From d8e0fca6094770513ebd92adb20409df582e306c Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Fri, 17 May 2024 08:40:01 +0200
Subject: [PATCH] Don't invoke `cleanupTextLayer` when there are pending
 textLayers

*Please note:* This doesn't really affect the viewer, but may affect the library API if multiple PDF documents are opened in parallel.

Since we clean-up "global" textLayer-data when destroying a PDF document, this means that other active PDFs could potentially break by invoking `cleanupTextLayer` unconditionally. Note that textLayer rendering is an asynchronous task, and we thus need to ensure those are all finished before running clean-up.
---
 src/display/text_layer.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/display/text_layer.js b/src/display/text_layer.js
index d69279467..3bcb2fb7a 100644
--- a/src/display/text_layer.js
+++ b/src/display/text_layer.js
@@ -63,6 +63,7 @@ const DEFAULT_FONT_SIZE = 30;
 const DEFAULT_FONT_ASCENT = 0.8;
 const ascentCache = new Map();
 let _canvasContext = null;
+const pendingTextLayers = new Set();
 
 function getCtx(lang = null) {
   if (!_canvasContext) {
@@ -85,6 +86,9 @@ function getCtx(lang = null) {
 }
 
 function cleanupTextLayer() {
+  if (pendingTextLayers.size > 0) {
+    return;
+  }
   _canvasContext?.canvas.remove();
   _canvasContext = null;
 }
@@ -245,9 +249,11 @@ class TextLayerRenderTask {
 
     setLayerDimensions(container, viewport);
 
+    pendingTextLayers.add(this);
     // Always clean-up the temporary canvas once rendering is no longer pending.
     this._capability.promise
       .finally(() => {
+        pendingTextLayers.delete(this);
         this._layoutTextParams = null;
         this._styleCache = null;
       })