Module org.apache.sis.feature
Package org.apache.sis.coverage.grid

Class BufferedGridCoverage

Object
BandedCoverage
GridCoverage
BufferedGridCoverage
public class BufferedGridCoverage extends GridCoverage
Basic access to grid data values backed by a n-dimensional Data­Buffer. Those data can be shown as an untiled Rendered­Image. Images are created when render(Grid­Extent) is invoked instead of at construction time. This delayed construction makes this class better suited to n-dimensional grids because those grids cannot be wrapped into a single Rendered­Image.

The number of bands is determined by the number of Sample­Dimensions specified at construction time. The number of banks is either 1 or the number of bands.

  • If the number of banks is 1, all data are packed in a single array with band indices varying fastest, then column indices (x), then row indices (y), then other dimensions.
  • If the number of banks is greater than 1, then each band is stored in a separated array. In each array, sample values are stored with column indices (x) varying fastest, then row indices (y), then other dimensions. In the two-dimensional case, this layout is also known as row-major.
The number of cells in each dimension is specified by the Grid­Extent of the geometry given at construction time. By default the extent size in the two first dimensions will define the image width and height, but different dimensions may be used depending on which dimensions are identified as the subspace dimensions.

Restrictions

This class expects all data to reside in-memory and does not support tiling. Pixels are stored in a row-major fashion with all bands in a single array or one array per band. By contrast, Grid­Coverage2D allows more flexibility in data layout and supports tiling with data loaded or computed on-the-fly, but is restricted to two-dimensional images (which may be slices in a n-dimensional grid).
Since:
1.1

  • Field Details

    • data

      protected final DataBuffer data
      The sample values, potentially multi-banded. The bands may be stored either in a single bank (pixel interleaved image) or in different banks (banded image). This class detects automatically which of those two sample models is used when render(Grid­Extent) is invoked.

      Sample values in this buffer shall not be packed.

  • Constructor Details

    • BufferedGridCoverage

      public BufferedGridCoverage(GridGeometry domain, List<? extends SampleDimension> range, DataBuffer data)
      Constructs a grid coverage using the specified grid geometry, sample dimensions and data buffer. This method stores the given buffer by reference (no copy). The bands in the given buffer can be stored either in a single bank (pixel interleaved image) or in different banks (banded image). This class detects automatically which of those two sample models is used (see class javadoc for more information).

      Note that Data­Buffer does not contain any information about image size. Consequently, render(Grid­Extent) depends on the domain Grid­Extent, which must be accurate. If the extent size does not reflect accurately the image size, then the image will not be rendered properly.

      Parameters:
      domain - the grid extent, CRS and conversion from cell indices to CRS.
      range - sample dimensions for each image band.
      data - the sample values, potentially multi-banded.
      Throws:
      Null­Pointer­Exception - if an argument is null.
      Illegal­Argument­Exception - if the data buffer has an incompatible number of banks.
      Illegal­Grid­Geometry­Exception - if the grid extent is larger than the data buffer capacity.
      Arithmetic­Exception - if the number of cells is larger than 64 bits integer capacity.

    • BufferedGridCoverage

      public BufferedGridCoverage(GridGeometry grid, List<? extends SampleDimension> bands, int dataType)
      Constructs a grid coverage using the specified grid geometry, sample dimensions and data type. This constructor creates a single-bank Data­Buffer (pixel interleaved sample model) with all sample values initialized to zero.
      Parameters:
      grid - the grid extent, CRS and conversion from cell indices to CRS.
      bands - sample dimensions for each image band.
      data­Type - one of Data­Buffer​.TYPE_* constants, the native data type used to store the coverage values.
      Throws:
      Arithmetic­Exception - if the grid size is too large.

  • Method Details

    • evaluator

      public GridCoverage.Evaluator evaluator()
      Creates a new function for computing or interpolating sample values at given locations.

      Multi-threading

      Evaluators are not thread-safe. For computing sample values concurrently, a new Grid­Coverage​.Evaluator instance should be created for each thread.
      Overrides:
      evaluator in class Grid­Coverage
      Returns:
      a new function for computing or interpolating sample values.

    • render

      public RenderedImage render(GridExtent sliceExtent)
      Returns a two-dimensional slice of grid data as a rendered image. This method returns a view; sample values are not copied.

      The default implementation prepares an Image­Renderer, then invokes configure(Image­Renderer) for allowing subclasses to complete the renderer configuration before to create the image.

      Specified by:
      render in class Grid­Coverage
      Parameters:
      slice­Extent - a subspace of this grid coverage where all dimensions except two have a size of 1 cell. May be null if this grid coverage has only two dimensions with a size greater than 1 cell.
      Returns:
      the grid slice as a rendered image.

    • configure

      protected void configure(ImageRenderer renderer)
      Invoked by the default implementation of render(Grid­Extent) for completing the renderer configuration before to create an image. The default implementation does nothing.

      Some examples of methods that subclasses may want to use are:

      Parameters:
      renderer - the renderer to configure before to create an image.
      Since:
      1.3