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Merge pull request #3526 from yurydelendik/cffchecksum

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Fixing CFF checksum for test font
This commit is contained in:
Brendan Dahl 2013-07-31 12:45:19 -07:00
commit 6bfb5d228a
1 changed files with 40 additions and 6 deletions
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src/fonts.js
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@ -664,6 +664,28 @@ var FontLoader = {
// font after the desired fonts and then test for the loading of that
// test font.
function int32(data, offset) {
return (data.charCodeAt(offset) << 24) |
(data.charCodeAt(offset + 1) << 16) |
(data.charCodeAt(offset + 2) << 8) |
(data.charCodeAt(offset + 3) & 0xff);
}
function string32(value) {
return String.fromCharCode((value >> 24) & 0xff) +
String.fromCharCode((value >> 16) & 0xff) +
String.fromCharCode((value >> 8) & 0xff) +
String.fromCharCode(value & 0xff);
}
function spliceString(s, offset, remove, insert) {
var chunk1 = data.substr(0, offset);
var chunk2 = data.substr(offset + remove);
return chunk1 + insert + chunk2;
}
var i, ii;
var canvas = document.createElement('canvas');
canvas.width = 1;
canvas.height = 1;
@ -695,10 +717,21 @@ var FontLoader = {
// TODO: This could maybe be made faster by avoiding the btoa of the full
// font by splitting it in chunks before hand and padding the font id.
var data = this.loadTestFont;
var COMMENT_OFFSET = 973;
var chunk1 = data.substr(0, COMMENT_OFFSET);
var chunk2 = data.substr(COMMENT_OFFSET + loadTestFontId.length);
data = chunk1 + loadTestFontId + chunk2;
var COMMENT_OFFSET = 976; // has to be on 4 byte boundary (for checksum)
data = spliceString(data, COMMENT_OFFSET, loadTestFontId.length,
loadTestFontId);
// CFF checksum is important for IE, adjusting it
var CFF_CHECKSUM_OFFSET = 16;
var XXXX_VALUE = 0x58585858; // the "comment" filled with 'X'
var checksum = int32(data, CFF_CHECKSUM_OFFSET);
for (i = 0, ii = loadTestFontId.length - 3; i < ii; i += 4) {
checksum = (checksum - XXXX_VALUE + int32(loadTestFontId, i)) | 0;
}
if (i < loadTestFontId.length) { // align to 4 bytes boundary
checksum = (checksum - XXXX_VALUE +
int32(loadTestFontId + 'XXX', i)) | 0;
}
data = spliceString(data, CFF_CHECKSUM_OFFSET, 4, string32(checksum));
var url = 'url(data:font/opentype;base64,' + btoa(data) + ');';
var rule = '@font-face { font-family:"' + loadTestFontId + '";src:' +
@ -706,8 +739,9 @@ var FontLoader = {
FontLoader.insertRule(rule);
var names = [];
for (var i = 0, ii = fonts.length; i < ii; i++)
for (i = 0, ii = fonts.length; i < ii; i++) {
names.push(fonts[i].loadedName);
}
names.push(loadTestFontId);
var div = document.createElement('div');
@ -715,7 +749,7 @@ var FontLoader = {
'visibility: hidden;' +
'width: 10px; height: 10px;' +
'position: absolute; top: 0px; left: 0px;');
for (var i = 0, ii = names.length; i < ii; ++i) {
for (i = 0, ii = names.length; i < ii; ++i) {
var span = document.createElement('span');
span.textContent = 'Hi';
span.style.fontFamily = names[i];