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package javax.imageio.spi;
import java.awt.image.RenderedImage;
import java.io.IOException;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageOutputStream;
/**
* The service provider interface (SPI) for {@code ImageWriter}s.
* For more information on service provider classes, see the class comment
* for the {@code IIORegistry} class.
*
* <p> Each {@code ImageWriterSpi} provides several types of information
* about the {@code ImageWriter} class with which it is associated.
*
* <p> The name of the vendor who defined the SPI class and a
* brief description of the class are available via the
* {@code getVendorName}, {@code getDescription},
* and {@code 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.
*
* <p> Lists of format names, file suffixes, and MIME types associated
* with the service may be obtained by means of the
* {@code getFormatNames}, {@code getFileSuffixes}, and
* {@code getMIMEType} methods. These methods may be used to
* identify candidate {@code ImageWriter}s for writing a
* particular file or stream based on manual format selection, file
* naming, or MIME associations.
*
* <p> A more reliable way to determine which {@code ImageWriter}s
* are likely to be able to parse a particular data stream is provided
* by the {@code canEncodeImage} method. This methods allows the
* service provider to inspect the actual image contents.
*
* <p> Finally, an instance of the {@code ImageWriter} class
* associated with this service provider may be obtained by calling
* the {@code 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 IIORegistry
* @see javax.imageio.ImageTypeSpecifier
* @see javax.imageio.ImageWriter
*
*/
public abstract class ImageWriterSpi extends ImageReaderWriterSpi {
/**
* A single-element array, initially containing
* {@code ImageOutputStream.class}, to be returned from
* {@code getOutputTypes}.
* @deprecated Instead of using this field, directly create
* the equivalent array {@code { ImageOutputStream.class }}.
*/
@Deprecated
public static final Class<?>[] STANDARD_OUTPUT_TYPE =
{ ImageOutputStream.class };
/**
* An array of {@code Class} objects to be returned from
* {@code getOutputTypes}, initially {@code null}.
*/
protected Class<?>[] outputTypes = null;
/**
* An array of strings to be returned from
* {@code getImageReaderSpiNames}, initially
* {@code null}.
*/
protected String[] readerSpiNames = null;
/**
* The {@code Class} of the writer, initially
* {@code null}.
*/
private Class<?> writerClass = null;
/**
* Constructs a blank {@code ImageWriterSpi}. It is up to
* the subclass to initialize instance variables and/or override
* method implementations in order to provide working versions of
* all methods.
*/
protected ImageWriterSpi() {
}
/**
* Constructs an {@code ImageWriterSpi} with a given
* set of values.
*
* @param vendorName the vendor name, as a non-{@code null}
* {@code String}.
* @param version a version identifier, as a non-{@code null}
* {@code String}.
* @param names a non-{@code null} array of
* {@code String}s indicating the format names. At least one
* entry must be present.
* @param suffixes an array of {@code String}s indicating the
* common file suffixes. If no suffixes are defined,
* {@code null} should be supplied. An array of length 0
* will be normalized to {@code null}.
* @param MIMETypes an array of {@code String}s indicating
* the format's MIME types. If no suffixes are defined,
* {@code null} should be supplied. An array of length 0
* will be normalized to {@code null}.
* @param writerClassName the fully-qualified name of the
* associated {@code ImageWriterSpi} class, as a
* non-{@code null String}.
* @param outputTypes an array of {@code Class} objects of
* length at least 1 indicating the legal output types.
* @param readerSpiNames an array {@code String}s of length
* at least 1 naming the classes of all associated
* {@code ImageReader}s, or {@code null}. An array of
* length 0 is normalized to {@code null}.
* @param supportsStandardStreamMetadataFormat a
* {@code boolean} that indicates whether a stream metadata
* object can use trees described by the standard metadata format.
* @param nativeStreamMetadataFormatName a
* {@code String}, or {@code null}, to be returned from
* {@code getNativeStreamMetadataFormatName}.
* @param nativeStreamMetadataFormatClassName a
* {@code String}, or {@code null}, to be used to instantiate
* a metadata format object to be returned from
* {@code getNativeStreamMetadataFormat}.
* @param extraStreamMetadataFormatNames an array of
* {@code String}s, or {@code null}, to be returned from
* {@code getExtraStreamMetadataFormatNames}. An array of length
* 0 is normalized to {@code null}.
