ShardBucketCollection (#184)

* ShardBucketCollection * PR comments addressed
osmlab · Aug 6, 2018 · 7f1e7a6 · 7f1e7a6
1 parent 61447c0
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diff --git a/src/main/java/org/openstreetmap/atlas/geography/Rectangle.java b/src/main/java/org/openstreetmap/atlas/geography/Rectangle.java
@@ -227,6 +227,55 @@ public Location center()
         return new Segment(this.lowerLeft, this.upperRight).middle();
     }
 
+    /**
+     * Contract the rectangle in 4 directions as far as possible. If the distance to move the
+     * corners would invert the rectangle then the side(s) will collapse into length 0. The most
+     * that it can contract is to a single point in the middle.
+     *
+     * @param distance
+     *            to contract the four corners
+     * @return new rectangle with contracted dimensions
+     */
+    public Rectangle contract(final Distance distance)
+    {
+        final Location newLowerLeft = this.lowerLeft.shiftAlongGreatCircle(Heading.NORTH, distance)
+                .shiftAlongGreatCircle(Heading.EAST, distance);
+        final Location newUpperRight = this.upperRight
+                .shiftAlongGreatCircle(Heading.SOUTH, distance)
+                .shiftAlongGreatCircle(Heading.WEST, distance);
+        final boolean tooShortHeight = newLowerLeft.getLatitude()
+                .isGreaterThan(newUpperRight.getLatitude());
+        final boolean tooShortWidth = newLowerLeft.getLongitude()
+                .isGreaterThan(newUpperRight.getLongitude());
+        if (tooShortHeight && tooShortWidth)
+        {
+            return this.center().bounds();
+        }
+        else
+        {
+            final Location lowerRight = new Location(this.lowerLeft().getLatitude(),
+                    this.upperRight().getLongitude());
+            if (tooShortHeight)
+            {
+                final Latitude sharedLatitude = lowerRight.midPoint(this.upperRight())
+                        .getLatitude();
+                return forCorners(new Location(sharedLatitude, newLowerLeft.getLongitude()),
+                        new Location(sharedLatitude, newUpperRight.getLongitude()));
+            }
+            else if (tooShortWidth)
+            {
+                final Longitude sharedLongitude = lowerRight.midPoint(this.lowerLeft())
+                        .getLongitude();
+                return forCorners(new Location(newLowerLeft.getLatitude(), sharedLongitude),
+                        new Location(newUpperRight.getLatitude(), sharedLongitude));
+            }
+            else
+            {
+                return forCorners(newLowerLeft, newUpperRight);
+            }
+        }
+    }
+
     /**
      * @param that
      *            The other {@link Rectangle} to combine