gifimagewriter.java

java1.6众多例子参考

            }

            if (streamMetadata.colorResolution ==
                GIFMetadata.UNDEFINED_INTEGER_VALUE)
            {
                streamMetadata.colorResolution = colorModel != null ?
                    colorModel.getComponentSize()[0] :
                    sampleModel.getSampleSize()[0];
            }
            
            // Set the Global Color Table if not set, i.e., if not
            // provided in the stream metadata.
            if (streamMetadata.globalColorTable == null) {
                if (isWritingSequence && imageMetadata != null &&
                    imageMetadata.localColorTable != null) {
                    // Writing a sequence and a local color table was
                    // provided in the metadata of the first image: use it.
                    streamMetadata.globalColorTable =
                        imageMetadata.localColorTable;
                } else if (imageMetadata == null ||
                           imageMetadata.localColorTable == null) {
                    // Create a color table.
                    streamMetadata.globalColorTable =
                        createColorTable(colorModel, sampleModel);
                }
            }

            // Set the Global Color Table. At this point it should be
            // A) the global color table provided in stream metadata, if any;
            // B) the local color table of the image metadata, if any, if
            //    writing a sequence;
            // C) a table created on the basis of the first image ColorModel
            //    and SampleModel if no local color table is available; or
            // D) null if none of the foregoing conditions obtain (which
            //    should only be if a sequence is not being written and
            //    a local color table is provided in image metadata).
            globalColorTable = streamMetadata.globalColorTable;
            
            // Write the header.
            int bitsPerPixel;
            if (globalColorTable != null) {
                bitsPerPixel = getNumBits(globalColorTable.length/3);
            } else if (imageMetadata != null &&
                       imageMetadata.localColorTable != null) {
                bitsPerPixel =
                    getNumBits(imageMetadata.localColorTable.length/3);
            } else {
                bitsPerPixel = sampleModel.getSampleSize(0);
            }
            writeHeader(streamMetadata, bitsPerPixel);
        } else if (isWritingSequence) {
            globalColorTable = theStreamMetadata.globalColorTable;
        } else {
            throw new IllegalArgumentException("Must write header for single image!");
        }
        
        // Write extension blocks, Image Descriptor, and image data.
        writeImage(iioimage.getRenderedImage(), imageMetadata, p,
                   globalColorTable, sourceBounds, destSize);
        
        // Write the trailer.
        if (writeTrailer) {
            writeTrailer();
        }
    }
    
    /**
     * Writes any extension blocks, the Image Descriptor, and the image data
     *
     * @param iioimage The image and image metadata.
     * @param param The write parameters.
     * @param globalColorTable The Global Color Table.
     * @param sourceBounds The source region.
     * @param destSize The destination dimensions.
     */
    private void writeImage(RenderedImage image,
                            GIFWritableImageMetadata imageMetadata,
                            ImageWriteParam param, byte[] globalColorTable,
                            Rectangle sourceBounds, Dimension destSize)
      throws IOException {
        ColorModel colorModel = image.getColorModel();
        SampleModel sampleModel = image.getSampleModel();
        
        boolean writeGraphicsControlExtension;
        if (imageMetadata == null) {
            // Create default metadata.
            imageMetadata = (GIFWritableImageMetadata)getDefaultImageMetadata(
                new ImageTypeSpecifier(image), param);
            
            // Set GraphicControlExtension flag only if there is
            // transparency.
            writeGraphicsControlExtension = imageMetadata.transparentColorFlag;
        } else {
            // Check for GraphicControlExtension element.
            NodeList list = null;
            try {
                IIOMetadataNode root = (IIOMetadataNode)
                    imageMetadata.getAsTree(IMAGE_METADATA_NAME);
                list = root.getElementsByTagName("GraphicControlExtension");
            } catch(IllegalArgumentException iae) {
                // Should never happen.
            }
            
            // Set GraphicControlExtension flag if element present.
            writeGraphicsControlExtension =
                list != null && list.getLength() > 0;
            
            // If progressive mode is not MODE_COPY_FROM_METADATA, ensure
            // the interlacing is set per the ImageWriteParam mode setting.
            if (param != null && param.canWriteProgressive()) {
                if (param.getProgressiveMode() ==
                    ImageWriteParam.MODE_DISABLED) {
                    imageMetadata.interlaceFlag = false;
                } else if (param.getProgressiveMode() ==
                           ImageWriteParam.MODE_DEFAULT) {
                    imageMetadata.interlaceFlag = true;
                }
            }
        }
        
        // Unset local color table if equal to global color table.
        if (Arrays.equals(globalColorTable, imageMetadata.localColorTable)) {
            imageMetadata.localColorTable = null;
        }
      
        // Override dimensions
        imageMetadata.imageWidth = destSize.width;
        imageMetadata.imageHeight = destSize.height;
        
        // Write Graphics Control Extension.
        if (writeGraphicsControlExtension) {
            writeGraphicControlExtension(imageMetadata);
        }
        
        // Write extension blocks.
        writePlainTextExtension(imageMetadata);
        writeApplicationExtension(imageMetadata);
        writeCommentExtension(imageMetadata);
        
        // Write Image Descriptor
        int bitsPerPixel =
            getNumBits(imageMetadata.localColorTable == null ?
                       (globalColorTable == null ?
                        sampleModel.getSampleSize(0) :
                        globalColorTable.length/3) :
                       imageMetadata.localColorTable.length/3);
        writeImageDescriptor(imageMetadata, bitsPerPixel);
        
