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package javax.imageio;
import java.awt.Dimension;
import java.awt.image.BufferedImage;
/**
* A class describing how a stream is to be decoded. Instances of
* this class or its subclasses are used to supply prescriptive
* "how-to" information to instances of {@code ImageReader}.
*
* <p> An image encoded as part of a file or stream may be thought of
* extending out in multiple dimensions: the spatial dimensions of
* width and height, a number of bands, and a number of progressive
* decoding passes. This class allows a contiguous (hyper)rectangular
* subarea of the image in all of these dimensions to be selected for
* decoding. Additionally, the spatial dimensions may be subsampled
* discontinuously. Finally, color and format conversions may be
* specified by controlling the {@code ColorModel} and
* {@code SampleModel} of the destination image, either by
* providing a {@code BufferedImage} or by using an
* {@code ImageTypeSpecifier}.
*
* <p> An {@code ImageReadParam} object is used to specify how an
* image, or a set of images, will be converted on input from
* a stream in the context of the Java Image I/O framework. A plug-in for a
* specific image format will return instances of
* {@code ImageReadParam} from the
* {@code getDefaultReadParam} method of its
* {@code ImageReader} implementation.
*
* <p> The state maintained by an instance of
* {@code ImageReadParam} is independent of any particular image
* being decoded. When actual decoding takes place, the values set in
* the read param are combined with the actual properties of the image
* being decoded from the stream and the destination
* {@code BufferedImage} that will receive the decoded pixel
* data. For example, the source region set using
* {@code setSourceRegion} will first be intersected with the
* actual valid source area. The result will be translated by the
* value returned by {@code getDestinationOffset}, and the
* resulting rectangle intersected with the actual valid destination
* area to yield the destination area that will be written.
*
* <p> The parameters specified by an {@code ImageReadParam} are
* applied to an image as follows. First, if a rendering size has
* been set by {@code setSourceRenderSize}, the entire decoded
* image is rendered at the size given by
* {@code getSourceRenderSize}. Otherwise, the image has its
* natural size given by {@code ImageReader.getWidth} and
* {@code ImageReader.getHeight}.
*
* <p> Next, the image is clipped against the source region
* specified by {@code getSourceXOffset}, {@code getSourceYOffset},
* {@code getSourceWidth}, and {@code getSourceHeight}.
*
* <p> The resulting region is then subsampled according to the
* factors given in {@link IIOParam#setSourceSubsampling
* IIOParam.setSourceSubsampling}. The first pixel,
* the number of pixels per row, and the number of rows all depend
* on the subsampling settings.
* Call the minimum X and Y coordinates of the resulting rectangle
* ({@code minX}, {@code minY}), its width {@code w}
* and its height {@code h}.
*
* <p> This rectangle is offset by
* ({@code getDestinationOffset().x},
* {@code getDestinationOffset().y}) and clipped against the
* destination bounds. If no destination image has been set, the
* destination is defined to have a width of
* {@code getDestinationOffset().x} + {@code w}, and a
* height of {@code getDestinationOffset().y} + {@code h} so
* that all pixels of the source region may be written to the
* destination.
*
* <p> Pixels that land, after subsampling, within the destination
* image, and that are written in one of the progressive passes
* specified by {@code getSourceMinProgressivePass} and
* {@code getSourceNumProgressivePasses} are passed along to the
* next step.
*
* <p> Finally, the source samples of each pixel are mapped into
* destination bands according to the algorithm described in the
* comment for {@code setDestinationBands}.
*
* <p> Plug-in writers may extend the functionality of
* {@code ImageReadParam} by providing a subclass that implements
* additional, plug-in specific interfaces. It is up to the plug-in
* to document what interfaces are available and how they are to be
* used. Readers will silently ignore any extended features of an
* {@code ImageReadParam} subclass of which they are not aware.
* Also, they may ignore any optional features that they normally
* disable when creating their own {@code ImageReadParam}
* instances via {@code getDefaultReadParam}.
