pngimagewriter.java

Mobile 应用程序使用 Java Micro Edition (Java ME) 平台

        // Create row buffers
        int samplesPerByte = 8/metadata.IHDR_bitDepth;
        int numSamples = width*numBands;
        int[] samples = new int[numSamples];

        int bytesPerRow = hpixels*numBands;
        if (metadata.IHDR_bitDepth < 8) {
            bytesPerRow = (bytesPerRow + samplesPerByte - 1)/samplesPerByte;
        } else if (metadata.IHDR_bitDepth == 16) {
            bytesPerRow *= 2;
        }

        IndexColorModel icm_gray_alpha = null;
        if (metadata.IHDR_colorType == PNGImageReader.PNG_COLOR_GRAY_ALPHA &&
            image.getColorModel() instanceof IndexColorModel)
        {
            // reserve space for alpha samples
            bytesPerRow *= 2;
            
            // will be used to calculate alpha value for the pixel
            icm_gray_alpha = (IndexColorModel)image.getColorModel();
        }
 
        currRow = new byte[bytesPerRow + bpp];
        prevRow = new byte[bytesPerRow + bpp];
        filteredRows = new byte[5][bytesPerRow + bpp];

	int bitDepth = metadata.IHDR_bitDepth;
        for (int row = minY + yOffset; row < minY + height; row += ySkip) {
            Rectangle rect = new Rectangle(minX, row, width, 1);
            Raster ras = image.getData(rect);
            if (sourceBands != null) {
                ras = ras.createChild(minX, row, width, 1, minX, row,
                                      sourceBands);
            }

            ras.getPixels(minX, row, width, 1, samples);

            if (image.getColorModel().isAlphaPremultiplied()) {
                WritableRaster wr = ras.createCompatibleWritableRaster();
                wr.setPixels(wr.getMinX(), wr.getMinY(),
                             wr.getWidth(), wr.getHeight(),
                             samples);

                image.getColorModel().coerceData(wr, false);
                wr.getPixels(wr.getMinX(), wr.getMinY(),
                             wr.getWidth(), wr.getHeight(),
                             samples);
            }

            // Reorder palette data if necessary
            int[] paletteOrder = metadata.PLTE_order;
            if (paletteOrder != null) {
                for (int i = 0; i < numSamples; i++) {
                    samples[i] = paletteOrder[samples[i]];
                }
            }

            int count = bpp; // leave first 'bpp' bytes zero
            int pos = 0;
            int tmp = 0;

            switch (bitDepth) {
            case 1: case 2: case 4:
                // Image can only have a single band
                
                int mask = samplesPerByte - 1;
                for (int s = xOffset; s < numSamples; s += xSkip) {
		    byte val = scale0[samples[s]];
                    tmp = (tmp << bitDepth) | val;

                    if ((pos++ & mask) == mask) {
                        currRow[count++] = (byte)tmp;
                        tmp = 0;
                        pos = 0;
                    }
                }

                // Left shift the last byte
                if ((pos & mask) != 0) {
                    tmp <<= ((8/bitDepth) - pos)*bitDepth;
                    currRow[count++] = (byte)tmp;
                }
                break;

            case 8:
		if (numBands == 1) {
		    for (int s = xOffset; s < numSamples; s += xSkip) {
			currRow[count++] = scale0[samples[s]];
			if (icm_gray_alpha != null) { 
                            currRow[count++] = 
                                scale0[icm_gray_alpha.getAlpha(0xff & samples[s])];
                        }
		    }
		} else {
		    for (int s = xOffset; s < numSamples; s += xSkip) {
			for (int b = 0; b < numBands; b++) {
			    currRow[count++] = scale[b][samples[s + b]];
			}
		    }
		}
                break;

            case 16:
                for (int s = xOffset; s < numSamples; s += xSkip) {
                    for (int b = 0; b < numBands; b++) {
                        currRow[count++] = scaleh[b][samples[s + b]];
                        currRow[count++] = scalel[b][samples[s + b]];
                    }
                }
                break;
            }

