Example usage for java.util.zip Deflater finish

Introduction

In this page you can find the example usage for java.util.zip Deflater finish.

Prototype

boolean finish

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Usage

From source file:org.pentaho.reporting.libraries.base.util.PngEncoder.java

/**
 * Write the image data into the pngBytes array. This will write one or more PNG "IDAT" chunks. In order to conserve
 * memory, this method grabs as many rows as will fit into 32K bytes, or the whole image; whichever is less.
 *
 * @return true if no errors; false if error grabbing pixels
 *//*from   w  ww.  java2 s . c  o  m*/
protected boolean writeImageData() {

    this.bytesPerPixel = (this.encodeAlpha) ? 4 : 3;

    final Deflater scrunch = new Deflater(this.compressionLevel);
    final ByteArrayOutputStream outBytes = new ByteArrayOutputStream(1024);
    final DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes, scrunch);
    try {
        int startRow = 0; // starting row to process this time through
        //noinspection SuspiciousNameCombination
        int rowsLeft = this.height; // number of rows remaining to write
        while (rowsLeft > 0) {
            final int nRows = Math.max(Math.min(32767 / (this.width * (this.bytesPerPixel + 1)), rowsLeft), 1);

            final int[] pixels = new int[this.width * nRows];

            final PixelGrabber pg = new PixelGrabber(this.image, 0, startRow, this.width, nRows, pixels, 0,
                    this.width);
            try {
                pg.grabPixels();
            } catch (Exception e) {
                logger.error("interrupted waiting for pixels!", e);
                return false;
            }
            if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
                logger.error("image fetch aborted or errored");
                return false;
            }

            /*
            * Create a data chunk. scanLines adds "nRows" for
            * the filter bytes.
            */
            final byte[] scanLines = new byte[this.width * nRows * this.bytesPerPixel + nRows];

            if (this.filter == PngEncoder.FILTER_SUB) {
                this.leftBytes = new byte[16];
            }
            if (this.filter == PngEncoder.FILTER_UP) {
                this.priorRow = new byte[this.width * this.bytesPerPixel];
            }

            int scanPos = 0;
            int startPos = 1;
            for (int i = 0; i < this.width * nRows; i++) {
                if (i % this.width == 0) {
                    scanLines[scanPos++] = (byte) this.filter;
                    startPos = scanPos;
                }
                scanLines[scanPos++] = (byte) ((pixels[i] >> 16) & 0xff);
                scanLines[scanPos++] = (byte) ((pixels[i] >> 8) & 0xff);
                scanLines[scanPos++] = (byte) ((pixels[i]) & 0xff);
                if (this.encodeAlpha) {
                    scanLines[scanPos++] = (byte) ((pixels[i] >> 24) & 0xff);
                }
                if ((i % this.width == this.width - 1) && (this.filter != PngEncoder.FILTER_NONE)) {
                    if (this.filter == PngEncoder.FILTER_SUB) {
                        filterSub(scanLines, startPos, this.width);
                    }
                    if (this.filter == PngEncoder.FILTER_UP) {
                        filterUp(scanLines, startPos, this.width);
                    }
                }
            }

            /*
            * Write these lines to the output area
            */
            compBytes.write(scanLines, 0, scanPos);

            startRow += nRows;
            rowsLeft -= nRows;
        }
        compBytes.close();

        /*
        * Write the compressed bytes
        */
        final byte[] compressedLines = outBytes.toByteArray();
        final int nCompressed = compressedLines.length;

        this.crc.reset();
        this.bytePos = writeInt4(nCompressed, this.bytePos);
        this.bytePos = writeBytes(PngEncoder.IDAT, this.bytePos);
        this.crc.update(PngEncoder.IDAT);
        this.bytePos = writeBytes(compressedLines, nCompressed, this.bytePos);
        this.crc.update(compressedLines, 0, nCompressed);

        this.crcValue = this.crc.getValue();
        this.bytePos = writeInt4((int) this.crcValue, this.bytePos);
        return true;
    } catch (IOException e) {
        logger.error("Failed to write PNG Data", e);
        return false;
    } finally {
        scrunch.finish();
        scrunch.end();
    }
}