ComponentSampleModel.java

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package java.awt.image;

import java.util.Arrays;

/**
 * ComponentSampleModel supports a flexible organization of pixel samples in
 * memory, permitting pixel samples to be interleaved by band, by scanline,
 * and by pixel.
 *
 * A DataBuffer for this sample model has K banks of data.  Pixels have N
 * samples, so there are N bands in the DataBuffer.  Each band is completely
 * contained in one bank of data, but a bank may contain more than one band.
 * Each pixel sample is stored in a single data element.
 *
 * Within a bank, each band begins at an offset stored in bandOffsets.  The
 * banks containing the band is given by bankIndices.  Within the bank, there
 * are three dimensions - band, pixel, and scanline.  The dimension ordering
 * is controlled by bandOffset, pixelStride, and scanlineStride, which means
 * that any combination of interleavings is supported.
 *
 * @author Rolf W. Rasmussen (rolfwr@ii.uib.no)
 */
public class ComponentSampleModel extends SampleModel
{
  /** The offsets to the first sample for each band. */
  protected int[] bandOffsets;
  
  /** The indices of the bank used to store each band in a data buffer. */
  protected int[] bankIndices;
  
  /** 
   * The number of bands in the image.
   * @specnote This field shadows the protected numBands in SampleModel.
   */
  protected int numBands;
  
  /** Used when creating data buffers. */
  protected int numBanks;

  /** 
   * The number of data elements between a sample in one row and the 
   * corresponding sample in the next row.
   */
  protected int scanlineStride;
  
  /**
   * The number of data elements between a sample for one pixel and the 
   * corresponding sample for the next pixel in the same row.
   */
  protected int pixelStride;

  /**
   * Creates a new sample model that assumes that all bands are stored in a 
   * single bank of the {@link DataBuffer}.
   * <p>
   * Note that the <code>bandOffsets</code> array is copied to internal storage
   * to prevent subsequent changes to the array from affecting this object.
   * 
   * @param dataType  the data type (one of {@link DataBuffer#TYPE_BYTE},
   *   {@link DataBuffer#TYPE_USHORT}, {@link DataBuffer#TYPE_SHORT},
   *   {@link DataBuffer#TYPE_INT}, {@link DataBuffer#TYPE_FLOAT} or 
   *   {@link DataBuffer#TYPE_DOUBLE}).
   * @param w  the width in pixels.
   * @param h  the height in pixels.
   * @param pixelStride  the number of data elements in the step from a sample
   *   in one pixel to the corresponding sample in the next pixel.
   * @param scanlineStride  the number of data elements in the step from a 
   *   sample in a pixel to the corresponding sample in the pixel in the next
   *   row.
   * @param bandOffsets  the offset to the first element for each band, with 
   *   the size of the array defining the number of bands (<code>null</code>
   *   not permitted).
   *   
   * @throws IllegalArgumentException if <code>dataType</code> is not one of
   *   the specified values.
   * @throws IllegalArgumentException if <code>w</code> is less than or equal
   *   to zero.
   * @throws IllegalArgumentException if <code>h</code> is less than or equal 
   *   to zero.
   * @throws IllegalArgumentException if <code>w * h</code> exceeds
   *   {@link Integer#MAX_VALUE}.
   * @throws IllegalArgumentException if <code>pixelStride</code> is negative.
   * @throws IllegalArgumentException if <code>scanlineStride</code> is less 
   *   than or equal to zero.
   * @throws IllegalArgumentException if <code>bandOffsets</code> has zero 
   *   length.
   */
  public ComponentSampleModel(int dataType,
                              int w, int h,
                              int pixelStride,
                              int scanlineStride,
                              int[] bandOffsets)
  {
    this(dataType, w, h, pixelStride, scanlineStride,
         new int[bandOffsets.length], bandOffsets);
  }
    