            // Perform filtering
            int filterType = rowFilter.filterRow(metadata.IHDR_colorType,
                                                 currRow, prevRow,
                                                 filteredRows,
                                                 bytesPerRow, bpp);
            
            os.write(filterType);
            os.write(filteredRows[filterType], bpp, bytesPerRow);
            
            // Swap current and previous rows
            byte[] swap = currRow;
            currRow = prevRow;
            prevRow = swap;

            pixelsDone += hpixels;
            processImageProgress(100.0F*pixelsDone/totalPixels);

            // If write has been aborted, just return;
            // processWriteAborted will be called later
            if (abortRequested()) {
                return;
            }
        }
    }

    // Use sourceXOffset, etc.
    private void write_IDAT(RenderedImage image) throws IOException {
        IDATOutputStream ios = new IDATOutputStream(stream, 32768);

        if (metadata.IHDR_interlaceMethod == 1) {
            for (int i = 0; i < 7; i++) {
                encodePass(ios, image,
                           PNGImageReader.adam7XOffset[i],
                           PNGImageReader.adam7YOffset[i],
                           PNGImageReader.adam7XSubsampling[i],
                           PNGImageReader.adam7YSubsampling[i]);
                if (abortRequested()) {
                    break;
                }
            }
        } else {
            encodePass(ios, image, 0, 0, 1, 1);
        }

        ios.finish();
    }

    private void writeIEND() throws IOException {
        ChunkStream cs = new ChunkStream(PNGImageReader.IEND_TYPE, stream);
        cs.finish();
    }

    // Check two int arrays for value equality, always returns false
    // if either array is null
    private boolean equals(int[] s0, int[] s1) {
	if (s0 == null || s1 == null) {
	    return false;
	}
	if (s0.length != s1.length) {
	    return false;
	}
	for (int i = 0; i < s0.length; i++) {
	    if (s0[i] != s1[i]) {
		return false;
	    }
	}
	return true;
    }

    // Initialize the scale/scale0 or scaleh/scalel arrays to
    // hold the results of scaling an input value to the desired
    // output bit depth
    private void initializeScaleTables(int[] sampleSize) {
	int bitDepth = metadata.IHDR_bitDepth;

	// If the existing tables are still valid, just return
	if (bitDepth == scalingBitDepth &&
	    equals(sampleSize, this.sampleSize)) {
	    return;
	}
	
	// Compute new tables
	this.sampleSize = sampleSize;
	this.scalingBitDepth = bitDepth;
	int maxOutSample = (1 << bitDepth) - 1;
	if (bitDepth <= 8) {
	    scale = new byte[numBands][];
	    for (int b = 0; b < numBands; b++) {
		int maxInSample = (1 << sampleSize[b]) - 1;
		int halfMaxInSample = maxInSample/2;
		scale[b] = new byte[maxInSample + 1];
		for (int s = 0; s <= maxInSample; s++) {
		    scale[b][s] =
			(byte)((s*maxOutSample + halfMaxInSample)/maxInSample);
		}
	    }
	    scale0 = scale[0];
	    scaleh = scalel = null;
	} else { // bitDepth == 16
	    // Divide scaling table into high and low bytes
	    scaleh = new byte[numBands][];
	    scalel = new byte[numBands][];

	    for (int b = 0; b < numBands; b++) {
		int maxInSample = (1 << sampleSize[b]) - 1;
		int halfMaxInSample = maxInSample/2;
		scaleh[b] = new byte[maxInSample + 1];
		scalel[b] = new byte[maxInSample + 1];
		for (int s = 0; s <= maxInSample; s++) {
		    int val = (s*maxOutSample + halfMaxInSample)/maxInSample;
		    scaleh[b][s] = (byte)(val >> 8);
		    scalel[b][s] = (byte)(val & 0xff);
		}
	    }
	    scale = null;
	    scale0 = null;
	}
    }

    public void write(IIOMetadata streamMetadata,
                      IIOImage image,
                      ImageWriteParam param) throws IIOException {
        if (stream == null) {
            throw new IllegalStateException("output == null!");
        }
        if (image == null) {
            throw new IllegalArgumentException("image == null!");
        }
        if (image.hasRaster()) {
            throw new UnsupportedOperationException("image has a Raster!");
        }

