Java Doc for ImageWriterSpi.java in  » 6.0-JDK-Core » image » javax » imageio » spi » Java Source Code / Java DocumentationJava Source Code and Java Documentation

Each ImageWriterSpi provides several types of information about the ImageWriter class with which it is associated.

The name of the vendor who defined the SPI class and a brief description of the class are available via the getVendorName, getDescription, and getVersion methods. These methods may be internationalized to provide locale-specific output. These methods are intended mainly to provide short, human-writable information that might be used to organize a pop-up menu or other list.

Lists of format names, file suffixes, and MIME types associated with the service may be obtained by means of the getFormatNames, getFileSuffixes, and getMIMEType methods. These methods may be used to identify candidate ImageWriters for writing a particular file or stream based on manual format selection, file naming, or MIME associations.

A more reliable way to determine which ImageWriters are likely to be able to parse a particular data stream is provided by the canEncodeImage method. This methods allows the service provider to inspect the actual image contents.

Finally, an instance of the ImageWriter class associated with this service provider may be obtained by calling the createWriterInstance method. Any heavyweight initialization, such as the loading of native libraries or creation of large tables, should be deferred at least until the first invocation of this method.
See Also:   IIORegistry
See Also:   javax.imageio.ImageTypeSpecifier
See Also:   javax.imageio.ImageWriter
version:
   0.5

An Object may be supplied to the plug-in at construction time.

A return value of true is not an absolute guarantee of successful encoding; the encoding process may still produce errors due to factors such as I/O errors, inconsistent or malformed data structures, etc. The intent is that a reasonable inspection of the basic structure of the image be performed in order to determine if it is within the scope of the encoding format. For example, a service provider for a format that can only encode greyscale would return false if handed an RGB BufferedImage. Similarly, a service provider for a format that can encode 8-bit RGB imagery might refuse to encode an image with an associated alpha channel.

Different ImageWriters, and thus service providers, may choose to be more or less strict. For example, they might accept an image with premultiplied alpha even though it will have to be divided out of each pixel, at some loss of precision, in order to be stored.
Parameters:
  type - an ImageTypeSpecifier specifying thelayout of the image to be written. true if this writer is likely to be ableto encode images with the given layout.
exception:
  IllegalArgumentException - if typeis null.

See the discussion for canEncodeImage(ImageTypeSpecifier) for information on the semantics of this method.
Parameters:
  im - an instance of RenderedImage to be encoded. true if this writer is likely to be ableto encode this image.
exception:
  IllegalArgumentException - if imis null.

The default implementation simply returns createWriterInstance(null). an ImageWriter instance.
exception:
  IOException - if an error occurs during loading, or initialization of the writer class, or during instantiationor initialization of the writer object.

An Object may be supplied to the plug-in at construction time. The nature of the object is entirely plug-in specific.

Typically, a plug-in will implement this method using code such as return new MyImageWriter(this).
Parameters:
  extension - a plug-in specific extension object, which maybe null. an ImageWriter instance.
exception:
  IOException - if the attempt to instantiatethe writer fails.
exception:
  IllegalArgumentException - if theImageWriter's constructor throws anIllegalArgumentException to indicate that theextension object is unsuitable.

The first item in the array must be the name of the service provider for the "preferred" reader, as it will be used to instantiate the ImageReader returned by ImageIO.getImageReader(ImageWriter).

This mechanism may be used to obtain ImageReaders that will generated non-pixel meta-data (see IIOExtraDataInfo) in a structure understood by an ImageWriter. By reading the image and obtaining this data from one of the ImageReaders obtained with this method and passing it on to the ImageWriter, a client program can read an image, modify it in some way, and write it back out preserving all meta-data, without having to understand anything about the internal structure of the meta-data, or even about the image format. an array of Strings of length at least 1containing names of ImageReaderSpis, ornull.
See Also:   javax.imageio.ImageIO.getImageReader(ImageWriter)
See Also:   ImageReaderSpi.getImageWriterSpiNames

For most writers, which only output to an ImageOutputStream, a single-element array containing ImageOutputStream.class should be returned. a non-null array ofClassobjects of length at least 1.