*
* <p> Note that unless a query method exists for a capability, it must
* be supported by all {@code ImageReader} implementations
* (<i>e.g.</i> source render size is optional, but subsampling must be
* supported).
*
*
* @see ImageReader
* @see ImageWriter
* @see ImageWriteParam
*/
public class ImageReadParam extends IIOParam {
/**
* {@code true} if this {@code ImageReadParam} allows
* the source rendering dimensions to be set. By default, the
* value is {@code false}. Subclasses must set this value
* manually.
*
* <p> {@code ImageReader}s that do not support setting of
* the source render size should set this value to
* {@code false}.
*/
protected boolean canSetSourceRenderSize = false;
/**
* The desired rendering width and height of the source, if
* {@code canSetSourceRenderSize} is {@code true}, or
* {@code null}.
*
* <p> {@code ImageReader}s that do not support setting of
* the source render size may ignore this value.
*/
protected Dimension sourceRenderSize = null;
/**
* The current destination {@code BufferedImage}, or
* {@code null} if none has been set. By default, the value
* is {@code null}.
*/
protected BufferedImage destination = null;
/**
* The set of destination bands to be used, as an array of
* {@code int}s. By default, the value is {@code null},
* indicating all destination bands should be written in order.
*/
protected int[] destinationBands = null;
/**
* The minimum index of a progressive pass to read from the
* source. By default, the value is set to 0, which indicates
* that passes starting with the first available pass should be
* decoded.
*
* <p> Subclasses should ensure that this value is
* non-negative.
*/
protected int minProgressivePass = 0;
/**
* The maximum number of progressive passes to read from the
* source. By default, the value is set to
* {@code Integer.MAX_VALUE}, which indicates that passes up
* to and including the last available pass should be decoded.
*
* <p> Subclasses should ensure that this value is positive.
* Additionally, if the value is not
* {@code Integer.MAX_VALUE}, then
* {@code minProgressivePass + numProgressivePasses - 1}
* should not exceed
* {@code Integer.MAX_VALUE}.
*/
protected int numProgressivePasses = Integer.MAX_VALUE;
/**
* Constructs an {@code ImageReadParam}.
*/
public ImageReadParam() {}
// Comment inherited
public void setDestinationType(ImageTypeSpecifier destinationType) {
super.setDestinationType(destinationType);
setDestination(null);
}
/**
* Supplies a {@code BufferedImage} to be used as the
* destination for decoded pixel data. The currently set image
* will be written to by the {@code read},
* {@code readAll}, and {@code readRaster} methods, and
* a reference to it will be returned by those methods.
*
* <p> Pixel data from the aforementioned methods will be written
* starting at the offset specified by
* {@code getDestinationOffset}.
*
* <p> If {@code destination} is {@code null}, a
* newly-created {@code BufferedImage} will be returned by
* those methods.
*
* <p> At the time of reading, the image is checked to verify that
* its {@code ColorModel} and {@code SampleModel}
* correspond to one of the {@code ImageTypeSpecifier}s
* returned from the {@code ImageReader}'s
* {@code getImageTypes} method. If it does not, the reader
* will throw an {@code IIOException}.
*
* @param destination the BufferedImage to be written to, or
* {@code null}.
*
* @see #getDestination
*/
public void setDestination(BufferedImage destination) {
this.destination = destination;
}
/**
* Returns the {@code BufferedImage} currently set by the
* {@code setDestination} method, or {@code null}
* if none is set.
*
* @return the BufferedImage to be written to.
*
* @see #setDestination
*/
public BufferedImage getDestination() {
return destination;
}
/**
* Sets the indices of the destination bands where data
* will be placed. Duplicate indices are not allowed.
*
* <p> A {@code null} value indicates that all destination
* bands will be used.
