is what I have (h, w, and rgb are integers and image.getPixelColor(CGPoint) returns a UIColor):
xArry[h][w][rgb] = image.getPixelColor(CGPoint(x: w, y: h))
如何将此 UIColor 更改为红色、绿色和蓝色值?谢谢!
How do I change this UIColor into the red, green, and blue values? Thanks!
推荐答案
您可以将 UIColor 转换为 CIColor,然后从中提取颜色分量,如下所示:
You can convert UIColor to CIColor and then extract the color components from it as follow:
更新:Xcode 8.3.2 • Swift 3.1
extension UIColor {
var coreImageColor: CIColor {
return CIColor(color: self)
}
var components: (red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) {
let coreImageColor = self.coreImageColor
return (coreImageColor.red, coreImageColor.green, coreImageColor.blue, coreImageColor.alpha)
}
}
用法:
let myColor = UIColor(red: 0.5, green: 1, blue: 0.25, alpha: 0.5)
let myCIColor = myColor.coreImageColor
let greencomponent = myColor.components.green
let myColorComponents = myColor.components
print(myColorComponents.red) // 0.5
print(myColorComponents.green) // 1.0
print(myColorComponents.blue) // 0.25
print(myColorComponents.alpha) // 0.5
您也可以使用函数 getRed() 并创建一个扩展来提取组件,如下所示,但结果是可选的:
You can also use the function getRed() and create an extension to extract the components as follow but the result would be optional:
extension UIColor {
typealias RGBA = (red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat)
var rgba: RGBA? {
var (r, g, b, a): RGBA = (0, 0, 0, 0)
return getRed(&r, green: &g, blue: &b, alpha: &a) ? (r,g,b,a) : nil
}
var r: CGFloat? {
var red: CGFloat = .zero
return getRed(&red, green: nil, blue: nil, alpha: nil) ? red : nil
}
var g: CGFloat? {
var green: CGFloat = .zero
return getRed(nil, green: &green, blue: nil, alpha: nil) ? green : nil
}
var b: CGFloat? {
var blue: CGFloat = .zero
return getRed(nil, green: nil, blue: &blue, alpha: nil) ? blue : nil
}
var a: CGFloat? {
var alpha: CGFloat = .zero
return getRed(nil, green: nil, blue: nil, alpha: &alpha) ? alpha : nil
}
}
用法
let color = UIColor(red: 0.5, green: 1, blue: 0.25, alpha: 0.5)
if let components = color.rgba {
print(components.red) // 0.5
print(components.green) // 1.0
print(components.blue) // 0.25
print(components.alpha) // 0.5
}
print(color.r ?? "nil") // 0.5
print(color.g ?? "nil") // 1.0
print(color.b ?? "nil") // 0.25
print(color.a ?? "nil") // 0.5
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