From de956f94730b0909affed27c7d010faafbb63da8 Mon Sep 17 00:00:00 2001
From: Maurice Parker <mo@vincode.io>
Date: Mon, 13 Sep 2021 21:03:27 -0500
Subject: [PATCH] Change to use JavaScript to detect scroll events as it will
 also capture scrollbar events

---
 Mac/MainWindow/Detail/DetailWebView.swift     | 10 -------
 .../Detail/DetailWebViewController.swift      | 28 ++++---------------
 Mac/MainWindow/Detail/main_mac.js             | 10 +++++--
 3 files changed, 14 insertions(+), 34 deletions(-)

diff --git a/Mac/MainWindow/Detail/DetailWebView.swift b/Mac/MainWindow/Detail/DetailWebView.swift
index 450468556..a6e4a5c45 100644
--- a/Mac/MainWindow/Detail/DetailWebView.swift
+++ b/Mac/MainWindow/Detail/DetailWebView.swift
@@ -10,13 +10,8 @@ import AppKit
 import WebKit
 import RSCore
 
-protocol DetailWebViewDelegate: AnyObject {
-	func didScroll(_ : DetailWebView)
-}
-
 final class DetailWebView: WKWebView {
 
-	weak var detailDelegate: DetailWebViewDelegate?
 	weak var keyboardDelegate: KeyboardDelegate?
 	
 	override func accessibilityLabel() -> String? {
@@ -67,11 +62,6 @@ final class DetailWebView: WKWebView {
 			bigSurOffsetFix()
 		}
 	}
-	
-	override func scrollWheel(with event: NSEvent) {
-		super.scrollWheel(with: event)
-		detailDelegate?.didScroll(self)
-	}
 		
 	private var inBigSurOffsetFix = false
 	
diff --git a/Mac/MainWindow/Detail/DetailWebViewController.swift b/Mac/MainWindow/Detail/DetailWebViewController.swift
index a3d9281c6..55e3ed89e 100644
--- a/Mac/MainWindow/Detail/DetailWebViewController.swift
+++ b/Mac/MainWindow/Detail/DetailWebViewController.swift
@@ -62,7 +62,6 @@ final class DetailWebViewController: NSViewController {
 	private let detailIconSchemeHandler = DetailIconSchemeHandler()
 	private var waitingForFirstReload = false
 	private let keyboardDelegate = DetailKeyboardDelegate()
-	private let scrollPositionQueue = CoalescingQueue(name: "Article Scroll Position", interval: 0.3, maxInterval: 0.3)
 	private var windowScrollY: CGFloat?
 
 	private var isShowingExtractedArticle: Bool {
@@ -77,6 +76,7 @@ final class DetailWebViewController: NSViewController {
 	private struct MessageName {
 		static let mouseDidEnter = "mouseDidEnter"
 		static let mouseDidExit = "mouseDidExit"
+		static let windowDidScroll = "windowDidScroll"
 	}
 
 	override func loadView() {
@@ -90,6 +90,7 @@ final class DetailWebViewController: NSViewController {
 		configuration.setURLSchemeHandler(detailIconSchemeHandler, forURLScheme: ArticleRenderer.imageIconScheme)
 
 		let userContentController = WKUserContentController()
+		userContentController.add(self, name: MessageName.windowDidScroll)
 		userContentController.add(self, name: MessageName.mouseDidEnter)
 		userContentController.add(self, name: MessageName.mouseDidExit)
 		configuration.userContentController = userContentController
@@ -97,7 +98,6 @@ final class DetailWebViewController: NSViewController {
 		webView = DetailWebView(frame: NSRect.zero, configuration: configuration)
 		webView.uiDelegate = self
 		webView.navigationDelegate = self
-		webView.detailDelegate = self
 		webView.keyboardDelegate = keyboardDelegate
 		webView.translatesAutoresizingMaskIntoConstraints = false
 		if let userAgent = UserAgent.fromInfoPlist() {
@@ -204,32 +204,16 @@ final class DetailWebViewController: NSViewController {
 	
 }
 
-// MARK: DetailWebViewDelegate
-
-extension DetailWebViewController: DetailWebViewDelegate {
-
-	func didScroll(_: DetailWebView) {
-		
-		scrollPositionQueue.add(self, #selector(scrollPositionDidChange))
-	}
-	
-	@objc func scrollPositionDidChange() {
-		fetchScrollInfo() { scrollInfo in
-			self.windowScrollY = scrollInfo?.offsetY
-		}
-	}
-	
-}
-
 // MARK: - WKScriptMessageHandler
 
 extension DetailWebViewController: WKScriptMessageHandler {
 
 	func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
-		if message.name == MessageName.mouseDidEnter, let link = message.body as? String {
+		if message.name == MessageName.windowDidScroll {
+			windowScrollY = message.body as? CGFloat
+		} else if message.name == MessageName.mouseDidEnter, let link = message.body as? String {
 			delegate?.mouseDidEnter(self, link: link)
-		}
-		else if message.name == MessageName.mouseDidExit {
+		} else if message.name == MessageName.mouseDidExit {
 			delegate?.mouseDidExit(self)
 		}
 	}
diff --git a/Mac/MainWindow/Detail/main_mac.js b/Mac/MainWindow/Detail/main_mac.js
index 90329f7b4..45995d080 100644
--- a/Mac/MainWindow/Detail/main_mac.js
+++ b/Mac/MainWindow/Detail/main_mac.js
@@ -1,4 +1,9 @@
-// Add the mouse listeners for the above functions
+function scrollDetection() {
+	window.onscroll = function(event) {
+		window.webkit.messageHandlers.windowDidScroll.postMessage(window.scrollY);
+	}
+}
+
 function linkHover() {
 	window.onmouseover = function(event) {
 		var closestAnchor = event.target.closest('a')
@@ -15,5 +20,6 @@ function linkHover() {
 }
 
 function postRenderProcessing() {
-	linkHover()
+	scrollDetection();
+	linkHover();
 }