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nolanlawson/blob-util.min.js

Last active February 24, 2022 00:17
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Read img tag, store it as a blob, then read it as a blob
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blob-util.min.js
!function(e){"object"==typeof exports?module.exports=e():"function"==typeof define&&define.amd?define(e):"undefined"!=typeof window?window.blobUtil=e():"undefined"!=typeof global?global.blobUtil=e():"undefined"!=typeof self&&(self.blobUtil=e())}(function(){return function e(t,n,r){function o(u,a){if(!n[u]){if(!t[u]){var s="function"==typeof require&&require;if(!a&&s)return s(u,!0);if(i)return i(u,!0);throw new Error("Cannot find module '"+u+"'")}var f=n[u]={exports:{}};t[u][0].call(f.exports,function(e){var n=t[u][1][e];return o(n?n:e)},f,f.exports,e,t,n,r)}return n[u].exports}for(var i="function"==typeof require&&require,u=0;u<r.length;u++)o(r[u]);return o}({1:[function(e,t){"use strict";function n(e){for(var t=e.length,n=new ArrayBuffer(t),r=new Uint8Array(n),o=-1;++o<t;)r[o]=e.charCodeAt(o);return n}function r(e){for(var t="",n=new Uint8Array(e),r=n.byteLength,o=-1;++o<r;)t+=String.fromCharCode(n[o]);return t}function o(e,t){return new L(function(n,r){var o=new Image;t&&(o.crossOrigin=t),o.onload=function(){n(o)},o.onerror=r,o.src=e})}function i(e){var t=document.createElement("canvas");t.width=e.width,t.height=e.height;var n=t.getContext("2d");return n.drawImage(e,0,0,e.width,e.height,0,0,e.width,e.height),t}function u(e,t){return t=t||{},"string"==typeof t&&(t={type:t}),new g(e,t)}function a(e){return(window.URL||window.webkitURL).createObjectURL(e)}function s(e){return(window.URL||window.webkitURL).revokeObjectURL(e)}function f(e){return new L(function(t,n){var o=new FileReader,i="function"==typeof o.readAsBinaryString;o.onloadend=function(e){var n=e.target.result||"";return i?t(n):void t(r(n))},o.onerror=n,i?o.readAsBinaryString(e):o.readAsArrayBuffer(e)})}function c(e,t){return L.resolve().then(function(){var r=[n(atob(e))];return t?u(r,{type:t}):u(r)})}function l(e,t){return L.resolve().then(function(){return c(btoa(e),t)})}function d(e){return f(e).then(function(e){return btoa(e)})}function h(e){return L.resolve().then(function(){var 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Raw
index.html
<html>
<body>
<img id="cat" src="meowth.png"/>
<pre id="display"></pre>
<script src="//cdn.jsdelivr.net/pouchdb/latest/pouchdb.min.js"></script>
<script src="blob-util.min.js"></script>
<script src="index.js"></script>
</body>
</html>
Raw
index.js
// Destroy the database before doing anything, because I want
// you to see the same thing if you reload.
// Ignore the man behind the curtain!
new PouchDB('sample').destroy().then(function () {
return new PouchDB('sample');
}).then(function (db) {
//
// IMPORTANT CODE STARTS HERE
//
var display = document.getElementById('display');
var catImage = document.getElementById('cat');
// we're using blobUtil because it actually works cross-browser
// blob-util is here: https://github.com/nolanlawson/blob-util
blobUtil.imgSrcToBlob(catImage.src).then(function (blob) {
document.getElementById('display').innerHTML = 'Read the content of the img as a blob of size ' + blob.size;
return db.putAttachment('meowth', 'meowth.png', blob, 'image/png');
}).then(function () {
return db.get('meowth', {attachments: true});
}).then(function (doc) {
display.innerHTML += '\nGot our doc with an attachment! It looks like this: ' + JSON.stringify(doc);
display.innerHTML += '\nAnd the base64-encoded content of the image is this: ' + JSON.stringify(doc._attachments['meowth.png'].data);
return db.getAttachment('meowth', 'meowth.png');
}).then(function (blob) {
var url = URL.createObjectURL(blob);
var img = document.createElement('img');
img.src = url;
document.body.appendChild(img);
display.innerHTML += "\nThe second image is our stored blob, after reading it out of the database.";
});
});
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