        // Write image data
        writeRasterData(image, sourceBounds, destSize,
                        param, imageMetadata.interlaceFlag);
    }
    
    private void writeRows(RenderedImage image, LZWCompressor compressor,
                           int sx, int sdx, int sy, int sdy, int sw,
                           int dy, int ddy, int dw, int dh,
                           int numRowsWritten, int progressReportRowPeriod)
      throws IOException {
        if (DEBUG) System.out.println("Writing unoptimized");
        
        int[] sbuf = new int[sw];
        byte[] dbuf = new byte[dw];
        
        Raster raster =
            image.getNumXTiles() == 1 && image.getNumYTiles() == 1 ?
            image.getTile(0, 0) : image.getData();
        for (int y = dy; y < dh; y += ddy) {
            if (numRowsWritten % progressReportRowPeriod == 0) {
                if (abortRequested()) {
                    processWriteAborted();
                    return;
                }
                processImageProgress((numRowsWritten*100.0F)/dh);
            }
            
            raster.getSamples(sx, sy, sw, 1, 0, sbuf);
            for (int i = 0, j = 0; i < dw; i++, j += sdx) {
                dbuf[i] = (byte)sbuf[j];
            }
            compressor.compress(dbuf, 0, dw);
            numRowsWritten++;
            sy += sdy;
        }
    }

    private void writeRowsOpt(byte[] data, int offset, int lineStride,
                              LZWCompressor compressor,
                              int dy, int ddy, int dw, int dh,
                              int numRowsWritten, int progressReportRowPeriod)
      throws IOException {
        if (DEBUG) System.out.println("Writing optimized");
        
        offset += dy*lineStride;
        lineStride *= ddy;
        for (int y = dy; y < dh; y += ddy) {
            if (numRowsWritten % progressReportRowPeriod == 0) {
                if (abortRequested()) {
                    processWriteAborted();
                    return;
                }
                processImageProgress((numRowsWritten*100.0F)/dh);
            }
            
            compressor.compress(data, offset, dw);
            numRowsWritten++;
            offset += lineStride;
        }
    }

    private void writeRasterData(RenderedImage image,
                                 Rectangle sourceBounds,
                                 Dimension destSize,
                                 ImageWriteParam param,
                                 boolean interlaceFlag) throws IOException {
        
        int sourceXOffset = sourceBounds.x;
        int sourceYOffset = sourceBounds.y;
        int sourceWidth = sourceBounds.width;
        int sourceHeight = sourceBounds.height;
        
        int destWidth = destSize.width;
        int destHeight = destSize.height;
        
        int periodX;
        int periodY;
        if (param == null) {
            periodX = 1;
            periodY = 1;
        } else {
            periodX = param.getSourceXSubsampling();
            periodY = param.getSourceYSubsampling();
        }
        
        SampleModel sampleModel = image.getSampleModel();
        int bitsPerPixel = sampleModel.getSampleSize()[0];
        
        int initCodeSize = bitsPerPixel;
        if (initCodeSize == 1) {
            initCodeSize++;
        }
        stream.write(initCodeSize);
        
        LZWCompressor compressor =
            new LZWCompressor(stream, initCodeSize, false);
        
        boolean isOptimizedCase =
            periodX == 1 && periodY == 1 &&
            sampleModel instanceof ComponentSampleModel &&
            image.getNumXTiles() == 1 && image.getNumYTiles() == 1 &&
            image.getTile(0, 0).getDataBuffer() instanceof DataBufferByte;
        
        int numRowsWritten = 0;
        
        int progressReportRowPeriod = Math.max(destHeight/20, 1);
        
        processImageStarted(imageIndex);
        
        if (interlaceFlag) {
            if (DEBUG) System.out.println("Writing interlaced");
            
            if (isOptimizedCase) {
                Raster tile = image.getTile(0, 0);
                byte[] data = ((DataBufferByte)tile.getDataBuffer()).getData();
                ComponentSampleModel csm =
                    (ComponentSampleModel)tile.getSampleModel();
                int offset = csm.getOffset(sourceXOffset, sourceYOffset, 0);
                int lineStride = csm.getScanlineStride();
                
                writeRowsOpt(data, offset, lineStride, compressor,
                             0, 8, destWidth, destHeight,
                             numRowsWritten, progressReportRowPeriod);
                
                if (abortRequested()) {
                    return;
                }
                
                numRowsWritten += destHeight/8;
                
                writeRowsOpt(data, offset, lineStride, compressor,
                             4, 8, destWidth, destHeight,
                             numRowsWritten, progressReportRowPeriod);
                
                if (abortRequested()) {
                    return;
                }
                
                numRowsWritten += (destHeight - 4)/8;
                
                writeRowsOpt(data, offset, lineStride, compressor,
                             2, 4, destWidth, destHeight,
                             numRowsWritten, progressReportRowPeriod);
                
                if (abortRequested()) {
                    return;
                }
                
                numRowsWritten += (destHeight - 2)/4;
                
                writeRowsOpt(data, offset, lineStride, compressor,
                             1, 2, destWidth, destHeight,
                             numRowsWritten, progressReportRowPeriod);
            } else {
                writeRows(image, compressor,
                          sourceXOffset, periodX,
                          sourceYOffset, 8*periodY,
                          sourceWidth,
                          0, 8, destWidth, destHeight,
                          numRowsWritten, progressReportRowPeriod);
                
                if (abortRequested()) {
                    return;
                }
                
                numRowsWritten += destHeight/8;
                
                writeRows(image, compressor, sourceXOffset, periodX,
                          sourceYOffset + 4*periodY, 8*periodY,
                          sourceWidth,
                          4, 8, destWidth, destHeight,
                          numRowsWritten, progressReportRowPeriod);
                
                if (abortRequested()) {