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MultiPixelPackedSampleModel.java

/* Copyright (C) 2004, 2006,  Free Software Foundation

This file is part of GNU Classpath.

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package java.awt.image;

import gnu.java.awt.Buffers;

/**
 * MultiPixelPackedSampleModel provides a single band model that supports
 * multiple pixels in a single unit.  Pixels have 2^n bits and 2^k pixels fit
 * per data element.
 *
 * @author Jerry Quinn (jlquinn@optonline.net)
 */
00048 public class MultiPixelPackedSampleModel extends SampleModel
{
  private int scanlineStride;
  private int[] bitMasks;
  private int[] bitOffsets;
  private int[] sampleSize;
  private int dataBitOffset;
  private int elemBits;
  private int numberOfBits;
  private int numElems;

  /**
   * Creates a new <code>MultiPixelPackedSampleModel</code> with the specified
   * data type, which should be one of:
   * <ul>
   *   <li>{@link DataBuffer#TYPE_BYTE};</li>
   *   <li>{@link DataBuffer#TYPE_USHORT};</li>
   *   <li>{@link DataBuffer#TYPE_INT};</li>
   * </ul>
   * 
   * @param dataType  the data type.
   * @param w  the width (in pixels).
   * @param h  the height (in pixels).
   * @param numberOfBits  the number of bits per pixel (must be a power of 2).
   */
00073   public MultiPixelPackedSampleModel(int dataType, int w, int h,
                             int numberOfBits)
  {
    this(dataType, w, h, numberOfBits, 0, 0);
  }

  /**
   * Creates a new <code>MultiPixelPackedSampleModel</code> with the specified
   * data type, which should be one of:
   * <ul>
   *   <li>{@link DataBuffer#TYPE_BYTE};</li>
   *   <li>{@link DataBuffer#TYPE_USHORT};</li>
   *   <li>{@link DataBuffer#TYPE_INT};</li>
   * </ul>
   * 
   * @param dataType  the data type.
   * @param w  the width (in pixels).
   * @param h  the height (in pixels).
   * @param numberOfBits  the number of bits per pixel (must be a power of 2).
   * @param scanlineStride  the number of data elements from a pixel on one 
   *     row to the corresponding pixel in the next row.
   * @param dataBitOffset  the offset to the first data bit.
   */
00096   public MultiPixelPackedSampleModel(int dataType, int w, int h,
                             int numberOfBits, int scanlineStride,
                             int dataBitOffset)
  {
    super(dataType, w, h, 1);

    switch (dataType)
      {
      case DataBuffer.TYPE_BYTE:
      elemBits = 8;
      break;
      case DataBuffer.TYPE_USHORT:
      elemBits = 16;
      break;
      case DataBuffer.TYPE_INT:
      elemBits = 32;
      break;
      default:
      throw new IllegalArgumentException("MultiPixelPackedSampleModel"
                                 + " unsupported dataType");
      }

    this.dataBitOffset = dataBitOffset;

    this.numberOfBits = numberOfBits;
    if (numberOfBits > elemBits)
      throw new RasterFormatException("MultiPixelPackedSampleModel pixel size"
                              + " larger than dataType");
    switch (numberOfBits)
      {
      case 1: case 2: case 4: case 8: case 16: case 32: break;
      default:
      throw new RasterFormatException("MultiPixelPackedSampleModel pixel"
                              + " size not 2^n bits");
      }
    numElems = elemBits / numberOfBits;

    // Compute scan line large enough for w pixels.
    if (scanlineStride == 0)
      scanlineStride = ((dataBitOffset + w * numberOfBits) - 1) / elemBits + 1;
    this.scanlineStride = scanlineStride;

    
    sampleSize = new int[1];
    sampleSize[0] = numberOfBits;

    bitMasks = new int[numElems];
    bitOffsets = new int[numElems];
    for (int i=0; i < numElems; i++)
      {
      bitOffsets[numElems - i- 1] = numberOfBits * i;
      bitMasks[numElems - i - 1] = ((1 << numberOfBits) - 1) << 
          bitOffsets[numElems - i - 1];
      }
  }

  /**
   * Creates a new <code>MultiPixelPackedSample</code> model with the same
   * data type and bits per pixel as this model, but with the specified
   * dimensions.
   * 
   * @param w  the width (in pixels).
   * @param h  the height (in pixels).
   * 
   * @return The new sample model.
   */
00162   public SampleModel createCompatibleSampleModel(int w, int h)
  {
    /* FIXME: We can avoid recalculation of bit offsets and sample
       sizes here by passing these from the current instance to a
       special private constructor. */
    return new MultiPixelPackedSampleModel(dataType, w, h, numberOfBits);
  }