  /**
   * Creates a new sample model that assumes that all bands are stored in a 
   * single bank of the {@link DataBuffer}.
   * 
   * @param dataType  the data type (one of {@link DataBuffer#TYPE_BYTE},
   *   {@link DataBuffer#TYPE_USHORT}, {@link DataBuffer#TYPE_SHORT},
   *   {@link DataBuffer#TYPE_INT}, {@link DataBuffer#TYPE_FLOAT} or 
   *   {@link DataBuffer#TYPE_DOUBLE}).
   * @param w  the width in pixels.
   * @param h  the height in pixels.
   * @param pixelStride  the number of data elements in the step from a sample
   *   in one pixel to the corresponding sample in the next pixel.
   * @param scanlineStride  the number of data elements in the step from a 
   *   sample in a pixel to the corresponding sample in the pixel in the next
   *   row.
   * @param bankIndices  the index of the bank in which each band is stored 
   *   (<code>null</code> not permitted).  This array is copied to internal
   *   storage so that subsequent updates to the array do not affect the sample 
   *   model.
   * @param bandOffsets  the offset to the first element for each band, with 
   *   the size of the array defining the number of bands (<code>null</code>
   *   not permitted).  This array is copied to internal storage so that 
   *   subsequent updates to the array do not affect the sample model.
   *   
   * @throws IllegalArgumentException if <code>dataType</code> is not one of
   *   the specified values.
   * @throws IllegalArgumentException if <code>w</code> is less than or equal
   *   to zero.
   * @throws IllegalArgumentException if <code>h</code> is less than or equal 
   *   to zero.
   * @throws IllegalArgumentException if <code>w * h</code> exceeds
   *   {@link Integer#MAX_VALUE}.
   * @throws IllegalArgumentException if <code>pixelStride</code> is negative.
   * @throws IllegalArgumentException if <code>scanlineStride</code> is less 
   *   than or equal to zero.
   * @throws IllegalArgumentException if <code>bandOffsets</code> has zero 
   *   length.
   */
  public ComponentSampleModel(int dataType,
                              int w, int h,
                              int pixelStride,
                              int scanlineStride,
                              int[] bankIndices,
                              int[] bandOffsets)
  {
    super(dataType, w, h, bandOffsets.length);
    
    // super permits DataBuffer.TYPE_UNDEFINED but this class doesn't...
    if (dataType == DataBuffer.TYPE_UNDEFINED)
      throw new IllegalArgumentException("Unsupported dataType.");
    
    if ((pixelStride < 0) || (scanlineStride < 0) || (bandOffsets.length < 1) 
        || (bandOffsets.length != bankIndices.length))
      throw new IllegalArgumentException();
    
    this.bandOffsets = (int[]) bandOffsets.clone();
    this.bankIndices = (int[]) bankIndices.clone();
    this.numBands = bandOffsets.length;

    this.numBanks = 0;
    for (int b = 0; b < bankIndices.length; b++)
      this.numBanks = Math.max(this.numBanks, bankIndices[b] + 1);

    this.scanlineStride = scanlineStride;
    this.pixelStride = pixelStride;

  }             

  /**
   * Creates a new sample model that is compatible with this one, but with the
   * specified dimensions.
   * 
   * @param w  the width (must be greater than zero).
   * @param h  the height (must be greater than zero).
   * 
   * @return A new sample model.
   */
  public SampleModel createCompatibleSampleModel(int w, int h)
  {
    return new ComponentSampleModel(dataType, w, h, pixelStride,
                                    scanlineStride, bankIndices,
                                    bandOffsets);
  }

  /**
   * Creates a new sample model that provides access to a subset of the bands
   * that this sample model supports.
   * 
   * @param bands  the bands (<code>null</code> not permitted).
   * 
   * @return The new sample model.
   */
  public SampleModel createSubsetSampleModel(int[] bands)
  {
    int numBands = bands.length;
    
    int[] bankIndices = new int[numBands];
    int[] bandOffsets = new int[numBands];
    for (int b = 0; b < numBands; b++)
      {
        bankIndices[b] = this.bankIndices[bands[b]];
        bandOffsets[b] = this.bandOffsets[bands[b]];
      }

    return new ComponentSampleModel(dataType, width, height, pixelStride,
                                    scanlineStride, bankIndices,
                                    bandOffsets);
  }

  /**
   * Creates a new data buffer that is compatible with this sample model.
   * 
   * @return The new data buffer.
   */
  public DataBuffer createDataBuffer()
  {
    // Maybe this value should be precalculated in the constructor?
    int highestOffset = 0;
    for (int b = 0; b < numBands; b++)
      highestOffset = Math.max(highestOffset, bandOffsets[b]);    
    int size = pixelStride * (width - 1) + scanlineStride * (height - 1) 
        + highestOffset + 1;

    DataBuffer buffer = null;
    switch (getTransferType())
      {
      case DataBuffer.TYPE_BYTE:
        buffer = new DataBufferByte(size, numBanks);
        break;
      case DataBuffer.TYPE_SHORT:
        buffer = new DataBufferShort(size, numBanks);
        break;
      case DataBuffer.TYPE_USHORT:
        buffer = new DataBufferUShort(size, numBanks);
        break;
      case DataBuffer.TYPE_INT:
        buffer = new DataBufferInt(size, numBanks);
        break;
      case DataBuffer.TYPE_FLOAT:
        buffer = new DataBufferFloat(size, numBanks);
        break;
      case DataBuffer.TYPE_DOUBLE:
        buffer = new DataBufferDouble(size, numBanks);
        break;
      }
    return buffer;
  }

