Determining coordinate relationship to extent

src/ol/extent.js

@@ -1,5 +1,6 @@
 goog.provide('ol.Extent');
 goog.provide('ol.extent');
+goog.provide('ol.extent.Relationship');
 
 goog.require('goog.asserts');
 goog.require('ol.Coordinate');
@@ -15,6 +16,20 @@ goog.require('ol.TransformFunction');
 ol.Extent;
 
 
+/**
+ * Relationship to an extent.
+ * @enum {number}
+ */
+ol.extent.Relationship = {
+  UNKNOWN: 0,
+  INTERSECTING: 1,
+  ABOVE: 2,
+  RIGHT: 4,
+  BELOW: 8,
+  LEFT: 16
+};
+
+
 /**
  * Builds an extent that includes all given coordinates.
  *
@@ -150,6 +165,38 @@ ol.extent.containsExtent = function(extent1, extent2) {
 };
 
 
+/**
+ * Get the relationship between a coordinate and extent.
+ * @param {ol.Extent} extent The extent.
+ * @param {ol.Coordinate} coordinate The coordinate.
+ * @return {number} The relationship (bitwise compare with
+ *     ol.extent.Relationship).
+ */
+ol.extent.coordinateRelationship = function(extent, coordinate) {
+  var minX = extent[0];
+  var minY = extent[1];
+  var maxX = extent[2];
+  var maxY = extent[3];
+  var x = coordinate[0];
+  var y = coordinate[1];
+  var relationship = ol.extent.Relationship.UNKNOWN;
+  if (x < minX) {
+    relationship = relationship | ol.extent.Relationship.LEFT;
+  } else if (x > maxX) {
+    relationship = relationship | ol.extent.Relationship.RIGHT;
+  }
+  if (y < minY) {
+    relationship = relationship | ol.extent.Relationship.BELOW;
+  } else if (y > maxY) {
+    relationship = relationship | ol.extent.Relationship.ABOVE;
+  }
+  if (relationship === ol.extent.Relationship.UNKNOWN) {
+    relationship = ol.extent.Relationship.INTERSECTING;
+  }
+  return relationship;
+};
+
+
 /**
  * @return {ol.Extent} Empty extent.
  * @todo stability experimental

test/spec/ol/extent.test.js

@@ -1,6 +1,5 @@
 goog.provide('ol.test.extent');
 
-
 describe('ol.extent', function() {
 
   describe('buffer', function() {
@@ -65,6 +64,86 @@ describe('ol.extent', function() {
     });
   });
 
+  describe('coordinateRelationship()', function() {
+
+    var extent = [-180, -90, 180, 90];
+    var INTERSECTING = ol.extent.Relationship.INTERSECTING;
+    var ABOVE = ol.extent.Relationship.ABOVE;
+    var RIGHT = ol.extent.Relationship.RIGHT;
+    var BELOW = ol.extent.Relationship.BELOW;
+    var LEFT = ol.extent.Relationship.LEFT;
+
+    it('returns intersecting for within', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [0, 0]);
+      expect(rel).to.be(INTERSECTING);
+    });
+
+    it('returns intersecting for touching top', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [0, 90]);
+      expect(rel).to.be(INTERSECTING);
+    });
+
+    it('returns intersecting for touching right', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [180, 0]);
+      expect(rel).to.be(INTERSECTING);
+    });
+
+    it('returns intersecting for touching bottom', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [0, -90]);
+      expect(rel).to.be(INTERSECTING);
+    });
+
+    it('returns intersecting for touching left', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [-180, 0]);
+      expect(rel).to.be(INTERSECTING);
+    });
+
+    it('above for north', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [0, 100]);
+      expect(rel).to.be(ABOVE);
+    });
+
+    it('above and right for northeast', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [190, 100]);
+      expect(rel & ABOVE).to.be(ABOVE);
+      expect(rel & RIGHT).to.be(RIGHT);
+    });
+
+    it('right for east', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [190, 0]);
+      expect(rel).to.be(RIGHT);
+    });
+
+    it('below and right for southeast', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [190, -100]);
+      expect(rel & BELOW).to.be(BELOW);
+      expect(rel & RIGHT).to.be(RIGHT);
+    });
+
+    it('below for south', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [0, -100]);
+      expect(rel).to.be(BELOW);
+    });
+
+    it('below and left for southwest', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [-190, -100]);
+      expect(rel & BELOW).to.be(BELOW);
+      expect(rel & LEFT).to.be(LEFT);
+    });
+
+    it('left for west', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [-190, 0]);
+      expect(rel).to.be(LEFT);
+    });
+
+    it('above and left for northwest', function() {
+      var rel = ol.extent.coordinateRelationship(extent, [-190, 100]);
+      expect(rel & ABOVE).to.be(ABOVE);
+      expect(rel & LEFT).to.be(LEFT);
+    });
+
+  });
+
   describe('getCenter', function() {
     it('returns the expected center', function() {
       var extent = [1, 2, 3, 4];
@@ -267,4 +346,5 @@ describe('ol.extent', function() {
 
 
 goog.require('ol.extent');
+goog.require('ol.extent.Relationship');
 goog.require('ol.proj');