The PixelGrabber class implements an ImageConsumer which can be attached
to an Image or ImageProducer object to retrieve a subset of the pixels
in that image. Here is an example:
public void handlesinglepixel(int x, int y, int pixel) {
int alpha = (pixel >> 24) & 0xff;
int red = (pixel >> 16) & 0xff;
int green = (pixel >> 8) & 0xff;
int blue = (pixel ) & 0xff;
// Deal with the pixel as necessary...
}
public void handlepixels(Image img, int x, int y, int w, int h) {
int[] pixels = new int[w * h];
PixelGrabber pg = new PixelGrabber(img, x, y, w, h, pixels, 0, w);
try {
pg.grabPixels();
} catch (InterruptedException e) {
System.err.println("interrupted waiting for pixels!");
return;
}
if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
System.err.println("image fetch aborted or errored");
return;
}
for (int j = 0; j < h; j++) {
for (int i = 0; i < w; i++) {
handlesinglepixel(x+i, y+j, pixels[j * w + i]);
}
}
}
Create a PixelGrabber object to grab the (x, y, w, h) rectangular
section of pixels from the image produced by the specified
ImageProducer into the given array.
Request the Image or ImageProducer to start delivering pixels and
wait for all of the pixels in the rectangle of interest to be
delivered or until the specified timeout has elapsed.
PixelGrabber
public PixelGrabber(Image img,
int x,
int y,
int w,
int h,
int pix[],
int off,
int scansize)
Create a PixelGrabber object to grab the (x, y, w, h) rectangular
section of pixels from the specified image into the given array.
The pixels are stored into the array in the default RGB ColorModel.
The RGB data for pixel (i, j) where (i, j) is inside the rectangle
(x, y, w, h) is stored in the array at
pix[(j - y) * scansize + (i - x) + off].
Parameters:
img - the image to retrieve pixels from
x - the x coordinate of the upper left corner of the rectangle
of pixels to retrieve from the image, relative to the default
(unscaled) size of the image
y - the y coordinate of the upper left corner of the rectangle
of pixels to retrieve from the image
w - the width of the rectangle of pixels to retrieve
h - the height of the rectangle of pixels to retrieve
pix - the array of integers which are to be used to hold the
RGB pixels retrieved from the image
off - the offset into the array of where to store the first pixel
scansize - the distance from one row of pixels to the next in
the array
PixelGrabber
public PixelGrabber(ImageProducer ip,
int x,
int y,
int w,
int h,
int pix[],
int off,
int scansize)
Create a PixelGrabber object to grab the (x, y, w, h) rectangular
section of pixels from the image produced by the specified
ImageProducer into the given array.
The pixels are stored into the array in the default RGB ColorModel.
The RGB data for pixel (i, j) where (i, j) is inside the rectangle
(x, y, w, h) is stored in the array at
pix[(j - y) * scansize + (i - x) + off].
Parameters:
img - the image to retrieve pixels from
x - the x coordinate of the upper left corner of the rectangle
of pixels to retrieve from the image, relative to the default
(unscaled) size of the image
y - the y coordinate of the upper left corner of the rectangle
of pixels to retrieve from the image
w - the width of the rectangle of pixels to retrieve
h - the height of the rectangle of pixels to retrieve
pix - the array of integers which are to be used to hold the
RGB pixels retrieved from the image
off - the offset into the array of where to store the first pixel
scansize - the distance from one row of pixels to the next in
the array
PixelGrabber
public PixelGrabber(Image img,
int x,
int y,
int w,
int h,
boolean forceRGB)
Create a PixelGrabber object to grab the (x, y, w, h) rectangular
section of pixels from the specified image. The pixels are
accumulated in the original ColorModel if the same ColorModel
is used for every call to setPixels, otherwise the pixels are
accumulated in the default RGB ColorModel. If the forceRGB
parameter is true, then the pixels will be accumulated in the
default RGB ColorModel anywya. A buffer is allocated by the
PixelGrabber to hold the pixels in either case. If (w < 0) or
(h < 0), then they will default to the remaining width and
height of the source data when that information is delivered.
Parameters:
img - the image to retrieve the image data from
x - the x coordinate of the upper left corner of the rectangle
of pixels to retrieve from the image, relative to the default
(unscaled) size of the image
y - the y coordinate of the upper left corner of the rectangle
of pixels to retrieve from the image
w - the width of the rectangle of pixels to retrieve
h - the height of the rectangle of pixels to retrieve
forceRGB - true if the pixels should always be converted to
the default RGB ColorModel
startGrabbing
public synchronized void startGrabbing()
Request the PixelGrabber to start fetching the pixels.
abortGrabbing
public synchronized void abortGrabbing()
Request the PixelGrabber to abort the image fetch.
Request the Image or ImageProducer to start delivering pixels and
wait for all of the pixels in the rectangle of interest to be
delivered or until the specified timeout has elapsed.
Parameters:
ms - the number of milliseconds to wait for the image pixels
to arrive before timing out
Returns:
true if the pixels were successfully grabbed, false on
abort, error or timeout
Get the width of the pixel buffer (after adjusting for image width).
If no width was specified for the rectangle of pixels to grab then
then this information will only be available after the image has
delivered the dimensions.
Returns:
the final width used for the pixel buffer or -1 if the width
is not yet known
Get the height of the pixel buffer (after adjusting for image height).
If no width was specified for the rectangle of pixels to grab then
then this information will only be available after the image has
delivered the dimensions.
Returns:
the final height used for the pixel buffer or -1 if the height
is not yet known
Get the pixel buffer. If the PixelGrabber was not constructed
with an explicit pixel buffer to hold the pixels then this method
will return null until the size and format of the image data is
known.
Since the PixelGrabber may fall back on accumulating the data
in the default RGB ColorModel at any time if the source image
uses more than one ColorModel to deliver the data, the array
object returned by this method may change over time until the
image grab is complete.
Get the ColorModel for the pixels stored in the array. If the
PixelGrabber was constructed with an explicit pixel buffer then
this method will always return the default RGB ColorModel,
otherwise it may return null until the ColorModel used by the
ImageProducer is known.
Since the PixelGrabber may fall back on accumulating the data
in the default RGB ColorModel at any time if the source image
uses more than one ColorModel to deliver the data, the ColorModel
object returned by this method may change over time until the
image grab is complete.
PixelGrabber(Image, int, int, int, int, boolean)
abortGrabbing()
PixelGrabber
startGrabbing