Split IterableInterval<Void> from IterableRegion

The Cursor<Void> of the inside pixels of a region can be obtained by
region.inside().cursor() now.

pom.xml

@@ -11,7 +11,7 @@
 
 	<groupId>net.imglib2</groupId>
 	<artifactId>imglib2-roi</artifactId>
-	<version>0.14.2-SNAPSHOT</version>
+	<version>0.15.0-SNAPSHOT</version>
 
 	<name>ImgLib2 ROI</name>
 	<description>Regions of interest in ImgLib2.</description>

src/main/java/net/imglib2/roi/IterableRegion.java

@@ -47,9 +47,10 @@
  * i.e., it is assumed that all pixels outside the interval have value
  * {@code false}.
  * <p>
- * Iterating only the pixels contained in the region is indicated by
- * {@code IterableInterval<Void>}, i.e., when iterating, only the coordinates
- * that are visited are interesting. There is no associated value.
+ * Iterating only the pixels contained in the region is done via the {@code
+ * IterableInterval<Void>} {@link #inside()}. (The pixel type is {@code Void}
+ * because, when iterating, only the coordinates that are visited are
+ * interesting. There is no associated value.)
  * <p>
  * We put interfaces {@code RandomAccessibleInterval<BooleanType>}, extended by
  * {@code IterableRegion<BooleanType>}, extended by
@@ -62,5 +63,13 @@
  *
  * @author Tobias Pietzsch
  */
-public interface IterableRegion< T extends BooleanType< T > > extends IterableInterval< Void >, RandomAccessibleInterval< T >
-{}
+public interface IterableRegion< T extends BooleanType< T > > extends RandomAccessibleInterval< T >
+{
+	/**
+	 * Get an {@code IterableInterval} view of only the pixels contained in the
+	 * region (having value {@code true}).
+	 *
+	 * @return iterable of the pixels in the region
+	 */
+	IterableInterval< Void > inside();
+}

src/main/java/net/imglib2/roi/PositionableIterableInterval.java

@@ -74,13 +74,13 @@ public interface PositionableIterableInterval< T > extends IterableInterval< T >
 	 *
 	 * @return the origin to which the interval is relative.
 	 */
-	public PositionableLocalizable origin();
+	PositionableLocalizable origin();
 
 	/**
 	 * Make a copy of this {@link PositionableIterableInterval} which can be
 	 * positioned independently.
 	 *
 	 * @return a copy with an independent position
 	 */
-	public PositionableIterableInterval< T > copy();
+	PositionableIterableInterval< T > copy();
 }

src/main/java/net/imglib2/roi/PositionableIterableRegion.java

@@ -33,11 +33,19 @@
  */
 package net.imglib2.roi;
 
+import net.imglib2.Localizable;
+import net.imglib2.Positionable;
+import net.imglib2.roi.util.PositionableLocalizable;
 import net.imglib2.type.BooleanType;
+import net.imglib2.type.logic.BitType;
 
 /**
  * An {@link IterableRegion} that can be moved around.
  * <p>
+ * The iterable view of {@link #inside()} pixels can also be moved around. Its
+ * position is the same as the position of this {@code
+ * PositionableIterableRegion}. Moving one will also move the other.
+ * <p>
  * We put interfaces {@code RandomAccessibleInterval<BooleanType>}, extended by
  * {@code IterableRegion<BooleanType>}, extended by
  * {@code PositionableIterableRegion<BooleanType>} into this sequence such that
@@ -49,9 +57,48 @@
  *
  * @author Tobias Pietzsch
  */
-public interface PositionableIterableRegion< T extends BooleanType< T > >
-	extends IterableRegion< T >, PositionableIterableInterval< Void >
+public interface PositionableIterableRegion< T extends BooleanType< T > > extends IterableRegion< T >, Localizable, Positionable
 {
+	/**
+	 * Get an {@code PositionableIterableInterval} view of only the pixels contained in the
+	 * region (having value {@code true}).
+	 * <p>
+	 * The position of the {@link #inside()} view is the same as the position of
+	 * this {@code PositionableIterableRegion}. Moving one will also move the
+	 * other.
+	 *
+	 * @return iterable of the pixels in the region
+	 */
 	@Override
-	public PositionableIterableRegion< T > copy();
+	PositionableIterableInterval< Void > inside();
+
+	/**
+	 * Get the {@link Positionable}, {@link Localizable} origin of this
+	 * interval.
+	 * <p>
+	 * The origin is the relative offset of the position to the minimum. For
+	 * example if a positionable (bitmask) region is made from a {@link BitType}
+	 * image with a circular pattern, then it is more natural if the region
+	 * position refers to the center of the pattern instead of the upper left
+	 * corner of the {@link BitType} image. This can be achieved by positioning
+	 * the origin.
+	 * <p>
+	 * Assume a region is created from a 9x9 bitmask. The region initially has
+	 * min=(0,0), max=(8,8), position=(0,0). Because both position and min are
+	 * (0,0), initially origin=(0,0). Now assume the origin is moved to the
+	 * center of the bitmask using
+	 * <code>origin().setPosition(new int[]{4,4})</code>. After this,
+	 * min=(-4,-4), max=(4,4), position=(0,0), and origin=(4,4).
+	 *
+	 * @return the origin to which the interval is relative.
+	 */
+	PositionableLocalizable origin();
+
+	/**
+	 * Make a copy of this {@link PositionableIterableInterval} which can be
+	 * positioned independently.
+	 *
+	 * @return a copy with an independent position
+	 */
+	PositionableIterableRegion< T > copy();
 }

src/main/java/net/imglib2/roi/Regions.java

@@ -60,6 +60,11 @@ public static < T > IterableInterval< T > sample( final IterableInterval< Void >
 		return SamplingIterableInterval.create( region, img );
 	}
 
