使用两个控制点时，SwiftUI 圆形滑块问题未显示正确的笔划
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【中文标题】使用两个控制点时，SwiftUI 圆形滑块问题未显示正确的笔划【英文标题】：SwiftUI Circular slider issue not displaying the correct stroke when using two control point 【发布时间】：2021-07-21 07:24:11 【问题描述】：我有一个带有两个控制旋钮的圆形视图，并且从图像中可以看出它们之间有一个笔划。
这些值是正确的，但问题是我怎样才能将蓝色笔画显示为相反？用户可能希望范围是 NW、N 到 NE，而不是 NE，包括 S 到 NE，但用户需要能够从两者中进行选择。下面的代码直接粘贴进去就可以和图片一样了。
import SwiftUI
struct CircularSliderView: View
var body: some View
VStack()
DirectionView()
Spacer()
struct SwellCircularSliderView_Previews: PreviewProvider
static var previews: some View
CircularSliderView()
struct DirectionView: View
@State var directionValue: CGFloat = 0.0
@State var secondaryDirectionValue: CGFloat = 0.0
var body: some View
VStack
Text("\(directionValue, specifier: "%.0f")° - \(secondaryDirectionValue, specifier: "%.0f")° \(Double().degreesToCompassDirection(degree: Double(directionValue))) - \(Double().degreesToCompassDirection(degree: Double(secondaryDirectionValue)))")
.font(.body)
DirectionControlView(directionValue: $directionValue, secondaryDirectionValue: $secondaryDirectionValue)
.padding(.top, 60)
Spacer()
//: VSTACK
struct DirectionControlView: View
@Binding var directionValue: CGFloat
@State var dirAngleValue: CGFloat = 0.0
@Binding var secondaryDirectionValue: CGFloat
@State var secondaryDirAngleValue: CGFloat = 0.0
let minimumValue: CGFloat = 0
let maximumValue: CGFloat = 360.0
let totalValue: CGFloat = 360.0
let knobRadius: CGFloat = 10.0
let radius: CGFloat = 125.0
private let tickHeight: CGFloat = 8
private let longTickHeight: CGFloat = 14
private let tickWidth: CGFloat = 2
func minimumTrimValue() -> CGFloat
if directionValue > secondaryDirectionValue
return secondaryDirectionValue/totalValue
else
return directionValue/totalValue
func maximumTrimValue() -> CGFloat
if directionValue > secondaryDirectionValue
return directionValue/totalValue
else
return secondaryDirectionValue/totalValue
var body: some View
ZStack
Circle()
.trim(from: minimumTrimValue(), to: maximumTrimValue())
.stroke(
AngularGradient(gradient: Gradient(
colors: [Color.blue.opacity(0.2), Color.blue.opacity(1), Color.blue.opacity(0.2)]),
center: .center,
startAngle: .degrees(Double(secondaryDirectionValue)),
endAngle: .degrees(Double(directionValue))),
style: StrokeStyle(lineWidth: 8, lineCap: .round)
)
.frame(width: radius * 2, height: radius * 2)
.rotationEffect(.degrees(-90))
KnobCircle(radius: knobRadius * 2, padding: 6)
.offset(y: -radius)
.rotationEffect(Angle.degrees(Double(dirAngleValue)))
.shadow(color: Color.black.opacity(0.2), radius: 3, x: -3)
.gesture(DragGesture(minimumDistance: 0.0)
.onChanged( angleValue in
knobChange(location: angleValue.location)
))
KnobCircle(radius: knobRadius * 2, padding: 6)
.offset(y: -radius)
.rotationEffect(Angle.degrees(Double(secondaryDirectionValue)))
.shadow(color: Color.black.opacity(0.2), radius: 3, x: -3)
.gesture(DragGesture(minimumDistance: 0.0)
.onChanged( angleValue in
knobSecondaryChange(location: angleValue.location)
))
CompassView(count: 240,
longDivider: 15,
longTickHeight: self.longTickHeight,
tickHeight: self.tickHeight,
tickWidth: self.tickWidth,
highlightedColorDivider: 30,
highlightedColor: .blue,
normalColor: .black.opacity(0.2))
.frame(width: 350, height: 350)
CompassNumber(numbers: self.getNumbers(count: 16))
.frame(width: 310, height: 310)
//: ZSTACK
.onAppear()
updateInitialValue()
private func getNumbers(count: Int) -> [Float]
var numbers: [Float] = []
numbers.append(Float(count) * 30)
for index in 1..<count
numbers.append(Float(index) * 30)
return numbers
private func updateInitialValue()
directionValue = minimumValue
dirAngleValue = CGFloat(directionValue/totalValue) * 360
private func knobChange(location: CGPoint)
let vector = CGVector(dx: location.x, dy: location.y)
