[英]SwiftUI - How to get correct RGB value from theme aware named color?
[英]How to get RGB components from Color in SwiftUI
如果我有 SwiftUI Color
:
let col: Color = Color(red: 0.5, green: 0.5, blue: 0.5)
如何從col
獲取 RGB 分量?
像這樣也許:
print(col.components.red)
在 UIKit 中,我可以使用UIColor.getRed
但在 SwiftUI 中似乎沒有等價物。
現在有一個新的初始化器,它接受一個Color
並返回一個UIColor
for iOS或NSColor
for macOS 。 在這些人的幫助下,您可以實現以下擴展:
import SwiftUI
#if canImport(UIKit)
import UIKit
#elseif canImport(AppKit)
import AppKit
#endif
extension Color {
var components: (red: CGFloat, green: CGFloat, blue: CGFloat, opacity: CGFloat) {
#if canImport(UIKit)
typealias NativeColor = UIColor
#elseif canImport(AppKit)
typealias NativeColor = NSColor
#endif
var r: CGFloat = 0
var g: CGFloat = 0
var b: CGFloat = 0
var o: CGFloat = 0
guard NativeColor(self).getRed(&r, green: &g, blue: &b, alpha: &o) else {
// You can handle the failure here as you want
return (0, 0, 0, 0)
}
return (r, g, b, o)
}
}
Color.red.components.red // 0.9999999403953552 // <- SwiftUI Colors are not pure!
等待 API 我濫用CustomStringConvertible
協議用於簡單的 rgba 案例,其中顏色描述格式為 #rrggbbaa
debugPrint(Color.red)
debugPrint(Color(red: 1.0, green: 0.0, blue: 0.0))
debugPrint(Color(red: 1.0, green: 0.3, blue: 0.0))
debugPrint(Color(.sRGB, red: 1.0, green: 0.0, blue: 0.5, opacity: 0.3))
debugPrint(Color(hue: 1.0, saturation: 0.0, brightness: 1.0))
debugPrint(Color(.displayP3, red: 1.0, green: 0.0, blue: 0.0, opacity: 1.0).description)
red
#FF0000FF
#FF4C00FF
#FF00804D
#FFFFFFFF
"DisplayP3(red: 1.0, green: 0.0, blue: 0.0, opacity: 1.0)"
如您所見,Color.red 之類的東西只是轉儲“紅色”,但是如果您正在使用由代碼(即來自顏色選擇器)生成的簡單 RGB 顏色,那么這還不錯
extension SwiftUI.Color {
var redComponent: Double? {
let val = description
guard val.hasPrefix("#") else { return nil }
let r1 = val.index(val.startIndex, offsetBy: 1)
let r2 = val.index(val.startIndex, offsetBy: 2)
return Double(Int(val[r1...r2], radix: 16)!) / 255.0
}
var greenComponent: Double? {
let val = description
guard val.hasPrefix("#") else { return nil }
let g1 = val.index(val.startIndex, offsetBy: 3)
let g2 = val.index(val.startIndex, offsetBy: 4)
return Double(Int(val[g1...g2], radix: 16)!) / 255.0
}
var blueComponent: Double? {
let val = description
guard val.hasPrefix("#") else { return nil }
let b1 = val.index(val.startIndex, offsetBy: 5)
let b2 = val.index(val.startIndex, offsetBy: 6)
return Double(Int(val[b1...b2], radix: 16)!) / 255.0
}
var opacityComponent: Double? {
let val = description
guard val.hasPrefix("#") else { return nil }
let b1 = val.index(val.startIndex, offsetBy: 7)
let b2 = val.index(val.startIndex, offsetBy: 8)
return Double(Int(val[b1...b2], radix: 16)!) / 255.0
}
}
您可以使用 UIColor 並將 UIColor 轉換為 Color 之后。 代碼:
extension UIColor {
func hexValue() -> String {
let values = self.cgColor.components
var outputR: Int = 0
var outputG: Int = 0
var outputB: Int = 0
var outputA: Int = 1
switch values!.count {
case 1:
outputR = Int(values![0] * 255)
outputG = Int(values![0] * 255)
outputB = Int(values![0] * 255)
outputA = 1
case 2:
outputR = Int(values![0] * 255)
outputG = Int(values![0] * 255)
outputB = Int(values![0] * 255)
outputA = Int(values![1] * 255)
case 3:
outputR = Int(values![0] * 255)
outputG = Int(values![1] * 255)
outputB = Int(values![2] * 255)
outputA = 1
case 4:
outputR = Int(values![0] * 255)
outputG = Int(values![1] * 255)
outputB = Int(values![2] * 255)
outputA = Int(values![3] * 255)
default:
break
}
return "#" + String(format:"%02X", outputR) + String(format:"%02X", outputG) + String(format:"%02X", outputB) + String(format:"%02X", outputA)
}
}
答案是否定的- 沒有 API 這樣做(還),但是......
