fstanis/audio2waveform.html

## audio2waveform.html
<!--
Copyright 2018 Google LLC

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Audio Visualizer</title>
  <style>
    body {
      margin: 0;
    }
    #drop {
      display: flex;
      justify-content: center;
      align-items: center;
      position: absolute;
      top: 0;
      width: 100vw;
      height: 100vh;
      overflow: hidden;
    }
  </style>
</head>
<body>
  <div id="dummy"></div>
  <a id="download" href="#" download="waveform.svg" hidden>Download</a>
  <div id="drop" ondrop="dropHandler(event)" ondragover="event.preventDefault()">
    <div>Drag and drop here!</div>
  </div>
  <script src="https://unpkg.com/wavesurfer.js"></script>
  <script src="https://cdn.jsdelivr.net/gh/gliffy/canvas2svg/canvas2svg.js"></script>
  <script>
    async function dropHandler(event) {
      event.preventDefault();
      const items = event.dataTransfer.items;
      if (items && items.length >= 1 && items[0].kind === 'file') {
        const file = items[0].getAsFile();
        triggerDownload(await audioToSvg(file));
      }
    }

    function audioToSvg(file) {
      return new Promise(resolve => {
        const canvas = new C2S('100%', '100%');
        canvas.style = {};
        HTMLCanvasElement.prototype.getContext = () => canvas;
        const wavesurfer = WaveSurfer.create({
          container: '#dummy',
          maxCanvasWidth: 100000
        });
        wavesurfer.on('ready', () => {
          canvas.save();
          requestIdleCallback(() => resolve(canvas.getSerializedSvg(true)));
        });
        wavesurfer.loadBlob(file);
      });
    }

    function triggerDownload(svg) {
      const blob = new Blob([svg], {type: "image/svg"});
      const url = URL.createObjectURL(blob);
      const download = document.querySelector('#download');
      download.href = url;
      download.click();
      URL.revokeObjectURL(url);
    }
</script>
</body>
</html>
	<!--
	Copyright 2018 Google LLC

	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at

	https://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	-->
	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<title>Audio Visualizer</title>
	<style>
	body {
	margin: 0;
	}
	#drop {
	display: flex;
	justify-content: center;
	align-items: center;
	position: absolute;
	top: 0;
	width: 100vw;
	height: 100vh;
	overflow: hidden;
	}
	</style>
	</head>
	<body>
	<div id="dummy"></div>
	<a id="download" href="#" download="waveform.svg" hidden>Download</a>
	<div id="drop" ondrop="dropHandler(event)" ondragover="event.preventDefault()">
	<div>Drag and drop here!</div>
	</div>
	<script src="https://unpkg.com/wavesurfer.js"></script>
	<script src="https://cdn.jsdelivr.net/gh/gliffy/canvas2svg/canvas2svg.js"></script>
	<script>
	async function dropHandler(event) {
	event.preventDefault();
	const items = event.dataTransfer.items;
	if (items && items.length >= 1 && items[0].kind === 'file') {
	const file = items[0].getAsFile();
	triggerDownload(await audioToSvg(file));
	}
	}

	function audioToSvg(file) {
	return new Promise(resolve => {
	const canvas = new C2S('100%', '100%');
	canvas.style = {};
	HTMLCanvasElement.prototype.getContext = () => canvas;
	const wavesurfer = WaveSurfer.create({
	container: '#dummy',
	maxCanvasWidth: 100000
	});
	wavesurfer.on('ready', () => {
	canvas.save();
	requestIdleCallback(() => resolve(canvas.getSerializedSvg(true)));
	});
	wavesurfer.loadBlob(file);
	});
	}

	function triggerDownload(svg) {
	const blob = new Blob([svg], {type: "image/svg"});
	const url = URL.createObjectURL(blob);
	const download = document.querySelector('#download');
	download.href = url;
	download.click();
	URL.revokeObjectURL(url);
	}
	</script>
	</body>
	</html>