  /**
   * Returns the offset of the sample in band 0 for the pixel at location
   * <code>(x, y)</code>.  This offset can be used to read a sample value from
   * a {@link DataBuffer}.
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * 
   * @return The offset.
   * 
   * @see #getOffset(int, int, int)
   */
  public int getOffset(int x, int y)
  {
    return getOffset(x, y, 0);
  }

  /**
   * Returns the offset of the sample in band <code>b</code> for the pixel at
   * location <code>(x, y)</code>.  This offset can be used to read a sample
   * value from a {@link DataBuffer}.
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * @param b  the band index.
   * 
   * @return The offset.
   */
  public int getOffset(int x, int y, int b)
  {
    return bandOffsets[b] + pixelStride * x + scanlineStride * y;
  }

  /**
   * Returns the size in bits for each sample (one per band).  For this sample
   * model, each band has the same sample size and this is determined by the
   * data type for the sample model.
   * 
   * @return The sample sizes.
   * 
   * @see SampleModel#getDataType()
   */
  public final int[] getSampleSize()
  {
    int size = DataBuffer.getDataTypeSize(getDataType());
    int[] sizes = new int[numBands];

    java.util.Arrays.fill(sizes, size);
    return sizes;
  }

  /**
   * Returns the size in bits for the samples in the specified band.  In this
   * class, the sample size is the same for every band and is determined from 
   * the data type for the model.
   * 
   * @param band  the band index (ignored here).
   * 
   * @return The sample size in bits.
   * 
   * @see SampleModel#getDataType()
   */
  public final int getSampleSize(int band)
  {
    return DataBuffer.getDataTypeSize(getDataType());
  }

  /**
   * Returns the indices of the bank(s) in the {@link DataBuffer} used to 
   * store the samples for each band.  The returned array is a copy, so that
   * altering it will not impact the sample model.
   * 
   * @return The bank indices.
   */
  public final int[] getBankIndices()
  {
    return (int[]) bankIndices.clone();
  }

  /**
   * Returns the offsets to the first sample in each band.  The returned array
   * is a copy, so that altering it will not impact the sample model.
   * 
   * @return The offsets.
   */
  public final int[] getBandOffsets()
  {
    return (int[]) bandOffsets.clone();
  }

  /**
   * Returns the distance (in terms of element indices) between the sample for
   * one pixel and the corresponding sample for the equivalent pixel in the 
   * next row.  This is used in the calculation of the element offset for
   * retrieving samples from a {@link DataBuffer}.
   * 
   * @return The distance between pixel samples in consecutive rows.
   */
  public final int getScanlineStride()
  {
    return scanlineStride;
  }

  /**
   * Returns the distance (in terms of element indices) between the sample for 
   * one pixel and the corresponding sample for the next pixel in a row.  This 
   * is used in the calculation of the element offset for retrieving samples 
   * from a {@link DataBuffer}.
   * 
   * @return The distance between pixel samples in the same row.
   */
  public final int getPixelStride()
  {
    return pixelStride;
  }

  /**
   * Returns the number of data elements used to store the samples for one 
   * pixel.  In this model, this is the same as the number of bands.
   * 
   * @return The number of data elements used to store the samples for one 
   *   pixel.
   */
  public final int getNumDataElements()
  {
    return numBands;
  }

