public void readSegment() throws IOException, JBIG2Exception {
if (JBIG2StreamDecoder.debug) System.out.println("==== Reading Immediate Generic Region ====");
super.readSegment();
/** read text region Segment flags */
readGenericRegionFlags();
boolean useMMR = genericRegionFlags.getFlagValue(GenericRegionFlags.MMR) != 0;
int template = genericRegionFlags.getFlagValue(GenericRegionFlags.GB_TEMPLATE);
short[] genericBAdaptiveTemplateX = new short[4];
short[] genericBAdaptiveTemplateY = new short[4];
if (!useMMR) {
if (template == 0) {
genericBAdaptiveTemplateX[0] = readATValue();
genericBAdaptiveTemplateY[0] = readATValue();
genericBAdaptiveTemplateX[1] = readATValue();
genericBAdaptiveTemplateY[1] = readATValue();
genericBAdaptiveTemplateX[2] = readATValue();
genericBAdaptiveTemplateY[2] = readATValue();
genericBAdaptiveTemplateX[3] = readATValue();
genericBAdaptiveTemplateY[3] = readATValue();
} else {
genericBAdaptiveTemplateX[0] = readATValue();
genericBAdaptiveTemplateY[0] = readATValue();
}
arithmeticDecoder.resetGenericStats(template, null);
arithmeticDecoder.start();
}
boolean typicalPredictionGenericDecodingOn =
genericRegionFlags.getFlagValue(GenericRegionFlags.TPGDON) != 0;
int length = segmentHeader.getSegmentDataLength();
if (length == -1) {
/**
* length of data is unknown, so it needs to be determined through examination of the data.
* See 7.2.7 - Segment data length of the JBIG2 specification.
*/
unknownLength = true;
short match1;
short match2;
if (useMMR) {
// look for 0x00 0x00 (0, 0)
match1 = 0;
match2 = 0;
} else {
// look for 0xFF 0xAC (255, 172)
match1 = 255;
match2 = 172;
}
int bytesRead = 0;
while (true) {
short bite1 = decoder.readByte();
bytesRead++;
if (bite1 == match1) {
short bite2 = decoder.readByte();
bytesRead++;
if (bite2 == match2) {
length = bytesRead - 2;
break;
}
}
}
decoder.movePointer(-bytesRead);
}
JBIG2Bitmap bitmap =
new JBIG2Bitmap(
regionBitmapWidth, regionBitmapHeight, arithmeticDecoder, huffmanDecoder, mmrDecoder);
bitmap.clear(0);
bitmap.readBitmap(
useMMR,
template,
typicalPredictionGenericDecodingOn,
false,
null,
genericBAdaptiveTemplateX,
genericBAdaptiveTemplateY,
useMMR ? 0 : length - 18);
if (inlineImage) {
PageInformationSegment pageSegment =
decoder.findPageSegement(segmentHeader.getPageAssociation());
JBIG2Bitmap pageBitmap = pageSegment.getPageBitmap();
int extCombOp = regionFlags.getFlagValue(RegionFlags.EXTERNAL_COMBINATION_OPERATOR);
if (pageSegment.getPageBitmapHeight() == -1
&& regionBitmapYLocation + regionBitmapHeight > pageBitmap.getHeight()) {
pageBitmap.expand(
regionBitmapYLocation + regionBitmapHeight,
pageSegment
.getPageInformationFlags()
.getFlagValue(PageInformationFlags.DEFAULT_PIXEL_VALUE));
}
pageBitmap.combine(bitmap, regionBitmapXLocation, regionBitmapYLocation, extCombOp);
} else {
bitmap.setBitmapNumber(getSegmentHeader().getSegmentNumber());
decoder.appendBitmap(bitmap);
}
if (unknownLength) {
decoder.movePointer(4);
}
}
