Move the coordinate <-> item position conversion to QGeoProjection

This patch simplifies the QGeoMap API removing all the API
necessary to convert to and from screen.
This is now demanded to a specific QGeoProjection class, that will
be independent of the map, except for using the same Geo projection
(currently only WebMercator, or EPSG:3857, although we use a sphere
instead of an ellipsoid, i believe)

The benefits are
- This relieves subclasses of QGeoMap from implementing a
GeoProjection API, especially since QtLocation currently supports
only WebMercator, and reimplementations would have to anyway
produce the same results as the inbuilt one.

- This avoids the several indirection steps previously necessary
to perform a map projection (qgeotiledmap -> private->mapscene->
private). Since these operation are quite frequent one per
map item coordinate at every redraw, shortening the indirection
chain is beneficial

- It simplifies the highly complex QGeoTiledMapScene, separating
all the logic that is not needed to draw the scene, but only
to perform geo coordinate <-> screen coordinate conversion

Change-Id: I9e3ca5280166f2d6430a32deb44c030d02d9d4e1
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>

1 files changed, 32 insertions, 31 deletions

diff --git a/src/location/maps/qgeomap.cpp b/src/location/maps/qgeomap.cpp
index f30dbce7..325ca83f 100644
--- a/src/location/maps/qgeomap.cpp
+++ b/src/location/maps/qgeomap.cpp
@@ -57,6 +57,7 @@ void QGeoMap::setViewportSize(const QSize& size)
     if (size == d->m_viewportSize)
         return;
     d->m_viewportSize = size;
+    d->m_geoProjection->setViewportSize(size);
     d->changeViewportSize(size);
 }
 
@@ -84,6 +85,7 @@ void QGeoMap::setCameraData(const QGeoCameraData &cameraData)
     if (cameraData == d->m_cameraData)
         return;
     d->m_cameraData = cameraData;
+    d->m_geoProjection->setCameraData(cameraData);
     d->changeCameraData(cameraData);
     emit cameraDataChanged(d->m_cameraData);
 }
@@ -110,48 +112,44 @@ const QGeoMapType QGeoMap::activeMapType() const
     return d->m_activeMapType;
 }
 
-
-QGeoCameraCapabilities QGeoMap::cameraCapabilities() const
+double QGeoMap::minimumZoom() const
 {
     Q_D(const QGeoMap);
-    if (!d->m_engine.isNull())
-        return d->m_engine->cameraCapabilities();
-    else
-        return QGeoCameraCapabilities();
+    return d->m_geoProjection->minimumZoom();
 }
 
-/* Default implementations */
-QGeoCoordinate QGeoMap::itemPositionToCoordinate(const QDoubleVector2D &pos, bool clipToViewport) const
+double QGeoMap::maximumCenterLatitudeAtZoom(double zoomLevel) const
 {
-    if (clipToViewport) {
-        int w = viewportWidth();
-        int h = viewportHeight();
-
-        if ((pos.x() < 0) || (w < pos.x()) || (pos.y() < 0) || (h < pos.y()))
-            return QGeoCoordinate();
-    }
+    Q_D(const QGeoMap);
+    return d->m_geoProjection->maximumCenterLatitudeAtZoom(zoomLevel);
+}
 
-    QDoubleVector2D wrappedMapProjection = itemPositionToWrappedMapProjection(pos);
-    // With rotation/tilting, a screen position might end up outside the projection space.
-    // TODO: test for it
-    return mapProjectionToGeo(unwrapMapProjection(wrappedMapProjection));
+double QGeoMap::mapWidth() const
+{
+    Q_D(const QGeoMap);
+    return d->m_geoProjection->mapWidth();
 }
 
-QDoubleVector2D QGeoMap::coordinateToItemPosition(const QGeoCoordinate &coordinate, bool clipToViewport) const
+double QGeoMap::mapHeight() const
 {
-    QDoubleVector2D pos = wrappedMapProjectionToItemPosition(wrapMapProjection(geoToMapProjection(coordinate)));
+    Q_D(const QGeoMap);
+    return d->m_geoProjection->mapHeight();
+}
 
-    if (clipToViewport) {
-        int w = viewportWidth();
-        int h = viewportHeight();
-        double x = pos.x();
-        double y = pos.y();
-        if ((x < -0.5) || (x > w + 0.5) || (y < -0.5) || (y > h + 0.5) || qIsNaN(x) || qIsNaN(y))
-            return QDoubleVector2D(qQNaN(), qQNaN());
-    }
-    return pos;
+const QGeoProjection &QGeoMap::geoProjection() const
+{
+    Q_D(const QGeoMap);
+    return *(d->m_geoProjection);
 }
 
+QGeoCameraCapabilities QGeoMap::cameraCapabilities() const
+{
+    Q_D(const QGeoMap);
+    if (!d->m_engine.isNull())
+        return d->m_engine->cameraCapabilities();
+    else
+        return QGeoCameraCapabilities();
+}
 
 void QGeoMap::prefetchData()
 {
@@ -189,8 +187,9 @@ void QGeoMap::clearParameters()
     d->m_mapParameters.clear();
 }
 
-QGeoMapPrivate::QGeoMapPrivate(QGeoMappingManagerEngine *engine)
+QGeoMapPrivate::QGeoMapPrivate(QGeoMappingManagerEngine *engine, QGeoProjection *geoProjection)
     : QObjectPrivate(),
+      m_geoProjection(geoProjection),
       m_engine(engine),
       m_activeMapType(QGeoMapType())
 {
@@ -198,6 +197,8 @@ QGeoMapPrivate::QGeoMapPrivate(QGeoMappingManagerEngine *engine)
 
 QGeoMapPrivate::~QGeoMapPrivate()
 {
+    if (m_geoProjection)
+        delete m_geoProjection;
 }
 
 void QGeoMapPrivate::addParameter(QGeoMapParameter *param)