readXRefStream and PNG predictor 12
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notmasteryet
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8ab68cf17a
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176
pdf.js
176
pdf.js
@ -506,6 +506,94 @@ var FlateStream = (function() {
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return constructor;
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})();
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var PredictorStream = (function() {
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function constructor(stream, params) {
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this.stream = stream;
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this.predictor = params.get("Predictor") || 1;
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if (this.predictor <= 1) {
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return stream; // no prediction
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}
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if (params.has("EarlyChange")) {
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error("EarlyChange predictor parameter is not supported");
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}
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this.colors = params.get("Colors") || 1;
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this.bitsPerComponent = params.get("BitsPerComponent") || 8;
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this.columns = params.get("Columns") || 1;
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if (this.colors !== 1 || this.bitsPerComponent !== 8) {
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error("Multi-color and multi-byte predictors are not supported");
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}
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if (this.predictor < 10 || this.predictor > 15) {
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error("Unsupported predictor");
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}
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this.currentRow = new Uint8Array(this.columns);
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this.pos = 0;
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this.bufferLength = 0;
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}
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constructor.prototype = {
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readRow : function() {
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var lastRow = this.currentRow;
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var predictor = this.stream.getByte();
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var currentRow = this.stream.getBytes(this.columns), i;
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switch (predictor) {
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default:
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error("Unsupported predictor");
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break;
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case 0:
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break;
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case 2:
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for (i = 0; i < currentRow.length; ++i) {
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currentRow[i] = (lastRow[i] + currentRow[i]) & 0xFF;
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}
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break;
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}
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this.pos = 0;
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this.bufferLength = currentRow.length;
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this.currentRow = currentRow;
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},
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getByte : function() {
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if (this.pos >= this.bufferLength) {
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this.readRow();
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}
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return this.currentRow[this.pos++];
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},
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getBytes : function(n) {
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var i, bytes;
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bytes = new Uint8Array(n);
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for (i = 0; i < n; ++i) {
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if (this.pos >= this.bufferLength) {
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this.readRow();
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}
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bytes[i] = this.currentRow[this.pos++];
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}
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return bytes;
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},
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getChar : function() {
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return String.formCharCode(this.getByte());
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},
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lookChar : function() {
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if (this.pos >= this.bufferLength) {
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this.readRow();
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}
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return String.formCharCode(this.currentRow[this.pos]);
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},
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skip : function(n) {
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var i;
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if (!n) {
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n = 1;
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}
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while (n > this.bufferLength - this.pos) {
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n -= this.bufferLength - this.pos;
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this.readRow();
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if (this.bufferLength === 0) break;
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}
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this.pos += n;
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}
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};
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return constructor;
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})();
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var DecryptStream = (function() {
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function constructor(str, fileKey, encAlgorithm, keyLength) {
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// TODO
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@ -1079,7 +1167,9 @@ var Parser = (function() {
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this.encAlgorithm,
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this.keyLength);
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}
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return this.filter(stream, dict);
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stream = this.filter(stream, dict);
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stream.parameters = dict;
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return stream;
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},
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filter: function(stream, dict) {
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var filter = dict.get2("Filter", "F");
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@ -1104,8 +1194,9 @@ var Parser = (function() {
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},
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makeFilter: function(stream, name, params) {
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if (name == "FlateDecode" || name == "Fl") {
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if (params)
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error("params not supported yet for FlateDecode");
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if (params) {
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return new PredictorStream(new FlateStream(stream), params);
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}
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return new FlateStream(stream);
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} else {
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error("filter '" + name + "' not supported yet");
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@ -1198,10 +1289,10 @@ var XRef = (function() {
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this.stream = stream;
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this.entries = [];
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this.xrefstms = {};
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this.readXRef(startXRef);
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var trailerDict = this.readXRef(startXRef);
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// get the root dictionary (catalog) object
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if (!IsRef(this.root = this.trailerDict.get("Root")))
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if (!IsRef(this.root = trailerDict.get("Root")))
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error("Invalid root reference");
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// prepare the XRef cache
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@ -1256,18 +1347,18 @@ var XRef = (function() {
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error("Invalid XRef table");
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// get the 'Prev' pointer
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var more = false;
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var prev;
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obj = dict.get("Prev");
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if (IsInt(obj)) {
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this.prev = obj;
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more = true;
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prev = obj;
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} else if (IsRef(obj)) {
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// certain buggy PDF generators generate "/Prev NNN 0 R" instead
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// of "/Prev NNN"
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this.prev = obj.num;
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more = true;
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prev = obj.num;
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}
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if (prev) {
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this.readXRef(prev);
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}
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this.trailerDict = dict;
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// check for 'XRefStm' key
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if (IsInt(obj = dict.get("XRefStm"))) {
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@ -1277,11 +1368,64 @@ var XRef = (function() {
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this.xrefstms[pos] = 1; // avoid infinite recursion
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this.readXRef(pos);
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}
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return more;
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return dict;
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},
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readXRefStream: function(parser) {
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error("Invalid XRef stream");
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readXRefStream: function(stream) {
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var streamParameters = stream.parameters;
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var length = streamParameters.get("Length");
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var byteWidths = streamParameters.get("W");
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var range = streamParameters.get("Index");
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if (!range) {
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range = [0, streamParameters.get("Size")];
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}
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var i, j;
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while (range.length > 0) {
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var first = range[0], n = range[1];
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if (!IsInt(first) || !IsInt(n)) {
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error("Invalid XRef range fields");
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}
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var typeFieldWidth = byteWidths[0], offsetFieldWidth = byteWidths[1], generationFieldWidth = byteWidths[2];
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if (!IsInt(typeFieldWidth) || !IsInt(offsetFieldWidth) || !IsInt(generationFieldWidth)) {
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error("Invalid XRef entry fields length");
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}
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for (i = 0; i < n; ++i) {
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var type = 0, offset = 0, generation = 0;
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for (j = 0; j < typeFieldWidth; ++j) {
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type = (type << 8) | stream.getByte();
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}
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for (j = 0; j < offsetFieldWidth; ++j) {
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offset = (offset << 8) | stream.getByte();
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}
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for (j = 0; j < generationFieldWidth; ++j) {
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generation = (generation << 8) | stream.getByte();
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}
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var entry = { offset: offset, gen: generation };
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if (typeFieldWidth > 0) {
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switch (type) {
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case 0:
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entry.free = true;
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break;
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case 1:
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entry.uncompressed = true;
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break;
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case 2:
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break;
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default:
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error("Invalid XRef entry type");
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break;
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}
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}
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if (!this.entries[first + i]) {
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this.entries[first + i] = entry;
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}
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}
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range.splice(0, 2);
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}
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var prev = streamParameters.get("Prev");
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if (IsInt(prev)) {
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this.readXRef(prev);
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}
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return streamParameters;
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},
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readXRef: function(startXRef) {
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var stream = this.stream;
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@ -1565,7 +1709,7 @@ var PDFDoc = (function() {
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},
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getPage: function(n) {
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var linearization = this.linearization;
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assert(!linearization, "linearized page access not implemented");
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// assert(!linearization, "linearized page access not implemented");
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return this.catalog.getPage(n);
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}
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};
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