public BufferedImage read(int imageIndex, ImageReadParam param) throws IOException {
BufferedImage dst = null;
try {
// Calculate and return a Rectangle that identifies the region of
// the
// source image that should be read:
//
// 1. If param is null, the upper-left corner of the region is (0,
// 0),
// and the width and height are specified by the width and height
// arguments. In other words, the entire image is read.
//
// 2. If param is not null
//
// 2.1 If param.getSourceRegion() returns a non-null Rectangle, the
// region is calculated as the intersection of param's Rectangle
// and the earlier (0, 0, width, height Rectangle).
//
// 2.2 param.getSubsamplingXOffset() is added to the region's x
// coordinate and subtracted from its width.
//
// 2.3 param.getSubsamplingYOffset() is added to the region's y
// coordinate and subtracted from its height.
int width = getWidth(imageIndex);
int height = getHeight(imageIndex);
Rectangle sourceRegion = getSourceRegion(param, width, height);
// Source subsampling is used to return a scaled-down source image.
// Default 1 values for X and Y subsampling indicate that a
// non-scaled
// source image will be returned.
int sourceXSubsampling = 1;
int sourceYSubsampling = 1;
// The destination offset determines the starting location in the
// destination where decoded pixels are placed. Default (0, 0)
// values indicate the upper-left corner.
Point destinationOffset = new Point(0, 0);
// If param is not null, override the source subsampling, and
// destination offset defaults.
if (param != null) {
sourceXSubsampling = param.getSourceXSubsampling();
sourceYSubsampling = param.getSourceYSubsampling();
destinationOffset = param.getDestinationOffset();
}
// Obtain a BufferedImage into which decoded pixels will be placed.
// This destination will be returned to the application.
//
// 1. If param is not null
//
// 1.1 If param.getDestination() returns a BufferedImage
//
// 1.1.1 Return this BufferedImage
//
// Else
//
// 1.1.2 Invoke param.getDestinationType ().
//
// 1.1.3 If the returned ImageTypeSpecifier equals
// getImageTypes (0) (see below), return its BufferedImage.
//
// 2. If param is null or a BufferedImage has not been obtained
//
// 2.1 Return getImageTypes (0)'s BufferedImage.
dst = getDestination(param, getImageTypes(0), width, height);
// Create a WritableRaster for the destination.
WritableRaster wrDst = dst.getRaster();
JBIG2Bitmap bitmap =
decoder
.getPageAsJBIG2Bitmap(imageIndex)
.getSlice(sourceRegion.x, sourceRegion.y, sourceRegion.width, sourceRegion.height);
BufferedImage image = bitmap.getBufferedImage();
int newWidth = (int) (image.getWidth() * (1 / (double) sourceXSubsampling));
int newHeight = (int) (image.getHeight() * (1 / (double) sourceYSubsampling));
BufferedImage scaledImage = scaleImage(image.getRaster(), newWidth, newHeight, 1, 1);
Raster raster = null;
if (scaledImage != null) {
raster = scaledImage.getRaster();
} else raster = image.getRaster();
wrDst.setRect(destinationOffset.x, destinationOffset.y, raster);
} catch (RuntimeException e) {
e.printStackTrace();
}
return dst;
}
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);
}
}