492 lines
15 KiB
Java
492 lines
15 KiB
Java
/* IIOParam.java --
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Copyright (C) 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package javax.imageio;
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import java.awt.Point;
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import java.awt.Rectangle;
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/**
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* An IIOParam stores parameters used when encoding or decoding image
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* streams. ImageReadParam and ImageWriteParam extend this abstract
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* base class.
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*
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* IIOParams allow control over how source pixels converted into
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* destination pixels. This conversion can take place between a
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* stream and in-memory image data, when an image reader is doing the
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* conversion, or a writer can be doing the conversion from an
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* in-memory source to a stream destination.
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*
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* An image reader can be restricted to only read from a given region;
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* likewise a writer can be restricted to only write output to a given
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* region.
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*
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* For image readers and writers, IIOParam supports image pixelation
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* -- where the input image is approximated by the output image using
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* larger-sized pixel blocks. For example: FIXME
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*
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* IIOParams can control how pixels are combined into larger blocks
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* using sub-sampling matrices. For example: FIXME
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*
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* They can also control which source bands are read and written; this
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* example reads the RGBA (red, green, blue, transparency) data from a
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* PNG image and outputs just the red and transparency bands: FIXME
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*
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* @author Thomas Fitzsimmons (fitzsim@redhat.com)
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* @author Michael Koch (konqueror@gmx.de)
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*/
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public abstract class IIOParam
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{
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/**
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* The controller called by this IIOParam to retrieve parameters.
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*/
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protected IIOParamController controller = null;
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/**
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* The default controller called by this IIOParam to retrieve
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* parameters.
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*/
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protected IIOParamController defaultController = null;
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/**
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* The offset in the destination where the upper-left
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* decoded/encoded pixel should be located.
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*/
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protected Point destinationOffset = new Point(0, 0);
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/**
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* Sets the output colour type when writing or the destination image
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* type when reading.
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*/
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protected ImageTypeSpecifier destinationType = null;
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/**
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* An array indicating which source bands will be used or null.
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*/
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protected int[] sourceBands = null;
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/**
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* The source pixel region or null.
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*/
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protected Rectangle sourceRegion = null;
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/**
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* Sample every sourceXSubsampling'th pixel in the source image when
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* pixelating the destination image in the horizontal direction.
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*/
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protected int sourceXSubsampling = 1;
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/**
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* Sample every sourceYSubsampling'th pixel in the source image when
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* pixelating the destination image in the vertical direction.
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*/
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protected int sourceYSubsampling = 1;
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/**
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* Start sampling at this horizontal offset within the source region
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* when pixelating the destination image in the horizontal
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* direction.
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*/
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protected int subsamplingXOffset = 0;
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/**
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* Start sampling at this vertical offset within the source region
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* when pixelating the destination image in the vertical direction.
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*/
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protected int subsamplingYOffset = 0;
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/**
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* Indicates whether or not the controller has been explicitly set
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* to null.
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*/
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private boolean no_controller = false;
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/**
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* Constructs an IIOParam object.
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*/
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protected IIOParam()
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{
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}
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/**
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* Activates the parameter controller by calling its activate method
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* and passing it this IIOParam. A true return value indicates that
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* this IIOParam's values are ready for the next read or write
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* operation. A return value of false means that this IIOParam's
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* values have not been affected because the controller operations
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* were cancelled.
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*
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* @return true if parameters were successfully set, false if
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* parameters were not changed
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*/
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public boolean activateController()
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{
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if (controller == null)
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{
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if (defaultController == null || no_controller)
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return false;
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else
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return defaultController.activate (this);
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}
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else
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return controller.activate(this);
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}
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/**
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* Retrieve the currently set controller if one has been set, or the
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* default controller, or null if the controller has been explicitly
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* set to null.
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*
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* @return the currently used controller or null
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*/
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public IIOParamController getController()
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{
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return controller == null ?
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(no_controller ? null : defaultController) : controller;
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}
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/**
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* Retrieve the default controller regardless of whether or not a
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* non-default controller has been set. The default controller may
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* be null.
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*
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* @return the default controller or null
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*/
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public IIOParamController getDefaultController()
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{
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return defaultController;
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}
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/**
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* Retrieve the offset in the destination where the upper-left
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* decoded/encoded pixel should be located. (0, 0) by default.
