@syncfusion/ej2-pdf
Version:
Feature-rich JavaScript PDF library with built-in support for loading and manipulating PDF document.
215 lines (214 loc) • 8.44 kB
JavaScript
var __extends = (this && this.__extends) || (function () {
var extendStatics = function (d, b) {
extendStatics = Object.setPrototypeOf ||
({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
return extendStatics(d, b);
};
return function (d, b) {
extendStatics(d, b);
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
})();
import { _PdfDecodeStream } from './decode-stream';
import { _PdfDictionary } from './pdf-primitives';
import { FormatError } from './utils';
var PdfPredictorStream = /** @class */ (function (_super) {
__extends(PdfPredictorStream, _super);
function PdfPredictorStream(stream, maybeLength, params) {
var _this = _super.call(this, maybeLength) || this;
if (!(params instanceof _PdfDictionary)) {
return stream;
}
var predictor = (_this.predictor = params.get('Predictor') || 1);
if (predictor <= 1) {
return stream;
}
if (predictor !== 2 && (predictor < 10 || predictor > 15)) {
throw new FormatError("Unsupported predictor: " + predictor);
}
if (predictor === 2) {
_this.readBlock = _this.readBlockTiff;
}
else {
_this.readBlock = _this.readBlockPng;
}
_this.stream = stream;
_this.dictionary = stream.dictionary;
var colors = (_this.colors = params.get('Colors') || 1);
var bits = (_this.bits = params.get('BPC', 'BitsPerComponent') || 8);
var columns = (_this.columns = params.get('Columns') || 1);
_this.pixBytes = (colors * bits + 7) >> 3;
_this.rowBytes = (columns * colors * bits + 7) >> 3;
return _this;
}
PdfPredictorStream.prototype.readBlockTiff = function () {
var rowBytes = this.rowBytes;
var bufferLength = this.bufferLength;
var buffer = this.ensureBuffer(bufferLength + rowBytes);
var bits = this.bits;
var colors = this.colors;
var rawBytes = this.stream.getBytes(rowBytes);
this.eof = !rawBytes.length;
if (this.eof) {
return;
}
var inbuf = 0;
var outbuf = 0;
var inbits = 0;
var outbits = 0;
var position = bufferLength;
var i;
if (bits === 1 && colors === 1) {
for (i = 0; i < rowBytes; ++i) {
var c = rawBytes[i] ^ inbuf; // eslint-disable-line
c ^= c >> 1;
c ^= c >> 2;
c ^= c >> 4;
inbuf = (c & 1) << 7;
buffer[position++] = c;
}
}
else if (bits === 8) {
for (i = 0; i < colors; ++i) {
buffer[position++] = rawBytes[i]; // eslint-disable-line
}
for (; i < rowBytes; ++i) {
buffer[position] = buffer[position - colors] + rawBytes[i]; // eslint-disable-line
position++;
}
}
else if (bits === 16) {
var bytesPerPixel = colors * 2;
for (i = 0; i < bytesPerPixel; ++i) {
buffer[position++] = rawBytes[i]; // eslint-disable-line
}
for (; i < rowBytes; i += 2) {
var sum = ((rawBytes[i] & 0xff) << 8) + // eslint-disable-line
(rawBytes[i + 1] & 0xff) +
((buffer[position - bytesPerPixel] & 0xff) << 8) +
(buffer[position - bytesPerPixel + 1] & 0xff);
buffer[position++] = (sum >> 8) & 0xff;
buffer[position++] = sum & 0xff;
}
}
else {
var compArray = new Uint8Array(colors + 1);
var bitMask = (1 << bits) - 1;
var j = 0;
var k = bufferLength;
var columns = this.columns;
for (i = 0; i < columns; ++i) {
for (var kk = 0; kk < colors; ++kk) {
if (inbits < bits) {
inbuf = (inbuf << 8) | (rawBytes[j++] & 0xff);
inbits += 8;
}
compArray[kk] = (compArray[kk] + (inbuf >> (inbits - bits))) & bitMask; // eslint-disable-line
inbits -= bits;
outbuf = (outbuf << bits) | compArray[kk]; // eslint-disable-line
outbits += bits;
if (outbits >= 8) {
buffer[k++] = (outbuf >> (outbits - 8)) & 0xff;
outbits -= 8;
}
}
}
if (outbits > 0) {
buffer[k++] = (outbuf << (8 - outbits)) + (inbuf & ((1 << (8 - outbits)) - 1));
}
}
this.bufferLength += rowBytes;
};
PdfPredictorStream.prototype.readBlockPng = function () {
var rowBytes = this.rowBytes;
var pixBytes = this.pixBytes;
var predictor = this.stream.getByte();
var rawBytes = this.stream.getBytes(rowBytes);
this.eof = !rawBytes.length;
if (this.eof) {
return;
}
var bufferLength = this.bufferLength;
var buffer = this.ensureBuffer(bufferLength + rowBytes);
var prevRow = buffer.subarray(bufferLength - rowBytes, bufferLength);
if (prevRow.length === 0) {
prevRow = new Uint8Array(rowBytes);
}
var i;
var j = bufferLength;
var up;
var c;
switch (predictor) {
case 0:
for (i = 0; i < rowBytes; ++i) {
buffer[j++] = rawBytes[i]; // eslint-disable-line
}
break;
case 1:
for (i = 0; i < pixBytes; ++i) {
buffer[j++] = rawBytes[i]; // eslint-disable-line
}
for (; i < rowBytes; ++i) {
buffer[j] = (buffer[j - pixBytes] + rawBytes[i]) & 0xff; // eslint-disable-line
j++;
}
break;
case 2:
for (i = 0; i < rowBytes; ++i) {
buffer[j++] = (prevRow[i] + rawBytes[i]) & 0xff; // eslint-disable-line
}
break;
case 3:
for (i = 0; i < pixBytes; ++i) {
buffer[j++] = (prevRow[i] >> 1) + rawBytes[i]; // eslint-disable-line
}
for (; i < rowBytes; ++i) {
buffer[j] = (((prevRow[i] + buffer[j - pixBytes]) >> 1) + rawBytes[i]) & 0xff; // eslint-disable-line
j++;
}
break;
case 4:
for (i = 0; i < pixBytes; ++i) {
up = prevRow[i]; // eslint-disable-line
c = rawBytes[i]; // eslint-disable-line
buffer[j++] = up + c;
}
for (; i < rowBytes; ++i) {
up = prevRow[i]; // eslint-disable-line
var upLeft = prevRow[i - pixBytes];
var left = buffer[j - pixBytes];
var p = left + up - upLeft;
var pa = p - left;
if (pa < 0) {
pa = -pa;
}
var pb = p - up;
if (pb < 0) {
pb = -pb;
}
var pc = p - upLeft;
if (pc < 0) {
pc = -pc;
}
c = rawBytes[i]; // eslint-disable-line
if (pa <= pb && pa <= pc) {
buffer[j++] = left + c;
}
else if (pb <= pc) {
buffer[j++] = up + c;
}
else {
buffer[j++] = upLeft + c;
}
}
break;
default:
throw new FormatError("Unsupported predictor: " + predictor);
}
this.bufferLength += rowBytes;
};
return PdfPredictorStream;
}(_PdfDecodeStream));
export { PdfPredictorStream };