  /**
   * Returns the samples for the pixel at location <code>(x, y)</code> in
   * a primitive array (the array type is determined by the data type for 
   * this model).  The <code>obj</code> argument provides an option to supply
   * an existing array to hold the result, if this is <code>null</code> a new
   * array will be allocated.
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * @param obj  a primitive array that, if not <code>null</code>, will be 
   *   used to store and return the sample values.
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @return An array of sample values for the specified pixel.
   */
  public Object getDataElements(int x, int y, Object obj, DataBuffer data)
  {
    int type = getTransferType();
    int numDataEls = getNumDataElements();
    int offset = y * scanlineStride + x * pixelStride;
    switch (type)
      {
      case DataBuffer.TYPE_BYTE:
        byte[] bData;
        if (obj == null)
          bData = new byte[numDataEls];
        else
          bData = (byte[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            bData[i] = (byte) data.getElem(bankIndices[i],
                                           offset + bandOffsets[i]);
          }
        obj = bData;
        break;
      case DataBuffer.TYPE_SHORT:
      case DataBuffer.TYPE_USHORT:
        short[] sData;
        if (obj == null)
          sData = new short[numDataEls];
        else
          sData = (short[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            sData[i] = (short) data.getElem(bankIndices[i],
                                            offset + bandOffsets[i]);
          }
        obj = sData;
        break;
      case DataBuffer.TYPE_INT:
        int[] iData;
        if (obj == null)
          iData = new int[numDataEls];
        else
          iData = (int[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            iData[i] = data.getElem(bankIndices[i], offset + bandOffsets[i]);
          }
        obj = iData;
        break;
      case DataBuffer.TYPE_FLOAT:
        float[] fData;
        if (obj == null)
          fData = new float[numDataEls];
        else
          fData = (float[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            fData[i] = data.getElemFloat(bankIndices[i],
                                         offset + bandOffsets[i]);
          }
        obj = fData;
        break;
      case DataBuffer.TYPE_DOUBLE:
        double[] dData;
        if (obj == null)
          dData = new double[numDataEls];
        else
          dData = (double[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            dData[i] = data.getElemDouble(bankIndices[i],
                                          offset + bandOffsets[i]);
          }
        obj = dData;
        break;
      }
    return obj;
  }


  /**
   * Returns all the samples for the pixel at location <code>(x, y)</code>
   * stored in the specified data buffer.
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * @param iArray  an array that will be populated with the sample values and
   *   returned as the result.  The size of this array should be equal to the 
   *   number of bands in the model.  If the array is <code>null</code>, a new
   *   array is created.
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @return The samples for the specified pixel.
   * 
   * @see #setPixel(int, int, int[], DataBuffer)
   */
  public int[] getPixel(int x, int y, int[] iArray, DataBuffer data)
  {
    if (x < 0 || x >= width || y < 0 || y >= height)
      throw new ArrayIndexOutOfBoundsException("Pixel (" + x + ", " + y 
                                               + ") is out of bounds.");
    int offset = pixelStride * x + scanlineStride * y;
    if (iArray == null)
      iArray = new int[numBands];
    for (int b = 0; b < numBands; b++)
      {
        iArray[b] = data.getElem(bankIndices[b], offset + bandOffsets[b]);
      }
    return iArray;
  }

  /**
   * Returns the samples for all the pixels in a rectangular region.
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * @param w  the width.
   * @param h  the height.
   * @param iArray  an array that if non-<code>null</code> will be populated 
   *   with the sample values and returned as the result.
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @return The samples for all the pixels in the rectangle.
   */
  public int[] getPixels(int x, int y, int w, int h, int[] iArray,
                         DataBuffer data)
  {
    int offset = pixelStride * x + scanlineStride * y;
    if (iArray == null) 
      iArray = new int[numBands * w * h];
    int outOffset = 0;
    for (y = 0; y < h; y++)
      {
        int lineOffset = offset;
        for (x = 0; x < w; x++)
          {
            for (int b = 0; b < numBands; b++)
              {
                iArray[outOffset++] 
                    = data.getElem(bankIndices[b], lineOffset+bandOffsets[b]);
              }
            lineOffset += pixelStride;
          }
        offset += scanlineStride;
      }
    return iArray;
  }
 
  /**
   * Returns the sample for band <code>b</code> of the pixel at 
   * <code>(x, y)</code> that is stored in the specified data buffer.
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * @param b  the band index.
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @return The sample value.
   * 
   * @throws ArrayIndexOutOfBoundsException if <code>(x, y)</code> is outside 
   *     the bounds <code>[0, 0, width, height]</code>.
   *     
   * @see #setSample(int, int, int, int, DataBuffer)
   */
  public int getSample(int x, int y, int b, DataBuffer data)
  {
    if (x < 0 || x >= width || y < 0 || y >= height)
      throw new ArrayIndexOutOfBoundsException("Sample (" + x + ", " + y 
                                               + ") is out of bounds.");
    return data.getElem(bankIndices[b], getOffset(x, y, b));
  }