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*
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* @return the destination offset
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*/
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public Point getDestinationOffset()
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{
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return destinationOffset;
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}
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/**
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* Retrieve the currently set image-type specifier or null if none
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* has been set.
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*
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* @return the current image-type specifier or null
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*/
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public ImageTypeSpecifier getDestinationType()
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{
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return destinationType;
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}
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/**
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* Retrieve the current source band values or null if source band
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* values have not been set.
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*
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* The returned array is a copy of this IIOParam's source band
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* array.
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*
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* @return the current set of source band values or null
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*/
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public int[] getSourceBands()
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{
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if (sourceBands == null)
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return null;
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int[] sourceBandsCopy = new int[sourceBands.length];
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System.arraycopy (sourceBands, 0, sourceBandsCopy, 0, sourceBands.length);
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return sourceBandsCopy;
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}
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/**
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* Retrieve the source rectangle from which pixels should be read or
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* null if no source region has been set.
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*
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* @return the current source region or null
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*/
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public Rectangle getSourceRegion()
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{
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return sourceRegion;
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}
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/**
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* Retrieve the number of pixel columns to advance before taking a
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* pixel sample.
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*
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* @return the horizontal sub-sampling interval
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*/
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public int getSourceXSubsampling()
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{
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return sourceXSubsampling;
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}
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/**
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* Retrieve the number of pixel rows to advance before taking a
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* pixel sample.
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*
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* @return the vertical sub-sampling interval
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*/
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public int getSourceYSubsampling()
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{
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return sourceYSubsampling;
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}
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/**
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* Retrieve the number of pixel columns to advance before taking any
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* pixel samples.
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*
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* @return the horizontal sub-sampling offset
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*/
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public int getSubsamplingXOffset()
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{
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return subsamplingXOffset;
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}
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/**
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* Retrieve the number of pixel rows to advance before taking any
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* pixel samples.
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*
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* @return the vertical sub-sampling offset
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*/
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public int getSubsamplingYOffset()
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{
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return subsamplingYOffset;
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}
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/**
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* Check if a non-null controller is currently available.
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*
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* @return true if getController returns a non-null value, false if
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* getController returns null
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*/
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public boolean hasController()
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{
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return getController() != null;
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}
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/**
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* Sets the controller for this IIOParam. This is the controller
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* that will be activated when activateController is called. The
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* argument controller overrides this IIOParam's default controller.
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* If the argument is null then no controller will be set, not even
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* the default one. To reset the default controller call
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* setController(getDefaultController()).
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*
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* @param controller the controller to set or null
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*/
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public void setController(IIOParamController controller)
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{
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if (controller == defaultController)
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{
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this.controller = null;
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no_controller = false;
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}
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else
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{
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no_controller = (controller == null);
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this.controller = controller;
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}
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}
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/**
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* Set the destination image type.
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*
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* If this value is set on an image reader then its read method will
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* return a new BufferedImage of the specified destination type. In
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* this case any destination image set using setDestination() is
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* ignored.
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*
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* If this is set on an image writer then the destination type
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* affects only the colour model of the destination image. The
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* destination type's SampleModel is ignored. The destination
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* type's ColorModel will override the source image's colour model.
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*
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* @param destinationType the sample and colour models of the
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* destination image
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*/
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public void setDestinationType (ImageTypeSpecifier destinationType)
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{
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this.destinationType = destinationType;
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}
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/**
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* Specify the destination pixel offset. Image writers are only
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* affected by this setting when ImageWriter.replacePixels is called
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* in which case the offset is into the region of pixels being
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* changed.
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*
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* @param destinationOffset the offset where pixel writing should
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* begin
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*/
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public void setDestinationOffset(Point destinationOffset)
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{
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if (destinationOffset == null)
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throw new IllegalArgumentException("destinationOffset is null");
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this.destinationOffset = destinationOffset;
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}
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/**
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* Set the indices of the source bands to be used. Duplicate
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* indices are not allowed. A value of null means use all source
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* bands. The argument array is copied and stored, so subsequent
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* updates to it will not be reflected in this IIOParam.
