New Unit for "Pixel per Inch" added.

common-java8/src/main/java/systems/uom/common/NonSI.java

@@ -25,7 +25,6 @@
  */
 package systems.uom.common;
 
-import static tec.uom.se.unit.Units.ONE;
 import static tec.uom.se.unit.MetricPrefix.CENTI;
 import static tec.uom.se.unit.Units.AMPERE;
 import static tec.uom.se.unit.Units.BECQUEREL;
@@ -41,6 +40,7 @@
 import static tec.uom.se.unit.Units.METRES_PER_SQUARE_SECOND;
 import static tec.uom.se.unit.Units.MOLE;
 import static tec.uom.se.unit.Units.NEWTON;
+import static tec.uom.se.unit.Units.ONE;
 import static tec.uom.se.unit.Units.PASCAL;
 import static tec.uom.se.unit.Units.RADIAN;
 import static tec.uom.se.unit.Units.SECOND;
@@ -84,6 +84,7 @@
 import si.uom.quantity.KinematicViscosity;
 import systems.uom.quantity.Information;
 import systems.uom.quantity.InformationRate;
+import systems.uom.quantity.Resolution;
 import tec.uom.se.AbstractSystemOfUnits;
 import tec.uom.se.AbstractUnit;
 import tec.uom.se.function.LogConverter;
@@ -247,20 +248,6 @@ static NonSI getInstance() {
 	static final Unit<Length> POINT = addUnit(INCH.multiply(13837)
 			.divide(1000000));
 
-	/**
-	 * A unit of length equal to <code>1/72 {@link #INCH}</code> (standard name
-	 * <code>pixel</code>). It is the American point rounded to an even 1/72
-	 * inch.
-	 * 
-	 * @see #POINT
-	 */
-	static final Unit<Length> PIXEL = addUnit(INCH.divide(72));
-
-	/**
-	 * Equivalent {@link #PIXEL}
-	 */
-	static final Unit<Length> COMPUTER_POINT = PIXEL;
-
 	// ////////////
 	// Duration //
 	// ////////////
@@ -446,6 +433,29 @@ static NonSI getInstance() {
 	 * Equivalent {@link #BYTE}
 	 */
 	static final Unit<Information> OCTET = BYTE;
+
+	/**
+	 * A pixel has 4 channels which define transparency (alpha), red, green and blue color values. 
+	 * Each channel is one byte wide.
+	 * 
+	 * @see #BYTE
+	 */
+	static final Unit<Information> PIXEL = addUnit(BYTE.multiply(4.0));
+
+	/**
+	 * Pixel per inch describe the resolution for any output device (monitor, printer) that deals with 
+	 * outputting digital raster images.
+	 * 
+	 * @see #INCH
+	 * @see #PIXEL
+	 */
+	static final Unit<Resolution> PIXEL_PER_INCH = addUnit(PIXEL
+			.divide(INCH).asType(Resolution.class));
+
+	/**
+	 * Equivalent {@link #PIXEL}
+	 */
+	static final Unit<Information> COMPUTER_POINT = PIXEL;
 
 	// ////////////////////
 	// Electric current //
@@ -700,4 +710,4 @@ private static <U extends AbstractUnit<?>>  U addUnit(U unit, Class<? extends Qu
 //	protected static <U extends Unit<?>> U addUnit(U unit, String name) {
 //		
 //	}
-}
+}

common-java8/src/test/java/systems/uom/common/PixelTest.java

@@ -0,0 +1,34 @@
+package systems.uom.common;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+import javax.measure.IncommensurableException;
+import javax.measure.UnconvertibleException;
+import javax.measure.quantity.Length;
+
+import org.junit.Test;
+
+import systems.uom.quantity.Information;
+import systems.uom.quantity.Resolution;
+import tec.uom.se.ComparableQuantity;
+import tec.uom.se.quantity.Quantities;
+import tec.uom.se.unit.MetricPrefix;
+import tec.uom.se.unit.Units;
+
+public class PixelTest {
+
+	@Test
+	public void testPPItoMetreConversion() throws UnconvertibleException, IncommensurableException {
+		/*
+		 * 960 Pixel are .254 m long if the PPI is 96. 1 inch (0.0254 m) / 96 ppi x (96 x 10) px = 0.254 m
+		 */
+		final ComparableQuantity<Information> screenWidth = Quantities.getQuantity(960, NonSI.PIXEL);
+		final ComparableQuantity<Resolution> screenResolution = Quantities.getQuantity(96, NonSI.PIXEL_PER_INCH);
+
+		ComparableQuantity<Length> ppi = screenWidth.divide(screenResolution).asType(Length.class);
+		ComparableQuantity<Length> pixelToMetre = ppi.to(Units.METRE);
+		assertThat(pixelToMetre.getValue().doubleValue(),is(.254));
+		assertThat(pixelToMetre.to(MetricPrefix.CENTI(Units.METRE)).getValue().doubleValue(), is(25.4));
+	}
+}

quantity/src/main/java/systems/uom/quantity/Resolution.java

@@ -0,0 +1,42 @@
+/*
+ *  Unit-API - Units of Measurement API for Java
+ *  Copyright (c) 2005-2015, Jean-Marie Dautelle, Werner Keil, V2COM.
+ *
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * 3. Neither the name of JSR-363 nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
+ *
+ * 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 HOLDER 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.
+ */
+package systems.uom.quantity;
+
+import javax.measure.Quantity;
+
+/**
+ * Measure of information per length.
+ * The metric system unit for this quantity is "bit".
+ *
+ * @author <a href="mailto:oliver+uom.bugabinga.net">Oliver Krylow</a>
+ * @author <a href="mailto:[email protected]">Jean-Marie Dautelle</a>
+ * @author <a href="mailto:[email protected]">Werner Keil</a>
+ * @version 1.2
+ *
+ * @see <a href="https://en.wikipedia.org/wiki/Display_resolution">Wikipedia: Display Resolution</a>
+ */
+public interface Resolution extends Quantity<Resolution> {
+}