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PixelGrabber.javaAPI DocJava SE 5 API22000Fri Aug 26 14:56:54 BST 2005java.awt.image

PixelGrabber

public class PixelGrabber extends Object implements ImageConsumer
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]);
}
}
}

see
ColorModel#getRGBdefault
version
1.25, 07/16/04
author
Jim Graham

Fields Summary
ImageProducer
producer
int
dstX
int
dstY
int
dstW
int
dstH
ColorModel
imageModel
byte[]
bytePixels
int[]
intPixels
int
dstOff
int
dstScan
private boolean
grabbing
private int
flags
private static final int
GRABBEDBITS
private static final int
DONEBITS
Constructors Summary
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].

see
ColorModel#getRGBdefault
param
img the image to retrieve pixels from
param
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
param
y the y coordinate of the upper left corner of the rectangle of pixels to retrieve from the image
param
w the width of the rectangle of pixels to retrieve
param
h the height of the rectangle of pixels to retrieve
param
pix the array of integers which are to be used to hold the RGB pixels retrieved from the image
param
off the offset into the array of where to store the first pixel
param
scansize the distance from one row of pixels to the next in the array


                                                                                                                                                                                                                 
              
			      
	this(img.getSource(), x, y, w, h, pix, off, scansize);
    
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].

param
ip the ImageProducer that produces the image from which to retrieve pixels
param
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
param
y the y coordinate of the upper left corner of the rectangle of pixels to retrieve from the image
param
w the width of the rectangle of pixels to retrieve
param
h the height of the rectangle of pixels to retrieve
param
pix the array of integers which are to be used to hold the RGB pixels retrieved from the image
param
off the offset into the array of where to store the first pixel
param
scansize the distance from one row of pixels to the next in the array
see
ColorModel#getRGBdefault

	producer = ip;
	dstX = x;
	dstY = y;
	dstW = w;
	dstH = h;
	dstOff = off;
	dstScan = scansize;
	intPixels = pix;
	imageModel = ColorModel.getRGBdefault();
    
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 anyway. 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.

param
img the image to retrieve the image data from
param
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
param
y the y coordinate of the upper left corner of the rectangle of pixels to retrieve from the image
param
w the width of the rectangle of pixels to retrieve
param
h the height of the rectangle of pixels to retrieve
param
forceRGB true if the pixels should always be converted to the default RGB ColorModel

	producer = img.getSource();
	dstX = x;
	dstY = y;
	dstW = w;
	dstH = h;
	if (forceRGB) {
	    imageModel = ColorModel.getRGBdefault();
	}
    
Methods Summary
public synchronized voidabortGrabbing()
Request the PixelGrabber to abort the image fetch.

	imageComplete(IMAGEABORTED);
    
private voidconvertToRGB()

	int size = dstW * dstH;
	int newpixels[] = new int[size];
	if (bytePixels != null) {
	    for (int i = 0; i < size; i++) {
		newpixels[i] = imageModel.getRGB(bytePixels[i] & 0xff);
	    }
	} else if (intPixels != null) {
	    for (int i = 0; i < size; i++) {
		newpixels[i] = imageModel.getRGB(intPixels[i]);
	    }
	}
	bytePixels = null;
	intPixels = newpixels;
	dstScan = dstW;
	dstOff = 0;
	imageModel = ColorModel.getRGBdefault();
    
public synchronized java.awt.image.ColorModelgetColorModel()
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 and may not reflect any of the ColorModel objects that was used by the ImageProducer to deliver the pixels.

return
the ColorModel object used for storing the pixels
see
#getStatus
see
ColorModel#getRGBdefault
see
#setColorModel(ColorModel)

	return imageModel;
    
public synchronized intgetHeight()
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.

return
the final height used for the pixel buffer or -1 if the height is not yet known
see
#getStatus

	return (dstH < 0) ? -1 : dstH;
    
public synchronized java.lang.ObjectgetPixels()
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.

return
either a byte array or an int array
see
#getStatus
see
#setPixels(int, int, int, int, ColorModel, byte[], int, int)
see
#setPixels(int, int, int, int, ColorModel, int[], int, int)

	return (bytePixels == null)
	    ? ((Object) intPixels)
	    : ((Object) bytePixels);
    
public synchronized intgetStatus()
Return the status of the pixels. The ImageObserver flags representing the available pixel information are returned.

return
the bitwise OR of all relevant ImageObserver flags
see
ImageObserver

	return flags;
    
public synchronized intgetWidth()
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.

return
the final width used for the pixel buffer or -1 if the width is not yet known
see
#getStatus

	return (dstW < 0) ? -1 : dstW;
    
public booleangrabPixels()
Request the Image or ImageProducer to start delivering pixels and wait for all of the pixels in the rectangle of interest to be delivered.

return
true if the pixels were successfully grabbed, false on abort, error or timeout
exception
InterruptedException Another thread has interrupted this thread.