* @param extraStreamMetadataFormatClassNames an array of
* {@code String}s, or {@code null}, to be used to instantiate
* a metadata format object to be returned from
* {@code getStreamMetadataFormat}. An array of length
* 0 is normalized to {@code null}.
* @param supportsStandardImageMetadataFormat a
* {@code boolean} that indicates whether an image metadata
* object can use trees described by the standard metadata format.
* @param nativeImageMetadataFormatName a
* {@code String}, or {@code null}, to be returned from
* {@code getNativeImageMetadataFormatName}.
* @param nativeImageMetadataFormatClassName a
* {@code String}, or {@code null}, to be used to instantiate
* a metadata format object to be returned from
* {@code getNativeImageMetadataFormat}.
* @param extraImageMetadataFormatNames an array of
* {@code String}s to be returned from
* {@code getExtraImageMetadataFormatNames}. An array of length 0
* is normalized to {@code null}.
* @param extraImageMetadataFormatClassNames an array of
* {@code String}s, or {@code null}, to be used to instantiate
* a metadata format object to be returned from
* {@code getImageMetadataFormat}. An array of length
* 0 is normalized to {@code null}.
*
* @exception IllegalArgumentException if {@code vendorName}
* is {@code null}.
* @exception IllegalArgumentException if {@code version}
* is {@code null}.
* @exception IllegalArgumentException if {@code names}
* is {@code null} or has length 0.
* @exception IllegalArgumentException if {@code writerClassName}
* is {@code null}.
* @exception IllegalArgumentException if {@code outputTypes}
* is {@code null} or has length 0.
*/
public ImageWriterSpi(String vendorName,
String version,
String[] names,
String[] suffixes,
String[] MIMETypes,
String writerClassName,
Class<?>[] outputTypes,
String[] readerSpiNames,
boolean supportsStandardStreamMetadataFormat,
String nativeStreamMetadataFormatName,
String nativeStreamMetadataFormatClassName,
String[] extraStreamMetadataFormatNames,
String[] extraStreamMetadataFormatClassNames,
boolean supportsStandardImageMetadataFormat,
String nativeImageMetadataFormatName,
String nativeImageMetadataFormatClassName,
String[] extraImageMetadataFormatNames,
String[] extraImageMetadataFormatClassNames) {
super(vendorName, version,
names, suffixes, MIMETypes, writerClassName,
supportsStandardStreamMetadataFormat,
nativeStreamMetadataFormatName,
nativeStreamMetadataFormatClassName,
extraStreamMetadataFormatNames,
extraStreamMetadataFormatClassNames,
supportsStandardImageMetadataFormat,
nativeImageMetadataFormatName,
nativeImageMetadataFormatClassName,
extraImageMetadataFormatNames,
extraImageMetadataFormatClassNames);
if (outputTypes == null) {
throw new IllegalArgumentException
("outputTypes == null!");
}
if (outputTypes.length == 0) {
throw new IllegalArgumentException
("outputTypes.length == 0!");
}
this.outputTypes = (outputTypes == STANDARD_OUTPUT_TYPE) ?
new Class<?>[] { ImageOutputStream.class } :
outputTypes.clone();
// If length == 0, leave it null
if (readerSpiNames != null && readerSpiNames.length > 0) {
this.readerSpiNames = readerSpiNames.clone();
}
}
/**
* Returns {@code true} if the format that this writer
* outputs preserves pixel data bit-accurately. The default
* implementation returns {@code true}.
*
* @return {@code true} if the format preserves full pixel
* accuracy.
*/
public boolean isFormatLossless() {
return true;
}
/**
* Returns an array of {@code Class} objects indicating what
* types of objects may be used as arguments to the writer's
* {@code setOutput} method.
*
* <p> For most writers, which only output to an
* {@code ImageOutputStream}, a single-element array
* containing {@code ImageOutputStream.class} should be
* returned.
*
* @return a non-{@code null} array of
* {@code Class} objects of length at least 1.
*/
public Class<?>[] getOutputTypes() {
return outputTypes.clone();
}
/**
* Returns {@code true} if the {@code ImageWriter}
* implementation associated with this service provider is able to
* encode an image with the given layout. The layout
* (<i>i.e.</i>, the image's {@code SampleModel} and
* {@code ColorModel}) is described by an
* {@code ImageTypeSpecifier} object.