let angle = atan2(vector.dy - knobRadius, vector.dx - knobRadius) + .pi/2.0
let fixedAngle = angle < 0.0 ? angle + 2.0 * .pi : angle
let value = fixedAngle / (2.0 * .pi) * totalValue
if value > minimumValue && value < maximumValue
directionValue = value
dirAngleValue = fixedAngle * 180 / .pi
private func knobSecondaryChange(location: CGPoint)
let vector = CGVector(dx: location.x, dy: location.y)
let angle = atan2(vector.dy - knobRadius, vector.dx - knobRadius) + .pi/2.0
let fixedAngle = angle < 0.0 ? angle + 2.0 * .pi : angle
let value = fixedAngle / (2.0 * .pi) * totalValue
if value > minimumValue && value < maximumValue
secondaryDirectionValue = value
secondaryDirAngleValue = fixedAngle * 180 / .pi
struct KnobCircle: View
let radius: CGFloat
let padding: CGFloat
var body: some View
ZStack()
Circle()
.fill(Color.init(white: 0.96))
.frame(width: radius, height: radius)
.shadow(color: Color.black.opacity(0.1), radius: 10, x: -10, y: 8)
Circle()
.fill(Color.white)
.frame(width: radius - padding, height: radius - padding)
//: ZSTACK
struct CompassView: View
let count: Int
let longDivider: Int
let longTickHeight: CGFloat
let tickHeight: CGFloat
let tickWidth: CGFloat
let highlightedColorDivider: Int
let highlightedColor: Color
let normalColor: Color
var body: some View
ZStack()
ForEach(0..<self.count) index in
let height = (index % self.longDivider == 0) ? self.longTickHeight : self.tickHeight
let color = (index % self.highlightedColorDivider == 0) ? self.highlightedColor : self.normalColor
let degree: Double = Double.pi * 2 / Double(self.count)
TickShape(tickHeight: height)
.stroke(lineWidth: self.tickWidth)
.rotationEffect(.radians(degree * Double(index)))
.foregroundColor(color)
//: ZSTACK
//: VIEW
struct TickShape: Shape
let tickHeight: CGFloat
func path(in rect: CGRect) -> Path
var path = Path()
path.move(to: CGPoint(x: rect.midX, y: rect.minY))
path.addLine(to: CGPoint(x: rect.midX, y: rect.minY + self.tickHeight))
return path
struct CompassNumber: View
let numbers: [Float]
let direction: [String] = ["N","NE","E","SE","S","SW","W","NW"]
var body: some View
ZStack()
ForEach(0..<self.direction.count) index in
let degree: Double = Double.pi * 2 / Double(self.direction.count)
let itemDegree = degree * Double(index)
VStack()
Text(self.direction[index])
.font(.footnote)
.rotationEffect(.radians(-itemDegree))
.foregroundColor(.blue)
Spacer()
//: VSTACK
.rotationEffect(.radians(itemDegree))
//: ZSTACK
extension Double
func degreesToCompassDirection(degree: Double) -> String
switch degree
case 0..<11.25:
return "N"
case 11.25..<33.75:
return "NNE"
case 33.75..<56.25:
return "NE"
case 56.25..<78.75:
return "ENE"
case 78.75..<101.25:
return "E"
case 101.25..<123.75:
return "ESE"
case 123.75..<146.25:
return "SE"
case 146.25..<168.75:
return "SSE"
case 168.75..<191.25:
return "S"
case 191.25..<213.75:
return "SSW"
case 213.75..<236.25:
return "SW"
case 236.25..<258.75:
return "WSW"
case 258.75..<281.25:
return "W"
case 281.25..<303.75:
return "WNW"
case 303.75..<326.25:
return "NW"
case 326.25..<348.75:
return "NNW"
case 348.75..<360:
return "N"
default:
return "ERROR"
感谢您的帮助。
【问题讨论】：
【参考方案1】：我做了一个 ZStack 并显示了背景描边。如果我想在 0 位置（北）上显示，我只是交换了背景和前景色。
var body: some View
ZStack
ZStack
Circle() //Background
.stroke((directionValue < secondaryDirectionValue) ? Color.white : Color.blue)
.frame(width: radius * 2, height: radius * 2)
.rotationEffect(.degrees(-90))
Circle() //Foreground
.trim(from: minimumTrimValue(), to: maximumTrimValue())
.stroke((directionValue < secondaryDirectionValue) ? Color.blue : Color.white)
.frame(width: radius * 2, height: radius * 2)
.rotationEffect(.degrees(-90))
【讨论】：
您的答案可以通过额外的支持信息得到改进。请edit 添加更多详细信息，例如引用或文档，以便其他人可以确认您的答案是正确的。你可以找到更多关于如何写好答案的信息in the help center。以上是关于使用两个控制点时，SwiftUI 圆形滑块问题未显示正确的笔划的主要内容，如果未能解决你的问题，请参考以下文章