  /**
   * Creates a DataBuffer for holding pixel data in the format and
   * layout described by this SampleModel. The returned buffer will
   * consist of one single bank.
   * 
   * @return A new data buffer.
   */
00177   public DataBuffer createDataBuffer()
  {
    int size = scanlineStride * height;
    if (dataBitOffset > 0)
      size += (dataBitOffset - 1) / elemBits + 1;
    return Buffers.createBuffer(getDataType(), size);
  }

  /**
   * Returns the number of data elements required to transfer a pixel in the
   * get/setDataElements() methods.
   * 
   * @return <code>1</code>.
   */
00191   public int getNumDataElements()
  {
    return 1;
  }

  /**
   * Returns an array containing the size (in bits) of the samples in each 
   * band.  The <code>MultiPixelPackedSampleModel</code> class supports only
   * one band, so this method returns an array with length <code>1</code>. 
   * 
   * @return An array containing the size (in bits) of the samples in band zero. 
   *     
   * @see #getSampleSize(int)
   */
00205   public int[] getSampleSize()
  {
    return (int[]) sampleSize.clone();
  }
  
  /**
   * Returns the size of the samples in the specified band.  Note that the
   * <code>MultiPixelPackedSampleModel</code> supports only one band -- this
   * method ignored the <code>band</code> argument, and always returns the size
   * of band zero.
   * 
   * @param band  the band (this parameter is ignored).
   * 
   * @return The size of the samples in band zero.
   * 
   * @see #getSampleSize()
   */
00222   public int getSampleSize(int band)
  {
    return sampleSize[0];
  }

  /**
   * Returns the index in the data buffer that stores the pixel at (x, y).
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * 
   * @return The index in the data buffer that stores the pixel at (x, y).
   * 
   * @see #getBitOffset(int)
   */
00237   public int getOffset(int x, int y)
  {
    return scanlineStride * y + ((dataBitOffset + x * numberOfBits) / elemBits);
  }

  /**
   * The bit offset (within an element in the data buffer) of the pixels with 
   * the specified x-coordinate.
   * 
   * @param x  the x-coordinate.
   * 
   * @return The bit offset.
   */
00250   public int getBitOffset(int x)
  {
    return (dataBitOffset + x * numberOfBits) % elemBits;
  }

  /**
   * Returns the offset to the first data bit.
   * 
   * @return The offset to the first data bit.
   */
00260   public int getDataBitOffset()
  {
    return dataBitOffset;
  }

  /**
   * Returns the number of data elements from a pixel in one row to the
   * corresponding pixel in the next row.
   * 
   * @return The scanline stride.
   */
00271   public int getScanlineStride()
  {
    return scanlineStride;
  }

  /**
   * Returns the number of bits per pixel.
   * 
   * @return The number of bits per pixel.
   */
00281   public int getPixelBitStride()
  {
    return numberOfBits;
  }
  
  /**
   * Returns the transfer type, which is one of the following (depending on
   * the number of bits per sample for this model):
   * <ul>
   *   <li>{@link DataBuffer#TYPE_BYTE};</li>
   *   <li>{@link DataBuffer#TYPE_USHORT};</li>
   *   <li>{@link DataBuffer#TYPE_INT};</li>
   * </ul>
   * 
   * @return The transfer type.
   */
00297   public int getTransferType()
  {
    if (numberOfBits <= DataBuffer.getDataTypeSize(DataBuffer.TYPE_BYTE))
      return DataBuffer.TYPE_BYTE;
    else if (numberOfBits <= DataBuffer.getDataTypeSize(DataBuffer.TYPE_USHORT))
      return DataBuffer.TYPE_USHORT;
    return DataBuffer.TYPE_INT;
  }

  /**
   * Normally this method returns a sample model for accessing a subset of
   * bands of image data, but since <code>MultiPixelPackedSampleModel</code>
   * only supports a single band, this overridden implementation just returns
   * a new instance of <code>MultiPixelPackedSampleModel</code>, with the same
   * attributes as this instance.
   * 
   * @param bands  the bands to include in the subset (this is ignored, except
   *     that if it is non-<code>null</code> a check is made to ensure that the
   *     array length is equal to <code>1</code>).
   *     
   * @throws RasterFormatException if <code>bands</code> is not 
   *     <code>null</code> and <code>bands.length != 1</code>.
   */
00320   public SampleModel createSubsetSampleModel(int[] bands)
  {
    if (bands != null && bands.length != 1)
      throw new RasterFormatException("MultiPixelPackedSampleModel only"
          + " supports one band");
    return new MultiPixelPackedSampleModel(dataType, width, height, 
        numberOfBits, scanlineStride, dataBitOffset);
  }

