From 8731d4c61b69f888c25491a69f0f5d3c96d909f9 Mon Sep 17 00:00:00 2001
From: Igor Dykhta <igorDykhta@users.noreply.github.com>
Date: Tue, 16 Feb 2021 16:22:48 +0200
Subject: [PATCH] exposed webgl context state from animation loop (#1453)

---
 docs/api-reference/engine/animation-loop.md    | 4 ++++
 modules/engine/src/lib/animation-loop.d.ts     | 1 +
 modules/engine/src/lib/animation-loop.js       | 8 ++++++++
 modules/engine/test/lib/animation-loop.spec.js | 2 ++
 4 files changed, 15 insertions(+)

diff --git a/docs/api-reference/engine/animation-loop.md b/docs/api-reference/engine/animation-loop.md
index 03aa0d0e5b..e4470fa9d2 100644
--- a/docs/api-reference/engine/animation-loop.md
+++ b/docs/api-reference/engine/animation-loop.md
@@ -135,6 +135,10 @@ Returns returns a `Promise` that resolves to the data URL of the canvas once dra
 
 `animationLoop.toDataURL()`
 
+### isContextLost()
+
+Returns the current state of the WebGL context used by the animation loop.
+
 ## Callback Parameters
 
 The callbacks `onInitialize`, `onRender` and `onFinalize` that the app supplies to the `AnimationLoop`, will be called with an object containing named parameters:
diff --git a/modules/engine/src/lib/animation-loop.d.ts b/modules/engine/src/lib/animation-loop.d.ts
index bd6eccbcc3..409a984f50 100644
--- a/modules/engine/src/lib/animation-loop.d.ts
+++ b/modules/engine/src/lib/animation-loop.d.ts
@@ -104,6 +104,7 @@ export default class AnimationLoop {
   toDataURL(): Promise<string>;
   setViewParameters(): AnimationLoop;
   getHTMLControlValue(id: string, defaultValue?: number): number;
+  isContextLost(): boolean;
 
   // Callbacks
   onCreateContext(opts: CreateGLContextOptions): WebGLRenderingContext;
diff --git a/modules/engine/src/lib/animation-loop.js b/modules/engine/src/lib/animation-loop.js
index a13d6286cf..0fe88c37b7 100644
--- a/modules/engine/src/lib/animation-loop.js
+++ b/modules/engine/src/lib/animation-loop.js
@@ -179,6 +179,10 @@ export default class AnimationLoop {
 
   // Redraw now
   redraw() {
+    if (this.isContextLost()) {
+      return this;
+    }
+
     this._beginTimers();
 
     this._setupFrame();
@@ -249,6 +253,10 @@ export default class AnimationLoop {
     return this.gl.canvas.toDataURL();
   }
 
+  isContextLost() {
+    return this.gl.isContextLost();
+  }
+
   onCreateContext(...args) {
     return this.props.onCreateContext(...args);
   }
diff --git a/modules/engine/test/lib/animation-loop.spec.js b/modules/engine/test/lib/animation-loop.spec.js
index 3ef98b0219..614fe555f0 100644
--- a/modules/engine/test/lib/animation-loop.spec.js
+++ b/modules/engine/test/lib/animation-loop.spec.js
@@ -25,6 +25,8 @@ test('core#AnimationLoop start,stop', t => {
     onRender: () => {
       renderCalled++;
 
+      t.is(animationLoop.isContextLost(), false, 'isContextLost returns false');
+
       animationLoop.stop();
 
       t.is(initializeCalled, 1, 'onInitialize called');