jpegimagewriter.java

java jdk 1.4的源码

     * must not be for a progressive image, or an exception
     * will be thrown when two Huffman tables with the same
     * table id are encountered.
     */
    private JPEGHuffmanTable[] collectHTablesFromMetadata
        (JPEGMetadata metadata, boolean wantDC) throws IIOException {
        ArrayList tables = new ArrayList();
        Iterator iter = metadata.markerSequence.iterator();
        while (iter.hasNext()) {
            MarkerSegment seg = (MarkerSegment) iter.next();
            if (seg instanceof DHTMarkerSegment) {
                DHTMarkerSegment dht = 
                    (DHTMarkerSegment) seg;
                for (int i = 0; i < dht.tables.size(); i++) {
                    DHTMarkerSegment.Htable htable = 
                        (DHTMarkerSegment.Htable) dht.tables.get(i);
                    if (htable.tableClass == (wantDC ? 0 : 1)) {
                        tables.add(htable);
                    }
                }
            }
        }
        JPEGHuffmanTable [] retval = null;
        if (tables.size() != 0) {
            DHTMarkerSegment.Htable [] htables = 
                new DHTMarkerSegment.Htable[tables.size()];
            tables.toArray(htables);
            retval = new JPEGHuffmanTable[tables.size()];
            for (int i = 0; i < retval.length; i++) {
                retval[i] = null;
                for (int j = 0; j < tables.size(); j++) {
                    if (htables[j].tableID == i) {
                        if (retval[i] != null) {
                            throw new IIOException("Metadata has duplicate Htables!");
                        }
                        retval[i] = new JPEGHuffmanTable(htables[j].numCodes, 
                                                         htables[j].values);
                    }
                }
            }
        }
        
        return retval;
    }

    /////////// End of metadata handling

    ////////////// ColorSpace conversion
    
    private int getSrcCSType(RenderedImage rimage) {
        int retval = JPEG.JCS_UNKNOWN;
        ColorModel cm = rimage.getColorModel();
        if (cm != null) {
            boolean alpha = cm.hasAlpha();
            ColorSpace cs = cm.getColorSpace();
            switch (cs.getType()) {
            case ColorSpace.TYPE_GRAY:
                retval = JPEG.JCS_GRAYSCALE;
                break;
            case ColorSpace.TYPE_RGB:
                if (alpha) {
                    retval = JPEG.JCS_RGBA;
                } else {
                    retval = JPEG.JCS_RGB;
                }
                break;
            case ColorSpace.TYPE_YCbCr:
                if (alpha) {
                    retval = JPEG.JCS_YCbCrA;
                } else {
                    retval = JPEG.JCS_YCbCr;
                }
                break;
            case ColorSpace.TYPE_3CLR:
                if (cs == JPEG.YCC) {
                    if (alpha) {
                        retval = JPEG.JCS_YCCA;
                    } else {
                        retval = JPEG.JCS_YCC;
                    }
                }
            case ColorSpace.TYPE_CMYK:
                retval = JPEG.JCS_CMYK;
                break;
            }
        }
        return retval;
    }

    private int getDestCSType(ImageTypeSpecifier destType) {
        ColorModel cm = destType.getColorModel();
        boolean alpha = cm.hasAlpha();
        ColorSpace cs = cm.getColorSpace();
        int retval = JPEG.JCS_UNKNOWN;
        switch (cs.getType()) {
        case ColorSpace.TYPE_GRAY:
                retval = JPEG.JCS_GRAYSCALE;
                break;
            case ColorSpace.TYPE_RGB:
                if (alpha) {
                    retval = JPEG.JCS_RGBA;
                } else {
                    retval = JPEG.JCS_RGB;
                }
                break;
            case ColorSpace.TYPE_YCbCr:
                if (alpha) {
                    retval = JPEG.JCS_YCbCrA;
                } else {
                    retval = JPEG.JCS_YCbCr;
                }
                break;
            case ColorSpace.TYPE_3CLR:
                if (cs == JPEG.YCC) {
                    if (alpha) {
                        retval = JPEG.JCS_YCCA;
                    } else {
                        retval = JPEG.JCS_YCC;
                    }
                }
            case ColorSpace.TYPE_CMYK:
                retval = JPEG.JCS_CMYK;
                break;
            }
        return retval;
        }

    private int getDefaultDestCSType(RenderedImage rimage) {
        int retval = JPEG.JCS_UNKNOWN;
        ColorModel cm = rimage.getColorModel();
        if (cm != null) {
            boolean alpha = cm.hasAlpha();
            ColorSpace cs = cm.getColorSpace();
            switch (cs.getType()) {
            case ColorSpace.TYPE_GRAY:
                retval = JPEG.JCS_GRAYSCALE;
                break;
            case ColorSpace.TYPE_RGB:
                if (alpha) {
                    retval = JPEG.JCS_YCbCrA;
                } else {
                    retval = JPEG.JCS_YCbCr;
                }
                break;
            case ColorSpace.TYPE_YCbCr:
                if (alpha) {
                    retval = JPEG.JCS_YCbCrA;
                } else {
                    retval = JPEG.JCS_YCbCr;
                }
                break;
            case ColorSpace.TYPE_3CLR:
                if (cs == JPEG.YCC) {
                    if (alpha) {
                        retval = JPEG.JCS_YCCA;
                    } else {
                        retval = JPEG.JCS_YCC;
                    }
                }
            case ColorSpace.TYPE_CMYK:
                retval = JPEG.JCS_YCCK;
                break;
            }
        }
        return retval;
    }

