68 lines
1.9 KiB
Swift
68 lines
1.9 KiB
Swift
//
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// WebViewProvider.swift
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// NetNewsWire-iOS
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//
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// Created by Maurice Parker on 9/21/19.
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// Copyright © 2019 Ranchero Software. All rights reserved.
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//
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import Foundation
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import WebKit
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/// WKWebView has an awful behavior of a flash to white on first load when in dark mode.
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/// Keep a queue of WebViews where we've already done a trivial load so that by the time we need them in the UI, they're past the flash-to-shite part of their lifecycle.
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class WebViewProvider: NSObject {
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let articleIconSchemeHandler: ArticleIconSchemeHandler
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private let minimumQueueDepth = 3
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private let maximumQueueDepth = 6
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private var queue = UIView()
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init(coordinator: SceneCoordinator, viewController: UIViewController) {
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articleIconSchemeHandler = ArticleIconSchemeHandler(coordinator: coordinator)
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super.init()
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viewController.view.insertSubview(queue, at: 0)
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replenishQueueIfNeeded()
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}
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func flushQueue() {
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queue.subviews.forEach { $0.removeFromSuperview() }
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}
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func replenishQueueIfNeeded() {
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while queue.subviews.count < minimumQueueDepth {
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enqueueWebView(PreloadedWebView(articleIconSchemeHandler: articleIconSchemeHandler))
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}
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}
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func dequeueWebView(completion: @escaping (PreloadedWebView) -> ()) {
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if let webView = queue.subviews.last as? PreloadedWebView {
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webView.ready { preloadedWebView in
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preloadedWebView.removeFromSuperview()
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self.replenishQueueIfNeeded()
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completion(preloadedWebView)
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}
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return
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}
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assertionFailure("Creating PreloadedWebView in \(#function); queue has run dry.")
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let webView = PreloadedWebView(articleIconSchemeHandler: articleIconSchemeHandler)
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webView.ready { preloadedWebView in
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self.replenishQueueIfNeeded()
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completion(preloadedWebView)
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}
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}
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func enqueueWebView(_ webView: PreloadedWebView) {
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guard queue.subviews.count < maximumQueueDepth else {
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return
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}
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queue.insertSubview(webView, at: 0)
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webView.preload()
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}
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}
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