feat/test: add FieldOfView class

* add offset/fov test in DfieldExportTest

src/main/java/bigwarp/FieldOfView.java

@@ -0,0 +1,68 @@
+package bigwarp;
+
+import bdv.viewer.Source;
+import net.imglib2.FinalRealInterval;
+import net.imglib2.RealInterval;
+import net.imglib2.realtransform.AffineTransform3D;
+import net.imglib2.realtransform.BoundingBoxEstimation;
+
+public class FieldOfView {
+
+	public static RealInterval getPhysicaInterval(final Source<?> source) {
+
+		final AffineTransform3D tform = new AffineTransform3D();
+		return BoundingBoxEstimation.corners(tform, source.getSource(0, 0));
+	}
+
+	public static RealInterval fromMinSize(final double[] min, final double[] size) {
+
+		final int nd = size.length;
+		final double[] max = new double[nd];
+		for (int i = 0; i < nd; i++)
+			max[i] = min[i] + size[i];
+
+		return new FinalRealInterval(min, max);
+	}
+
+	public static RealInterval fromPixelMinSize(final double[] minPixel, final double[] sizePixel, final double[] resolution) {
+
+		final int nd = sizePixel.length;
+		final double[] min = new double[nd];
+		final double[] max = new double[nd];
+		for (int i = 0; i < nd; i++) {
+			min[i] = resolution[i] * min[i];
+			max[i] = resolution[i] * (min[i] + sizePixel[i]);
+		}
+
+		return new FinalRealInterval(min, max);
+	}
+
+	public static RealInterval computeInterval(
+			final double[] resolution,
+			final double[] offset,
+			final long[] dimensions) {
+
+		final int nd = resolution.length;
+		final double[] max = new double[resolution.length];
+		for (int i = 0; i < nd; i++) {
+			max[i] = offset[i] + resolution[i] * dimensions[i];
+		}
+		return new FinalRealInterval(offset, max);
+	}
+
+	public static RealInterval expand(
+			final RealInterval interval,
+			final double... amounts) {
+
+		final int nd = interval.numDimensions();
+		final double[] min = new double[nd];
+		final double[] max = new double[nd];
+
+		for (int i = 0; i < nd; i++) {
+			min[i] = interval.realMin(i) - amounts[i];
+			max[i] = interval.realMax(i) + amounts[i];
+		}
+		return new FinalRealInterval(min, max);
+	}
+
+}