+	public static < T > IterableInterval< T > sample( final IterableRegion< ? > region, final RandomAccessible< T > img )
+	{
+		return sample( region.inside(), img );
+	}
+
 	/**
 	 * Given a mask and an image, return an {@link IterableInterval} over the
 	 * pixels of the image inside the mask.
@@ -106,8 +111,7 @@ public static < T > IterableInterval< T > sample( final RealMaskRealInterval mas
 	// NB: this method is not named "sample" to avoid ambiguation with sample(IterableInterval<Void>, RandomAccessible<T>)
 	public static < T, B extends BooleanType< B > > IterableInterval< T > sampleWithRandomAccessible( final RandomAccessible< B > mask, final RandomAccessibleInterval< T > img )
 	{
-		final IterableInterval< Void > region = iterable( Views.interval( mask, img ) );
-		return sample( region, img );
+		return sample( iterable( Views.interval( mask, img ) ), img );
 	}
 
 	/**

src/main/java/net/imglib2/roi/boundary/Boundary.java

@@ -39,6 +39,7 @@
 import net.imglib2.AbstractWrappedInterval;
 import net.imglib2.Cursor;
 import net.imglib2.Interval;
+import net.imglib2.IterableInterval;
 import net.imglib2.Localizable;
 import net.imglib2.Point;
 import net.imglib2.RandomAccess;
@@ -70,7 +71,8 @@
 public final class Boundary< T extends BooleanType< T > >
 	extends AbstractWrappedInterval< RandomAccessibleInterval< T > > implements IterableRegion< BoolType >
 {
-	public static enum StructuringElement
+
+	public enum StructuringElement
 	{
 		FOUR_CONNECTED,
 		EIGHT_CONNECTED
@@ -84,6 +86,8 @@ public static enum StructuringElement
 
 	private final int size;
 
+	private final BoundaryIterable inside;
+
 	public Boundary( final RandomAccessibleInterval< T > region )
 	{
 		this( region, FOUR_CONNECTED );
@@ -108,56 +112,71 @@ public Boundary( final RandomAccessibleInterval< T > region, final StructuringEl
 				break;
 		}
 		size = coords.size() / n;
+		inside = new BoundaryIterable();
 	}
 
 	@Override
-	public long size()
+	public IterableInterval< Void > inside()
 	{
-		return size;
+		return inside;
 	}
 
 	@Override
-	public Object iterationOrder()
+	public RandomAccess< BoolType > randomAccess()
 	{
-		return this;
+		return structuringElement == FOUR_CONNECTED
+				? new BoundaryRandomAccess4< T >( sourceInterval )
+				: new BoundaryRandomAccess8< T >( sourceInterval );
 	}
 
 	@Override
-	public BoundaryCursor cursor()
+	public RandomAccess< BoolType > randomAccess( final Interval interval )
 	{
-		return new BoundaryCursor();
+		return randomAccess();
 	}
 
-	@Override
-	public BoundaryCursor localizingCursor()
+	final class BoundaryIterable extends AbstractWrappedInterval< Interval > implements IterableInterval< Void >
 	{
-		return cursor();
-	}
+		BoundaryIterable()
+		{
+			super( Boundary.this );
+		}
 
-	@Override
-	public BoundaryCursor iterator()
-	{
-		return cursor();
-	}
+		@Override
+		public long size()
+		{
+			return size;
+		}
 
-	@Override
-	public Void firstElement()
-	{
-		return cursor().next();
-	}
+		@Override
+		public Object iterationOrder()
+		{
+			return this;
+		}
 
-	@Override
-	public RandomAccess< BoolType > randomAccess()
-	{
-		return structuringElement == FOUR_CONNECTED
-				? new BoundaryRandomAccess4< T >( sourceInterval )
-				: new BoundaryRandomAccess8< T >( sourceInterval );
-	}
+		@Override
+		public BoundaryCursor cursor()
+		{
+			return new BoundaryCursor();
+		}
 
-	@Override
-	public RandomAccess< BoolType > randomAccess( final Interval interval )
-	{
-		return randomAccess();
+		@Override
+		public BoundaryCursor localizingCursor()
+		{
+			return cursor();
+		}
+
+		@Override
+		public BoundaryCursor iterator()
+		{
+			return cursor();
+		}
+
+		@Override
+		public Void firstElement()
+		{
+			return cursor().next();
+		}
 	}
 
 	final class BoundaryCursor extends Point implements Cursor< Void >
@@ -246,7 +265,7 @@ static final class BoundaryConstructor< T extends BooleanType< T > > implements
 
 		public BoundaryConstructor( final RandomAccessibleInterval< T > region, final StructuringElement structuringElement )
 		{
-			c = Regions.iterable( region ).localizingCursor();
+			c = Regions.iterable( region ).inside().localizingCursor();
 			a = structuringElement == FOUR_CONNECTED
 					? new BoundaryRandomAccess4< T >( region )
 					: new BoundaryRandomAccess8< T >( region );