*
* <p> Choosing a destination band subset will not affect the
* number of bands in the output image of a read if no destination
* image is specified; the created destination image will still
* have the same number of bands as if this method had never been
* called. If a different number of bands in the destination
* image is desired, an image must be supplied using the
* {@code ImageReadParam.setDestination} method.
*
* <p> At the time of reading or writing, an
* {@code IllegalArgumentException} will be thrown by the
* reader or writer if a value larger than the largest destination
* band index has been specified, or if the number of source bands
* and destination bands to be used differ. The
* {@code ImageReader.checkReadParamBandSettings} method may
* be used to automate this test.
*
* @param destinationBands an array of integer band indices to be
* used.
*
* @exception IllegalArgumentException if {@code destinationBands}
* contains a negative or duplicate value.
*
* @see #getDestinationBands
* @see #getSourceBands
* @see ImageReader#checkReadParamBandSettings
*/
public void setDestinationBands(int[] destinationBands) {
if (destinationBands == null) {
this.destinationBands = null;
} else {
int numBands = destinationBands.length;
for (int i = 0; i < numBands; i++) {
int band = destinationBands[i];
if (band < 0) {
throw new IllegalArgumentException("Band value < 0!");
}
for (int j = i + 1; j < numBands; j++) {
if (band == destinationBands[j]) {
throw new IllegalArgumentException("Duplicate band value!");
}
}
}
this.destinationBands = destinationBands.clone();
}
}
/**
* Returns the set of band indices where data will be placed.
* If no value has been set, {@code null} is returned to
* indicate that all destination bands will be used.
*
* @return the indices of the destination bands to be used,
* or {@code null}.
*
* @see #setDestinationBands
*/
public int[] getDestinationBands() {
if (destinationBands == null) {
return null;
} else {
return destinationBands.clone();
}
}
/**
* Returns {@code true} if this reader allows the source
* image to be rendered at an arbitrary size as part of the
* decoding process, by means of the
* {@code setSourceRenderSize} method. If this method
* returns {@code false}, calls to
* {@code setSourceRenderSize} will throw an
* {@code UnsupportedOperationException}.
*
* @return {@code true} if setting source rendering size is
* supported.
*
* @see #setSourceRenderSize
*/
public boolean canSetSourceRenderSize() {
return canSetSourceRenderSize;
}
/**
* If the image is able to be rendered at an arbitrary size, sets
* the source width and height to the supplied values. Note that
* the values returned from the {@code getWidth} and
* {@code getHeight} methods on {@code ImageReader} are
* not affected by this method; they will continue to return the
* default size for the image. Similarly, if the image is also
* tiled the tile width and height are given in terms of the default
* size.
*
* <p> Typically, the width and height should be chosen such that
* the ratio of width to height closely approximates the aspect
* ratio of the image, as returned from
* {@code ImageReader.getAspectRatio}.
*
* <p> If this plug-in does not allow the rendering size to be
* set, an {@code UnsupportedOperationException} will be
* thrown.
*
* <p> To remove the render size setting, pass in a value of
* {@code null} for {@code size}.
*
* @param size a {@code Dimension} indicating the desired
* width and height.
*
* @exception IllegalArgumentException if either the width or the
* height is negative or 0.
* @exception UnsupportedOperationException if image resizing
* is not supported by this plug-in.
*
* @see #getSourceRenderSize
* @see ImageReader#getWidth
* @see ImageReader#getHeight
* @see ImageReader#getAspectRatio
*/
public void setSourceRenderSize(Dimension size)
throws UnsupportedOperationException {
if (!canSetSourceRenderSize()) {
throw new UnsupportedOperationException
("Can't set source render size!");
}
if (size == null) {
this.sourceRenderSize = null;
} else {
if (size.width <= 0 || size.height <= 0) {
throw new IllegalArgumentException("width or height <= 0!");
}
this.sourceRenderSize = (Dimension)size.clone();
}
}
/**
* Returns the width and height of the source image as it
* will be rendered during decoding, if they have been set via the
* {@code setSourceRenderSize} method. A
* {@code null} value indicates that no setting has been made.
