javax.media.jai.tilecodec
Interface TileDecoder

All Known Implementing Classes:
TileDecoderImpl

public interface TileDecoder

An interface describing objects that transform an InputStream into a Raster.

This interface is designed to allow decoding of formats that include information about the format of the encoded tile as well as ones that don't. In order to create a Raster, at the very least, a Point specifying the top left corner of the Raster, a SampleModel specifying the data layout and a DataBuffer with the decoded pixel data are needed. The DataBuffer can be created from the information from the SampleModel and the decoded data. Therefore the absolute minimum information that is required in order to create a Raster on decoding (aside from the decoded data itself) is a Point specifying the top left corner of the Raster and a SampleModel specifying the data layout. The formats that do include this information should return true from the includesSampleModelInfo() and includesLocationInfo() from the associated TileCodecDescriptor if they include information needed to create a SampleModel and information needed to create the Point respectively. The formats that do not include this information in the encoded stream should return false. The TileCodecParameterList providing the decoding parameters will in this case be expected to contain a parameter named "sampleModel" with a non-null SampleModel as its value. This SampleModel will be used to create the decoded Raster.

The formats that return true from includesSampleModelInfo() should use the decode() method to cause the decoding to take place, the ones that return false should specify the Point location to the decoding process by using the decode(Point) method. Similarly the SampleModel must be specified as a parameter with a non-null value on the TileCodecParameterList passed to this TileDecoder if includesSampleModelInfo() returns false. It is expected that the SampleModel specified in the parameter list is the SampleModel of the encoded tiles, in order to get a decoded Raster that is equivalent to the one encoded. If the SampleModel specified through the parameter list is different from those of the encoded tiles, the result of decoding is undefined.

If includesSampleModelInfo() returns true, the SampleModel (if present) on the TileCodecParameterList is ignored.

Since:
JAI 1.1
See Also:
TileCodecDescriptor, TileEncoder

Method Summary
 Raster decode()
          Returns a Raster that contains the decoded contents of the InputStream associated with this TileDecoder.
 Raster decode(Point location)
          Returns a Raster that contains the decoded contents of the InputStream associated with this TileDecoder.
 TileCodecParameterList getDecodeParameterList()
          Returns the current parameters as an instance of the TileCodecParameterList interface.
 String getFormatName()
          Returns the name of the format.
 InputStream getInputStream()
          Returns the InputStream containing the encoded data.
 

Method Detail

getFormatName

public String getFormatName()
Returns the name of the format.


getDecodeParameterList

public TileCodecParameterList getDecodeParameterList()
Returns the current parameters as an instance of the TileCodecParameterList interface.


getInputStream

public InputStream getInputStream()
Returns the InputStream containing the encoded data.


decode

public Raster decode()
              throws IOException
Returns a Raster that contains the decoded contents of the InputStream associated with this TileDecoder.

This method can perform the decoding correctly only when includesLocationInfo() returns true.

Throws:
IOException - if an I/O error occurs while reading from the associated InputStream.
IllegalArgumentException - if the associated TileCodecDescriptor's includesLocationInfo() returns false.

decode

public Raster decode(Point location)
              throws IOException
Returns a Raster that contains the decoded contents of the InputStream associated with this TileDecoder.

This method should be used when includesLocationInfo() returns false. If includesLocationInfo() returns true, then the supplied Point is ignored.

Parameters:
location - The Point specifying the upper left corner of the Raster.
Throws:
IOException - if an I/O error occurs while reading from the associated InputStream.
IllegalArgumentException - if includesLocationInfo() returns false and location is null.