6c1ed8d0dd
Allow to set just the gradient colors, without locations, relying on CAGradientLayer's uniform color distribution logic. Also update all the uses of GradientView to only specify colors because all the places were using just two locations: 0 and 1.
95 lines
3.2 KiB
Swift
95 lines
3.2 KiB
Swift
//
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// Copyright (c) 2022 Open Whisper Systems. All rights reserved.
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//
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public class GradientView: UIView {
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public override class var layerClass: AnyClass { CAGradientLayer.self }
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public var gradientLayer: CAGradientLayer { layer as! CAGradientLayer }
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public var colors: [UIColor] {
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didSet {
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updateGradientColors()
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}
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}
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public var locations: [CGFloat]? {
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didSet {
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updateGradientLocations()
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}
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}
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public convenience init(from fromColor: UIColor, to toColor: UIColor) {
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self.init(colors: [ fromColor, toColor ])
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}
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public required init(colors: [UIColor], locations: [CGFloat]? = nil) {
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self.colors = colors
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self.locations = locations
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super.init(frame: .zero)
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updateGradientColors()
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updateGradientLocations()
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}
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public required init?(coder aDecoder: NSCoder) {
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fatalError("init(coder:) has not been implemented")
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}
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private func updateGradientColors() {
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gradientLayer.colors = colors.map { $0.cgColor }
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}
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private func updateGradientLocations() {
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if let locations = locations {
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gradientLayer.locations = locations.map { NSNumber(value: $0) }
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} else {
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gradientLayer.locations = nil
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}
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}
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/// Sets the `startPoint` and `endPoint` of the layer to reflect an angle in degrees
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/// where 0° starts at 12 o'clock and proceeds in a clockwise direction.
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public func setAngle(_ angle: UInt32) {
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// While design provides gradients with 0° at 12 o'clock, core animation's
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// coordinate system works with 0° at 3 o'clock moving in a counter clockwise
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// direction. We need to convert the provided angle accordingly before
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// calculating the gradient's start and end points.
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let caAngle =
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(360 - angle) // Invert to counter clockwise direction
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+ 90 // Rotate 90° counter clockwise to shift the start from 3 o'clock to 12 o'clock
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let radians = CGFloat(caAngle) * .pi / 180.0
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// (x,y) in terms of the signed unit circle
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var endPoint = CGPoint(x: cos(radians), y: sin(radians))
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// extrapolate to signed unit square
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if abs(endPoint.x) > abs(endPoint.y) {
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endPoint.x = endPoint.x > 0 ? 1 : -1
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endPoint.y = endPoint.x * tan(radians)
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} else {
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endPoint.y = endPoint.y > 0 ? 1 : -1
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endPoint.x = endPoint.y / tan(radians)
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}
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// The signed unit square is a coordinate space from:
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// (-1,-1) to (1,1), but the gradient coordinate space
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// ranges from (0,0) to (1,1) with 0 being the top
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// left. Convert each point accordingly to calculate
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// the final points.
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func convertPointToGradientSpace(_ point: CGPoint) -> CGPoint {
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return CGPoint(
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x: (point.x + 1) * 0.5,
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y: 1.0 - (point.y + 1) * 0.5
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)
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}
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// The start point will always be at the opposite side of the signed unit square.
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gradientLayer.startPoint = convertPointToGradientSpace(CGPoint(x: -endPoint.x, y: -endPoint.y))
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gradientLayer.endPoint = convertPointToGradientSpace(endPoint)
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}
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}
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