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

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

Each ImageReaderSpi provides several types of information about the ImageReader 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-readable 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 getMIMETypes methods. These methods may be used to identify candidate ImageReaders for decoding a particular file or stream based on manual format selection, file naming, or MIME associations (for example, when accessing a file over HTTP or as an email attachment).

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

Finally, an instance of the ImageReader class associated with this service provider may be obtained by calling the createReaderInstance 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-input-type clj

Static Constant.

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

type: java.lang.Class[]

->image-reader-spi clj

(->image-reader-spi vendor-name
                    version
                    names
                    suffixes
                    mime-types
                    reader-class-name
                    input-types
                    writer-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 ImageReaderSpi 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 MIME types are defined, null should be supplied. An array of length 0 will be normalized to null. - java.lang.String[] reader-class-name - the fully-qualified name of the associated ImageReader class, as a non-null String. - java.lang.String input-types - a non-null array of Class objects of length at least 1 indicating the legal input types. - java.lang.Class[] writer-spi-names - an array Strings naming the classes of all associated ImageWriters, 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 inputTypes is null or has length 0.

can-decode-input? clj

(can-decode-input? this source)

Returns true if the supplied source object appears to be of the format supported by this reader. Returning true from this method does not guarantee that reading will succeed, only that there appears to be a reasonable chance of success based on a brief inspection of the stream contents. If the source is an ImageInputStream, implementations will commonly check the first several bytes of the stream for a "magic number" associated with the format. Once actual reading has commenced, the reader may still indicate failure at any time prior to the completion of decoding.

It is important that the state of the object not be disturbed in order that other ImageReaderSpis can properly determine whether they are able to decode the object. In particular, if the source is an ImageInputStream, a mark/reset pair should be used to preserve the stream position.

Formats such as "raw," which can potentially attempt to read nearly any stream, should return false in order to avoid being invoked in preference to a closer match.

If source is not an instance of one of the classes returned by getInputTypes, the method should simply return false.

source - the object (typically an ImageInputStream) to be decoded. - java.lang.Object

returns: true if it is likely that this stream can be decoded. - boolean

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

create-reader-instance clj

(create-reader-instance this)

(create-reader-instance this extension)

Returns an instance of the ImageReader 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 MyImageReader(this).

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

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

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

get-image-writer-spi-names clj

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

Returns an array of Strings containing the fully qualified names of all the ImageWriterSpi classes that can understand the internal metadata representation used by the ImageReader associated with this service provider, or null if there are no such ImageWriters 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" writer, as it will be used to instantiate the ImageWriter returned by ImageIO.getImageWriter(ImageReader).

This mechanism may be used to obtain ImageWriters that will understand the internal structure of non-pixel meta-data (see IIOTreeInfo) generated by an ImageReader. By obtaining this data from the ImageReader and passing it on to one of the ImageWriters obtained with this method, a client program can read an image, modify it in some way, and write it back out while 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 ImageWriterSpi, or null. - java.lang.String[]

get-input-types clj

(get-input-types this)

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

For most readers, which only accept input from an ImageInputStream, a single-element array containing ImageInputStream.class should be returned.

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

own-reader? clj

(own-reader? this reader)

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

The default implementation compares the fully-qualified class name of the reader argument with the class name passed into the constructor. This method may be overridden if more sophisticated checking is required.

reader - an ImageReader instance. - javax.imageio.ImageReader

returns: true if reader is recognized. - boolean

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