Change article rendering to use loadHTMLString instead of JavaScript. Issue #1923

iOS/Article/PreloadedWebView.swift

@@ -11,10 +11,6 @@ import WebKit
 
 class PreloadedWebView: WKWebView {
 	
-	private struct MessageName {
-		static let domContentLoaded = "domContentLoaded"
-	}
-	
 	private var isReady: Bool = false
 	private var readyCompletion: ((PreloadedWebView) -> Void)?
 	
@@ -38,8 +34,8 @@ class PreloadedWebView: WKWebView {
 	}
 	
 	func preload() {
-		configuration.userContentController.add(WrapperScriptMessageHandler(self), name: MessageName.domContentLoaded)
-		loadFileURL(ArticleRenderer.page.url, allowingReadAccessTo: ArticleRenderer.page.baseURL)
+		navigationDelegate = self
+		loadFileURL(ArticleRenderer.blank.url, allowingReadAccessTo: ArticleRenderer.blank.baseURL)
 	}
 	
 	func ready(completion: @escaping (PreloadedWebView) -> Void) {
@@ -54,18 +50,16 @@ class PreloadedWebView: WKWebView {
 
 // MARK: WKScriptMessageHandler
 
-extension PreloadedWebView: WKScriptMessageHandler {
+extension PreloadedWebView: WKNavigationDelegate {
 
-	func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
-		if message.name == MessageName.domContentLoaded {
-			isReady = true
-			if let completion = readyCompletion {
-				completeRequest(completion: completion)
-				readyCompletion = nil
-			}
+	func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
+		isReady = true
+		if let completion = readyCompletion {
+			completeRequest(completion: completion)
+			readyCompletion = nil
 		}
 	}
-	
+		
 }
 
 // MARK: Private
@@ -74,7 +68,7 @@ private extension PreloadedWebView {
 	
 	func completeRequest(completion: @escaping (PreloadedWebView) -> Void) {
 		isReady = false
-		configuration.userContentController.removeScriptMessageHandler(forName: MessageName.domContentLoaded)
+		navigationDelegate = nil
 		completion(self)
 	}
 	

iOS/Article/WebViewController.swift

@@ -325,7 +325,7 @@ extension WebViewController: WKNavigationDelegate {
 		}
 		
 	}
-
+	
 }
 
 // MARK: WKUIDelegate
@@ -393,13 +393,6 @@ extension WebViewController: UIScrollViewDelegate {
 
 // MARK: JSON
 
-private struct TemplateData: Codable {
-	let style: String
-	let body: String
-	let title: String
-	let baseURL: String
-}
-
 private struct ImageClickMessage: Codable {
 	let x: Float
 	let y: Float
@@ -416,11 +409,13 @@ private extension WebViewController {
 	func loadWebView() {
 		guard isViewLoaded else { return }
 		
+		if let webView = webView {
+			self.renderPage(webView)
+			return
+		}
+		
 		coordinator.webViewProvider.dequeueWebView() { webView in
 			
-			let webViewToRecycle = self.webView
-			self.renderPage(webViewToRecycle)
-
 			// Add the webview
 			webView.translatesAutoresizingMaskIntoConstraints = false
 			self.view.insertSubview(webView, at: 0)
@@ -451,9 +446,6 @@ private extension WebViewController {
 			webView.configuration.userContentController.add(WrapperScriptMessageHandler(self), name: MessageName.imageWasShown)
 
 			self.renderPage(webView)
-			DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
-				self.recycleWebView(webViewToRecycle)
-			}
 			
 		}
 		
@@ -498,16 +490,16 @@ private extension WebViewController {
 			rendering = ArticleRenderer.noSelectionHTML(style: style)
 		}
 		
-		let templateData = TemplateData(style: rendering.style, body: rendering.html, title: rendering.title, baseURL: rendering.baseURL)
-		
-		let encoder = JSONEncoder()
-		var render = "error();"
-		if let data = try? encoder.encode(templateData) {
-			let json = String(data: data, encoding: .utf8)!
-			render = "render(\(json), \(windowScrollY));"
-		}
+		let substitutions = [
+			"title": rendering.title,
+			"baseURL": rendering.baseURL,
+			"style": rendering.style,
+			"body": rendering.html,
+			"windowScrollY": String(windowScrollY)
+		]
 
-		webView.evaluateJavaScript(render)
+		let html = try! MacroProcessor.renderedText(withTemplate: ArticleRenderer.page.html, substitutions: substitutions)
+		webView.loadHTMLString(html, baseURL: ArticleRenderer.page.baseURL)
 		
 	}
 	

iOS/Resources/blank.html

@@ -0,0 +1,11 @@
+<html>
+	<head>
+		<style>
+			:root {
+				color-scheme: light dark;
+			}
+		</style>
+	</head>
+	<body>
+	</body>
+</html>

iOS/Resources/page.html

@@ -1,17 +1,22 @@
 <html>
 	<head>
-		<title></title>
-		<base href="">
+		<title>[[title]]</title>
 		<meta name="viewport" content="width=device-width, initial-scale=1">
 		<style>
-			:root {
-				color-scheme: light dark;
-			}
+			[[style]]
 		</style>
 		<script src="main.js"></script>
 		<script src="main_ios.js"></script>
 		<script src="newsfoot.js" async="async"></script>
+		<script type="text/javascript">
+			document.addEventListener("DOMContentLoaded", function(event) {
+				window.scrollTo(0, [[windowScrollY]]);
+				processPage();
+			})
+		</script>
+		<base href="[[baseURL]]">
 	</head>
 	<body>
+		[[body]]
 	</body>
 </html>

iOS/Resources/styleSheet.css

@@ -1,4 +1,5 @@
 :root {
+	color-scheme: light dark;
 	font: -apple-system-body;
 	font-size: [[font-size]]px;
 }