From c3e26ea307248b5ed0b8638098a17b2abfd94f2e Mon Sep 17 00:00:00 2001
From: Brent Simmons <brent@ranchero.com>
Date: Sat, 14 Sep 2019 22:41:13 -0700
Subject: [PATCH] =?UTF-8?q?Scale=20images,=20when=20needed,=20before=20gen?=
 =?UTF-8?q?erating=20inline=20HTML=20data=20in=20ArticleRenderer=20?=
 =?UTF-8?q?=E2=80=94=C2=A0this=20keeps=20us=20from=20getting=20huge=20amou?=
 =?UTF-8?q?nts=20of=20data,=20which=20slows=20down=20rendering.?=
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---
 .../Article Rendering/ArticleRenderer.swift   | 49 +++++++++++++++++--
 1 file changed, 46 insertions(+), 3 deletions(-)

diff --git a/Shared/Article Rendering/ArticleRenderer.swift b/Shared/Article Rendering/ArticleRenderer.swift
index 833228120..d66aac5a2 100644
--- a/Shared/Article Rendering/ArticleRenderer.swift	
+++ b/Shared/Article Rendering/ArticleRenderer.swift	
@@ -159,6 +159,48 @@ private extension ArticleRenderer {
 		return permalink != preferredLink // Make date a link if it’s a different link from the title’s link
 	}
 
+	static let avatarDimension = 48
+	static let doubledDimension = CGFloat(avatarDimension * 2)
+
+	static func imageScaledForDisplay(image: RSImage) -> RSImage {
+		// Aspect fit.
+		#if os(macOS)
+
+		if image.size.height <= doubledDimension && image.size.width <= doubledDimension {
+			return image
+		}
+
+		let scaledImage = NSImage.init(size: NSSize(width: doubledDimension, height: doubledDimension))
+		scaledImage.lockFocus()
+
+		var imageRectWidth = doubledDimension
+		var imageRectHeight = doubledDimension
+		var imageRectOriginX = CGFloat(0.0)
+		var imageRectOriginY = CGFloat(0.0)
+
+		if image.size.width > image.size.height {
+			let factor: CGFloat = doubledDimension / image.size.width
+			imageRectHeight = image.size.height * factor
+			imageRectOriginY = (doubledDimension - imageRectHeight) / 2.0
+		}
+		else if image.size.height > image.size.width {
+			let factor: CGFloat = doubledDimension / image.size.height
+			imageRectWidth = image.size.width * factor
+			imageRectOriginX = (doubledDimension - imageRectWidth) / 2.0
+		}
+
+		image.draw(in: NSRect(x: imageRectOriginX, y: imageRectOriginY, width: imageRectWidth, height: imageRectHeight))
+		scaledImage.unlockFocus()
+		return scaledImage
+
+		#else //iOS
+
+		// TODO: https://github.com/brentsimmons/NetNewsWire/issues/1021
+
+		return image
+		#endif
+	}
+
 	func faviconImgTag(forFeed feed: Feed) -> String? {
 
 		if let cachedImgTag = ArticleRenderer.faviconImgTagCache[feed] {
@@ -166,7 +208,8 @@ private extension ArticleRenderer {
 		}
 
 		if let favicon = appDelegate.faviconDownloader.favicon(for: feed) {
-			if let s = base64String(forImage: favicon) {
+			let scaledImage = ArticleRenderer.imageScaledForDisplay(image: favicon)
+			if let s = base64String(forImage: scaledImage) {
 				var dimension = min(favicon.size.height, CGFloat(ArticleRenderer.avatarDimension)) // Assuming square images.
 				dimension = max(dimension, 16) // Some favicons say they’re < 16. Force them larger.
 				if dimension >= CGFloat(ArticleRenderer.avatarDimension) * 0.8 { //Close enough to scale up.
@@ -195,7 +238,8 @@ private extension ArticleRenderer {
 		}
 
 		if let icon = appDelegate.feedIconDownloader.icon(for: feed) {
-			if let s = base64String(forImage: icon) {
+			let scaledImage = ArticleRenderer.imageScaledForDisplay(image: icon)
+			if let s = base64String(forImage: scaledImage) {
 				#if os(macOS)
 				let imgTag = "<img src=\"data:image/tiff;base64, " + s + "\" height=48 width=48 />"
 				#else
@@ -228,7 +272,6 @@ private extension ArticleRenderer {
 		return nil
 	}
 
-	static let avatarDimension = 48
 
 	struct Avatar {
 		let imageURL: String