Cache coordinate projections in map items

This patch caches the result of geoToMapProjection() for the coordinates
of the map items, regenerating this data only upon coordinate changes.
This allows avoiding to perform a (mercator) projection basically
every time the item has to be drawn, and instead do only the wrapping
around the camera center and the projection to screen

Task-number: QTBUG-59479
Change-Id: Iea5ec04f360d2fe7495cd9c1dd278e83200e0f8d
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

1 files changed, 36 insertions, 9 deletions

diff --git a/src/location/declarativemaps/qdeclarativepolygonmapitem.cpp b/src/location/declarativemaps/qdeclarativepolygonmapitem.cpp
index 857aec41..44d1787f 100644
--- a/src/location/declarativemaps/qdeclarativepolygonmapitem.cpp
+++ b/src/location/declarativemaps/qdeclarativepolygonmapitem.cpp
@@ -141,7 +141,7 @@ QGeoMapPolygonGeometry::QGeoMapPolygonGeometry()
     \internal
 */
 void QGeoMapPolygonGeometry::updateSourcePoints(const QGeoMap &map,
-                                                const QList<QGeoCoordinate> &path)
+                                                const QList<QDoubleVector2D> &path)
 {
     if (!sourceDirty_)
         return;
@@ -161,11 +161,8 @@ void QGeoMapPolygonGeometry::updateSourcePoints(const QGeoMap &map,
     QDoubleVector2D wrappedLeftBound(qInf(), qInf());
     // 1)
     for (int i = 0; i < path.size(); ++i) {
-        const QGeoCoordinate &coord = path.at(i);
-        if (!coord.isValid())
-            continue;
-
-        QDoubleVector2D wrappedProjection = map.geoProjection().wrapMapProjection(map.geoProjection().geoToMapProjection(coord));
+        const QDoubleVector2D &coord = path.at(i);
+        QDoubleVector2D wrappedProjection = map.geoProjection().wrapMapProjection(coord);
 
         // We can get NaN if the map isn't set up correctly, or the projection
         // is faulty -- probably best thing to do is abort
@@ -380,6 +377,7 @@ void QDeclarativePolygonMapItem::setMap(QDeclarativeGeoMap *quickMap, QGeoMap *m
 {
     QDeclarativeGeoMapItemBase::setMap(quickMap,map);
     if (map) {
+        regenerateCache();
         geometry_.markSourceDirty();
         borderGeometry_.markSourceDirty();
         polishAndUpdate();
@@ -437,6 +435,7 @@ void QDeclarativePolygonMapItem::setPath(const QJSValue &value)
 
     geopath_.setPath(pathList);
 
+    regenerateCache();
     geometry_.setPreserveGeometry(true, geopath_.boundingGeoRectangle().topLeft());
     borderGeometry_.setPreserveGeometry(true, geopath_.boundingGeoRectangle().topLeft());
     markSourceDirtyAndUpdate();
@@ -453,8 +452,11 @@ void QDeclarativePolygonMapItem::setPath(const QJSValue &value)
 
 void QDeclarativePolygonMapItem::addCoordinate(const QGeoCoordinate &coordinate)
 {
-    geopath_.addCoordinate(coordinate);
+    if (!coordinate.isValid())
+        return;
 
+    geopath_.addCoordinate(coordinate);
+    updateCache();
     geometry_.setPreserveGeometry(true, geopath_.boundingGeoRectangle().topLeft());
     borderGeometry_.setPreserveGeometry(true, geopath_.boundingGeoRectangle().topLeft());
     markSourceDirtyAndUpdate();
@@ -478,6 +480,7 @@ void QDeclarativePolygonMapItem::removeCoordinate(const QGeoCoordinate &coordina
     if (geopath_.path().length() == length)
         return;
 
+    regenerateCache();
     geometry_.setPreserveGeometry(true, geopath_.boundingGeoRectangle().topLeft());
     borderGeometry_.setPreserveGeometry(true, geopath_.boundingGeoRectangle().topLeft());
     markSourceDirtyAndUpdate();
@@ -542,7 +545,7 @@ void QDeclarativePolygonMapItem::updatePolish()
     QScopedValueRollback<bool> rollback(updatingGeometry_);
     updatingGeometry_ = true;
 
-    geometry_.updateSourcePoints(*map(), geopath_.path());
+    geometry_.updateSourcePoints(*map(), geopathProjected_);
     geometry_.updateScreenPoints(*map());
 
     QList<QGeoMapItemGeometry *> geoms;
@@ -550,7 +553,7 @@ void QDeclarativePolygonMapItem::updatePolish()
     borderGeometry_.clear();
 
     if (border_.color() != Qt::transparent && border_.width() > 0) {
-        QList<QGeoCoordinate> closedPath = geopath_.path();
+        QList<QDoubleVector2D> closedPath = geopathProjected_;
         closedPath << closedPath.first();
 
         borderGeometry_.setPreserveGeometry(true, geopath_.boundingGeoRectangle().topLeft());
@@ -605,6 +608,29 @@ void QDeclarativePolygonMapItem::afterViewportChanged(const QGeoMapViewportChang
 /*!
     \internal
 */
+void QDeclarativePolygonMapItem::regenerateCache()
+{
+    if (!map())
+        return;
+    geopathProjected_.clear();
+    geopathProjected_.reserve(geopath_.path().size());
+    for (const QGeoCoordinate &c : geopath_.path())
+        geopathProjected_ << map()->geoProjection().geoToMapProjection(c);
+}
+
+/*!
+    \internal
+*/
+void QDeclarativePolygonMapItem::updateCache()
+{
+    if (!map())
+        return;
+    geopathProjected_ << map()->geoProjection().geoToMapProjection(geopath_.path().last());
+}
+
+/*!
+    \internal
+*/
 bool QDeclarativePolygonMapItem::contains(const QPointF &point) const
 {
     return (geometry_.contains(point) || borderGeometry_.contains(point));
@@ -640,6 +666,7 @@ void QDeclarativePolygonMapItem::geometryChanged(const QRectF &newGeometry, cons
         return;
 
     geopath_.translate(offsetLati, offsetLongi);
+    regenerateCache();
     geometry_.setPreserveGeometry(true, geopath_.boundingGeoRectangle().topLeft());
     borderGeometry_.setPreserveGeometry(true, geopath_.boundingGeoRectangle().topLeft());
     markSourceDirtyAndUpdate();