107 lines
2.8 KiB
JavaScript
107 lines
2.8 KiB
JavaScript
define([
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'/bower_components/tweetnacl/nacl-fast.min.js',
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], function () {
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var Nacl = window.nacl;
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var Thumb = {
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dimension: 100,
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};
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var supportedTypes = [
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'image/png',
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'image/jpeg',
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'image/jpg',
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'image/gif', // TODO confirm this is true
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];
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Thumb.isSupportedType = function (type) {
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return supportedTypes.indexOf(type) !== -1;
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};
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// create thumbnail image from metadata
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// return an img tag, or undefined if anything goes wrong
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Thumb.fromMetadata = function (metadata) {
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if (!metadata || typeof(metadata) !== 'object' || !metadata.thumbnail) { return; }
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try {
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var u8 = Nacl.util.decodeBase64(metadata.thumbnail);
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var blob = new Blob([u8], {
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type: 'image/png'
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});
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var url = URL.createObjectURL(blob);
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var img = new Image();
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img.src = url;
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img.width = Thumb.dimension;
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img.height = Thumb.dimension;
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return img;
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} catch (e) {
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console.error(e);
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return;
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}
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};
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var getResizedDimensions = function (img) {
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var h = img.height;
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var w = img.width;
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var dim = Thumb.dimension;
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// if the image is too small, don't bother making a thumbnail
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if (h <= dim || w <= dim) { return null; }
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// the image is taller than it is wide, so scale to that.
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var r = dim / (h > w? h: w); // ratio
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var d;
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if (h > w) {
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d = Math.floor(((h * r) - dim) / 2);
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return {
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x1: 0,
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x2: dim,
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y1: d,
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y2: dim + d,
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};
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} else {
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d = Math.floor(((w * r) - dim) / 2);
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return {
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x1: d,
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x2: dim + d,
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y1: 0,
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y2: dim,
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};
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}
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};
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// assumes that your canvas is square
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// nodeback returning blob
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Thumb.fromCanvas = Thumb.fromImage = function (canvas, cb) {
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var c2 = document.createElement('canvas');
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var D = getResizedDimensions(canvas);
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if (!D) { return void cb('TOO_SMALL'); }
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c2.width = Thumb.dimension;
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c2.height = Thumb.dimension;
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var ctx = c2.getContext('2d');
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ctx.drawImage(canvas, D.x1, D.y1, D.x2, D.y2);
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c2.toBlob(function (blob) {
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cb(void 0, blob);
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});
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};
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Thumb.fromImageBlob = function (blob, cb) {
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var url = URL.createObjectURL(blob);
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var img = new Image();
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img.onload = function () {
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Thumb.fromImage(img, cb);
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};
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img.onerror = function () {
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cb('ERROR');
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};
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img.src = url;
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};
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Thumb.fromVideo = function (video, cb) {
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cb = cb; // WIP
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};
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return Thumb;
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});
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