  /**
   * Extract one pixel and return in an array of transfer type.
   *
   * Extracts the pixel at x, y from data and stores into the 0th index of the
   * array obj, since there is only one band.  If obj is null, a new array of
   * getTransferType() is created.
   *
   * @param x The x-coordinate of the pixel rectangle to store in 
   *     <code>obj</code>.
   * @param y The y-coordinate of the pixel rectangle to store in 
   *     <code>obj</code>.
   * @param obj The primitive array to store the pixels into or null to force 
   *     creation.
   * @param data The DataBuffer that is the source of the pixel data.
   * @return The primitive array containing the pixel data.
   * @see java.awt.image.SampleModel#getDataElements(int, int, Object, 
   *     DataBuffer)
   */
00347   public Object getDataElements(int x, int y, Object obj, DataBuffer data)
  {
    int pixel = getSample(x, y, 0, data);
    switch (getTransferType())
      {
        case DataBuffer.TYPE_BYTE:
          if (obj == null) 
            obj = new byte[1];
          ((byte[]) obj)[0] = (byte) pixel;
          return obj;
        case DataBuffer.TYPE_USHORT:
          if (obj == null) 
            obj = new short[1];
          ((short[]) obj)[0] = (short) pixel;
          return obj;
        case DataBuffer.TYPE_INT:
          if (obj == null) 
            obj = new int[1];
          ((int[]) obj)[0] = pixel;
          return obj;
        default:
          // Seems like the only sensible thing to do.
          throw new ClassCastException();
      }
  }

  /**
   * Returns an array (of length 1) containing the sample for the pixel at 
   * (x, y) in the specified data buffer.  If <code>iArray</code> is not 
   * <code>null</code>, it will be populated with the sample value and 
   * returned as the result of this function (this avoids allocating a new 
   * array instance).
   * 
   * @param x  the x-coordinate of the pixel.
   * @param y  the y-coordinate of the pixel.
   * @param iArray  an array to populate with the sample values and return as 
   *     the result (if <code>null</code>, a new array will be allocated).
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @return An array containing the pixel sample value.
   * 
   * @throws NullPointerException if <code>data</code> is <code>null</code>.
   */
00390   public int[] getPixel(int x, int y, int[] iArray, DataBuffer data)
  {
    if (iArray == null) 
      iArray = new int[1];
    iArray[0] = getSample(x, y, 0, data);
    return iArray;
  }

  /**
   * Returns the sample value for the pixel at (x, y) in the specified data 
   * buffer.
   * 
   * @param x  the x-coordinate of the pixel.
   * @param y  the y-coordinate of the pixel.
   * @param b  the band (in the range <code>0</code> to 
   *     <code>getNumBands() - 1</code>).
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @return The sample value.
   * 
   * @throws NullPointerException if <code>data</code> is <code>null</code>.
   */
00412   public int getSample(int x, int y, int b, DataBuffer data)
  {
    int pos =
      ((dataBitOffset + x * numberOfBits) % elemBits) / numberOfBits;
    int offset = getOffset(x, y);
    int samples = data.getElem(offset);
    return (samples & bitMasks[pos]) >>> bitOffsets[pos];
  }
  
  /**
   * Set the pixel at x, y to the value in the first element of the primitive
   * array obj.
   *
   * @param x The x-coordinate of the data elements in <code>obj</code>.
   * @param y The y-coordinate of the data elements in <code>obj</code>.
   * @param obj The primitive array containing the data elements to set.
   * @param data The DataBuffer to store the data elements into.
   */
00430   public void setDataElements(int x, int y, Object obj, DataBuffer data)
  {
    int transferType = getTransferType();
    try
      {
        switch (transferType)
          {
            case DataBuffer.TYPE_BYTE:
              {
                byte[] in = (byte[]) obj;
                setSample(x, y, 0, in[0] & 0xFF, data);
                return;
              }
            case DataBuffer.TYPE_USHORT:
              {
                short[] in = (short[]) obj;
                setSample(x, y, 0, in[0] & 0xFFFF, data);
                return;
              }
            case DataBuffer.TYPE_INT:
              {
                int[] in = (int[]) obj;
                setSample(x, y, 0, in[0], data);
                return;
              }
            default:
              throw new ClassCastException("Unsupported data type");
          }
      }
    catch (ArrayIndexOutOfBoundsException aioobe)
      {
        String msg = "While writing data elements" +
          ", x=" + x + ", y=" + y +
          ", width=" + width + ", height=" + height +
          ", scanlineStride=" + scanlineStride +
          ", offset=" + getOffset(x, y) +
          ", data.getSize()=" + data.getSize() +
          ", data.getOffset()=" + data.getOffset() +
          ": " + aioobe;
        throw new ArrayIndexOutOfBoundsException(msg);
      }
  }

