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[loadFonts] optionally avoid duplicate XHRs for same files; closes #28 #30

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140 changes: 104 additions & 36 deletions lib/loadFonts.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,40 +4,74 @@ define([
opentype
) {
"use strict";
/*globals FileReader, XMLHttpRequest, console*/
/*globals setTimeout, FileReader, XMLHttpRequest, console*/

/**
* Callback for when a fontfile has been loaded
*
* @param i: index of the font loaded
* @param fontFileName
* @param err: null, error-object or string with error message
* @param fontArraybuffer
*/
function onLoadFont(i, fontFileName, err, fontArraybuffer) {
/* jshint validthis: true */
var font;
function _publishLoaded(task, data) {
var state = task.state
, index = task.index
, fontFileName = task.name
, err = data.error
, font = data.font
, fontArraybuffer = data.arraybuffer
;

if(err) {
console.warn('Can\'t load font', fontFileName, ' with error:', err);
state.countAll--;
}
else {
state.pubsub.publish('loadFont', index, fontFileName, font, fontArraybuffer);
state.countLoaded += 1;
}

if(state.countLoaded === state.countAll)
state.pubsub.publish('allFontsLoaded', state.countAll);
}

function _getLoadedFontData(err, fontArraybuffer) {
var err_ = err || null
, font = null
;
if(!err) {
try {
font = opentype.parse(fontArraybuffer);
font = opentype.parse(fontArraybuffer);
}
catch (parseError) {
err = parseError;
err_ = parseError;
}
}

if(err) {
console.warn('Can\'t load font', fontFileName, ' with error:', err);
this.countAll--;
}
else {
this.pubsub.publish('loadFont', i, fontFileName, font, fontArraybuffer);
this.countLoaded += 1;
}
return {
error:err_
, font: font
, arraybuffer:fontArraybuffer
};
}

function _onLoadQueued(cache, key, err, fontArraybuffer) {
var data, queue, i, l, task;

if(this.countLoaded === this.countAll)
this.pubsub.publish('allFontsLoaded', this.countAll);
cache.loaded[key] = data = _getLoadedFontData(err, fontArraybuffer);
queue = cache.queues[key];
delete cache.queues[key];

for(i=0,l=queue.length;i<l;i++) {
task = queue[i];
_publishLoaded(task, data);
}
}

/**
* Callback for when a fontfile has been loaded
*
* @param i: index of the font loaded
* @param fontFileName
* @param err: null, error-object or string with error message
* @param fontArraybuffer
*/
function _onLoadFont(task, err, fontArraybuffer) {
var data = _getLoadedFontData(err, fontArraybuffer);
_publishLoaded(task, data);
}

function loadFromUrl(fontInfo, callback) {
Expand Down Expand Up @@ -75,40 +109,74 @@ define([
}
loadFontsFromFileInput.needsPubSub = true;


function loadFontsFromUrl(pubsub, fontFiles) {
function loadFontsFromUrl(pubsub, fontFiles, cache) {
var i, l
, fontInfo = []
;
for(i=0,l=fontFiles.length;i<l;i++) {
if (!fontFiles[i])
throw new Error('The url at index '+i+' appears to be invalid.');
fontInfo.push({
name: fontFiles[i]
name: fontFiles[i]
, url: fontFiles[i]
// this is for the cache and must be the same as url in this case,
// to ensure we request a file only once
, key: fontFiles[i]
});
}
_loadFonts(pubsub, fontInfo, loadFromUrl);
_loadFonts(pubsub, fontInfo, loadFromUrl, cache);
}

function _initCache(cache) {
if(!('loaded' in cache))
cache.loaded = Object.create(null);
if(!('queues' in cache))
cache.queues = Object.create(null);
}

function _loadFonts(pubsub, fontFiles, loadFont) {
var i, l, fontInfo, onload
function _loadFonts(pubsub, fontFiles, loadFont, cache) {
var i, l, fontInfo, key, onload, task, data
, loaderState = {
countLoaded: 0
, countAll: fontFiles.length
, pubsub: pubsub
}
;
if(cache)
_initCache(cache);

filesLoop:
for(i=0,l=fontFiles.length;i<l;i++) {
fontInfo = fontFiles[i];
pubsub.publish('prepareFont', i, fontInfo.name, l);
onload = onLoadFont.bind(loaderState, i, fontInfo.name);
// The timeout thing is handy to slow down the load progress,
// if development is done on that part.
// setTimeout(function(fontInfo, onload) {
loadFont(fontInfo, onload);
// }.bind(null, fontInfo, onload), Math.random() * 5000);
task = {
state: loaderState
, index: i
, name: fontInfo.name
};
onload = null;
if(cache) {
key = fontInfo.key;
if(key in cache.loaded) {
data = cache.loaded[key];
// execute async
setTimeout(_publishLoaded.bind(null, task, data), 0);
continue filesLoop;
}
// put into queue
if(!(key in cache.queues)) {
// initiate queue
cache.queues[key] = [];
onload = _onLoadQueued.bind(null, cache, key);
}
cache.queues[key].push(task);
}
else // no cache
onload = _onLoadFont.bind(null, task);

// if no cache or of queue was just initiated
if(onload)
loadFont(fontInfo, onload);
}
}

Expand Down