jpegimagewriter.java

java1.6众多例子参考

                                                bandOffs,
                                                null);

        // Call the writer, who will call back for every scanline

        processImageStarted(currentImage);
            
        boolean aborted = false;

        if (debug) {
            System.out.println("inCsType: " + inCsType);
            System.out.println("outCsType: " + outCsType);
        }

        aborted = writeImage(structPointer,
                             buffer.getData(), 
                             inCsType, outCsType,
                             numBandsUsed,
                             bandSizes,
                             sourceWidth,
                             destWidth, destHeight,
                             periodX, periodY,
                             qTables,
                             writeDQT,
                             DCHuffmanTables,
                             ACHuffmanTables,
                             writeDHT,
                             optimizeHuffman,
                             (progressiveMode 
                              != ImageWriteParam.MODE_DISABLED),
                             numScans,
                             scans,
                             componentIds,
                             HsamplingFactors,
                             VsamplingFactors,
                             QtableSelectors,
                             haveMetadata,
                             restartInterval);

        if (aborted) {
            processWriteAborted();
        } else {
            processImageComplete();
        }

        ios.flush();
        currentImage++;  // After a successful write
    }

    public void prepareWriteSequence(IIOMetadata streamMetadata) 
        throws IOException {
        if (ios == null) {
            throw new IllegalStateException("Output has not been set!");
        }

        /*
         * from jpeg_metadata.html:
         * If no stream metadata is supplied to
         * <code>ImageWriter.prepareWriteSequence</code>, then no 
         * tables-only image is written.  If stream metadata containing
         * no tables is supplied to
         * <code>ImageWriter.prepareWriteSequence</code>, then a tables-only
         * image containing default visually lossless tables is written.
         */
        if (streamMetadata != null) {
            if (streamMetadata instanceof JPEGMetadata) {
                // write a complete tables-only image at the beginning of 
                // the stream.
                JPEGMetadata jmeta = (JPEGMetadata) streamMetadata;
                if (jmeta.isStream == false) {
                    throw new IllegalArgumentException
                        ("Invalid stream metadata object.");
                }
                // Check that we are
                // at the beginning of the stream, or can go there, and haven't
                // written out the metadata already.
                if (currentImage != 0) {
                    throw new IIOException
                        ("JPEG Stream metadata must precede all images");
                }
                if (sequencePrepared == true) {
                    throw new IIOException("Stream metadata already written!");
                }
                
                // Set the tables
                // If the metadata has no tables, use default tables.
                streamQTables = collectQTablesFromMetadata(jmeta);
                if (debug) {
                    System.out.println("after collecting from stream metadata, "
                                       + "streamQTables.length is " 
                                       + streamQTables.length);
                }
                if (streamQTables == null) {
                    streamQTables = JPEG.getDefaultQTables();
                }
                streamDCHuffmanTables = 
                    collectHTablesFromMetadata(jmeta, true);
                if (streamDCHuffmanTables == null) {
                    streamDCHuffmanTables = JPEG.getDefaultHuffmanTables(true);
                }
                streamACHuffmanTables = 
                    collectHTablesFromMetadata(jmeta, false);
                if (streamACHuffmanTables == null) {
                    streamACHuffmanTables = JPEG.getDefaultHuffmanTables(false);
                }

                // Now write them out
                writeTables(structPointer,
                            streamQTables, 
                            streamDCHuffmanTables, 
                            streamACHuffmanTables);
            } else { 
                throw new IIOException("Stream metadata must be JPEG metadata");
            }
        }
        sequencePrepared = true;
    }

    public void writeToSequence(IIOImage image, ImageWriteParam param)
        throws IOException {
        if (sequencePrepared == false) {
            throw new IllegalStateException("sequencePrepared not called!");
        }
        // In the case of JPEG this does nothing different from write
        write(null, image, param);
    }

    public void endWriteSequence() throws IOException {
        if (sequencePrepared == false) {
            throw new IllegalStateException("sequencePrepared not called!");
        }
        sequencePrepared = false;
    }

    public synchronized void abort() {
        super.abort();
        abortWrite(structPointer);
    }

    private void resetInternalState() {
        // reset C structures
        resetWriter(structPointer);

        // reset local Java structures
        srcRas = null;
        raster = null;
        convertTosRGB = false;
        currentImage = 0;
        numScans = 0;
        metadata = null;
    }

    /**
     * Note that there is no need to override reset() here, as the default
     * implementation will call setOutput(null), which will invoke
     * resetInternalState().
     */

    public void dispose() {
        if (structPointer != 0) {
            disposerRecord.dispose();
            structPointer = 0;
        }
    }

    ////////// End of public API

    ///////// Package-access API

    /**
     * Called by the native code or other classes to signal a warning.  
     * The code is used to lookup a localized message to be used when
     * sending warnings to listeners.
     */
    void warningOccurred(int code) {
        if ((code < 0) || (code > MAX_WARNING)){
            throw new InternalError("Invalid warning index");
        }
        processWarningOccurred
            (currentImage, 
             "com.sun.imageio.plugins.jpeg.JPEGImageWriterResources",
             Integer.toString(code));
    }

