Extract OverviewWaveform to its own component

frontend/src/Waveform.tsx

@@ -1,5 +1,6 @@
 import { useEffect, useState, useRef, MouseEvent } from 'react';
-import { WaveformCanvas } from './WaveformCanvas';
+import { Waveform as WaveformOverview } from './Waveform/Overview';
+import { Canvas as WaveformCanvas } from './Waveform/Canvas';
 
 type Props = {
   audioContext: AudioContext;
@@ -19,18 +20,20 @@ type ZoomSettings = {
 
 const defaultZoomSettings: ZoomSettings = { startFrame: 0, endFrame: 0 };
 
+export const CanvasLogicalWidth = 2000;
+export const CanvasLogicalHeight = 500;
+
 export const Waveform: React.FC<Props> = ({ audioContext }: Props) => {
   const [audioFile, setAudioFile] = useState<AudioFile | null>(null);
   const [currentTime, setCurrentTime] = useState(0);
+  // TODO: fix linter error
   const [audio, setAudio] = useState(new Audio());
   const [zoomSettings, setZoomSettings] = useState(defaultZoomSettings);
   const [waveformPeaks, setWaveformPeaks] = useState(null);
   const [overviewPeaks, setOverviewPeaks] = useState(null);
-
   const hudCanvasRef = useRef<HTMLCanvasElement>(null);
-  const canvasLogicalWidth = 2000;
-  const canvasLogicalHeight = 500;
 
+  // TODO: error handling
   const videoID = new URLSearchParams(window.location.search).get('video_id');
 
   // helpers
@@ -47,7 +50,7 @@ export const Waveform: React.FC<Props> = ({ audioContext }: Props) => {
     if (audioFile == null) {
       return 0;
     }
-    return Math.floor((x / canvasLogicalWidth) * audioFile.frames);
+    return Math.floor((x / CanvasLogicalWidth) * audioFile.frames);
   };
 
   const secsToCanvasX = (canvasWidth: number, secs: number): number => {
@@ -112,7 +115,7 @@ export const Waveform: React.FC<Props> = ({ audioContext }: Props) => {
       }
 
       const resp = await fetch(
-        `http://localhost:8888/api/peaks?video_id=${videoID}&start=${zoomSettings.startFrame}&end=${endFrame}&bins=${canvasLogicalWidth}`
+        `http://localhost:8888/api/peaks?video_id=${videoID}&start=${zoomSettings.startFrame}&end=${endFrame}&bins=${CanvasLogicalWidth}`
       );
       const peaks = await resp.json();
       console.log('respBody from peaks =', peaks);
@@ -240,13 +243,10 @@ export const Waveform: React.FC<Props> = ({ audioContext }: Props) => {
     zIndex: 1,
   } as React.CSSProperties;
 
-  const overviewCanvasProps = {
-    width: '90%',
-    height: '90px',
-    margin: '0 auto',
-    display: 'block',
-  } as React.CSSProperties;
+  const overviewStyles = { ...wrapperProps, height: '90px' };
 
+  // TODO: why is the margin needed?
+  const controlPanelStyles = { margin: '1em' } as React.CSSProperties;
   const clockTextAreaProps = { color: '#999', width: '400px' };
 
