add some useful and interesting functions

src/main/java/net/imglib2/position/Functions.java

@@ -0,0 +1,138 @@
+/*
+ * #%L
+ * ImgLib2: a general-purpose, multidimensional image processing library.
+ * %%
+ * Copyright (C) 2009 - 2020 Tobias Pietzsch, Stephan Preibisch, Stephan Saalfeld,
+ * John Bogovic, Albert Cardona, Barry DeZonia, Christian Dietz, Jan Funke,
+ * Aivar Grislis, Jonathan Hale, Grant Harris, Stefan Helfrich, Mark Hiner,
+ * Martin Horn, Steffen Jaensch, Lee Kamentsky, Larry Lindsey, Melissa Linkert,
+ * Mark Longair, Brian Northan, Nick Perry, Curtis Rueden, Johannes Schindelin,
+ * Jean-Yves Tinevez and Michael Zinsmaier.
+ * %%
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ * #L%
+ */
+package net.imglib2.position;
+
+import net.imglib2.type.Type;
+
+/**
+ * Convenience methods to create some typical functions in integer and real
+ * space.
+ *
+ * @author Stephan Saalfeld <[email protected]>
+ *
+ */
+public interface Functions
+{
+	/**
+	 * Creates a one pixel checker board pattern.
+	 *
+	 * @param <T>
+	 * @param n number of dimensions
+	 * @param on on value
+	 * @param off off value (at 0^n)
+	 *
+	 * @return
+	 */
+	public static < T extends Type< T > > FunctionRandomAccessible< T > checker(
+			final int n,
+			final T on,
+			final T off)
+	{
+		return new FunctionRandomAccessible<>(
+				n,
+				(position, value ) -> {
+					boolean isOn = ( position.getLongPosition( 0 ) & 1 ) == 1;
+					for ( int d = 1; d < n; ++d ) {
+						isOn ^= ( position.getLongPosition( d ) & 1 ) == 1;
+					}
+					if ( isOn )
+						value.set( on );
+					else
+						value.set( off );
+				},
+				on::createVariable );
+	}
+
+	/**
+	 * Creates a checker board pattern with a step size of 2<sup>bit</sup>.
+	 *
+	 * @param <T>
+	 * @param n number of dimensions
+	 * @param on on value
+	 * @param off off value (at 0^n)
+	 * @param bit the size of blocks is 2<sup>bit</sup>
+	 *
+	 * @return
+	 */
+	public static < T extends Type< T > > FunctionRandomAccessible< T > checker(
+			final int n,
+			final T on,
+			final T off,
+			final int bit )
+	{
+		return new FunctionRandomAccessible<>(
+				n,
+				(position, value ) -> {
+					boolean isOn = ( ( position.getLongPosition( 0 ) >> bit ) & 1 ) == 1;
+					for ( int d = 1; d < n; ++d ) {
+						isOn ^= ( ( position.getLongPosition( d ) >> bit ) & 1 ) == 1;
+					}
+					if ( isOn )
+						value.set( on );
+					else
+						value.set( off );
+				},
+				on::createVariable );
+	}
+
+	/**
+	 * Creates a one pixel checker board pattern.
+	 *
+	 * @param <T>
+	 * @param n number of dimensions
+	 * @param on on value
+	 * @param off off value (at 0^n)
+	 *
+	 * @return
+	 */
+	public static < T extends Type< T > > FunctionRealRandomAccessible< T > realChecker(
+			final int n,
+			final T on,
+			final T off)
+	{
+		return new FunctionRealRandomAccessible<>(
+				n,
+				(position, value ) -> {
+					boolean isOn = ( ( long )Math.floor( position.getDoublePosition( 0 ) ) & 1 ) == 1;
+					for ( int d = 1; d < n; ++d ) {
+						isOn ^= ( ( long )Math.floor( position.getDoublePosition( d ) ) & 1 ) == 1;
+					}
+					if ( isOn )
+						value.set( on );
+					else
+						value.set( off );
+				},
+				on::createVariable );
+	}
+}

src/test/java/net/imglib2/position/FunctionsTest.java

@@ -0,0 +1,91 @@
+package net.imglib2.position;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import net.imglib2.type.numeric.integer.IntType;
+import net.imglib2.util.Intervals;
+import net.imglib2.view.Views;
+
+public class FunctionsTest
+{
+
+	private static final String checker1 = "01010";
+	private static final String checker2 = "01010101010101010101010101010101010";
+	private static final String checker3 = "01010101010101010101101010101010101010100101010101010101010110101010101010101010010101010101010101011010101010101010101001010101010101010101";
+
+	private static final String checker12 = "00110";
+	private static final String checker22 = "00001000010000100001111101111011110";
+	private static final String checker32 = "00110001101100111001001100011011001110011100111001001100011011001110010011000110001100011011001110010011000110110011100111001110010011000110";
+
+
+	@BeforeClass
+	public static void setUpBeforeClass() throws Exception
+	{}
+
+	@Test
+	public void testChecker()
+	{
+		final IntType on = new IntType( 1 );
+		final IntType off = new IntType( 0 );
+
+		int i = 0;
+		for ( final IntType t : Views.interval( Functions.checker( 1, on, off ), Intervals.createMinSize( 0, 5 ) ) )
+		{
+			assertEquals( Integer.parseInt( checker1.substring( i, ++i ) ), t.get() );
+		}
+
+		final int width = 5;
+		i = 0;
+		for ( final IntType t : Views.interval( Functions.checker( 2, on, off ), Intervals.createMinSize( 0, 0, width, 7 ) ) ) {
+			assertEquals( Integer.parseInt( checker2.substring( i, ++i ) ), t.get() );
+		}
+
+		final int height = 4;
+		i = 0;
+		for ( final IntType t : Views.interval( Functions.checker( 3, on, off ), Intervals.createMinSize( 0, 0, 0, width, height, 7 ) ) ) {
+			assertEquals( Integer.parseInt( checker3.substring( i, ++i ) ), t.get() );
+		}
+	}
+
+	@Test
+	public void testChecker2()
+	{
+		final IntType on = new IntType( 1 );
+		final IntType off = new IntType( 0 );
+
+		int i = 0;
+		for ( final IntType t : Views.interval( Functions.checker( 1, on, off, 1 ), Intervals.createMinSize( 0, 5 ) ) )
+		{
+//			System.out.print( t.get() );
+			assertEquals( Integer.parseInt( checker12.substring( i, ++i ) ), t.get() );
+		}
+
+		System.out.println(  );
+
+		final int width = 5;
+		i = 0;
+		for ( final IntType t : Views.interval( Functions.checker( 2, on, off, 2 ), Intervals.createMinSize( 0, 0, width, 7 ) ) )
+		{
+//			if ( i % width == 0 )
+//				System.out.println(  );
+//
+//			System.out.print( t.get() );
+//			++i;
+			assertEquals( Integer.parseInt( checker22.substring( i, ++i ) ), t.get() );
+		}
+
+		System.out.println(  );
+
+		final int height = 4;
+		i = 0;
+		for ( final IntType t : Views.interval( Functions.checker( 3, on, off, 1 ), Intervals.createMinSize( 0, 0, 0, width, height, 7 ) ) )
+		{
+//			System.out.print( t.get() );
+			assertEquals( Integer.parseInt( checker32.substring( i, ++i ) ), t.get() );
+		}
+	}
+
+}