From 7ab3b3dd825ce74c31450354bbdaf50c94002048 Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Sat, 4 Aug 2012 15:50:06 +0200
Subject: [PATCH] Add rotation constraints

---
 src/ol/base/createmap.js                 |  4 ++-
 src/ol/control/constraints.js            | 13 ++++++--
 src/ol/control/control.js                | 17 ++++++-----
 src/ol/control/rotationconstraint.js     | 39 ++++++++++++++++++++++++
 src/ol/control/shiftdragrotate.js        |  2 +-
 src/ol/control/shiftdragrotateandzoom.js |  2 +-
 6 files changed, 63 insertions(+), 14 deletions(-)
 create mode 100644 src/ol/control/rotationconstraint.js

diff --git a/src/ol/base/createmap.js b/src/ol/base/createmap.js
index d1e1cdddcd..9638897381 100644
--- a/src/ol/base/createmap.js
+++ b/src/ol/base/createmap.js
@@ -14,6 +14,7 @@ goog.require('ol.control.KeyboardPan');
 goog.require('ol.control.KeyboardZoom');
 goog.require('ol.control.MouseWheelZoom');
 goog.require('ol.control.ResolutionConstraint');
+goog.require('ol.control.RotationConstraint');
 goog.require('ol.control.ShiftDragRotateAndZoom');
 goog.require('ol.control.ShiftDragZoom');
 goog.require('ol.dom');
@@ -82,8 +83,9 @@ ol.createMap = function(target, opt_values, opt_rendererHints) {
   var centerConstraint = ol.control.CenterConstraint.snapToPixel;
   var resolutionConstraint = ol.control.ResolutionConstraint.createSnapToPower(
       2, ol.Projection.EPSG_3857_HALF_SIZE / 128);
+  var rotationConstraint = ol.control.RotationConstraint.none;
   var constraints = new ol.control.Constraints(
-      centerConstraint, resolutionConstraint);
+      centerConstraint, resolutionConstraint, rotationConstraint);
 
   if (!goog.object.containsKey(values, ol.MapProperty.CONTROLS)) {
     var controls = new ol.Collection();
diff --git a/src/ol/control/constraints.js b/src/ol/control/constraints.js
index df47aca5fe..b9f0acc99d 100644
--- a/src/ol/control/constraints.js
+++ b/src/ol/control/constraints.js
@@ -1,9 +1,8 @@
-// FIXME add rotation constraint
-
 goog.provide('ol.control.Constraints');
 
 goog.require('ol.control.CenterConstraintType');
 goog.require('ol.control.ResolutionConstraintType');
+goog.require('ol.control.RotationConstraintType');
 
 
 
@@ -12,8 +11,11 @@ goog.require('ol.control.ResolutionConstraintType');
  * @param {ol.control.CenterConstraintType} centerConstraint Center constraint.
  * @param {ol.control.ResolutionConstraintType} resolutionConstraint
  *     Resolution constraint.
+ * @param {ol.control.RotationConstraintType} rotationConstraint
+ *     Rotation constraint.
  */
-ol.control.Constraints = function(centerConstraint, resolutionConstraint) {
+ol.control.Constraints =
+    function(centerConstraint, resolutionConstraint, rotationConstraint) {
 
   /**
    * @type {ol.control.CenterConstraintType}
@@ -25,4 +27,9 @@ ol.control.Constraints = function(centerConstraint, resolutionConstraint) {
    */
   this.resolution = resolutionConstraint;
 
+  /**
+   * @type {ol.control.RotationConstraintType}
+   */
+  this.rotation = rotationConstraint;
+
 };
diff --git a/src/ol/control/control.js b/src/ol/control/control.js
index 3488557d84..b8eefd1b31 100644
--- a/src/ol/control/control.js
+++ b/src/ol/control/control.js
@@ -59,21 +59,22 @@ ol.Control.prototype.pan = function(map, delta, opt_anchor) {
 