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*
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* @param sourceBands the array of source bands to use
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*/
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public void setSourceBands(int[] sourceBands)
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{
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int[] sourceBandsCopy = new int[sourceBands.length];
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System.arraycopy (sourceBands, 0, sourceBandsCopy, 0, sourceBands.length);
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this.sourceBands = sourceBandsCopy;
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}
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/**
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* Set the source region from which to read. The number of pixels
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* sampled from the source region depends on the source sub-sampling
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* settings. If the combination of this sourceRegion and the
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* current sub-sampling settings would result in no pixels being
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* sampled then an IllegalStateException will be thrown.
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*
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* The source region is specified in the source image coordinate
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* system which has point (0, 0) at the top-left and increases down
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* and to the right. The argument source region is clipped to the
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* image boundaries at read-time.
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*
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* A null argument sets the source region to null meaning that the
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* whole image should be read.
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*
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* @param sourceRegion the rectangular source region
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*
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* @exception IllegalArgumentException if sourceRegion has width or
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* height <= 0 or x or y < 0
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* @exception IllegalStateException if the given sourceRegion and
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* the current sampling settings would produce zero samples
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*/
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public void setSourceRegion(Rectangle sourceRegion)
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{
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if (sourceRegion != null
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&& (sourceRegion.x < 0
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|| sourceRegion.y < 0
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|| sourceRegion.width <= 0
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|| sourceRegion.height <= 0))
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throw new IllegalArgumentException("illegal source region");
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if (sourceRegion != null)
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{
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int num_rows =
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(sourceRegion.height - subsamplingYOffset + sourceYSubsampling - 1)
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/ sourceYSubsampling;
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int num_columns =
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(sourceRegion.width - subsamplingXOffset + sourceXSubsampling - 1)
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/ sourceXSubsampling;
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if (num_rows <= 0 || num_columns <= 0)
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throw new IllegalStateException("zero pixels in source region");
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}
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this.sourceRegion = sourceRegion;
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}
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/**
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* Set the source sampling intervals and offsets. Every
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* sourceXSubsampling'th pixel horizontally and
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* sourceYSubsampling'th pixel vertically will be sampled. Sampling
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* will being a the subsamplingXOffset'th column and the
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* subsamplingYOffset'th row.
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*
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* Horizontally, the number of sampled pixels will be:
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*
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* floor((width - subsamplingXOffset + sourceXSubsampling - 1) / sourceXSubsampling)
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*
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* Vertically:
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*
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* floor((height - subsamplingYOffset + sourceYSubsampling - 1) / sourceYSubsampling)
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*
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* If the current source region setting is such that the given
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* sub-sampling arguments would produce zero pixel samples, an
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* IllegalStateException is thrown.
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*
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* The offset parameters can be used to make source regions overlap
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* when tiling across an image. This can eliminate seams and
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* better-tile images whose width or height is not a multiple of the
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* sampling interval.
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*
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* @param sourceXSubsampling the horizontal sampling interval
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* @param sourceYSubsampling the vertical sampling interval
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* @param subsamplingXOffset the horizontal offset of the initial
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* sample
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* @param subsamplingYOffset the vertical offset of the initial
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* sample
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*
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* @exception IllegalArgumentException if either subsamplingXOffset
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* or subsamplingYOffset is < 0
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* @exception IllegalStateException if the current source region
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* combined with the given sub-sampling parameters would produce
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* zero pixel samples
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*/
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public void setSourceSubsampling(int sourceXSubsampling, int sourceYSubsampling,
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int subsamplingXOffset, int subsamplingYOffset)
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{
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if (subsamplingXOffset < 0 || subsamplingYOffset < 0)
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throw new IllegalArgumentException("subsampling offset < 0");
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if (sourceRegion != null)
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{
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int num_rows =
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(sourceRegion.height - subsamplingYOffset + sourceYSubsampling - 1)
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/ sourceYSubsampling;
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int num_columns =
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(sourceRegion.width - subsamplingXOffset + sourceXSubsampling - 1)
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/ sourceXSubsampling;
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if (num_rows <= 0 || num_columns <= 0)
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throw new IllegalStateException("subsampling parameters would"
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+ " produce zero pixel samples"
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+ " in source region");
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}
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this.sourceXSubsampling = sourceXSubsampling;
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this.sourceYSubsampling = sourceYSubsampling;
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this.subsamplingXOffset = subsamplingXOffset;
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this.subsamplingYOffset = subsamplingYOffset;
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}
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}
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