javax.imageio.spi.ImageWriterSpi — clojure-interop/javax.imageio 1.0.5

The service provider interface (SPI) for ImageWriters. For more information on service provider classes, see the class comment for the IIORegistry class.

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.

*-standard-output-type clj

Static Constant.

Deprecated. Instead of using this field, directly create the equivalent array { ImageOutputStream.class }.

type: java.lang.Class[]

->image-writer-spi clj

(->image-writer-spi vendor-name
                    version
                    names
                    suffixes
                    mime-types
                    writer-class-name
                    output-types
                    reader-spi-names
                    supports-standard-stream-metadata-format
                    native-stream-metadata-format-name
                    native-stream-metadata-format-class-name
                    extra-stream-metadata-format-names
                    extra-stream-metadata-format-class-names
                    supports-standard-image-metadata-format
                    native-image-metadata-format-name
                    native-image-metadata-format-class-name
                    extra-image-metadata-format-names
                    extra-image-metadata-format-class-names)

Constructor.

Constructs an ImageWriterSpi with a given set of values.

vendor-name - the vendor name, as a non-null String. - java.lang.String version - a version identifier, as a non-null String. - java.lang.String names - a non-null array of Strings indicating the format names. At least one entry must be present. - java.lang.String[] suffixes - an array of Strings indicating the common file suffixes. If no suffixes are defined, null should be supplied. An array of length 0 will be normalized to null. - java.lang.String[] mime-types - an array of Strings indicating the format's MIME types. If no suffixes are defined, null should be supplied. An array of length 0 will be normalized to null. - java.lang.String[] writer-class-name - the fully-qualified name of the associated ImageWriterSpi class, as a non-null String. - java.lang.String output-types - an array of Class objects of length at least 1 indicating the legal output types. - java.lang.Class[] reader-spi-names - an array Strings of length at least 1 naming the classes of all associated ImageReaders, or null. An array of length 0 is normalized to null. - java.lang.String[] supports-standard-stream-metadata-format - a boolean that indicates whether a stream metadata object can use trees described by the standard metadata format. - boolean native-stream-metadata-format-name - a String, or null, to be returned from getNativeStreamMetadataFormatName. - java.lang.String native-stream-metadata-format-class-name - a String, or null, to be used to instantiate a metadata format object to be returned from getNativeStreamMetadataFormat. - java.lang.String extra-stream-metadata-format-names - an array of Strings, or null, to be returned from getExtraStreamMetadataFormatNames. An array of length 0 is normalized to null. - java.lang.String[] extra-stream-metadata-format-class-names - an array of Strings, or null, to be used to instantiate a metadata format object to be returned from getStreamMetadataFormat. An array of length 0 is normalized to null. - java.lang.String[] supports-standard-image-metadata-format - a boolean that indicates whether an image metadata object can use trees described by the standard metadata format. - boolean native-image-metadata-format-name - a String, or null, to be returned from getNativeImageMetadataFormatName. - java.lang.String native-image-metadata-format-class-name - a String, or null, to be used to instantiate a metadata format object to be returned from getNativeImageMetadataFormat. - java.lang.String extra-image-metadata-format-names - an array of Strings to be returned from getExtraImageMetadataFormatNames. An array of length 0 is normalized to null. - java.lang.String[] extra-image-metadata-format-class-names - an array of Strings, or null, to be used to instantiate a metadata format object to be returned from getImageMetadataFormat. An array of length 0 is normalized to null. - java.lang.String[]

throws: java.lang.IllegalArgumentException - if outputTypes is null or has length 0.

can-encode-image? clj

(can-encode-image? this type)

Returns true if the ImageWriter implementation associated with this service provider is able to encode an image with the given layout. The layout (i.e., the image's SampleModel and ColorModel) is described by an ImageTypeSpecifier object.

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.

type - an ImageTypeSpecifier specifying the layout of the image to be written. - javax.imageio.ImageTypeSpecifier

returns: true if this writer is likely to be able to encode images with the given layout. - boolean

throws: java.lang.IllegalArgumentException - if type is null.

create-writer-instance clj

(create-writer-instance this)

(create-writer-instance this extension)

Returns an instance of the ImageWriter implementation associated with this service provider. The returned object will initially be in an initial state as if its reset method had been called.

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).

extension - a plug-in specific extension object, which may be null. - java.lang.Object

returns: an ImageWriter instance. - javax.imageio.ImageWriter

throws: java.io.IOException - if the attempt to instantiate the writer fails.

format-lossless? clj

(format-lossless? this)

Returns true if the format that this writer outputs preserves pixel data bit-accurately. The default implementation returns true.

returns: true if the format preserves full pixel accuracy. - boolean

get-image-reader-spi-names clj

(get-image-reader-spi-names this)

Returns an array of Strings containing all the fully qualified names of all the ImageReaderSpi classes that can understand the internal metadata representation used by the ImageWriter associated with this service provider, or null if there are no such ImageReaders specified. If a non-null value is returned, it must have non-zero length.

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.

returns: an array of Strings of length at least 1 containing names of ImageReaderSpis, or null. - java.lang.String[]

get-output-types clj

(get-output-types this)

Returns an array of Class objects indicating what types of objects may be used as arguments to the writer's setOutput method.

For most writers, which only output to an ImageOutputStream, a single-element array containing ImageOutputStream.class should be returned.

returns: a non-null array of Classobjects of length at least 1. - java.lang.Class[]

own-writer? clj

(own-writer? this writer)

Returns true if the ImageWriter object passed in is an instance of the ImageWriter associated with this service provider.

writer - an ImageWriter instance. - javax.imageio.ImageWriter

returns: true if writer is recognized - boolean

throws: java.lang.IllegalArgumentException - if writer is null.