    private boolean isSubsampled(SOFMarkerSegment.ComponentSpec [] specs) {
        int hsamp0 = specs[0].HsamplingFactor;
        int vsamp0 = specs[0].VsamplingFactor;
        for (int i = 1; i < specs.length; i++) {
            if ((specs[i].HsamplingFactor != hsamp0) ||
                (specs[i].HsamplingFactor != hsamp0))
                return true;
        }
        return false;
    }

    ////////////// End of ColorSpace conversion

    ////////////// Native methods and callbacks

    /** Sets up static native structures. */
    private static native void initWriterIDs(Class iosClass, 
                                             Class qTableClass,
                                             Class huffClass);

    /** Sets up per-writer native structure and returns a pointer to it. */
    private native long initJPEGImageWriter();

    /** Sets up native structures for output stream */
    private native void setDest(long structPointer,
                                ImageOutputStream ios);

    /**
     * Returns <code>true</code> if the write was aborted.
     */
    private native boolean writeImage(long structPointer,
                                      byte [] data,
                                      int inCsType, int outCsType,
                                      int numBands,
                                      int [] bandSizes,
                                      int srcWidth,
                                      int destWidth, int destHeight,
                                      int stepX, int stepY,
                                      JPEGQTable [] qtables,
                                      boolean writeDQT,
                                      JPEGHuffmanTable[] DCHuffmanTables,
                                      JPEGHuffmanTable[] ACHuffmanTables,
                                      boolean writeDHT,
                                      boolean optimizeHuffman,
                                      boolean progressive,
                                      int numScans,
                                      int [] scans,
                                      int [] componentIds,
                                      int [] HsamplingFactors,
                                      int [] VsamplingFactors,
                                      int [] QtableSelectors,
                                      boolean haveMetadata,
                                      int restartInterval);


    /**
     * Writes the metadata out when called by the native code, 
     * which will have already written the header to the stream
     * and established the library state.  This is simpler than
     * breaking the write call in two.
     */
    private void writeMetadata() throws IOException {
        if (metadata == null) {
            if (writeDefaultJFIF) {
                JFIFMarkerSegment.writeDefaultJFIF(ios, 
                                                   thumbnails, 
                                                   iccProfile,
                                                   this);
            }
            if (writeAdobe) {
                AdobeMarkerSegment.writeAdobeSegment(ios, newAdobeTransform);
            }
        } else {
            metadata.writeToStream(ios, 
                                   ignoreJFIF, 
                                   forceJFIF,
                                   thumbnails,
                                   iccProfile,
                                   ignoreAdobe, 
                                   newAdobeTransform,
                                   this);
        }
    }

    /**
     * Write out a tables-only image to the stream.
     */
    private native void writeTables(long structPointer,
                                    JPEGQTable [] qtables,
                                    JPEGHuffmanTable[] DCHuffmanTables,
                                    JPEGHuffmanTable[] ACHuffmanTables);

    /**
     * Put the scanline y of the source ROI view Raster into the
     * 1-line Raster for writing.  This handles ROI and band
     * rearrangements, and expands indexed images.  Subsampling is
     * done in the native code.
     * This is called by the native code.
     */
    private void grabPixels(int y) {

        Raster sourceLine = null;
        if (indexed) {
            sourceLine = srcRas.createChild(sourceXOffset, 
                                            sourceYOffset+y,
                                            sourceWidth, 1,
                                            0, 0,
                                            new int [] {0});
            // If the image has BITMASK transparency, we need to make sure
            // it gets converted to 32-bit ARGB, because the JPEG encoder
            // relies upon the full 8-bit alpha channel.
            boolean forceARGB =
                (indexCM.getTransparency() != Transparency.OPAQUE);
            BufferedImage temp = indexCM.convertToIntDiscrete(sourceLine,
                                                              forceARGB);
            sourceLine = temp.getRaster();
        } else {
            sourceLine = srcRas.createChild(sourceXOffset, 
                                            sourceYOffset+y,
                                            sourceWidth, 1,
                                            0, 0,
                                            srcBands);
        }
        if (convertTosRGB) {
            if (debug) {
                System.out.println("Converting to sRGB");
            }
            // The first time through, converted is null, so
            // a new raster is allocated.  It is then reused
            // on subsequent lines.
            converted = convertOp.filter(sourceLine, converted);
            sourceLine = converted;
        }
        raster.setRect(sourceLine);
        if ((y > 7) && (y%8 == 0)) {  // Every 8 scanlines
            processImageProgress((float) y / (float) sourceHeight * 100.0F);
        }
    }

    /** Aborts the current write in the native code */
    private native void abortWrite(long structPointer);

    /** Resets native structures */
    private native void resetWriter(long structPointer);

    /** Releases native structures */
    private native void disposeWriter(long structPointer);

}