    /**
     * The library has it's own error facility that emits warning messages.
     * This routine is called by the native code when it has already 
     * formatted a string for output.  
     * XXX  For truly complete localization of all warning messages,
     * the sun_jpeg_output_message routine in the native code should
     * send only the codes and parameters to a method here in Java,
     * which will then format and send the warnings, using localized
     * strings.  This method will have to deal with all the parameters
     * and formats (%u with possibly large numbers, %02d, %02x, etc.)
     * that actually occur in the JPEG library.  For now, this prevents 
     * library warnings from being printed to stderr.
     */
    void warningWithMessage(String msg) {
        processWarningOccurred(currentImage, msg);
    }

    void thumbnailStarted(int thumbnailIndex) {
        processThumbnailStarted(currentImage, thumbnailIndex);
    }

    // Provide access to protected superclass method
    void thumbnailProgress(float percentageDone) {
        processThumbnailProgress(percentageDone);
    }    

    // Provide access to protected superclass method
    void thumbnailComplete() {
        processThumbnailComplete();
    }

    ///////// End of Package-access API

    ///////// Private methods

    ///////// Metadata handling

    private void checkSOFBands(SOFMarkerSegment sof, int numBandsUsed) 
        throws IIOException {
        // Does the metadata frame header, if any, match numBandsUsed?
        if (sof != null) {
            if (sof.componentSpecs.length != numBandsUsed) {
                throw new IIOException
                    ("Metadata components != number of destination bands");
            }
        }
    }

    private void checkJFIF(JFIFMarkerSegment jfif,
                           ImageTypeSpecifier type,
                           boolean input) {
        if (jfif != null) {
            if (!JPEG.isJFIFcompliant(type, input)) {
                ignoreJFIF = true;  // type overrides metadata
                warningOccurred(input 
                                ? WARNING_IMAGE_METADATA_JFIF_MISMATCH
                                : WARNING_DEST_METADATA_JFIF_MISMATCH);
            }
        }
    }

    private void checkAdobe(AdobeMarkerSegment adobe,
                           ImageTypeSpecifier type,
                           boolean input) {
        if (adobe != null) {
            int rightTransform = JPEG.transformForType(type, input);
            if (adobe.transform != rightTransform) {
                warningOccurred(input 
                                ? WARNING_IMAGE_METADATA_ADOBE_MISMATCH
                                : WARNING_DEST_METADATA_ADOBE_MISMATCH);
                if (rightTransform == JPEG.ADOBE_IMPOSSIBLE) {
                    ignoreAdobe = true;
                } else {
                    newAdobeTransform = rightTransform;
                }
            }
        }
    }

    /**
     * Collect all the scan info from the given metadata, and 
     * organize it into the scan info array required by the
     * IJG libray.  It is much simpler to parse out this
     * data in Java and then just copy the data in C.
     */
    private int [] collectScans(JPEGMetadata metadata, 
                                SOFMarkerSegment sof) {
        List segments = new ArrayList();
        int SCAN_SIZE = 9;
        int MAX_COMPS_PER_SCAN = 4;
        for (Iterator iter = metadata.markerSequence.iterator();
             iter.hasNext();) {
            MarkerSegment seg = (MarkerSegment) iter.next();
            if (seg instanceof SOSMarkerSegment) {
                segments.add(seg);
            }
        }
        int [] retval = null;
        numScans = 0;
        if (!segments.isEmpty()) {
            numScans = segments.size();
            retval = new int [numScans*SCAN_SIZE];
            int index = 0;
            for (int i = 0; i < numScans; i++) {
                SOSMarkerSegment sos = (SOSMarkerSegment) segments.get(i);
                retval[index++] = sos.componentSpecs.length; // num comps
                for (int j = 0; j < MAX_COMPS_PER_SCAN; j++) {
                    if (j < sos.componentSpecs.length) {
                        int compSel = sos.componentSpecs[j].componentSelector;
                        for (int k = 0; k < sof.componentSpecs.length; k++) {
                            if (compSel == sof.componentSpecs[k].componentId) {
                                retval[index++] = k;
                                break; // out of for over sof comps
                            }
                        }
                    } else {
                        retval[index++] = 0;
                    }
                }
                retval[index++] = sos.startSpectralSelection;
                retval[index++] = sos.endSpectralSelection;
                retval[index++] = sos.approxHigh;
                retval[index++] = sos.approxLow;
            }
        }
        return retval;
    }

    /**
     * Finds all DQT marker segments and returns all the q 
     * tables as a single array of JPEGQTables.
     */
    private JPEGQTable [] collectQTablesFromMetadata
        (JPEGMetadata metadata) {
        ArrayList tables = new ArrayList();
        Iterator iter = metadata.markerSequence.iterator();
        while (iter.hasNext()) {
            MarkerSegment seg = (MarkerSegment) iter.next();
            if (seg instanceof DQTMarkerSegment) {
                DQTMarkerSegment dqt = 
                    (DQTMarkerSegment) seg;
                tables.addAll(dqt.tables);
            }