	return grabPixels(0);
    
public synchronized booleangrabPixels(long ms)
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. This method behaves in the following ways, depending on the value of ms:
  • If ms == 0, waits until all pixels are delivered
  • If ms > 0, waits until all pixels are delivered as timeout expires.
  • If ms < 0, returns true if all pixels are grabbed, false otherwise and does not wait.

param
ms the number of milliseconds to wait for the image pixels to arrive before timing out
return
true if the pixels were successfully grabbed, false on abort, error or timeout
exception
InterruptedException Another thread has interrupted this thread.

	if ((flags & DONEBITS) != 0) {
	    return (flags & GRABBEDBITS) != 0;
	}
	long end = ms + System.currentTimeMillis();
	if (!grabbing) {
	    grabbing = true;
	    flags &= ~(ImageObserver.ABORT);
	    producer.startProduction(this);
	}
	while (grabbing) {
	    long timeout;
	    if (ms == 0) {
		timeout = 0;
	    } else {
		timeout = end - System.currentTimeMillis();
		if (timeout <= 0) {
		    break;
		}
	    }
	    wait(timeout);
	}
	return (flags & GRABBEDBITS) != 0;
    
public synchronized voidimageComplete(int status)
The imageComplete method is part of the ImageConsumer API which this class must implement to retrieve the pixels.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being grabbed. Developers using this class to retrieve pixels from an image should avoid calling this method directly since that operation could result in problems with retrieving the requested pixels.

param
status the status of image loading

	grabbing = false;
	switch (status) {
	default:
	case IMAGEERROR:
	    flags |= ImageObserver.ERROR | ImageObserver.ABORT;
	    break;
	case IMAGEABORTED:
	    flags |= ImageObserver.ABORT;
	    break;
	case STATICIMAGEDONE:
	    flags |= ImageObserver.ALLBITS;
	    break;
	case SINGLEFRAMEDONE:
	    flags |= ImageObserver.FRAMEBITS;
	    break;
	}
	producer.removeConsumer(this);
	notifyAll();
    
public voidsetColorModel(java.awt.image.ColorModel model)
The setColorModel method is part of the ImageConsumer API which this class must implement to retrieve the pixels.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being grabbed. Developers using this class to retrieve pixels from an image should avoid calling this method directly since that operation could result in problems with retrieving the requested pixels.

param
model the specified ColorModel
see
#getColorModel

	return;
    
public voidsetDimensions(int width, int height)
The setDimensions method is part of the ImageConsumer API which this class must implement to retrieve the pixels.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being grabbed. Developers using this class to retrieve pixels from an image should avoid calling this method directly since that operation could result in problems with retrieving the requested pixels.

param
width the width of the dimension
param
height the height of the dimension

	if (dstW < 0) {
	    dstW = width - dstX;
	}
	if (dstH < 0) {
	    dstH = height - dstY;
	}
	if (dstW <= 0 || dstH <= 0) {
	    imageComplete(STATICIMAGEDONE);
	} else if (intPixels == null &&
		   imageModel == ColorModel.getRGBdefault()) {
	    intPixels = new int[dstW * dstH];
	    dstScan = dstW;
	    dstOff = 0;
	}
	flags |= (ImageObserver.WIDTH | ImageObserver.HEIGHT);
    
public voidsetHints(int hints)
The setHints method is part of the ImageConsumer API which this class must implement to retrieve the pixels.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being grabbed. Developers using this class to retrieve pixels from an image should avoid calling this method directly since that operation could result in problems with retrieving the requested pixels.

param
hints a set of hints used to process the pixels

	return;
    
public voidsetPixels(int srcX, int srcY, int srcW, int srcH, java.awt.image.ColorModel model, byte[] pixels, int srcOff, int srcScan)
The setPixels method is part of the ImageConsumer API which this class must implement to retrieve the pixels.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being grabbed. Developers using this class to retrieve pixels from an image should avoid calling this method directly since that operation could result in problems with retrieving the requested pixels.

param
srcX, srcY the coordinates of the upper-left corner of the area of pixels to be set
param
srcW the width of the area of pixels
param
srcH the height of the area of pixels
param
model the specified ColorModel
param
pixels the array of pixels
param
srcOff the offset into the pixels array
param
srcScan the distance from one row of pixels to the next in the pixels array
see
#getPixels

