Package org.opengis.test.coverage.image

Class PixelIterator

Object

PixelIterator

public class PixelIterator
extends Object

A row-major iterator over sample values in a Raster or RenderedImage. For any image (tiled or not), this class iterates first over the bands, then over the columns and finally over the rows. If the image is tiled, then this iterator will perform the necessary calls to the RenderedImage.getTile(int, int) method for each row in order to perform the iteration as if the image was untiled.

On creation, this iterator is positioned before the first sample value. To use this iterator, invoke the next() method in a while loop as below:

PixelIterator it = new PixelIterator(image);
while (it.next()) {
    float value = it.getSampleFloat();
    // Do some processing with the value here...
}

Since:

3.1

See Also:

Assert.assertSampleValuesEqual(String, RenderedImage, RenderedImage, double)

Constructor Summary

Constructors

Constructor	Description
PixelIterator(Raster raster)	Creates an iterator for the whole area of the given raster.
PixelIterator(Raster raster, Rectangle subArea, int xSubsampling, int ySubsampling, int[] sourceBands)	Creates an iterator for a sub-area of the given raster.
PixelIterator(RenderedImage image)	Creates an iterator for the whole area of the given image.
PixelIterator(RenderedImage image, Rectangle subArea, int xSubsampling, int ySubsampling, int[] sourceBands)	Creates an iterator for a sub-area of the given image.

Method Summary

Modifier and Type	Method	Description
void	assertSampleValuesEqual(PixelIterator actual, double tolerance)	Compares all sample values iterated by this PixelIterator with the sample values iterated by the given iterator.
int	getBand()	Returns the current band index.
int	getDataType()	Returns the type of the sample values, as one of the TYPE_* constants defined in the DataBuffer class.
int	getSample()	Returns the sample value at the current position, as an integer.
double	getSampleDouble()	Returns the sample value at the current position, as a double-precision floating point number.
float	getSampleFloat()	Returns the sample value at the current position, as a floating point number.
int	getX()	Returns the current x coordinate.
int	getY()	Returns the current y coordinate.
boolean	next()	Moves to the next sample values and returns true if the iteration has more pixels.
String	toString()	Returns a string representation of this iterator position for debugging purpose.

Methods inherited from class Object

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

Constructor Detail

PixelIterator

public PixelIterator(Raster raster)

Creates an iterator for the whole area of the given raster.

Parameters:

raster - The raster for which to create an iterator.

PixelIterator

public PixelIterator(RenderedImage image)

Creates an iterator for the whole area of the given image.

Parameters:

image - The image for which to create an iterator.

PixelIterator

public PixelIterator(Raster raster,
                     Rectangle subArea,
                     int xSubsampling,
                     int ySubsampling,
                     int[] sourceBands)

Creates an iterator for a sub-area of the given raster.

Parameters:

raster - the raster to iterate over.

subArea - rectangle which represent raster sub area iteration, or null if none.

xSubsampling - the iteration step when moving to the next pixel.

ySubsampling - the iteration step when moving to the next scan line.

sourceBands - the source bands, or null if none.

PixelIterator

public PixelIterator(RenderedImage image,
                     Rectangle subArea,
                     int xSubsampling,
                     int ySubsampling,
                     int[] sourceBands)

Creates an iterator for a sub-area of the given image.

Parameters:

image - the image to iterate over.

subArea - rectangle which represent image sub area iteration, or null if none.

xSubsampling - the iteration step when moving to the next pixel.

ySubsampling - the iteration step when moving to the next scan line.

sourceBands - the source bands, or null if none.

Method Detail

next

public boolean next()

Moves to the next sample values and returns true if the iteration has more pixels.

Returns:

true if the next sample value exist.

getX

public int getX()

Returns the current x coordinate. The coordinate values range from image X minimum (inclusive) to that minimum plus the image width (exclusive).

Returns:

the current x coordinate.

See Also:

RenderedImage.getMinX(), RenderedImage.getWidth()

getY

public int getY()

Returns the current y coordinate. The coordinate values range from image Y minimum (inclusive) to that minimum plus the image height (exclusive).

Returns:

the current y coordinate.

See Also:

RenderedImage.getMinY(), RenderedImage.getHeight()

getBand

public int getBand()

Returns the current band index. The index values range from 0 (inclusive) to the number of bands (exclusive), or to the sourceBands array length (exclusive) if the array given to the constructor was non-null.

Returns:

the current band index.

See Also:

SampleModel.getNumBands()

getDataType

public int getDataType()

Returns the type of the sample values, as one of the TYPE_* constants defined in the DataBuffer class.

Returns:

the type of the sample values.

See Also:

SampleModel.getDataType(), DataBuffer.TYPE_BYTE, DataBuffer.TYPE_SHORT, DataBuffer.TYPE_USHORT, DataBuffer.TYPE_INT, DataBuffer.TYPE_FLOAT, DataBuffer.TYPE_DOUBLE

getSample

public int getSample()

Returns the sample value at the current position, as an integer. This method is appropriate for the byte, short, unsigned short and integer datatypes.

Returns:

the sample value at the current position.

See Also:

Raster.getSample(int, int, int), DataBuffer.TYPE_BYTE, DataBuffer.TYPE_SHORT, DataBuffer.TYPE_USHORT, DataBuffer.TYPE_INT

getSampleFloat

public float getSampleFloat()

Returns the sample value at the current position, as a floating point number.

Returns:

the sample value at the current position.

See Also:

Raster.getSampleFloat(int, int, int), DataBuffer.TYPE_FLOAT

getSampleDouble

public double getSampleDouble()

Returns the sample value at the current position, as a double-precision floating point number.

Returns:

the sample value at the current position.

See Also:

Raster.getSampleDouble(int, int, int), DataBuffer.TYPE_DOUBLE

assertSampleValuesEqual

public void assertSampleValuesEqual(PixelIterator actual,
                                    double tolerance)
                             throws AssertionError

Compares all sample values iterated by this PixelIterator with the sample values iterated by the given iterator. If a mismatch is found, then an AssertionError is thrown with a detailed error message.

This method does not verify the image sizes, number of tiles, number of bands, color model or datatype. Consequently this method is robust to the following differences:

• Differences in the (x, y) origin;
• Differences in tile layout (images are compared as if they were untiled);
• Differences in the datatype (values are compared using the widest of this iterator datatype and the datatype of the given iterator).

If the images have different sizes, then an "Unexpected end of iteration" exception will be thrown when the first iterator reaches the iteration end.

Parameters:

actual - the iterator that contains the actual values to be compared with the "expected" sample values.

tolerance - the tolerance threshold for floating point comparison. This threshold does not apply to integer types.

Throws:

AssertionError - if a value in this iterator is not equals to a value in the given iterator with the given tolerance threshold.

toString

public String toString()

Returns a string representation of this iterator position for debugging purpose.

Overrides:

toString in class Object

Returns:

a string representation if this iterator position.