  /**
   * Sets the samples for the pixel at location <code>(x, y)</code> from the 
   * supplied primitive array (the array type must be consistent with the data 
   * type for this model).
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * @param obj  a primitive array containing the pixel's sample values.
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @see #setDataElements(int, int, Object, DataBuffer)
   */
  public void setDataElements(int x, int y, Object obj, DataBuffer data)
  {
    int type = getTransferType();
    int numDataEls = getNumDataElements();
    int offset = y * scanlineStride + x * pixelStride;
    switch (type)
      {
      case DataBuffer.TYPE_BYTE:
        byte[] bData = (byte[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            data.setElem(bankIndices[i], offset + bandOffsets[i],
                         ((int) bData[i]) & 0xFF);
          }
        break;
      case DataBuffer.TYPE_SHORT:
      case DataBuffer.TYPE_USHORT:
        short[] sData = (short[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            data.setElem(bankIndices[i], offset + bandOffsets[i],
                         ((int) sData[i]) & 0xFFFF);
          }
        break;
      case DataBuffer.TYPE_INT:
        int[] iData = (int[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            data.setElem(bankIndices[i], offset + bandOffsets[i], iData[i]);
          }
        break;
      case DataBuffer.TYPE_FLOAT:
        float[] fData = (float[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            data.setElemFloat(bankIndices[i], offset + bandOffsets[i],
                              fData[i]);
          }
        break;
      case DataBuffer.TYPE_DOUBLE:
        double[] dData = (double[]) obj;
        for (int i = 0; i < numDataEls; i++)
          {
            data.setElemDouble(bankIndices[i], offset + bandOffsets[i],
                               dData[i]);
          }
        break;
      }
  }
  
  /**
   * Sets the sample values for the pixel at location <code>(x, y)</code>
   * stored in the specified data buffer.
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * @param iArray  the pixel sample values (<code>null</code> not permitted).
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @see #getPixel(int, int, int[], DataBuffer)
   */
  public void setPixel(int x, int y, int[] iArray, DataBuffer data)
  {
    int offset = pixelStride * x + scanlineStride * y;
    for (int b = 0; b < numBands; b++)
      data.setElem(bankIndices[b], offset + bandOffsets[b], iArray[b]);
  }
    
  /**
   * Sets the sample value for band <code>b</code> of the pixel at location
   * <code>(x, y)</code> in the specified data buffer.
   * 
   * @param x  the x-coordinate.
   * @param y  the y-coordinate.
   * @param b  the band index.
   * @param s  the sample value.
   * @param data  the data buffer (<code>null</code> not permitted).
   * 
   * @see #getSample(int, int, int, DataBuffer)
   */
  public void setSample(int x, int y, int b, int s, DataBuffer data)
  {
    data.setElem(bankIndices[b], getOffset(x, y, b), s);
  }
  
  /**
   * Tests this sample model for equality with an arbitrary object.  Returns
   * <code>true</code> if and only if:
   * <ul>
   * <li><code>obj</code> is not <code>null</code>;</li>
   * <li><code>obj</code> is an instance of <code>ComponentSampleModel</code>;
   *   </li>
   * <li>both models have the same values for the <code>dataType</code>,
   *   <code>width</code>, <code>height</code>, <code>pixelStride</code>,
   *   <code>scanlineStride</code>, <code>bandOffsets</code> and
   *   <code>bankIndices</code> fields.</li>
   * </ul>
   * 
   * @param obj  the object to test (<code>null</code> permitted).
   * 
   * @return <code>true</code> if this sample model is equal to 
   *   <code>obj</code>, and <code>false</code> otherwise.
   */
  public boolean equals(Object obj)
  {
    if (obj == null)
      return false;
    if (! (obj instanceof ComponentSampleModel))
      return false;
    ComponentSampleModel that = (ComponentSampleModel) obj;
    if (this.dataType != that.dataType)
      return false;
    if (this.width != that.width)
      return false;
    if (this.height != that.height)
      return false;
    if (this.pixelStride != that.pixelStride)
      return false;
    if (this.scanlineStride != that.scanlineStride)
      return false;
    if (! Arrays.equals(this.bandOffsets, that.bandOffsets))
      return false;
    if (! Arrays.equals(this.bankIndices, that.bankIndices))
      return false;
    // couldn't find any difference, so...
    return true;
  }
  
  /**
   * Returns a hash code for this sample model.
   * 
   * @return The hash code.
   */
  public int hashCode()
  {
    // this computation is based on the method described in Chapter 3
    // of Joshua Bloch's Effective Java...
    int result = 17;
    result = 37 * result + dataType;
    result = 37 * result + width;
    result = 37 * result + height;
    result = 37 * result + pixelStride;
    result = 37 * result + scanlineStride;
    for (int i = 0; i < bandOffsets.length; i++)
      result = 37 * result + bandOffsets[i];
    for (int i = 0; i < bankIndices.length; i++)
      result = 37 * result + bankIndices[i];
    return result;
  }
}