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Class RGBImageFilter

java.lang.Object
java.awt.image.ImageFilter
java.awt.image.RGBImageFilter
All Implemented Interfaces:
ImageConsumer, Cloneable
Direct Known Subclasses:
GrayFilter
public abstract class RGBImageFilter extends ImageFilter
This class provides an easy way to create an ImageFilter which modifies the pixels of an image in the default RGB ColorModel. It is meant to be used in conjunction with a FilteredImageSource object to produce filtered versions of existing images. It is an abstract class that provides the calls needed to channel all of the pixel data through a single method which converts pixels one at a time in the default RGB ColorModel regardless of the ColorModel being used by the ImageProducer. The only method which needs to be defined to create a usable image filter is the filterRGB method. Here is an example of a definition of a filter which swaps the red and blue components of an image: 


      class RedBlueSwapFilter extends RGBImageFilter {
          public RedBlueSwapFilter() {
              // The filter's operation does not depend on the
              // pixel's location, so IndexColorModels can be
              // filtered directly.
              canFilterIndexColorModel = true;
          }

          public int filterRGB(int x, int y, int rgb) {
              return ((rgb & 0xff00ff00)
                      | ((rgb & 0xff0000) >> 16)
                      | ((rgb & 0xff) << 16));
          }
      }
See Also:

Field Summary

Modifier and Type Field Description
protected boolean canFilterIndexColorModel
This boolean indicates whether or not it is acceptable to apply the color filtering of the filterRGB method to the color table entries of an IndexColorModel object in lieu of pixel by pixel filtering.
protected ColorModel newmodel
The ColorModel with which to replace origmodel when the user calls substituteColorModel.
protected ColorModel origmodel
The ColorModel to be replaced by newmodel when the user calls substituteColorModel.

Fields declared in class java.awt.image.ImageFilter

consumer

Fields declared in interface java.awt.image.ImageConsumer

COMPLETESCANLINES, IMAGEABORTED, IMAGEERROR, RANDOMPIXELORDER, SINGLEFRAME, SINGLEFRAMEDONE, SINGLEPASS, STATICIMAGEDONE, TOPDOWNLEFTRIGHT

Constructor Summary

RGBImageFilter()
Modifier Constructor Description
protected
Constructor for subclasses to call.

Method Summary

Modifier and Type Method Description
IndexColorModel filterIndexColorModel(IndexColorModel icm)
Filters an IndexColorModel object by running each entry in its color tables through the filterRGB function that RGBImageFilter subclasses must provide.
abstract int filterRGB(int x, int y, int rgb)
Subclasses must specify a method to convert a single input pixel in the default RGB ColorModel to a single output pixel.
void filterRGBPixels(int x, int y, int w, int h, int[] pixels, int off, int scansize)
Filters a buffer of pixels in the default RGB ColorModel by passing them one by one through the filterRGB method.
void setColorModel(ColorModel model)
If the ColorModel is an IndexColorModel and the subclass has set the canFilterIndexColorModel flag to true, we substitute a filtered version of the color model here and wherever that original ColorModel object appears in the setPixels methods.
void setPixels(int x, int y, int w, int h, ColorModel model, byte[] pixels, int off, int scansize)
If the ColorModel object is the same one that has already been converted, then simply passes the pixels through with the converted ColorModel.
void setPixels(int x, int y, int w, int h, ColorModel model, int[] pixels, int off, int scansize)
If the ColorModel object is the same one that has already been converted, then simply passes the pixels through with the converted ColorModel, otherwise converts the buffer of integer pixels to the default RGB ColorModel and passes the converted buffer to the filterRGBPixels method to be converted one by one.
void substituteColorModel(ColorModel oldcm, ColorModel newcm)
Registers two ColorModel objects for substitution.

Methods declared in class java.awt.image.ImageFilter

clone, getFilterInstance, imageComplete, resendTopDownLeftRight, setDimensions, setHints, setProperties

Methods declared in class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

origmodel

protected ColorModel origmodel
The ColorModel to be replaced by newmodel when the user calls substituteColorModel.

newmodel

protected ColorModel newmodel
The ColorModel with which to replace origmodel when the user calls substituteColorModel.

canFilterIndexColorModel

protected boolean canFilterIndexColorModel
This boolean indicates whether or not it is acceptable to apply the color filtering of the filterRGB method to the color table entries of an IndexColorModel object in lieu of pixel by pixel filtering. Subclasses should set this variable to true in their constructor if their filterRGB method does not depend on the coordinate of the pixel being filtered.
See Also:

Constructor Details

RGBImageFilter

protected RGBImageFilter()
Constructor for subclasses to call.

