Package org.gnome.gio

Interface Seekable

All Superinterfaces:

Proxy

All Known Implementing Classes:

BufferedInputStream, BufferedOutputStream, DataInputStream, DataOutputStream, FileInputStream, FileIOStream, FileOutputStream, MemoryInputStream, MemoryOutputStream, Seekable.SeekableImpl

@Generated("io.github.jwharm.JavaGI")
public interface Seekable
extends Proxy

GSeekable is implemented by streams (implementations of InputStream or OutputStream) that support seeking.

Seekable streams largely fall into two categories: resizable and fixed-size.

GSeekable on fixed-sized streams is approximately the same as POSIX lseek()) on a block device (for example: attempting to seek past the end of the device is an error). Fixed streams typically cannot be truncated.

GSeekable on resizable streams is approximately the same as POSIX lseek()) on a normal file. Seeking past the end and writing data will usually cause the stream to resize by introducing zero bytes.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	Seekable.SeekableIface	Provides an interface for implementing seekable functionality on I/O Streams.
static class	Seekable.SeekableImpl	The SeekableImpl type represents a native instance of the Seekable interface.

Method Summary

Modifier and Type	Method	Description
default boolean	canSeek()	Tests if the stream supports the GSeekableIface.
default boolean	canTruncate()	Tests if the length of the stream can be adjusted with g_seekable_truncate().
static Type	getType()	Get the GType of the Seekable class
default boolean	seek(long offset, SeekType type, @Nullable Cancellable cancellable)	Seeks in the stream by the given offset, modified by type.
default long	tell()	Tells the current position within the stream.
default boolean	truncate(long offset, @Nullable Cancellable cancellable)	Sets the length of the stream to offset.

Methods inherited from interface io.github.jwharm.javagi.base.Proxy

handle

Method Details

getType

static Type getType()

Get the GType of the Seekable class

Returns:

the GType

canSeek

default boolean canSeek()

Tests if the stream supports the GSeekableIface.

Returns:

true if this Seekable can be seeked. false otherwise.

canTruncate

default boolean canTruncate()

Tests if the length of the stream can be adjusted with g_seekable_truncate().

Returns:

true if the stream can be truncated, false otherwise.

seek

default boolean seek(long offset,
 SeekType type,
 @Nullable
 @Nullable Cancellable cancellable)
              throws GErrorException

Seeks in the stream by the given offset, modified by type.

Attempting to seek past the end of the stream will have different results depending on if the stream is fixed-sized or resizable. If the stream is resizable then seeking past the end and then writing will result in zeros filling the empty space. Seeking past the end of a resizable stream and reading will result in EOF. Seeking past the end of a fixed-sized stream will fail.

Any operation that would result in a negative offset will fail.

If cancellable is not null, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error IOErrorEnum.CANCELLED will be returned.

Parameters:

offset - a goffset.

type - a GSeekType.

cancellable - optional GCancellable object, null to ignore.

Returns:

true if successful. If an error has occurred, this function will return false and set error appropriately if present.

Throws:

GErrorException - see GError

tell

default long tell()

Tells the current position within the stream.

Returns:

the (positive or zero) offset from the beginning of the buffer, zero if the target is not seekable.

truncate

default boolean truncate(long offset,
 @Nullable
 @Nullable Cancellable cancellable)
                  throws GErrorException

Sets the length of the stream to offset. If the stream was previously larger than offset, the extra data is discarded. If the stream was previously shorter than offset, it is extended with NUL ('\\0') bytes.

If cancellable is not null, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error IOErrorEnum.CANCELLED will be returned. If an operation was partially finished when the operation was cancelled the partial result will be returned, without an error.

Parameters:

offset - new length for this Seekable, in bytes.

cancellable - optional GCancellable object, null to ignore.

Returns:

true if successful. If an error has occurred, this function will return false and set error appropriately if present.

Throws:

GErrorException - see GError