Add RandomAccessibleInterval.getType

Open questions:
 - We cannot deprecate Utils.getTypeFromInterval because it does not use RAI as argument. We could change the argument to RAI but this would be a breaking change (see comment in JavaDoc for that function)
 - What about getType in other places like RA, RRA, RRARI?
 - Name preference getType vs type?

src/main/java/net/imglib2/RandomAccessibleInterval.java

@@ -34,6 +34,8 @@
 
 package net.imglib2;
 
+import net.imglib2.util.Intervals;
+
 /**
  * <p>
  * <em>f</em>:{x&isin;Z<sup><em>n</em></sup>|[min,max]&rarr;T}
@@ -58,6 +60,19 @@
  * </p>
  *
  * @author Stephan Saalfeld
+ * @author Philipp Hanslovsky
  */
 public interface RandomAccessibleInterval< T > extends RandomAccessible< T >, Interval
-{}
+{
+	/**
+	 *
+	 * Gets an instance of T from the {@link RandomAccessibleInterval}.
+	 * By default, this queries the value at the min coordinate but individual classes
+	 * may choose different implementations for improved performance.
+	 *
+	 * @return - an instance of T
+	 */
+	default T getType() {
+		return getAt( Intervals.minAsLongArray(this) );
+	}
+}

src/main/java/net/imglib2/img/AbstractNativeImg.java

@@ -42,6 +42,7 @@
  * 
  * @author Stephan Preibisch
  * @author Stephan Saalfeld
+ * @author Philipp Hanslovsky
  */
 public abstract class AbstractNativeImg< T extends NativeType< T >, A >
 		extends AbstractImg< T >
@@ -77,4 +78,13 @@ public T createLinkedType()
 			return null;
 		}
 	}
+
+	@Override
+	public T getType() {
+		try {
+			return linkedType.createVariable();
+		} catch ( final NullPointerException e ) {
+			return super.getType();
+		}
+	}
 }

src/main/java/net/imglib2/util/Util.java

@@ -69,6 +69,7 @@
  * @author Stephan Preibisch
  * @author Stephan Saalfeld
  * @author Curtis Rueden
+ * @author Philipp Hanslovsky
  */
 public class Util
 {
@@ -791,6 +792,11 @@ final static public long[] int2long( final int[] i )
 	}
 
 	/**
+	 *
+	 * This method has been deprecated.
+	 * Use {@link RandomAccessibleInterval#getType()} instead.
+	 * TODO: Cannot deprecate because rai parameter is not actually a RandomAccessibleInterval
+	 *
 	 * Gets an instance of T from the {@link RandomAccessibleInterval} by
 	 * querying the value at the min coordinate
 	 * 
@@ -800,8 +806,14 @@ final static public long[] int2long( final int[] i )
 	 *            - the {@link RandomAccessibleInterval}
 	 * @return - an instance of T
 	 */
+	@Deprecated
 	final public static < T, F extends Interval & RandomAccessible< T > > T getTypeFromInterval( final F rai )
 	{
+		if (rai instanceof RandomAccessibleInterval)
+			return ((RandomAccessibleInterval<T>) rai).getType();
+		// TODO can we remove generic parameter F and use
+		//      RandomAccessible<T> rai instead?
+		//      This would be a breaking change, though.
 		// create RandomAccess
 		final RandomAccess< T > randomAccess = rai.randomAccess();
 

src/test/java/net/imglib2/RandomAccessibleIntervalTest.java

@@ -0,0 +1,59 @@
+/*
+ * #%L
+ * ImgLib2: a general-purpose, multidimensional image processing library.
+ * %%
+ * Copyright (C) 2009 - 2022 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;
+
+import net.imglib2.img.array.ArrayImgs;
+import net.imglib2.type.numeric.integer.ByteType;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Tests {@link RandomAccessibleInterval}.
+ *
+ * @author Philipp Hanslovsky
+ */
+public class RandomAccessibleIntervalTest
+{
+
+	@Test
+	public void testGetType()
+	{
+		// setup
+		final RandomAccessibleInterval< ? > rai = ArrayImgs.bytes( 1 );
+		// process & test
+		assertEquals( ByteType.class, rai.getType().getClass() );
+	}
+}