public final class BitmapRegionDecoder extends Object
To create a BitmapRegionDecoder, call newInstance(...). Given a BitmapRegionDecoder, users can call decodeRegion() repeatedly to get a decoded Bitmap of the specified region.
Modifier and Type | Method and Description |
---|---|
Bitmap |
decodeRegion(Rect rect,
BitmapFactory.Options options)
Decodes a rectangle region in the image specified by rect.
|
protected void |
finalize()
Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
|
int |
getHeight()
Returns the original image's height
|
int |
getWidth()
Returns the original image's width
|
boolean |
isRecycled()
Returns true if this region decoder has been recycled.
|
static BitmapRegionDecoder |
newInstance(byte[] data,
int offset,
int length,
boolean isShareable)
Create a BitmapRegionDecoder from the specified byte array.
|
static BitmapRegionDecoder |
newInstance(FileDescriptor fd,
boolean isShareable)
Create a BitmapRegionDecoder from the file descriptor.
|
static BitmapRegionDecoder |
newInstance(InputStream is,
boolean isShareable)
Create a BitmapRegionDecoder from an input stream.
|
static BitmapRegionDecoder |
newInstance(String pathName,
boolean isShareable)
Create a BitmapRegionDecoder from a file path.
|
void |
recycle()
Frees up the memory associated with this region decoder, and mark the
region decoder as "dead", meaning it will throw an exception if decodeRegion(),
getWidth() or getHeight() is called.
|
public static BitmapRegionDecoder newInstance(byte[] data, int offset, int length, boolean isShareable) throws IOException
data
- byte array of compressed image data.offset
- offset into data for where the decoder should begin
parsing.length
- the number of bytes, beginning at offset, to parseisShareable
- If this is true, then the BitmapRegionDecoder may keep a
shallow reference to the input. If this is false,
then the BitmapRegionDecoder will explicitly make a copy of the
input data, and keep that. Even if sharing is allowed,
the implementation may still decide to make a deep
copy of the input data. If an image is progressively encoded,
allowing sharing may degrade the decoding speed.IOException
- if the image format is not supported or can not be decoded.public static BitmapRegionDecoder newInstance(FileDescriptor fd, boolean isShareable) throws IOException
fd
- The file descriptor containing the data to decodeisShareable
- If this is true, then the BitmapRegionDecoder may keep a
shallow reference to the input. If this is false,
then the BitmapRegionDecoder will explicitly make a copy of the
input data, and keep that. Even if sharing is allowed,
the implementation may still decide to make a deep
copy of the input data. If an image is progressively encoded,
allowing sharing may degrade the decoding speed.IOException
- if the image format is not supported or can not be decoded.public static BitmapRegionDecoder newInstance(InputStream is, boolean isShareable) throws IOException
is
- The input stream that holds the raw data to be decoded into a
BitmapRegionDecoder.isShareable
- If this is true, then the BitmapRegionDecoder may keep a
shallow reference to the input. If this is false,
then the BitmapRegionDecoder will explicitly make a copy of the
input data, and keep that. Even if sharing is allowed,
the implementation may still decide to make a deep
copy of the input data. If an image is progressively encoded,
allowing sharing may degrade the decoding speed.IOException
- if the image format is not supported or can not be decoded.
Prior to Build.VERSION_CODES.KITKAT
,
if is.markSupported()
returns true,
is.mark(1024)
would be called. As of
Build.VERSION_CODES.KITKAT
, this is no longer the case.
public static BitmapRegionDecoder newInstance(String pathName, boolean isShareable) throws IOException
pathName
- complete path name for the file to be decoded.isShareable
- If this is true, then the BitmapRegionDecoder may keep a
shallow reference to the input. If this is false,
then the BitmapRegionDecoder will explicitly make a copy of the
input data, and keep that. Even if sharing is allowed,
the implementation may still decide to make a deep
copy of the input data. If an image is progressively encoded,
allowing sharing may degrade the decoding speed.IOException
- if the image format is not supported or can not be decoded.public Bitmap decodeRegion(Rect rect, BitmapFactory.Options options)
rect
- The rectangle that specified the region to be decode.options
- null-ok; Options that control downsampling.
inPurgeable is not supported.public int getWidth()
public int getHeight()
public void recycle()
This operation cannot be reversed, so it should only be called if you are sure there are no further uses for the region decoder. This is an advanced call, and normally need not be called, since the normal GC process will free up this memory when there are no more references to this region decoder.
public final boolean isRecycled()
protected void finalize() throws Throwable
Object
finalize
method to dispose of
system resources or to perform other cleanup.
The general contract of finalize
is that it is invoked
if and when the JavaTM virtual
machine has determined that there is no longer any
means by which this object can be accessed by any thread that has
not yet died, except as a result of an action taken by the
finalization of some other object or class which is ready to be
finalized. The finalize
method may take any action, including
making this object available again to other threads; the usual purpose
of finalize
, however, is to perform cleanup actions before
the object is irrevocably discarded. For example, the finalize method
for an object that represents an input/output connection might perform
explicit I/O transactions to break the connection before the object is
permanently discarded.
The finalize
method of class Object
performs no
special action; it simply returns normally. Subclasses of
Object
may override this definition.
The Java programming language does not guarantee which thread will
invoke the finalize
method for any given object. It is
guaranteed, however, that the thread that invokes finalize will not
be holding any user-visible synchronization locks when finalize is
invoked. If an uncaught exception is thrown by the finalize method,
the exception is ignored and finalization of that object terminates.
After the finalize
method has been invoked for an object, no
further action is taken until the Java virtual machine has again
determined that there is no longer any means by which this object can
be accessed by any thread that has not yet died, including possible
actions by other objects or classes which are ready to be finalized,
at which point the object may be discarded.
The finalize
method is never invoked more than once by a Java
virtual machine for any given object.
Any exception thrown by the finalize
method causes
the finalization of this object to be halted, but is otherwise
ignored.