From bf8b1adf73812aa0918032573ba17fae0b47f9c1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Fri, 11 Sep 2020 12:13:30 +0200
Subject: [PATCH] canvas: Properly restore all the remaining items in
 stateStack in endDrawing.

We were correctly finishing the SMask group but not restoring all the extra
transformations applied in stateStack, so if somebody ends up drawing to the
same context after canceling mid-draw we'd get artifacts.

This re-lands #12363 and fixes Mozilla bug 1664178[1].

[1]: https://bugzilla.mozilla.org/show_bug.cgi?id=1664178
---
 src/display/canvas.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/display/canvas.js b/src/display/canvas.js
index abf958e96..b98d0598c 100644
--- a/src/display/canvas.js
+++ b/src/display/canvas.js
@@ -1009,8 +1009,8 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
 
     endDrawing: function CanvasGraphics_endDrawing() {
       // Finishing all opened operations such as SMask group painting.
-      if (this.current.activeSMask !== null) {
-        this.endSMaskGroup();
+      while (this.stateStack.length || this.current.activeSMask !== null) {
+        this.restore();
       }
 
       this.ctx.restore();