RegisterableService
public abstract class ImageWriterSpi extends ImageReaderWriterSpi
ImageWriter
s. 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 ImageWriter
s for writing a particular file or stream based on manual format selection, file naming, or MIME associations.
A more reliable way to determine which ImageWriter
s 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.
Modifier and Type | Field | Description |
---|---|---|
protected Class<?>[] |
outputTypes |
An array of Class objects to be returned from getOutputTypes , initially null . |
protected String[] |
readerSpiNames |
An array of strings to be returned from getImageReaderSpiNames , initially null . |
static final Class<?>[] |
STANDARD_OUTPUT_TYPE |
Deprecated. |
extraImageMetadataFormatClassNames, extraImageMetadataFormatNames, extraStreamMetadataFormatClassNames, extraStreamMetadataFormatNames, MIMETypes, names, nativeImageMetadataFormatClassName, nativeImageMetadataFormatName, nativeStreamMetadataFormatClassName, nativeStreamMetadataFormatName, pluginClassName, suffixes, supportsStandardImageMetadataFormat, supportsStandardStreamMetadataFormat
vendorName, version
Modifier | Constructor | Description |
---|---|---|
protected |
Constructs a blank ImageWriterSpi . |
|
Constructs an ImageWriterSpi with a given set of values. |
Modifier and Type | Method | Description |
---|---|---|
boolean |
canEncodeImage |
Returns true if the ImageWriter implementation associated with this service provider is able to encode the given RenderedImage instance. |
abstract boolean |
canEncodeImage |
Returns true if the ImageWriter implementation associated with this service provider is able to encode an image with the given layout. |
ImageWriter |
createWriterInstance() |
Returns an instance of the ImageWriter implementation associated with this service provider. |
abstract ImageWriter |
createWriterInstance |
Returns an instance of the ImageWriter implementation associated with this service provider. |
String[] |
getImageReaderSpiNames() |
Returns an array of String s 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. |
Class<?>[] |
getOutputTypes() |
Returns an array of Class objects indicating what types of objects may be used as arguments to the writer's setOutput method. |
boolean |
isFormatLossless() |
Returns true if the format that this writer outputs preserves pixel data bit-accurately. |
boolean |
isOwnWriter |
Returns true if the ImageWriter object passed in is an instance of the ImageWriter associated with this service provider. |
getExtraImageMetadataFormatNames, getExtraStreamMetadataFormatNames, getFileSuffixes, getFormatNames, getImageMetadataFormat, getMIMETypes, getNativeImageMetadataFormatName, getNativeStreamMetadataFormatName, getPluginClassName, getStreamMetadataFormat, isStandardImageMetadataFormatSupported, isStandardStreamMetadataFormatSupported
getDescription, getVendorName, getVersion, onDeregistration, onRegistration
@Deprecated public static final Class<?>[] STANDARD_OUTPUT_TYPE
{ ImageOutputStream.class }
.ImageOutputStream.class
, to be returned from getOutputTypes
.protected Class<?>[] outputTypes
Class
objects to be returned from getOutputTypes
, initially null
.protected String[] readerSpiNames
getImageReaderSpiNames
, initially null
.protected ImageWriterSpi()
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.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)
ImageWriterSpi
with a given set of values.vendorName
- the vendor name, as a non-null
String
.version
- a version identifier, as a non-null
String
.names
- a non-null
array of String
s indicating the format names. At least one entry must be present.suffixes
- an array of String
s indicating the common file suffixes. If no suffixes are defined, null
should be supplied. An array of length 0 will be normalized to null
.MIMETypes
- an array of String
s 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
.writerClassName
- the fully-qualified name of the associated ImageWriterSpi
class, as a non-null String
.outputTypes
- an array of Class
objects of length at least 1 indicating the legal output types.readerSpiNames
- an array String
s of length at least 1 naming the classes of all associated ImageReader
s, or null
. An array of length 0 is normalized to null
.supportsStandardStreamMetadataFormat
- a boolean
that indicates whether a stream metadata object can use trees described by the standard metadata format.nativeStreamMetadataFormatName
- a String
, or null
, to be returned from getNativeStreamMetadataFormatName
.nativeStreamMetadataFormatClassName
- a String
, or null
, to be used to instantiate a metadata format object to be returned from getNativeStreamMetadataFormat
.extraStreamMetadataFormatNames
- an array of String
s, or null
, to be returned from getExtraStreamMetadataFormatNames
. An array of length 0 is normalized to null
.extraStreamMetadataFormatClassNames
- an array of String
s, 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
.supportsStandardImageMetadataFormat
- a boolean
that indicates whether an image metadata object can use trees described by the standard metadata format.nativeImageMetadataFormatName
- a String
, or null
, to be returned from getNativeImageMetadataFormatName
.nativeImageMetadataFormatClassName
- a String
, or null
, to be used to instantiate a metadata format object to be returned from getNativeImageMetadataFormat
.extraImageMetadataFormatNames
- an array of String
s to be returned from getExtraImageMetadataFormatNames
. An array of length 0 is normalized to null
.extraImageMetadataFormatClassNames
- an array of String
s, 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
.IllegalArgumentException
- if vendorName
is null
.IllegalArgumentException
- if version
is null
.IllegalArgumentException
- if names
is null
or has length 0.IllegalArgumentException
- if writerClassName
is null
.IllegalArgumentException
- if outputTypes
is null
or has length 0.public boolean isFormatLossless()
true
if the format that this writer outputs preserves pixel data bit-accurately. The default implementation returns true
.true
if the format preserves full pixel accuracy.public Class<?>[] getOutputTypes()
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.
null
array of Class
objects of length at least 1.public abstract boolean canEncodeImage(ImageTypeSpecifier type)
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 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.
type
- an ImageTypeSpecifier
specifying the layout of the image to be written.true
if this writer is likely to be able to encode images with the given layout.IllegalArgumentException
- if type
is null
.public boolean canEncodeImage(RenderedImage im)
true
if the ImageWriter
implementation associated with this service provider is able to encode the given RenderedImage
instance. Note that this includes instances of java.awt.image.BufferedImage
. See the discussion for canEncodeImage(ImageTypeSpecifier)
for information on the semantics of this method.
im
- an instance of RenderedImage
to be encoded.true
if this writer is likely to be able to encode this image.IllegalArgumentException
- if im
is null
.public ImageWriter createWriterInstance() throws IOException
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. The default implementation simply returns createWriterInstance(null)
.
ImageWriter
instance.IOException
- if an error occurs during loading, or initialization of the writer class, or during instantiation or initialization of the writer object.public abstract ImageWriter createWriterInstance(Object extension) throws IOException
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
.ImageWriter
instance.IOException
- if the attempt to instantiate the writer fails.IllegalArgumentException
- if the ImageWriter
's constructor throws an IllegalArgumentException
to indicate that the extension object is unsuitable.public boolean isOwnWriter(ImageWriter writer)
true
if the ImageWriter
object passed in is an instance of the ImageWriter
associated with this service provider.writer
- an ImageWriter
instance.true
if writer
is recognizedIllegalArgumentException
- if writer
is null
.public String[] getImageReaderSpiNames()
String
s 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.
String
s of length at least 1 containing names of ImageReaderSpi
s, or null
.
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/javax/imageio/spi/ImageWriterSpi.html
{ ImageOutputStream.class }
.