From cabc2cc4fcc5c2361c693e4324419f3b49b2479b Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sun, 21 Jun 2020 15:38:09 +0200
Subject: [PATCH] Add a `InternalRenderTask.completed` getter and use it to
 simplify `PDFPageProxy._destroy`

This patch aims to simplify the `PDFPageProxy._destroy` method, by:
 - Replacing the unnecessary `forEach` with a "regular" `for`-loop instead.
 - Use a more appropriate variable name, since `intentState.renderTasks` contain instances of `InternalRenderTask`.
 - Move the "is rendering completed"-handling to a new `InternalRenderTask.completed` getter, to abstract away some (mostly) internal `InternalRenderTask` state.
---
 src/display/api.js | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/display/api.js b/src/display/api.js
index 8a556c40a..784995825 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -1234,13 +1234,10 @@ class PDFPageProxy {
         // Avoid errors below, since the renderTasks are just stubs.
         return;
       }
-      intentState.renderTasks.forEach(function (renderTask) {
-        const renderCompleted = renderTask.capability.promise.catch(
-          function () {}
-        ); // ignoring failures
-        waitOn.push(renderCompleted);
-        renderTask.cancel();
-      });
+      for (const internalRenderTask of intentState.renderTasks) {
+        waitOn.push(internalRenderTask.completed);
+        internalRenderTask.cancel();
+      }
     });
     this.objs.clear();
     this.annotationsPromise = null;
@@ -2650,6 +2647,13 @@ const InternalRenderTask = (function InternalRenderTaskClosure() {
       this._canvas = params.canvasContext.canvas;
     }
 
+    get completed() {
+      return this.capability.promise.catch(function () {
+        // Ignoring errors, since we only want to know when rendering is
+        // no longer pending.
+      });
+    }
+
     initializeGraphics(transparency = false) {
       if (this.cancelled) {
         return;