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Add IdentityToUnicodeMap class.

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When loading the PDF from issue #4935, this change reduces peak RSS from
~2400 to ~300 MiB, and improves overall speed by ~81%, from 6336 ms to
1222 ms.
This commit is contained in:
Nicholas Nethercote 2014-08-07 18:29:53 -07:00
parent 9576047f0d
commit 6c8cca1284
1 changed files with 34 additions and 6 deletions
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40
src/core/fonts.js
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@ -2191,6 +2191,38 @@ var ToUnicodeMap = (function ToUnicodeMapClosure() {
return ToUnicodeMap;
})();
var IdentityToUnicodeMap = (function IdentityToUnicodeMapClosure() {
function IdentityToUnicodeMap(firstChar, lastChar) {
this.firstChar = firstChar;
this.lastChar = lastChar;
}
IdentityToUnicodeMap.prototype = {
get length() {
error('should not access .length');
},
forEach: function(callback) {
for (var i = this.firstChar, ii = this.lastChar; i <= ii; i++) {
callback(i, i);
}
},
get: function(i) {
if (this.firstChar <= i && i <= this.lastChar) {
return String.fromCharCode(i);
}
return undefined;
},
charCodeOf: function(v) {
error('should not call .charCodeOf');
}
};
return IdentityToUnicodeMap;
})();
/**
* 'Font' is the class the outside world should use, it encapsulate all the font
* decoding logics whatever type it is (assuming the font type is supported).
@ -4453,13 +4485,9 @@ var Font = (function FontClosure() {
}
// The viewer's choice, just use an identity map.
toUnicode = [];
var firstChar = properties.firstChar, lastChar = properties.lastChar;
for (var i = firstChar; i <= lastChar; i++) {
toUnicode[i] = String.fromCharCode(i);
}
map.isIdentity = true;
map.toUnicode = new ToUnicodeMap(toUnicode);
map.toUnicode =
new IdentityToUnicodeMap(properties.firstChar, properties.lastChar);
return map;
},