*
* @return the rendered width and height of the source image
* as a {@code Dimension}.
*
* @see #setSourceRenderSize
*/
public Dimension getSourceRenderSize() {
return (sourceRenderSize == null) ?
null : (Dimension)sourceRenderSize.clone();
}
/**
* Sets the range of progressive passes that will be decoded.
* Passes outside of this range will be ignored.
*
* <p> A progressive pass is a re-encoding of the entire image,
* generally at progressively higher effective resolutions, but
* requiring greater transmission bandwidth. The most common use
* of progressive encoding is found in the JPEG format, where
* successive passes include more detailed representations of the
* high-frequency image content.
*
* <p> The actual number of passes to be decoded is determined
* during decoding, based on the number of actual passes available
* in the stream. Thus if {@code minPass + numPasses - 1} is
* larger than the index of the last available passes, decoding
* will end with that pass.
*
* <p> A value of {@code numPasses} of
* {@code Integer.MAX_VALUE} indicates that all passes from
* {@code minPass} forward should be read. Otherwise, the
* index of the last pass (<i>i.e.</i>, {@code minPass + numPasses - 1})
* must not exceed {@code Integer.MAX_VALUE}.
*
* <p> There is no {@code unsetSourceProgressivePasses}
* method; the same effect may be obtained by calling
* {@code setSourceProgressivePasses(0, Integer.MAX_VALUE)}.
*
* @param minPass the index of the first pass to be decoded.
* @param numPasses the maximum number of passes to be decoded.
*
* @exception IllegalArgumentException if {@code minPass} is
* negative, {@code numPasses} is negative or 0, or
* {@code numPasses} is smaller than
* {@code Integer.MAX_VALUE} but
* {@code minPass + numPasses - 1} is greater than
* {@code INTEGER.MAX_VALUE}.
*
* @see #getSourceMinProgressivePass
* @see #getSourceMaxProgressivePass
*/
public void setSourceProgressivePasses(int minPass, int numPasses) {
if (minPass < 0) {
throw new IllegalArgumentException("minPass < 0!");
}
if (numPasses <= 0) {
throw new IllegalArgumentException("numPasses <= 0!");
}
if ((numPasses != Integer.MAX_VALUE) &&
(((minPass + numPasses - 1) & 0x80000000) != 0)) {
throw new IllegalArgumentException
("minPass + numPasses - 1 > INTEGER.MAX_VALUE!");
}
this.minProgressivePass = minPass;
this.numProgressivePasses = numPasses;
}
/**
* Returns the index of the first progressive pass that will be
* decoded. If no value has been set, 0 will be returned (which is
* the correct value).
*
* @return the index of the first pass that will be decoded.
*
* @see #setSourceProgressivePasses
* @see #getSourceNumProgressivePasses
*/
public int getSourceMinProgressivePass() {
return minProgressivePass;
}
/**
* If {@code getSourceNumProgressivePasses} is equal to
* {@code Integer.MAX_VALUE}, returns
* {@code Integer.MAX_VALUE}. Otherwise, returns
* {@code getSourceMinProgressivePass() +
* getSourceNumProgressivePasses() - 1}.
*
* @return the index of the last pass to be read, or
* {@code Integer.MAX_VALUE}.
*/
public int getSourceMaxProgressivePass() {
if (numProgressivePasses == Integer.MAX_VALUE) {
return Integer.MAX_VALUE;
} else {
return minProgressivePass + numProgressivePasses - 1;
}
}
/**
* Returns the number of the progressive passes that will be
* decoded. If no value has been set,
* {@code Integer.MAX_VALUE} will be returned (which is the
* correct value).
*
* @return the number of the passes that will be decoded.
*
* @see #setSourceProgressivePasses
* @see #getSourceMinProgressivePass
*/
public int getSourceNumProgressivePasses() {
return numProgressivePasses;
}
}