jj2000.j2k.image

Interface BlkImgDataSrc

All Superinterfaces:

ImgData

All Known Implementing Classes:

ForwCompTransf, ImgDataConverter, ImgDataJoiner, ImgReader, ImgReaderPGM, InvCompTransf, InverseWT, InvWTFull, RenderedImageSrc, Tiler

public interface BlkImgDataSrc
extends ImgData

This interface defines the methods to transfer image data in blocks, without following any particular order (random access). This interface does not define the methods to access the image characteristics, such as width, height, number of components, tiles, etc., or to change the current tile. That is provided by other interfaces such as ImgData.

This interface has the notion of a current tile. All data, coordinates and dimensions are always relative to the current tile. If there is only one tile then it is equivalent as having no tiles.

A block of requested data may never cross tile boundaries. This should be enforced by the implementing class, or the source of image data.

This interface defines the methods that can be used to retrieve image data. Implementing classes need not buffer all the image data, they can ask their source to load the data they need.

See Also:

ImgData

Method Summary

Modifier and Type	Method and Description
DataBlk	getCompData(DataBlk blk, int c) Returns, in the blk argument, a block of image data containing the specifed rectangular area, in the specified component.
int	getFixedPoint(int c) Returns the position of the fixed point in the specified component, or equivalently the number of fractional bits.
DataBlk	getInternCompData(DataBlk blk, int c) Returns, in the blk argument, a block of image data containing the specifed rectangular area, in the specified component.

Methods inherited from interface jj2000.j2k.image.ImgData

getCompImgHeight, getCompImgWidth, getCompSubsX, getCompSubsY, getCompULX, getCompULY, getImgHeight, getImgULX, getImgULY, getImgWidth, getNomRangeBits, getNomTileHeight, getNomTileWidth, getNumComps, getNumTiles, getNumTiles, getTile, getTileCompHeight, getTileCompWidth, getTileHeight, getTileIdx, getTilePartULX, getTilePartULY, getTileWidth, nextTile, setTile

Method Detail

getFixedPoint

int getFixedPoint(int c)

Returns the position of the fixed point in the specified component, or equivalently the number of fractional bits. This is the position of the least significant integral (i.e. non-fractional) bit, which is equivalent to the number of fractional bits. For instance, for fixed-point values with 2 fractional bits, 2 is returned. For floating-point data this value does not apply and 0 should be returned. Position 0 is the position of the least significant bit in the data.

Parameters:

c - The index of the component.

Returns:

The position of the fixed-point, which is the same as the number of fractional bits. For floating-point data 0 is returned.

getInternCompData

DataBlk getInternCompData(DataBlk blk,
                          int c)

Returns, in the blk argument, a block of image data containing the specifed rectangular area, in the specified component. The data is returned, as a reference to the internal data, if any, instead of as a copy, therefore the returned data should not be modified.

The rectangular area to return is specified by the 'ulx', 'uly', 'w' and 'h' members of the 'blk' argument, relative to the current tile. These members are not modified by this method. The 'offset' and 'scanw' of the returned data can be arbitrary. See the 'DataBlk' class.

This method, in general, is more efficient than the 'getCompData()' method since it may not copy the data. However if the array of returned data is to be modified by the caller then the other method is probably preferable.

If possible, the data in the returned 'DataBlk' should be the internal data itself, instead of a copy, in order to increase the data transfer efficiency. However, this depends on the particular implementation (it may be more convenient to just return a copy of the data). This is the reason why the returned data should not be modified.

If the data array in blk is null, then a new one is created if necessary. The implementation of this interface may choose to return the same array or a new one, depending on what is more efficient. Therefore, the data array in blk prior to the method call should not be considered to contain the returned data, a new array may have been created. Instead, get the array from blk after the method has returned.

The returned data may have its 'progressive' attribute set. In this case the returned data is only an approximation of the "final" data.

Parameters:

blk - Its coordinates and dimensions specify the area to return, relative to the current tile. Some fields in this object are modified to return the data.

c - The index of the component from which to get the data.

Returns:

The requested DataBlk

See Also:

getCompData(jj2000.j2k.image.DataBlk, int)

getCompData

DataBlk getCompData(DataBlk blk,
                    int c)

Returns, in the blk argument, a block of image data containing the specifed rectangular area, in the specified component. The data is returned, as a copy of the internal data, therefore the returned data can be modified "in place".

The rectangular area to return is specified by the 'ulx', 'uly', 'w' and 'h' members of the 'blk' argument, relative to the current tile. These members are not modified by this method. The 'offset' of the returned data is 0, and the 'scanw' is the same as the block's width. See the 'DataBlk' class.

This method, in general, is less efficient than the 'getInternCompData()' method since, in general, it copies the data. However if the array of returned data is to be modified by the caller then this method is preferable.

If the data array in 'blk' is 'null', then a new one is created. If the data array is not 'null' then it is reused, and it must be large enough to contain the block's data. Otherwise an 'ArrayStoreException' or an 'IndexOutOfBoundsException' is thrown by the Java system.

The returned data may have its 'progressive' attribute set. In this case the returned data is only an approximation of the "final" data.

Parameters:

blk - Its coordinates and dimensions specify the area to return, relative to the current tile. If it contains a non-null data array, then it must be large enough. If it contains a null data array a new one is created. Some fields in this object are modified to return the data.

c - The index of the component from which to get the data.

See Also:

getInternCompData(jj2000.j2k.image.DataBlk, int)