*
* <p> A return value of {@code 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
* {@code false} if handed an RGB {@code 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.
*
* <p> Different {@code ImageWriter}s, 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.
*
* @param type an {@code ImageTypeSpecifier} specifying the
* layout of the image to be written.
*
* @return {@code true} if this writer is likely to be able
* to encode images with the given layout.
*
* @exception IllegalArgumentException if {@code type}
* is {@code null}.
*/
public abstract boolean canEncodeImage(ImageTypeSpecifier type);
/**
* Returns {@code true} if the {@code ImageWriter}
* implementation associated with this service provider is able to
* encode the given {@code RenderedImage} instance. Note
* that this includes instances of
* {@code java.awt.image.BufferedImage}.
*
* <p> See the discussion for
* {@code canEncodeImage(ImageTypeSpecifier)} for information
* on the semantics of this method.
*
* @param im an instance of {@code RenderedImage} to be encoded.
*
* @return {@code true} if this writer is likely to be able
* to encode this image.
*
* @exception IllegalArgumentException if {@code im}
* is {@code null}.
*/
public boolean canEncodeImage(RenderedImage im) {
return canEncodeImage(ImageTypeSpecifier.createFromRenderedImage(im));
}
/**
* Returns an instance of the {@code ImageWriter}
* implementation associated with this service provider.
* The returned object will initially be in an initial state as if
* its {@code reset} method had been called.
*
* <p> The default implementation simply returns
* {@code createWriterInstance(null)}.
*
* @return an {@code ImageWriter} instance.
*
* @exception IOException if an error occurs during loading,
* or initialization of the writer class, or during instantiation
* or initialization of the writer object.
*/
public ImageWriter createWriterInstance() throws IOException {
return createWriterInstance(null);
}
/**
* Returns an instance of the {@code ImageWriter}
* implementation associated with this service provider.
* The returned object will initially be in an initial state
* as if its {@code reset} method had been called.
*
* <p> An {@code Object} may be supplied to the plug-in at
* construction time. The nature of the object is entirely
* plug-in specific.
*
* <p> Typically, a plug-in will implement this method using code
* such as {@code return new MyImageWriter(this)}.
*
* @param extension a plug-in specific extension object, which may
* be {@code null}.
*
* @return an {@code ImageWriter} instance.
*
* @exception IOException if the attempt to instantiate
* the writer fails.
* @exception IllegalArgumentException if the
* {@code ImageWriter}'s constructor throws an
* {@code IllegalArgumentException} to indicate that the
* extension object is unsuitable.
*/
public abstract ImageWriter createWriterInstance(Object extension)
throws IOException;
/**
* Returns {@code true} if the {@code ImageWriter} object
* passed in is an instance of the {@code ImageWriter}
* associated with this service provider.
*
* @param writer an {@code ImageWriter} instance.
*
* @return {@code true} if {@code writer} is recognized
*
* @exception IllegalArgumentException if {@code writer} is
* {@code null}.
*/
public boolean isOwnWriter(ImageWriter writer) {
if (writer == null) {
throw new IllegalArgumentException("writer == null!");
}
String name = writer.getClass().getName();
return name.equals(pluginClassName);
}
/**
* Returns an array of {@code String}s containing all the
* fully qualified names of all the {@code ImageReaderSpi}
* classes that can understand the internal metadata
* representation used by the {@code ImageWriter} associated
* with this service provider, or {@code null} if there are
* no such {@code ImageReaders} specified. If a
* non-{@code null} value is returned, it must have non-zero
* length.
*
* <p> 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 {@code ImageReader} returned by
* {@code ImageIO.getImageReader(ImageWriter)}.
*
* <p> This mechanism may be used to obtain
* {@code ImageReaders} that will generated non-pixel
* meta-data (see {@code IIOExtraDataInfo}) in a structure
* understood by an {@code ImageWriter}. By reading the
* image and obtaining this data from one of the
* {@code ImageReaders} obtained with this method and passing
* it on to the {@code 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.
*
* @return an array of {@code String}s of length at least 1
* containing names of {@code ImageReaderSpi}s, or
* {@code null}.
*
* @see javax.imageio.ImageIO#getImageReader(ImageWriter)
* @see ImageReaderSpi#getImageWriterSpiNames()
*/
public String[] getImageReaderSpiNames() {
return readerSpiNames == null ?
null : readerSpiNames.clone();
}
}