	if (srcY < dstY) {
	    int diff = dstY - srcY;
	    if (diff >= srcH) {
		return;
	    }
	    srcOff += srcScan * diff;
	    srcY += diff;
	    srcH -= diff;
	}
	if (srcY + srcH > dstY + dstH) {
	    srcH = (dstY + dstH) - srcY;
	    if (srcH <= 0) {
		return;
	    }
	}
	if (srcX < dstX) {
	    int diff = dstX - srcX;
	    if (diff >= srcW) {
		return;
	    }
	    srcOff += diff;
	    srcX += diff;
	    srcW -= diff;
	}
	if (srcX + srcW > dstX + dstW) {
	    srcW = (dstX + dstW) - srcX;
	    if (srcW <= 0) {
		return;
	    }
	}
	int dstPtr = dstOff + (srcY - dstY) * dstScan + (srcX - dstX);
	if (intPixels == null) {
	    if (bytePixels == null) {
		bytePixels = new byte[dstW * dstH];
		dstScan = dstW;
		dstOff = 0;
		imageModel = model;
	    } else if (imageModel != model) {
		convertToRGB();
	    }
	    if (bytePixels != null) {
		for (int h = srcH; h > 0; h--) {
		    System.arraycopy(pixels, srcOff, bytePixels, dstPtr, srcW);
		    srcOff += srcScan;
		    dstPtr += dstScan;
		}
	    }
	}
	if (intPixels != null) {
	    int dstRem = dstScan - srcW;
	    int srcRem = srcScan - srcW;
	    for (int h = srcH; h > 0; h--) {
		for (int w = srcW; w > 0; w--) {
		    intPixels[dstPtr++] = model.getRGB(pixels[srcOff++]&0xff);
		}
		srcOff += srcRem;
		dstPtr += dstRem;
	    }
	}
	flags |= ImageObserver.SOMEBITS;
    
public voidsetPixels(int srcX, int srcY, int srcW, int srcH, java.awt.image.ColorModel model, int[] pixels, int srcOff, int srcScan)
The setPixels method is part of the ImageConsumer API which this class must implement to retrieve the pixels.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being grabbed. Developers using this class to retrieve pixels from an image should avoid calling this method directly since that operation could result in problems with retrieving the requested pixels.

param
srcX, srcY the coordinates of the upper-left corner of the area of pixels to be set
param
srcW the width of the area of pixels
param
srcH the height of the area of pixels
param
model the specified ColorModel
param
pixels the array of pixels
param
srcOff the offset into the pixels array
param
srcScan the distance from one row of pixels to the next in the pixels array
see
#getPixels

	if (srcY < dstY) {
	    int diff = dstY - srcY;
	    if (diff >= srcH) {
		return;
	    }
	    srcOff += srcScan * diff;
	    srcY += diff;
	    srcH -= diff;
	}
	if (srcY + srcH > dstY + dstH) {
	    srcH = (dstY + dstH) - srcY;
	    if (srcH <= 0) {
		return;
	    }
	}
	if (srcX < dstX) {
	    int diff = dstX - srcX;
	    if (diff >= srcW) {
		return;
	    }
	    srcOff += diff;
	    srcX += diff;
	    srcW -= diff;
	}
	if (srcX + srcW > dstX + dstW) {
	    srcW = (dstX + dstW) - srcX;
	    if (srcW <= 0) {
		return;
	    }
	}
	if (intPixels == null) {
	    if (bytePixels == null) {
		intPixels = new int[dstW * dstH];
		dstScan = dstW;
		dstOff = 0;
		imageModel = model;
	    } else {
		convertToRGB();
	    }
	}
	int dstPtr = dstOff + (srcY - dstY) * dstScan + (srcX - dstX);
	if (imageModel == model) {
	    for (int h = srcH; h > 0; h--) {
		System.arraycopy(pixels, srcOff, intPixels, dstPtr, srcW);
		srcOff += srcScan;
		dstPtr += dstScan;
	    }
	} else {
	    if (imageModel != ColorModel.getRGBdefault()) {
		convertToRGB();
	    }
	    int dstRem = dstScan - srcW;
	    int srcRem = srcScan - srcW;
	    for (int h = srcH; h > 0; h--) {
		for (int w = srcW; w > 0; w--) {
		    intPixels[dstPtr++] = model.getRGB(pixels[srcOff++]);
		}
		srcOff += srcRem;
		dstPtr += dstRem;
	    }
	}
	flags |= ImageObserver.SOMEBITS;
    
public voidsetProperties(java.util.Hashtable props)
The setProperties method is part of the ImageConsumer API which this class must implement to retrieve the pixels.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being grabbed. Developers using this class to retrieve pixels from an image should avoid calling this method directly since that operation could result in problems with retrieving the requested pixels.

param
props the list of properties

	return;
    
public synchronized voidstartGrabbing()
Request the PixelGrabber to start fetching the pixels.

	if ((flags & DONEBITS) != 0) {
	    return;
	}
	if (!grabbing) {
	    grabbing = true;
	    flags &= ~(ImageObserver.ABORT);
	    producer.startProduction(this);
	}
    
public synchronized intstatus()
Returns the status of the pixels. The ImageObserver flags representing the available pixel information are returned. This method and {@link #getStatus() getStatus} have the same implementation, but getStatus is the preferred method because it conforms to the convention of naming information-retrieval methods with the form "getXXX".

return
the bitwise OR of all relevant ImageObserver flags
see
ImageObserver
see
#getStatus()

	return flags;