 /**
  * @param {ol.Map} map Map.
- * @param {number|undefined} resolution Resolution.
+ * @param {number|undefined} rotation Rotation.
+ * @param {number} delta Delta.
  */
-ol.Control.prototype.setResolution = function(map, resolution) {
-  resolution = this.constraints.resolution(resolution, 0);
-  map.setResolution(resolution);
+ol.Control.prototype.rotate = function(map, rotation, delta) {
+  rotation = this.constraints.rotation(rotation, delta);
+  map.setRotation(rotation);
 };
 
 
 /**
  * @param {ol.Map} map Map.
- * @param {number} rotation Rotation.
+ * @param {number|undefined} resolution Resolution.
  */
-ol.Control.prototype.setRotation = function(map, rotation) {
-  // FIXME use a constraint
-  map.setRotation(rotation);
+ol.Control.prototype.setResolution = function(map, resolution) {
+  resolution = this.constraints.resolution(resolution, 0);
+  map.setResolution(resolution);
 };
 
 
diff --git a/src/ol/control/rotationconstraint.js b/src/ol/control/rotationconstraint.js
new file mode 100644
index 0000000000..dde5403272
--- /dev/null
+++ b/src/ol/control/rotationconstraint.js
@@ -0,0 +1,39 @@
+goog.provide('ol.control.RotationConstraint');
+goog.provide('ol.control.RotationConstraintType');
+
+
+/**
+ * @typedef {function((number|undefined), number): (number|undefined)}
+ */
+ol.control.RotationConstraintType;
+
+
+/**
+ * @param {number|undefined} rotation Rotation.
+ * @param {number} delta Delta.
+ * @return {number|undefined} Rotation.
+ */
+ol.control.RotationConstraint.none = function(rotation, delta) {
+  if (goog.isDef(rotation)) {
+    return rotation + delta;
+  } else {
+    return undefined;
+  }
+};
+
+
+/**
+ * @param {number} n N.
+ * @return {ol.control.RotationConstraintType} Rotation constraint.
+ */
+ol.control.RotationConstraint.createSnapToN = function(n) {
+  var theta = 2 * Math.PI / n;
+  return function(rotation, delta) {
+    if (goog.isDef(rotation)) {
+      rotation = Math.floor((rotation + delta) / theta + 0.5) * theta;
+      return rotation;
+    } else {
+      return undefined;
+    }
+  };
+};
diff --git a/src/ol/control/shiftdragrotate.js b/src/ol/control/shiftdragrotate.js
index 2faa029c84..1d5e8d2b8a 100644
--- a/src/ol/control/shiftdragrotate.js
+++ b/src/ol/control/shiftdragrotate.js
@@ -33,7 +33,7 @@ ol.control.ShiftDragRotate.prototype.handleDrag = function(mapBrowserEvent) {
   var theta = Math.atan2(
       size.height / 2 - browserEvent.offsetY,
       browserEvent.offsetX - size.width / 2);
-  map.setRotation(this.startRotation_ - theta);
+  this.rotate(map, this.startRotation_, -theta);
 };
 
 
diff --git a/src/ol/control/shiftdragrotateandzoom.js b/src/ol/control/shiftdragrotateandzoom.js
index 5f3ebcc9b0..3a1f276c20 100644
--- a/src/ol/control/shiftdragrotateandzoom.js
+++ b/src/ol/control/shiftdragrotateandzoom.js
@@ -45,7 +45,7 @@ ol.control.ShiftDragRotateAndZoom.prototype.handleDrag =
       size.height / 2 - browserEvent.offsetY);
   var theta = Math.atan2(delta.y, delta.x);
   // FIXME this should use map.withFrozenRendering but an assertion fails :-(
-  this.setRotation(map, this.startRotation_ - theta);
+  this.rotate(map, this.startRotation_, -theta);
   var resolution = this.startRatio_ * delta.magnitude();
   this.setResolution(map, resolution);
 };