Merge pull request #1602 from twpayne/configurable-rotation-constraints

Configurable rotation constraints

src/objectliterals.jsdoc

@@ -91,6 +91,13 @@
  *     The coordinate system for the center is specified with the `projection`
  *     option. Default is `undefined`, and layer sources will not be fetched if
  *     this is not set.
+ * @property {boolean|number|undefined} constrainRotation Rotation constraint.
+ *     `false` means no constraint. `true` means no constraint, but snap to
+ *     zero near zero. A number constraints the rotation to that number of
+ *     values. For example, `4` will constrain the rotation to 0, 90, 180, and
+ *     270 degrees.  The default is `true`.
+ * @property {boolean|undefined} enableRotation Enable rotation. Default is
+ *     `true`.
  * @property {ol.Extent|undefined} extent The extent that constrains the center,
  *     in other words, center cannot be set outside this extent.
  *     Default is `undefined`.

src/ol/rotationconstraint.js

@@ -1,6 +1,8 @@
 goog.provide('ol.RotationConstraint');
 goog.provide('ol.RotationConstraintType');
 
+goog.require('goog.math');
+
 
 /**
  * @typedef {function((number|undefined), number): (number|undefined)}
@@ -8,6 +10,20 @@ goog.provide('ol.RotationConstraintType');
 ol.RotationConstraintType;
 
 
+/**
+ * @param {number|undefined} rotation Rotation.
+ * @param {number} delta Delta.
+ * @return {number|undefined} Rotation.
+ */
+ol.RotationConstraint.disable = function(rotation, delta) {
+  if (goog.isDef(rotation)) {
+    return 0;
+  } else {
+    return undefined;
+  }
+};
+
+
 /**
  * @param {number|undefined} rotation Rotation.
  * @param {number} delta Delta.
@@ -50,7 +66,7 @@ ol.RotationConstraint.createSnapToN = function(n) {
  * @return {ol.RotationConstraintType} Rotation constraint.
  */
 ol.RotationConstraint.createSnapToZero = function(opt_tolerance) {
-  var tolerance = opt_tolerance || 0.1;
+  var tolerance = opt_tolerance || goog.math.toRadians(5);
   return (
       /**
        * @param {number|undefined} rotation Rotation.

src/ol/view2d.js

@@ -573,6 +573,21 @@ ol.View2D.createResolutionConstraint_ = function(options) {
  * @return {ol.RotationConstraintType} Rotation constraint.
  */
 ol.View2D.createRotationConstraint_ = function(options) {
-  // FIXME rotation constraint is not configurable at the moment
-  return ol.RotationConstraint.createSnapToZero();
+  var enableRotation = goog.isDef(options.enableRotation) ?
+      options.enableRotation : true;
+  if (enableRotation) {
+    var constrainRotation = options.constrainRotation;
+    if (!goog.isDef(constrainRotation) || constrainRotation === true) {
+      return ol.RotationConstraint.createSnapToZero();
+    } else if (constrainRotation === false) {
+      return ol.RotationConstraint.none;
+    } else if (goog.isNumber(constrainRotation)) {
+      return ol.RotationConstraint.createSnapToN(constrainRotation);
+    } else {
+      goog.asserts.fail();
+      return ol.RotationConstraint.none;
+    }
+  } else {
+    return ol.RotationConstraint.disable;
+  }
 };