cryptpad/www/common/common-thumbnail.js

108 lines
2.8 KiB
JavaScript

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