Reports that a given region of the image has been updated.
The application might choose to redisplay the specified area,
for example, in order to provide a progressive display effect,
or perform other incremental processing.
Note that different image format readers may produce
decoded pixels in a variety of different orders. Many readers
will produce pixels in a simple top-to-bottom,
left-to-right-order, but others may use multiple passes of
interlacing, tiling, etc. The sequence of updates may even
differ from call to call depending on network speeds, for
example. A call to this method does not guarantee that all the
specified pixels have actually been updated, only that some
activity has taken place within some subregion of the one
specified.
The particular ImageReader
implementation may
choose how often to provide updates. Each update specifies
that a given region of the image has been updated since the
last update. A region is described by its spatial bounding box
(minX
, minY
, width
, and
height
); X and Y subsampling factors
(periodX
and periodY
); and a set of
updated bands (bands
). For example, the update:
minX = 10
minY = 20
width = 3
height = 4
periodX = 2
periodY = 3
bands = { 1, 3 }
would indicate that bands 1 and 3 of the following pixels were
updated:
(10, 20) (12, 20) (14, 20)
(10, 23) (12, 23) (14, 23)
(10, 26) (12, 26) (14, 26)
(10, 29) (12, 29) (14, 29)
Parameters:
-
source - the
ImageReader
object calling this method.
-
theImage - the
BufferedImage
being updated.
-
minX - the X coordinate of the leftmost updated column
of pixels.
-
minY - the Y coordinate of the uppermost updated row
of pixels.
-
width - the number of updated pixels horizontally.
-
height - the number of updated pixels vertically.
-
periodX - the horizontal spacing between updated pixels;
a value of 1 means no gaps.
-
periodY - the vertical spacing between updated pixels;
a value of 1 means no gaps.
-
bands - an array of
int
s indicating which
bands are being updated.