From 99659adb9edd32fe2be8cc0215ce4c011c1baf94 Mon Sep 17 00:00:00 2001
From: Rob Watson <rob@netflux.io>
Date: Fri, 12 Nov 2021 13:36:03 +0100
Subject: [PATCH] Basic error handling when reading peaks

---
 frontend/src/WaveformCanvas.tsx | 80 +++++++++++++++++----------------
 1 file changed, 42 insertions(+), 38 deletions(-)

diff --git a/frontend/src/WaveformCanvas.tsx b/frontend/src/WaveformCanvas.tsx
index ee46fde..675753c 100644
--- a/frontend/src/WaveformCanvas.tsx
+++ b/frontend/src/WaveformCanvas.tsx
@@ -26,45 +26,49 @@ export const WaveformCanvas: React.FC<Props> = (props: Props) => {
   const canvasRef = useRef<HTMLCanvasElement>(null);
 
   useEffect(() => {
-    const canvas = canvasRef.current;
-    if (canvas == null) {
-      console.error('no canvas ref available');
-      return;
-    }
-
-    const ctx = canvas.getContext('2d');
-    if (ctx == null) {
-      console.error('no 2d context available');
-      return;
-    }
-
-    ctx.strokeStyle = props.strokeStyle;
-    ctx.fillStyle = props.fillStyle;
-    ctx.fillRect(0, 0, canvas.width, canvas.height);
-
-    if (props.peaks == null) {
-      return;
-    }
-
-    const chanHeight = canvas.height / props.channels;
-
-    let frameIndex = 0;
-    props.peaks.forEach((peaks) => {
-      for (let chanIndex = 0; chanIndex < peaks.length; chanIndex++) {
-        const yOffset = chanHeight * chanIndex;
-        const val = peaks[chanIndex];
-        const height = Math.floor((val / maxPeakValue) * chanHeight);
-        const y1 = (chanHeight - height) / 2 + yOffset;
-        const y2 = y1 + height;
-        ctx.beginPath();
-        ctx.globalAlpha = props.alpha;
-        ctx.moveTo(frameIndex, y1);
-        ctx.lineTo(frameIndex, y2);
-        ctx.stroke();
-        ctx.globalAlpha = 1;
+    (async function () {
+      const canvas = canvasRef.current;
+      if (canvas == null) {
+        console.error('no canvas ref available');
+        return;
       }
-      frameIndex++;
-    });
+
+      const ctx = canvas.getContext('2d');
+      if (ctx == null) {
+        console.error('no 2d context available');
+        return;
+      }
+
+      ctx.strokeStyle = props.strokeStyle;
+      ctx.fillStyle = props.fillStyle;
+      ctx.fillRect(0, 0, canvas.width, canvas.height);
+
+      if (props.peaks == null) {
+        return;
+      }
+
+      const chanHeight = canvas.height / props.channels;
+
+      let frameIndex = 0;
+      await props.peaks
+        .forEach((peaks) => {
+          for (let chanIndex = 0; chanIndex < peaks.length; chanIndex++) {
+            const yOffset = chanHeight * chanIndex;
+            const val = peaks[chanIndex];
+            const height = Math.floor((val / maxPeakValue) * chanHeight);
+            const y1 = (chanHeight - height) / 2 + yOffset;
+            const y2 = y1 + height;
+            ctx.beginPath();
+            ctx.globalAlpha = props.alpha;
+            ctx.moveTo(frameIndex, y1);
+            ctx.lineTo(frameIndex, y2);
+            ctx.stroke();
+            ctx.globalAlpha = 1;
+          }
+          frameIndex++;
+        })
+        .catch(console.error);
+    })();
   }, [props.peaks]);
 
   const canvasStyles = {