Move anchorCoordinateToPoint into QGeoProjection

anchorCoordinateToPoint functionality actually
belongs to QGeoProjection.
Moving it there so that it can be used in other
parts of the module.

Change-Id: Id135a7a4bbe14d9c83ef160682a317e3426b15ac
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>

2 files changed, 23 insertions, 0 deletions

diff --git a/src/location/maps/qgeoprojection.cpp b/src/location/maps/qgeoprojection.cpp
index 783193ed..7fefba27 100644
--- a/src/location/maps/qgeoprojection.cpp
+++ b/src/location/maps/qgeoprojection.cpp
@@ -73,6 +73,17 @@ QGeoProjection::~QGeoProjection()
 
 }
 
+QGeoCoordinate QGeoProjection::anchorCoordinateToPoint(const QGeoCoordinate &coordinate, const QPointF &anchorPoint) const
+{
+    // Approach: find the displacement in (wrapped) mercator space, and apply that to the center
+    QDoubleVector2D centerProj = geoToWrappedMapProjection(cameraData().center());
+    QDoubleVector2D coordProj  = geoToWrappedMapProjection(coordinate);
+
+    QDoubleVector2D anchorProj = itemPositionToWrappedMapProjection(QDoubleVector2D(anchorPoint));
+    // Y-clamping done in mercatorToCoord
+    return wrappedMapProjectionToGeo(centerProj + coordProj - anchorProj);
+}
+
 /*
  * QGeoProjectionWebMercator implementation
 */
@@ -490,6 +501,11 @@ void QGeoProjectionWebMercator::updateVisibleRegion()
         m_visibleRegion = QClipperUtils::pathToQList(res[0]); // Intersection between two convex quadrilaterals should always be a single polygon
 }
 
+QGeoCameraData QGeoProjectionWebMercator::cameraData() const
+{
+    return m_cameraData;
+}
+
 /*
  *
  *  Line implementation
diff --git a/src/location/maps/qgeoprojection_p.h b/src/location/maps/qgeoprojection_p.h
index 3a0dec1d..d3be1177 100644
--- a/src/location/maps/qgeoprojection_p.h
+++ b/src/location/maps/qgeoprojection_p.h
@@ -91,6 +91,12 @@ public:
     virtual QDoubleVector2D geoToWrappedMapProjection(const QGeoCoordinate &coordinate) const = 0;
     virtual QGeoCoordinate wrappedMapProjectionToGeo(const QDoubleVector2D &wrappedProjection) const = 0;
     virtual QMatrix4x4 quickItemTransformation(const QGeoCoordinate &coordinate, const QPointF &anchorPoint, qreal zoomLevel) const = 0;
+
+    // Returns the new map center after anchoring coordinate to anchorPoint on the screen
+    QGeoCoordinate anchorCoordinateToPoint(const QGeoCoordinate &coordinate, const QPointF &anchorPoint) const;
+
+private:
+    virtual QGeoCameraData cameraData() const = 0;
 };
 
 class Q_LOCATION_PRIVATE_EXPORT QGeoProjectionWebMercator : public QGeoProjection
@@ -132,6 +138,7 @@ public:
 private:
     void setupCamera();
     void updateVisibleRegion();
+    QGeoCameraData cameraData() const Q_DECL_OVERRIDE;
 
 public:
     struct Line2D