/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.imaging;
  
  /**
   * Used to specify pixel density and physical dimensions when reading or storing image information.
   */
  public final class PixelDensity {
      private static final int PIXEL_NO_UNIT = 0;
      private static final int PIXEL_PER_INCH = 254;
      private static final int PIXEL_PER_METRE = 10000;
      private static final int PIXEL_PER_CENTIMETRE = 100;
  
      public static PixelDensity createFromPixelsPerCentimetre(final double x, final double y) {
          return new PixelDensity(x, y, PIXEL_PER_CENTIMETRE);
      }
  
      public static PixelDensity createFromPixelsPerInch(final double x, final double y) {
          return new PixelDensity(x, y, PIXEL_PER_INCH);
      }
  
      public static PixelDensity createFromPixelsPerMetre(final double x, final double y) {
          return new PixelDensity(x, y, PIXEL_PER_METRE);
      }
  
      public static PixelDensity createUnitless(final double x, final double y) {
          return new PixelDensity(x, y, PIXEL_NO_UNIT);
      }
  
      private final double horizontalDensity;
  
      private final double verticalDensity;
  
      // / One-tenth of a millimetre units.
      private final int unitLength;
  
      private PixelDensity(final double horizontalDensity, final double verticalDensity, final int unitLength) {
          this.horizontalDensity = horizontalDensity;
          this.verticalDensity = verticalDensity;
          this.unitLength = unitLength;
      }
  
      public double getRawHorizontalDensity() {
          return horizontalDensity;
      }
  
      public double getRawVerticalDensity() {
          return verticalDensity;
      }
  
      public double horizontalDensityCentimetres() {
          if (isInCentimetres()) {
              return horizontalDensity;
          }
          return horizontalDensity * PIXEL_PER_CENTIMETRE / unitLength;
      }
  
      public double horizontalDensityInches() {
          if (isInInches()) {
              return horizontalDensity;
          }
          return horizontalDensity * PIXEL_PER_INCH / unitLength;
      }
  
      public double horizontalDensityMetres() {
          if (isInMetres()) {
              return horizontalDensity;
          }
          return horizontalDensity * PIXEL_PER_METRE / unitLength;
      }
  
      public boolean isInCentimetres() {
          return unitLength == PIXEL_PER_CENTIMETRE;
      }
  
      public boolean isInInches() {
          return unitLength == PIXEL_PER_INCH;
      }
  
      public boolean isInMetres() {
          return unitLength == PIXEL_PER_METRE;
      }
  
      public boolean isUnitless() {
          return unitLength == PIXEL_NO_UNIT;
     }
 
     public double verticalDensityCentimetres() {
         if (isInCentimetres()) {
             return verticalDensity;
         }
         return verticalDensity * PIXEL_PER_CENTIMETRE / unitLength;
     }
 
     public double verticalDensityInches() {
         if (isInInches()) {
             return verticalDensity;
         }
         return verticalDensity * PIXEL_PER_INCH / unitLength;
     }
 
     public double verticalDensityMetres() {
         if (isInMetres()) {
             return verticalDensity;
         }
         return verticalDensity * PIXEL_PER_METRE / unitLength;
     }
 }