  /**
   * Sets the sample value for the pixel at (x, y) in the specified data 
   * buffer to the specified value. 
   * 
   * @param x  the x-coordinate of the pixel.
   * @param y  the y-coordinate of the pixel.
   * @param iArray  the sample value (<code>null</code> not permitted).
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @throws NullPointerException if either <code>iArray</code> or 
   *     <code>data</code> is <code>null</code>.
   *     
   * @see #setSample(int, int, int, int, DataBuffer)
   */
00487   public void setPixel(int x, int y, int[] iArray, DataBuffer data)
  {
    setSample(x, y, 0, iArray[0], data);
  }

  /**
   * Sets the sample value for a band for the pixel at (x, y) in the 
   * specified data buffer. 
   * 
   * @param x  the x-coordinate of the pixel.
   * @param y  the y-coordinate of the pixel.
   * @param b  the band (in the range <code>0</code> to 
   *     <code>getNumBands() - 1</code>).
   * @param s  the sample value.
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @throws NullPointerException if <code>data</code> is <code>null</code>.
   */
00505   public void setSample(int x, int y, int b, int s, DataBuffer data)
  {
    int bitpos =
      ((dataBitOffset + x * numberOfBits) % elemBits) / numberOfBits;
    int offset = getOffset(x, y);

    s = s << bitOffsets[bitpos];
    s = s & bitMasks[bitpos];

    int sample = data.getElem(offset);
    sample |= s;
    data.setElem(offset, sample);
  }
  
  /**
   * Tests this sample model for equality with an arbitrary object.  This 
   * method returns <code>true</code> if and only if:
   * <ul>
   *   <li><code>obj</code> is not <code>null</code>;
   *   <li><code>obj</code> is an instance of 
   *       <code>MultiPixelPackedSampleModel</code>;
   *   <li>both models have the same:
   *     <ul>
   *       <li><code>dataType</code>;
   *       <li><code>width</code>;
   *       <li><code>height</code>;
   *       <li><code>numberOfBits</code>;
   *       <li><code>scanlineStride</code>;
   *       <li><code>dataBitOffsets</code>.
   *     </ul>
   *   </li>
   * </ul>
   * 
   * @param obj  the object (<code>null</code> permitted)
   * 
   * @return <code>true</code> if this model is equal to <code>obj</code>, and
   *     <code>false</code> otherwise.
   */
00543   public boolean equals(Object obj) 
  {
    if (this == obj) 
      return true;
    if (! (obj instanceof MultiPixelPackedSampleModel)) 
      return false;
    MultiPixelPackedSampleModel that = (MultiPixelPackedSampleModel) obj;
    if (this.dataType != that.dataType)
      return false;
    if (this.width != that.width)
      return false;
    if (this.height != that.height)
      return false;
    if (this.numberOfBits != that.numberOfBits)
      return false;
    if (this.scanlineStride != that.scanlineStride)
      return false;
    if (this.dataBitOffset != that.dataBitOffset)
      return false;
    return true;
  }
  
  /**
   * Returns a hash code for this <code>MultiPixelPackedSampleModel</code>.
   * 
   * @return A hash code.
   */
00570   public int hashCode()
  {
    // this hash code won't match Sun's, but that shouldn't matter...
    int result = 193;
    result = 37 * result + dataType;
    result = 37 * result + width;
    result = 37 * result + height;
    result = 37 * result + numberOfBits;
    result = 37 * result + scanlineStride;
    result = 37 * result + dataBitOffset;
    return result;
  }
  
  /**
   * Creates a String with some information about this SampleModel.
   * @return A String describing this SampleModel.
   * @see java.lang.Object#toString()
   */
00588   public String toString()
  {
    StringBuffer result = new StringBuffer();
    result.append(getClass().getName());
    result.append("[");
    result.append("scanlineStride=").append(scanlineStride);
    for(int i=0; i < bitMasks.length; i+=1)
    {
      result.append(", mask[").append(i).append("]=0x").append(Integer.toHexString(bitMasks[i]));
    }
    
    result.append("]");
    return result.toString();
  }
}

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