Adapt QQuickGeoMapGestureArea to work with tilted and rotated maps

This patch fixes the handling of pan/flick/pinch in
presence of tilt or bearing.

Change-Id: Iad04fd92e1c8e318e3b1b0d344852c81e554ebb7
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

2 files changed, 8 insertions, 1 deletions

diff --git a/src/location/maps/qgeoprojection.cpp b/src/location/maps/qgeoprojection.cpp
index 77a91a15..15f400d9 100644
--- a/src/location/maps/qgeoprojection.cpp
+++ b/src/location/maps/qgeoprojection.cpp
@@ -84,7 +84,8 @@ QGeoProjectionWebMercator::QGeoProjectionWebMercator()
       m_nearPlane(0.0),
       m_farPlane(0.0),
       m_halfWidth(0.0),
-      m_halfHeight(0.0)
+      m_halfHeight(0.0),
+      m_minimumUnprojectableY(0.0)
 {
 }
 
@@ -195,6 +196,9 @@ QDoubleVector2D QGeoProjectionWebMercator::wrappedMapProjectionToItemPosition(co
 QDoubleVector2D QGeoProjectionWebMercator::itemPositionToWrappedMapProjection(const QDoubleVector2D &itemPosition) const
 {
     QDoubleVector2D pos = itemPosition;
+    // when the camera is tilted, picking a point above the horizon returns a coordinate behind the camera
+    if (pos.y() < m_minimumUnprojectableY)
+        pos.setY(m_minimumUnprojectableY);
     pos *= QDoubleVector2D(m_1_viewportWidth, m_1_viewportHeight);
     pos *= 2.0;
     pos -= QDoubleVector2D(1.0,1.0);
@@ -399,6 +403,8 @@ void QGeoProjectionWebMercator::setupCamera()
         verticalEstateToSkip = 1.0 - maxHalfAperture / verticalAperture;
     }
 
+    m_minimumUnprojectableY = verticalEstateToSkip * 0.5 * m_viewportHeight; // verticalEstateToSkip is relative to half aperture
+
     QDoubleVector2D tl = viewportToWrappedMapProjection(QDoubleVector2D(-1, -1 + verticalEstateToSkip ));
     QDoubleVector2D tr = viewportToWrappedMapProjection(QDoubleVector2D( 1, -1 + verticalEstateToSkip ));
     QDoubleVector2D bl = viewportToWrappedMapProjection(QDoubleVector2D(-1,  1 ));
diff --git a/src/location/maps/qgeoprojection_p.h b/src/location/maps/qgeoprojection_p.h
index d8508578..6ea8fd6e 100644
--- a/src/location/maps/qgeoprojection_p.h
+++ b/src/location/maps/qgeoprojection_p.h
@@ -183,6 +183,7 @@ private:
     double           m_farPlane;
     double           m_halfWidth;
     double           m_halfHeight;
+    double           m_minimumUnprojectableY;
 
     // For the clipping region
     QDoubleVector3D  m_centerMercator;