        RenderedImage im = image.getRenderedImage();
        SampleModel sampleModel = im.getSampleModel();
        this.numBands = sampleModel.getNumBands();

        // Set source region and subsampling to default values
        this.sourceXOffset = im.getMinX();
        this.sourceYOffset = im.getMinY();
        this.sourceWidth = im.getWidth();
        this.sourceHeight = im.getHeight();
        this.sourceBands = null;
        this.periodX = 1;
        this.periodY = 1;

        if (param != null) {
            // Get source region and subsampling factors
            Rectangle sourceRegion = param.getSourceRegion();
            if (sourceRegion != null) {
                Rectangle imageBounds = new Rectangle(im.getMinX(),
                                                      im.getMinY(),
                                                      im.getWidth(),
                                                      im.getHeight());
                // Clip to actual image bounds
                sourceRegion = sourceRegion.intersection(imageBounds);
                sourceXOffset = sourceRegion.x;
                sourceYOffset = sourceRegion.y;
                sourceWidth = sourceRegion.width;
                sourceHeight = sourceRegion.height;
            }

            // Adjust for subsampling offsets
            int gridX = param.getSubsamplingXOffset();
            int gridY = param.getSubsamplingYOffset();
            sourceXOffset += gridX;
            sourceYOffset += gridY;
            sourceWidth -= gridX;
            sourceHeight -= gridY;

            // Get subsampling factors
            periodX = param.getSourceXSubsampling();
            periodY = param.getSourceYSubsampling();

            int[] sBands = param.getSourceBands();
            if (sBands != null) {
                sourceBands = sBands;
                numBands = sourceBands.length;
            }
        }

        // Compute output dimensions
        int destWidth = (sourceWidth + periodX - 1)/periodX;
        int destHeight = (sourceHeight + periodY - 1)/periodY;
        if (destWidth <= 0 || destHeight <= 0) {
            throw new IllegalArgumentException("Empty source region!");
        }

        // Compute total number of pixels for progress notification
        this.totalPixels = destWidth*destHeight;
        this.pixelsDone = 0;

        // Create metadata
        IIOMetadata imd = image.getMetadata();
        if (imd != null) {
            metadata = (PNGMetadata)convertImageMetadata(imd,
                               ImageTypeSpecifier.createFromRenderedImage(im),
                                                         null);
        } else {
            metadata = new PNGMetadata();
        }

        if (param != null) {
            // Use Adam7 interlacing if set in write param
            switch (param.getProgressiveMode()) {
            case ImageWriteParam.MODE_DEFAULT:
                metadata.IHDR_interlaceMethod = 1;
                break;
            case ImageWriteParam.MODE_DISABLED:
                metadata.IHDR_interlaceMethod = 0;
                break;
                // MODE_COPY_FROM_METADATA should alreay be taken care of
                // MODE_EXPLICIT is not allowed
            }
        }

        // Initialize bitDepth and colorType
        metadata.initialize(new ImageTypeSpecifier(im), numBands);

        // Overwrite IHDR width and height values with values from image
        metadata.IHDR_width = destWidth;
        metadata.IHDR_height = destHeight;

        this.bpp = numBands*((metadata.IHDR_bitDepth == 16) ? 2 : 1);

	// Initialize scaling tables for this image
	initializeScaleTables(sampleModel.getSampleSize());

        clearAbortRequest();

        processImageStarted(0);

        try {
            write_magic();
            write_IHDR();

            write_cHRM();
            write_gAMA();
            write_iCCP();
            write_sBIT();
            write_sRGB();
        
            write_PLTE();
            
            write_hIST();
            write_tRNS();
            write_bKGD();
            
            write_pHYs();
            write_sPLT();
            write_tIME();
            write_tEXt();
            write_iTXt();
            write_zTXt();
            
            writeUnknownChunks();
            
            write_IDAT(im);

            if (abortRequested()) {
                processWriteAborted();
            } else {
                // Finish up and inform the listeners we are done
                writeIEND();
                processImageComplete();
            }
        } catch (IOException e) {
            throw new IIOException("I/O error writing PNG file!", e);
        }
    }
}