Class StandardImageTiler

java.lang.Object
nom.tam.image.StandardImageTiler
All Implemented Interfaces:
ImageTiler
Direct Known Subclasses:
ImageData.ImageDataTiler
public abstract class StandardImageTiler extends Object implements ImageTiler
This class provides a subset of an N-dimensional image. Modified May 2, 2000 by T. McGlynn to permit tiles that go off the edge of the image.

  • Field Details

    • randomAccessFile

      private final RandomAccess randomAccessFile

    • fileOffset

      private final long fileOffset

    • dims

      private final int[] dims

    • base

      private final Class<?> base

  • Constructor Details

    • StandardImageTiler

      public StandardImageTiler(RandomAccess f, long fileOffset, int[] dims, Class<?> base)
      Create a tiler.
      Parameters:
      f - The random access device from which image data may be read. This may be null if the tile information is available from memory.
      fileOffset - The file offset within the RandomAccess device at which the data begins.
      dims - The actual dimensions of the image.
      base - The base class (should be a primitive type) of the image.

  • Method Details

    • getOffset

      public static long getOffset(int[] dims, int[] pos)
      Parameters:
      dims - The dimensions of the array.
      pos - The index requested.
      Returns:
      the offset of a given position.

    • incrementPosition

      protected static boolean incrementPosition(int[] start, int[] current, int[] lengths)
      Increment the offset within the position array. Note that we never look at the last index since we copy data a block at a time and not byte by byte.
      Parameters:
      start - The starting corner values.
      current - The current offsets.
      lengths - The desired dimensions of the subset.
      Returns:
      true if the current array was changed

    • fillFileData

      protected void fillFileData(Object output, long delta, int outputOffset, int segment) throws IOException
      File a tile segment from a file.
      Parameters:
      output - The output tile.
      delta - The offset from the beginning of the image in bytes.
      outputOffset - The index into the output array.
      segment - The number of elements to be read for this segment.
      Throws:
      IOException - if the underlying stream failed

    • fillMemData

      protected void fillMemData(Object data, int[] posits, int length, Object output, int outputOffset, int dim)
      Fill a single segment from memory. This routine is called recursively to handle multi-dimensional arrays. E.g., if data is three-dimensional, this will recurse two levels until we get a call with a single dimensional datum. At that point the appropriate data will be copied into the output.
      Parameters:
      data - The in-memory image data.
      posits - The current position for which data is requested.
      length - The size of the segments.
      output - The output tile.
      outputOffset - The current offset into the output tile.
      dim - The current dimension being

    • fillTile

      protected void fillTile(Object data, Object o, int[] newDims, int[] corners, int[] lengths) throws IOException
      Fill the subset.
      Parameters:
      data - The memory-resident data image. This may be null if the image is to be read from a file. This should be a multi-dimensional primitive array.
      o - The tile to be filled. This is a simple primitive array.
      newDims - The dimensions of the full image.
      corners - The indices of the corner of the image.
      lengths - The dimensions of the subset.
      Throws:
      IOException - if the underlying stream failed

    • getCompleteImage

      public Object getCompleteImage() throws IOException
      Read the entire image into a multidimensional array.
      Specified by:
      getCompleteImage in interface ImageTiler
      Throws:
      IOException - if the underlying stream failed

    • getMemoryImage

      protected abstract Object getMemoryImage()
      See if we can get the image data from memory. This may be overridden by other classes, notably in nom.tam.fits.ImageData.
      Returns:
      the image data

    • getTile

      public Object getTile(int[] corners, int[] lengths) throws IOException
      Get a subset of the image. An image tile is returned as a one-dimensional array although the image will normally be multi-dimensional.
      Specified by:
      getTile in interface ImageTiler
      Parameters:
      corners - The starting corner (using 0 as the start) for the image.
      lengths - The length requested in each dimension.
      Throws:
      IOException - if the underlying stream failed

    • getTile

      public void getTile(Object outArray, int[] corners, int[] lengths) throws IOException
      Get a tile, filling in a prespecified array. This version does not check that the user hase entered a valid set of corner and length arrays. ensure that out matches the length implied by the lengths array.
      Specified by:
      getTile in interface ImageTiler
      Parameters:
      outArray - The output tile array. A one-dimensional array. Data not within the valid limits of the image will be left unchanged. The length of this array should be the product of lengths.
      corners - The corners of the tile.
      lengths - The dimensions of the tile.
      Throws:
      IOException - if the underlying stream failed