fixes #33: rotate around arbitrary point

include/llmr/map/map.hpp

@@ -54,7 +54,7 @@ public:
 
     /* rotation */
     void rotateBy(double cx, double cy, double sx, double sy, double ex, double ey);
-    void setAngle(double angle);
+    void setAngle(double angle, double cx = -1, double cy = -1);
     double getAngle() const;
     void resetNorth();
 

ios/MBXViewController.mm

@@ -210,7 +210,7 @@ class MBXMapView
     }
     else if (rotate.state == UIGestureRecognizerStateChanged)
     {
-        mapView->map.setAngle(self.angle + rotate.rotation);
+        mapView->map.setAngle(self.angle + rotate.rotation, [rotate locationInView:rotate.view].x, [rotate locationInView:rotate.view].y);
     }
 }
 

src/map/map.cpp

@@ -93,10 +93,24 @@ void Map::setScale(double scale) {
     settings.save();
 }
 
-void Map::setAngle(double angle) {
+void Map::setAngle(double angle, double x, double y) {
+    double dx, dy;
+
+    if (x >= 0 && y >= 0) {
+        dx = (transform.width  / 2) - x;
+        dy = (transform.height / 2) - y;
+        transform.moveBy(dx, dy);
+    }
+
     transform.setAngle(angle);
+
+    if (x >= 0 && y >= 0) {
+        transform.moveBy(-dx, -dy);
+    }
+
     update();
 
+    transform.getLonLat(settings.longitude, settings.latitude);
     settings.angle = transform.getAngle();
     settings.save();
 }