大多數 SwiftUI 結構都具有private
字段,例如Color
。
您可以使用Mirror
來提取此類信息 - 但請記住它效率不高。
以下是如何提取 SwiftUI Color
的十六進制表示 - 用於教育目的。
將其復制並粘貼到Xcode 11 playground。
import UIKit
import SwiftUI
let systemColor = Color.red
let color = Color(red: 0.3, green: 0.5, blue: 1)
extension Color {
var hexRepresentation: String? {
let children = Mirror(reflecting: color).children
let _provider = children.filter { $0.label == "provider" }.first
guard let provider = _provider?.value else {
return nil
}
let providerChildren = Mirror(reflecting: provider).children
let _base = providerChildren.filter { $0.label == "base" }.first
guard let base = _base?.value else {
return nil
}
var baseValue: String = ""
dump(base, to: &baseValue)
guard let firstLine = baseValue.split(separator: "\n").first,
let hexString = firstLine.split(separator: " ")[1] as Substring? else {
return nil
}
return hexString.trimmingCharacters(in: .newlines)
}
}
systemColor.hexRepresentation
color.hexRepresentation
喜歡的顏色.red
, .white
等,似乎沒有對他們有許多信息,當dumped
。
只是他們的“系統”名稱。
▿ red
▿ provider: SwiftUI.(unknown context at $1297483bc).ColorBox<SwiftUI.SystemColorType> #0
- super: SwiftUI.(unknown context at $129748300).AnyColorBox
- base: SwiftUI.SystemColorType.red
用red
/ blue
/ green
組件實例化的Color
代替。
▿ #4C80FFFF
▿ provider: SwiftUI.(unknown context at $11cd2e3bc).ColorBox<SwiftUI.Color._Resolved> #0
- super: SwiftUI.(unknown context at $11cd2e300).AnyColorBox
▿ base: #4C80FFFF
- linearRed: 0.073238954
- linearGreen: 0.21404114
- linearBlue: 1.0
- opacity: 1.0
在 Playground 中,您將看到:
systemColor.hexRepresentation
返回nil
color.hexRepresentation
返回"#4C80FFFF"
根據@Mojtaba 的回答,我想出了一個更短、更靈活的版本:
#if canImport(UIKit)
import UIKit
#elseif canImport(AppKit)
import AppKit
#endif
extension Color {
#if canImport(UIKit)
var asNative: UIColor { UIColor(self) }
#elseif canImport(AppKit)
var asNative: NSColor { NSColor(self) }
#endif
var rgba: (red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) {
let color = asNative.usingColorSpace(.deviceRGB)!
var t = (CGFloat(), CGFloat(), CGFloat(), CGFloat())
color.getRed(&t.0, green: &t.1, blue: &t.2, alpha: &t.3)
return t
}
var hsva: (hue: CGFloat, saturation: CGFloat, value: CGFloat, alpha: CGFloat) {
let color = asNative.usingColorSpace(.deviceRGB)!
var t = (CGFloat(), CGFloat(), CGFloat(), CGFloat())
color.getHue(&t.0, saturation: &t.1, brightness: &t.2, alpha: &t.3)
return t
}
}
做 asNative.redComponent 等也可能有效,僅供參考。
簡單的單線:
print(UIColor(Color.blue).cgColor.components)
你得到一個[CGFloat]?
[紅色,綠色,藍色,alpha]。
我發現@Mojtaba Hosseinis 的答案工作正常,除非您在資產中聲明了顏色的明暗外觀。
然后我發現使用UIColor(self)
時,深色外觀不知何故丟失了。 這是我想出的解決方法:
請注意,這只是針對iOS
,因為我的應用程序是iOS
唯一,你當然可以做同樣的@Mojtaba侯賽尼和它適應macOS
為好。
extension Color {
var components: (r: Double, g: Double, b: Double, o: Double)? {
let uiColor: UIColor
var r: CGFloat = 0
var g: CGFloat = 0
var b: CGFloat = 0
var o: CGFloat = 0
if self.description.contains("NamedColor") {
let lowerBound = self.description.range(of: "name: \"")!.upperBound
let upperBound = self.description.range(of: "\", bundle")!.lowerBound
let assetsName = String(self.description[lowerBound..<upperBound])
uiColor = UIColor(named: assetsName)!
} else {
uiColor = UIColor(self)
}
guard uiColor.getRed(&r, green: &g, blue: &b, alpha: &o) else { return nil }
return (Double(r), Double(g), Double(b), Double(o))
}
}
這個想法是使用UIColor(named:)
初始值設定項,所有外觀都是正確的。 幸運的是,我們在 assets 中設置的名稱保存在Color
的描述中。 我們只需要抽象它,因為還有其他信息,即 bundle 等。
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