Activates the installed IIOParamController for this IIOParam object and returns the resulting value.

  Activates the installed IIOParamController for this IIOParam object and returns the resulting value. When this method returns true, all values for this IIOParam object will be ready for the next read or write operation. If false is returned, no settings in this object will have been disturbed (i.e., the user canceled the operation).

Ordinarily, the controller will be a GUI providing a user interface for a subclass of IIOParam for a particular plug-in. Controllers need not be GUIs, however.
Returns: true if the controller completed normally.
Throws:
- IllegalStateException - if there is no controller currently installed.
See Also: IIOParamController, IIOParam.setController(IIOParamController), IIOParam.getController(), IIOParam.getDefaultController(), IIOParam.hasController(),

  Returns whatever IIOParamController is currently installed.

  Returns whatever IIOParamController is currently
installed. This could be the default if there is one,
null, or the argument of the most recent call
to setController.
Returns: the currently installed IIOParamController, or null.
See Also: IIOParamController, IIOParam.setController(javax.imageio.IIOParamController), IIOParam.getDefaultController(), IIOParam.hasController(), IIOParam.activateController(),

  Returns the default IIOParamController, if there is one, regardless of the currently installed controller.

  Returns the default IIOParamController, if there
is one, regardless of the currently installed controller. If
there is no default controller, returns null.
Returns: the default IIOParamController, or null.
See Also: IIOParamController, IIOParam.setController(IIOParamController), IIOParam.getController(), IIOParam.hasController(), IIOParam.activateController(),

  Returns the offset in the destination image at which pixels are to be placed.

  Returns the offset in the destination image at which pixels are to be placed.

If setDestinationOffsets has not been called, a Point with zero X and Y values is returned (which is the correct value).
Returns: the destination offset as a Point.
See Also: IIOParam.setDestinationOffset(java.awt.Point),

  Returns the type of image to be returned by the read, if one was set by a call to setDestination(ImageTypeSpecifier), as an ImageTypeSpecifier.

  Returns the type of image to be returned by the read, if one
was set by a call to
setDestination(ImageTypeSpecifier), as an
ImageTypeSpecifier. If none was set,
null is returned.
Returns: an ImageTypeSpecifier describing the destination type, or null.
See Also: IIOParam.setDestinationType(javax.imageio.ImageTypeSpecifier),

  Returns the set of of source bands to be used.

  Returns the set of of source bands to be used. The returned value is that set by the most recent call to setSourceBands, or null if there have been no calls to setSourceBands.

Semantically, the array returned is a copy; changes to array contents subsequent to this call have no effect on this IIOParam.
Returns: the set of source bands to be used, or null.
See Also: IIOParam.setSourceBands(int[]),

  Returns the source region to be used.

  Returns the source region to be used. The returned value is
that set by the most recent call to
setSourceRegion, and will be null if
there is no region set.
Returns: the source region of interest as a Rectangle, or null.
See Also: IIOParam.setSourceRegion(java.awt.Rectangle),

  Returns the number of source columns to advance for each pixel.

  Returns the number of source columns to advance for each pixel.

If setSourceSubsampling has not been called, 1 is returned (which is the correct value).
Returns: the source subsampling X period.
See Also: IIOParam.setSourceSubsampling(int, int, int, int), IIOParam.getSourceYSubsampling(),

  Returns the number of rows to advance for each pixel.

  Returns the number of rows to advance for each pixel.

If setSourceSubsampling has not been called, 1 is returned (which is the correct value).
Returns: the source subsampling Y period.
See Also: IIOParam.setSourceSubsampling(int, int, int, int), IIOParam.getSourceXSubsampling(),

  Returns the horizontal offset of the subsampling grid.

  Returns the horizontal offset of the subsampling grid.

If setSourceSubsampling has not been called, 0 is returned (which is the correct value).
Returns: the source subsampling grid X offset.
See Also: IIOParam.setSourceSubsampling(int, int, int, int), IIOParam.getSubsamplingYOffset(),

  Returns the vertical offset of the subsampling grid.

  Returns the vertical offset of the subsampling grid.

If setSourceSubsampling has not been called, 0 is returned (which is the correct value).
Returns: the source subsampling grid Y offset.
See Also: IIOParam.setSourceSubsampling(int, int, int, int), IIOParam.getSubsamplingXOffset(),

  Returns true if there is a controller installed for this IIOParam object.

  Returns true if there is a controller installed
for this IIOParam object. This will return
true if getController would not
return null.
Returns: true if a controller is installed.
See Also: IIOParamController, IIOParam.setController(IIOParamController), IIOParam.getController(), IIOParam.getDefaultController(), IIOParam.activateController(),

  Sets the IIOParamController to be used to provide settings for this IIOParam object when the activateController method is called, overriding any default controller.

  Sets the IIOParamController to be used
to provide settings for this IIOParam
object when the activateController method
is called, overriding any default controller. If the
argument is null, no controller will be
used, including any default. To restore the default, use
setController(getDefaultController()).
Parameters:
- controller - An appropriate IIOParamController, or null.
See Also: IIOParamController, IIOParam.getController(), IIOParam.getDefaultController(), IIOParam.hasController(), IIOParam.activateController(),

  Specifies the offset in the destination image at which future decoded pixels are to be placed, when reading, or where a region will be written, when writing.

