-
Notifications
You must be signed in to change notification settings - Fork 30
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
- Loading branch information
Showing
3 changed files
with
204 additions
and
25 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
177 changes: 177 additions & 0 deletions
177
dotcom-rendering/src/components/AudioPlayer/components/WaveForm.tsx
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,177 @@ | ||
| import { useId, useMemo } from 'react'; | ||
|
|
||
| const sumArray = (array: number[]) => array.reduce((a, b) => a + b, 0); | ||
|
|
||
| /** | ||
| * Pseudo random number generator ([linear congruential | ||
| * generator](https://en.wikipedia.org/wiki/Linear_congruential_generator)). | ||
| * | ||
| * I'll be honest, I don't fully understand this, but it generates a random | ||
| * number based on a seed, in this case an array of numbers. | ||
| * | ||
| * It's deterministic, so the same seed will always generate the same results. | ||
| * | ||
| * Copilot helped me with it... | ||
| */ | ||
| const getSeededRandomNumberGenerator = (array: number[]) => { | ||
| const modulus = 2147483648; | ||
| const seed = sumArray(array) % modulus; | ||
| const multiplier = 1103515245; | ||
| const increment = 12345; | ||
|
|
||
| let state = seed; | ||
|
|
||
| return function () { | ||
| state = (multiplier * state + increment) % modulus; | ||
| return state / modulus; | ||
| }; | ||
| }; | ||
|
|
||
| function shuffle(array: number[]) { | ||
| // Create a random number generator that's seeded with array. | ||
| const getSeededRandomNumber = getSeededRandomNumberGenerator(array); | ||
|
|
||
| // Sort the array using the seeded random number generator. This means that | ||
| // the same array will always be sorted in the same (pseudo random) way. | ||
| return array.sort(() => getSeededRandomNumber() - getSeededRandomNumber()); | ||
| } | ||
|
|
||
| const normalizeAmplitude = (data: number[]) => { | ||
| const multiplier = Math.pow(Math.max(...data), -1); | ||
| return data.map((n) => n * multiplier * 100); | ||
| }; | ||
|
|
||
| function padString(str: string, length: number) { | ||
| // Repeat the string until it is longer than the desired length | ||
| const result = str.repeat(Math.ceil(length / str.length)); | ||
|
|
||
| // Return the truncated result to the specified length | ||
| return result.slice(0, length); | ||
| } | ||
|
|
||
| // Generate an array of fake audio peaks based on the URL | ||
| function generateWaveform(url: string, bars: number) { | ||
| // convert the URL to a base64 string | ||
| const base64 = btoa(url); | ||
|
|
||
| // Pad the base64 string to the number of bars we want | ||
| const stringOfBarLength = padString(base64, bars); | ||
|
|
||
| // Convert the string to an array of char codes (fake audio data) | ||
| const valuesFromString = Array.from(stringOfBarLength).map((_, i) => | ||
| stringOfBarLength.charCodeAt(i), | ||
| ); | ||
|
|
||
| // Shuffle (sort) the fake audio data using a deterministic algorithm. This | ||
| // means the same URL will always produce the same waveform, but the | ||
| // waveforms of two similar URLs (e.g. guardian podcast URLs) won't _look_ | ||
| // all that similar. | ||
| const shuffled = shuffle(valuesFromString); | ||
|
|
||
| // Normalize the amplitude of the fake audio data | ||
| const normalized = normalizeAmplitude(shuffled); | ||
|
|
||
| // Return the normalized the amplitude of the fake audio data | ||
| return normalized; | ||
| } | ||
|
|
||
| type Theme = { | ||
| progress?: string; | ||
| buffer?: string; | ||
| wave?: string; | ||
| }; | ||
|
|
||
| const defaultTheme: Theme = { | ||
| progress: 'green', | ||
| buffer: 'orange', | ||
| wave: 'grey', | ||
| }; | ||
|
|
||
| type Props = { | ||
| src: string; | ||
| progress: number; | ||
| buffer: number; | ||
| theme?: Theme; | ||
| gap?: number; | ||
| bars?: number; | ||
| barWidth?: number; | ||
| } & React.SVGProps<SVGSVGElement>; | ||
|
|
||
| export const WaveForm = ({ | ||
| src, | ||
| progress, | ||
| buffer, | ||
| theme: userTheme, | ||
| gap = 1, | ||
| bars = 150, | ||
| barWidth = 4, | ||
| ...props | ||
| }: Props) => { | ||
| // memoise the waveform data so they aren't recalculated on every render | ||
| const barHeights = useMemo(() => generateWaveform(src, bars), [src, bars]); | ||
| const totalWidth = useMemo( | ||
| () => bars * (barWidth + gap) - gap, | ||
| [bars, barWidth, gap], | ||
| ); | ||
| const theme = useMemo( | ||
| () => ({ ...defaultTheme, ...userTheme }), | ||
| [userTheme], | ||
| ); | ||
|
|
||
| // needed in case we have multiple waveforms on the same page | ||
| const id = useId(); | ||
|
|
||
| return ( | ||
| <svg | ||
| viewBox={`0 0 ${totalWidth} 100`} | ||
| preserveAspectRatio="none" | ||
| width={totalWidth} | ||
| height={100} | ||
| xmlns="http://www.w3.org/2000/svg" | ||
| {...props} | ||
| > | ||
| {/* the base bars we'll use to create the variants we need below */} | ||
| <defs> | ||
| <g id={`bars-${id}`}> | ||
| {barHeights.map((barHeight, index) => { | ||
| const x = index * (barWidth + gap); | ||
| return ( | ||
| <rect | ||
| key={x} | ||
| x={x} | ||
| y={100 - barHeight} // place it on the bottom | ||
| width={barWidth} | ||
| height={barHeight} | ||
| /> | ||
| ); | ||
| })} | ||
| </g> | ||
|
|
||
| <clipPath id="buffer-clip-path"> | ||
| <rect height="100" width={(buffer / 100) * totalWidth} /> | ||
| </clipPath> | ||
|
|
||
| <clipPath id="progress-clip-path"> | ||
| <rect height="100" width={(progress / 100) * totalWidth} /> | ||
| </clipPath> | ||
| </defs> | ||
|
|
||
| {/* default wave colours */} | ||
| <use href={`#bars-${id}`} fill={theme.wave} /> | ||
|
|
||
| {/* buffer wave */} | ||
| <use | ||
| href={`#bars-${id}`} | ||
| clipPath="url(#buffer-clip-path)" | ||
| fill={theme.buffer} | ||
| /> | ||
|
|
||
| {/* progress wave */} | ||
| <use | ||
| href={`#bars-${id}`} | ||
| clipPath="url(#progress-clip-path)" | ||
| fill={theme.progress} | ||
| /> | ||
| </svg> | ||
| ); | ||
| }; |