   return (
@@ -255,35 +255,31 @@ export const Waveform: React.FC<Props> = ({ audioContext }: Props) => {
       <div style={wrapperProps}>
         <WaveformCanvas
           peaks={waveformPeaks}
-          logicalWidth={canvasLogicalWidth}
-          logicalHeight={canvasLogicalHeight}
           fillStyle="black"
           strokeStyle="green"
           style={waveformCanvasProps}
         ></WaveformCanvas>
         <canvas
           ref={hudCanvasRef}
-          width={canvasLogicalWidth}
-          height={canvasLogicalHeight}
           onMouseMove={handleMouseMove}
           onMouseDown={handleMouseDown}
           onMouseUp={handleMouseUp}
           style={hudCanvasProps}
+          width={CanvasLogicalWidth}
+          height={CanvasLogicalHeight}
         ></canvas>
       </div>
-      <WaveformCanvas
+      <WaveformOverview
         peaks={overviewPeaks}
-        logicalWidth={canvasLogicalWidth}
-        logicalHeight={canvasLogicalHeight}
-        fillStyle="grey"
-        strokeStyle="black"
-        style={overviewCanvasProps}
-      ></WaveformCanvas>
+        style={overviewStyles}
+      ></WaveformOverview>
+      <div style={controlPanelStyles}>
         <button onClick={handlePlay}>Play</button>
         <button onClick={handlePause}>Pause</button>
         <button onClick={handleZoomIn}>+</button>
         <button onClick={handleZoomOut}>-</button>
         <input type="readonly" style={clockTextAreaProps} />
+      </div>
     </>
   );
 };

frontend/src/Waveform/Canvas.tsx

@@ -1,17 +1,24 @@
-import { useEffect, useState, useRef, MouseEvent } from 'react';
+import { useEffect, useRef } from 'react';
+import { CanvasLogicalWidth, CanvasLogicalHeight } from '../Waveform';
 
-const maxPeakValue = 32768;
+const maxPeakValue = 32_768;
 
 type Props = {
   peaks: number[][] | null;
-  logicalWidth: number;
-  logicalHeight: number;
   strokeStyle: string;
   fillStyle: string;
   style: React.CSSProperties;
 };
 
-export const WaveformCanvas: React.FC<Props> = (props: Props) => {
+// Canvas is a generic component that renders a waveform to a canvas.
+//
+// Properties:
+//
+// peaks: a 2d array of uint16s representing the peak values. Each inner array length should match logicalWidth
+// strokeStyle: waveform style
+// fillStyle: background style
+// style: React.CSSProperties applied to canvas element
+export const Canvas: React.FC<Props> = (props: Props) => {
   const canvasRef = useRef<HTMLCanvasElement>(null);
 
   useEffect(() => {
@@ -57,8 +64,8 @@ export const WaveformCanvas: React.FC<Props> = (props: Props) => {
     <>
       <canvas
         ref={canvasRef}
-        width={props.logicalWidth}
-        height={props.logicalHeight}
+        width={CanvasLogicalWidth}
+        height={CanvasLogicalHeight}
         style={props.style}
       ></canvas>
     </>

frontend/src/Waveform/Overview.tsx

@@ -0,0 +1,58 @@
+import { useEffect, useRef } from 'react';
+import { Canvas as WaveformCanvas } from './Canvas';
+import { CanvasLogicalWidth, CanvasLogicalHeight } from '../Waveform';
+
+type Props = {
+  peaks: number[][] | null;
+  style: React.CSSProperties;
+};
+
+export const Waveform: React.FC<Props> = (props: Props) => {
+  const hudCanvasRef = useRef<HTMLCanvasElement>(null);
+
+  // handlers
+
+  const handleMouseDown = () => {
+    console.log('mousedown');
+  };
+
+  // render component
+
+  const canvasStyles = {
+    width: '100%',
+    height: '100px',
+    margin: '0 auto',
+    display: 'block',
+  } as React.CSSProperties;
+
+  const hudCanvasStyles = {
+    width: '100%',
+    height: '100%',
+    position: 'absolute',
+    top: 0,
+    left: 0,
+    right: 0,
+    bottom: 0,
+    zIndex: 1,
+  } as React.CSSProperties;
+
+  return (
+    <>
+      <div style={props.style}>
+        <WaveformCanvas
+          peaks={props.peaks}
+          fillStyle="grey"
+          strokeStyle="black"
+          style={canvasStyles}
+        ></WaveformCanvas>
+        <canvas
+          ref={hudCanvasRef}
+          style={hudCanvasStyles}
+          width={CanvasLogicalWidth}
+          height={CanvasLogicalHeight}
+          onMouseDown={handleMouseDown}
+        ></canvas>
+      </div>
+    </>
+  );
+};