  Specifies the offset in the destination image at which future decoded pixels are to be placed, when reading, or where a region will be written, when writing.

When reading, the region to be written within the destination BufferedImage will start at this offset and have a width and height determined by the source region of interest, the subsampling parameters, and the destination bounds.

Normal writes are not affected by this method, only writes performed using ImageWriter.replacePixels. For such writes, the offset specified is within the output stream image whose pixels are being modified.

There is no unsetDestinationOffset method; simply call setDestinationOffset(new Point(0, 0)) to restore default values.
Parameters:
- destinationOffset - the offset in the destination, as a Point.
Throws:
- IllegalArgumentException - if destinationOffset is null.
See Also: IIOParam.getDestinationOffset(), ImageWriter.replacePixels(java.awt.image.RenderedImage, javax.imageio.ImageWriteParam),

  Sets the indices of the source bands to be used.

  Sets the indices of the source bands to be used. Duplicate indices are not allowed.

A null value indicates that all source bands will be used.

At the time of reading, an IllegalArgumentException will be thrown by the reader or writer if a value larger than the largest available source band index has been specified or if the number of source bands and destination bands to be used differ. The ImageReader.checkReadParamBandSettings method may be used to automate this test.

Semantically, a copy is made of the array; changes to the array contents subsequent to this call have no effect on this IIOParam.
Parameters:
- sourceBands - an array of integer band indices to be used.
Throws:
- IllegalArgumentException - if sourceBands contains a negative or duplicate value.
See Also: IIOParam.getSourceBands(), ImageReadParam.setDestinationBands(int[]), ImageReader.checkReadParamBandSettings(javax.imageio.ImageReadParam, int, int),

  Sets the source region of interest.

  Sets the source region of interest. The region of interest is described as a rectangle, with the upper-left corner of the source image as pixel (0, 0) and increasing values down and to the right. The actual number of pixels used will depend on the subsampling factors set by setSourceSubsampling. If subsampling has been set such that this number is zero, an IllegalStateException will be thrown.

The source region of interest specified by this method will be clipped as needed to fit within the source bounds, as well as the destination offsets, width, and height at the time of actual I/O.

A value of null for sourceRegion will remove any region specification, causing the entire image to be used.
Parameters:
- sourceRegion - a Rectangle specifying the source region of interest, or null.
Throws:
- IllegalArgumentException - if sourceRegion is non-null and either sourceRegion.x or sourceRegion.y is negative.
- IllegalArgumentException - if sourceRegion is non-null and either sourceRegion.width or sourceRegion.height is negative or 0.
- IllegalStateException - if subsampling is such that this region will have a subsampled width or height of zero.
See Also: IIOParam.getSourceRegion(), IIOParam.setSourceSubsampling(int, int, int, int), IIOParam.setDestinationOffset(java.awt.Point), IIOParam.getDestinationOffset(),

  Specifies a decimation subsampling to apply on I/O.

  Specifies a decimation subsampling to apply on I/O. The sourceXSubsampling and sourceYSubsampling parameters specify the subsampling period (i.e., the number of rows and columns to advance after every source pixel). Specifically, a period of 1 will use every row or column; a period of 2 will use every other row or column. The subsamplingXOffset and subsamplingYOffset parameters specify an offset from the region (or image) origin for the first subsampled pixel. Adjusting the origin of the subsample grid is useful for avoiding seams when subsampling a very large source image into destination regions that will be assembled into a complete subsampled image. Most users will want to simply leave these parameters at 0.

The number of pixels and scanlines to be used are calculated as follows.

The number of subsampled pixels in a scanline is given by

truncate[(width - subsamplingXOffset + sourceXSubsampling - 1) / sourceXSubsampling].

If the region is such that this width is zero, an IllegalStateException is thrown.

The number of scanlines to be used can be computed similarly.

The ability to set the subsampling grid to start somewhere other than the source region origin is useful if the region is being used to create subsampled tiles of a large image, where the tile width and height are not multiples of the subsampling periods. If the subsampling grid does not remain consistent from tile to tile, there will be artifacts at the tile boundaries. By adjusting the subsampling grid offset for each tile to compensate, these artifacts can be avoided. The tradeoff is that in order to avoid these artifacts, the tiles are not all the same size. The grid offset to use in this case is given by:
grid offset = [period - (region offset modulo period)] modulo period)

If either sourceXSubsampling or sourceYSubsampling is 0 or negative, an IllegalArgumentException will be thrown.

If either subsamplingXOffset or subsamplingYOffset is negative or greater than or equal to the corresponding period, an IllegalArgumentException will be thrown.

There is no unsetSourceSubsampling method; simply call setSourceSubsampling(1, 1, 0, 0) to restore default values.
Parameters:
- sourceXSubsampling - the number of columns to advance between pixels.
- sourceYSubsampling - the number of rows to advance between pixels.
- subsamplingXOffset - the horizontal offset of the first subsample within the region, or within the image if no region is set.
- subsamplingYOffset - the horizontal offset of the first subsample within the region, or within the image if no region is set.
Throws:
- IllegalArgumentException - if either period is negative or 0, or if either grid offset is negative or greater than the corresponding period.
- IllegalStateException - if the source region is such that the subsampled output would contain no pixels.