Method Details

setColorModel

public void setColorModel(ColorModel model)
If the ColorModel is an IndexColorModel and the subclass has set the canFilterIndexColorModel flag to true, we substitute a filtered version of the color model here and wherever that original ColorModel object appears in the setPixels methods. If the ColorModel is not an IndexColorModel or is null, this method overrides the default ColorModel used by the ImageProducer and specifies the default RGB ColorModel instead.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation.

Specified by:
setColorModel in interface ImageConsumer
Overrides:
setColorModel in class ImageFilter
Parameters:
model - the specified ColorModel
See Also:

substituteColorModel

public void substituteColorModel(ColorModel oldcm, ColorModel newcm)
Registers two ColorModel objects for substitution. If the oldcm is encountered during any of the setPixels methods, the newcm is substituted and the pixels passed through untouched (but with the new ColorModel object).
Parameters:
oldcm - the ColorModel object to be replaced on the fly
newcm - the ColorModel object to replace oldcm on the fly

filterIndexColorModel

public IndexColorModel filterIndexColorModel(IndexColorModel icm)
Filters an IndexColorModel object by running each entry in its color tables through the filterRGB function that RGBImageFilter subclasses must provide. Uses coordinates of -1 to indicate that a color table entry is being filtered rather than an actual pixel value.
Parameters:
icm - the IndexColorModel object to be filtered
Returns:
a new IndexColorModel representing the filtered colors
Throws:
NullPointerException - if icm is null

filterRGBPixels

public void filterRGBPixels(int x, int y, int w, int h, int[] pixels, int off, int scansize)
Filters a buffer of pixels in the default RGB ColorModel by passing them one by one through the filterRGB method.
Parameters:
x - the X coordinate of the upper-left corner of the region of pixels
y - the Y coordinate of the upper-left corner of the region of pixels
w - the width of the region of pixels
h - the height of the region of pixels
pixels - the array of pixels
off - the offset into the pixels array
scansize - the distance from one row of pixels to the next in the array
See Also:

setPixels

public void setPixels(int x, int y, int w, int h, ColorModel model, byte[] pixels, int off, int scansize)
If the ColorModel object is the same one that has already been converted, then simply passes the pixels through with the converted ColorModel. Otherwise converts the buffer of byte pixels to the default RGB ColorModel and passes the converted buffer to the filterRGBPixels method to be converted one by one.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation.

Specified by:
setPixels in interface ImageConsumer
Overrides:
setPixels in class ImageFilter
Parameters:
x - the X coordinate of the upper-left corner of the area of pixels to be set
y - the Y coordinate of the upper-left corner of the area of pixels to be set
w - the width of the area of pixels
h - the height of the area of pixels
model - the specified ColorModel
pixels - the array of pixels
off - the offset into the pixels array
scansize - the distance from one row of pixels to the next in the pixels array
See Also:

setPixels

public void setPixels(int x, int y, int w, int h, ColorModel model, int[] pixels, int off, int scansize)
If the ColorModel object is the same one that has already been converted, then simply passes the pixels through with the converted ColorModel, otherwise converts the buffer of integer pixels to the default RGB ColorModel and passes the converted buffer to the filterRGBPixels method to be converted one by one. Converts a buffer of integer pixels to the default RGB ColorModel and passes the converted buffer to the filterRGBPixels method.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation.

Specified by:
setPixels in interface ImageConsumer
Overrides:
setPixels in class ImageFilter
Parameters:
x - the X coordinate of the upper-left corner of the area of pixels to be set
y - the Y coordinate of the upper-left corner of the area of pixels to be set
w - the width of the area of pixels
h - the height of the area of pixels
model - the specified ColorModel
pixels - the array of pixels
off - the offset into the pixels array
scansize - the distance from one row of pixels to the next in the pixels array
See Also:

filterRGB

public abstract int filterRGB(int x, int y, int rgb)
Subclasses must specify a method to convert a single input pixel in the default RGB ColorModel to a single output pixel.
Parameters:
x - the X coordinate of the pixel
y - the Y coordinate of the pixel
rgb - the integer pixel representation in the default RGB color model
Returns:
a filtered pixel in the default RGB color model.
See Also:

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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/java/awt/image/RGBImageFilter.html