126 lines
3.5 KiB
JavaScript
126 lines
3.5 KiB
JavaScript
/* canvas-toBlob.js
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* A canvas.toBlob() implementation.
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* 2016-05-26
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*
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* By Eli Grey, http://eligrey.com and Devin Samarin, https://github.com/eboyjr
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* License: MIT
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* See https://github.com/eligrey/canvas-toBlob.js/blob/master/LICENSE.md
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*/
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/*global self */
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/*jslint bitwise: true, regexp: true, confusion: true, es5: true, vars: true, white: true,
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plusplus: true */
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/*! @source http://purl.eligrey.com/github/canvas-toBlob.js/blob/master/canvas-toBlob.js */
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(function(view) {
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"use strict";
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var
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Uint8Array = view.Uint8Array
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, HTMLCanvasElement = view.HTMLCanvasElement
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, canvas_proto = HTMLCanvasElement && HTMLCanvasElement.prototype
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, is_base64_regex = /\s*;\s*base64\s*(?:;|$)/i
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, to_data_url = "toDataURL"
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, base64_ranks
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, decode_base64 = function(base64) {
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var
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len = base64.length
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, buffer = new Uint8Array(len / 4 * 3 | 0)
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, i = 0
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, outptr = 0
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, last = [0, 0]
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, state = 0
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, save = 0
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, rank
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, code
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, undef
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;
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while (len--) {
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code = base64.charCodeAt(i++);
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rank = base64_ranks[code-43];
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if (rank !== 255 && rank !== undef) {
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last[1] = last[0];
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last[0] = code;
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save = (save << 6) | rank;
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state++;
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if (state === 4) {
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buffer[outptr++] = save >>> 16;
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if (last[1] !== 61 /* padding character */) {
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buffer[outptr++] = save >>> 8;
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}
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if (last[0] !== 61 /* padding character */) {
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buffer[outptr++] = save;
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}
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state = 0;
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}
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}
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}
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// 2/3 chance there's going to be some null bytes at the end, but that
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// doesn't really matter with most image formats.
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// If it somehow matters for you, truncate the buffer up outptr.
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return buffer;
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}
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;
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if (Uint8Array) {
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base64_ranks = new Uint8Array([
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62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1
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, -1, -1, 0, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
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, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25
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, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35
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, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
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]);
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}
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if (HTMLCanvasElement && (!canvas_proto.toBlob || !canvas_proto.toBlobHD)) {
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if (!canvas_proto.toBlob)
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canvas_proto.toBlob = function(callback, type /*, ...args*/) {
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if (!type) {
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type = "image/png";
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} if (this.mozGetAsFile) {
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callback(this.mozGetAsFile("canvas", type));
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return;
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} if (this.msToBlob && /^\s*image\/png\s*(?:$|;)/i.test(type)) {
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callback(this.msToBlob());
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return;
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}
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var
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args = Array.prototype.slice.call(arguments, 1)
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, dataURI = this[to_data_url].apply(this, args)
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, header_end = dataURI.indexOf(",")
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, data = dataURI.substring(header_end + 1)
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, is_base64 = is_base64_regex.test(dataURI.substring(0, header_end))
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, blob
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;
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if (Blob.fake) {
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// no reason to decode a data: URI that's just going to become a data URI again
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blob = new Blob
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if (is_base64) {
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blob.encoding = "base64";
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} else {
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blob.encoding = "URI";
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}
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blob.data = data;
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blob.size = data.length;
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} else if (Uint8Array) {
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if (is_base64) {
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blob = new Blob([decode_base64(data)], {type: type});
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} else {
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blob = new Blob([decodeURIComponent(data)], {type: type});
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}
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}
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callback(blob);
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};
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if (!canvas_proto.toBlobHD && canvas_proto.toDataURLHD) {
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canvas_proto.toBlobHD = function() {
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to_data_url = "toDataURLHD";
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var blob = this.toBlob();
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to_data_url = "toDataURL";
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return blob;
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}
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} else {
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canvas_proto.toBlobHD = canvas_proto.toBlob;
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}
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}
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}(typeof self !== "undefined" && self || typeof window !== "undefined" && window || this.content || this));
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