79 lines
2.4 KiB
Swift
79 lines
2.4 KiB
Swift
//
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// GradientView.swift
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// App
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//
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// Created by James Magahern on 8/14/20.
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//
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import UIKit
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class GradientView: UIImageView
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{
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enum Direction {
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case horizontal
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case vertical
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}
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var direction: Direction = .horizontal {
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didSet { image = nil; setNeedsLayout() }
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}
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var colors: [UIColor] = [] {
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didSet { image = nil; setNeedsLayout() }
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}
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private var generatedImageSize: CGSize?
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convenience init(direction: Direction, colors: [UIColor]) {
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self.init(image: nil)
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self.direction = direction
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self.colors = colors
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registerForTraitChanges([UITraitUserInterfaceStyle.self]) { [weak self] (traitEnvironment: Self, previousTraitCollection) in
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self?.image = nil
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self?.setNeedsLayout()
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}
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}
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private func gradientImage(forSize size: CGSize) -> UIImage? {
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guard size.width > .leastNonzeroMagnitude && size.height > .leastNonzeroMagnitude else { return nil }
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var image: UIImage? = nil
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UIGraphicsBeginImageContext(size)
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if let context = UIGraphicsGetCurrentContext() {
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let gradientColorsArray = self.colors.map { $0.cgColor }
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if let gradient = CGGradient(colorsSpace: nil, colors: gradientColorsArray as CFArray, locations: nil) {
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if direction == .horizontal {
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context.drawLinearGradient(gradient, start: .zero, end: CGPoint(x: size.width, y: 0.0), options: CGGradientDrawingOptions())
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} else if direction == .vertical {
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context.drawLinearGradient(gradient, start: CGPoint(x: size.width / 2, y: 0), end: CGPoint(x: size.width / 2, y: size.height), options: CGGradientDrawingOptions())
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}
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}
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image = UIGraphicsGetImageFromCurrentImageContext()
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UIGraphicsEndImageContext();
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}
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return image
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}
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override func layoutSubviews() {
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super.layoutSubviews()
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var needsNewImage: Bool = image == nil
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if let generatedImageSize = generatedImageSize {
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if generatedImageSize != bounds.size {
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needsNewImage = true
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}
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} else {
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needsNewImage = true
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}
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if needsNewImage {
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image = gradientImage(forSize: bounds.size)
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generatedImageSize = bounds.size
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}
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}
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}
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