From 1b0006093da4b0d9dba5813039e844d8ec349c50 Mon Sep 17 00:00:00 2001
From: Calixte Denizet <calixte.denizet@gmail.com>
Date: Fri, 28 May 2021 11:06:11 +0200
Subject: [PATCH] Italic angle is defined clockwise in CSS when it's
 counterclockwise in PDF

---
 src/core/document.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/core/document.js b/src/core/document.js
index d5cec7c94..9cfe0decd 100644
--- a/src/core/document.js
+++ b/src/core/document.js
@@ -901,7 +901,11 @@ class PDFDocument {
       }
       const fontFamily = descriptor.get("FontFamily");
       const fontWeight = descriptor.get("FontWeight");
-      const italicAngle = descriptor.get("ItalicAngle");
+
+      // Angle is expressed in degrees counterclockwise in PDF
+      // when it's clockwise in CSS
+      // (see https://drafts.csswg.org/css-fonts-4/#valdef-font-style-oblique-angle)
+      const italicAngle = -descriptor.get("ItalicAngle");
       const cssFontInfo = { fontFamily, fontWeight, italicAngle };
 
       if (!validateCSSFont(cssFontInfo)) {