[core] Added PrecisionPoint to represent pixel points

include/mbgl/map/map.hpp

@@ -100,7 +100,7 @@ public:
     void easeTo(CameraOptions options);
 
     // Position
-    void moveBy(double dx, double dy, const Duration& = Duration::zero());
+    void moveBy(const PrecisionPoint&, const Duration& = Duration::zero());
     void setLatLng(LatLng latLng, vec2<double> point, const Duration& = Duration::zero());
     void setLatLng(LatLng latLng, const Duration& = Duration::zero());
     LatLng getLatLng() const;

include/mbgl/util/geo.hpp

@@ -3,10 +3,24 @@
 
 #include <mbgl/util/vec.hpp>
 
+#include <cmath>
+
 namespace mbgl {
 
 class TileID;
 
+struct PrecisionPoint {
+    double x = 0;
+    double y = 0;
+
+    inline PrecisionPoint(double x_ = 0, double y_ = 0)
+        : x(x_), y(y_) {}
+
+    inline bool isValid() const {
+        return !(std::isnan(x) || std::isnan(y));
+    }
+};
+
 struct LatLng {
     double latitude = 0;
     double longitude = 0;
@@ -21,7 +35,7 @@ struct LatLng {
     // Constructs a LatLng object with the top left position of the specified tile.
     LatLng(const TileID& id);
 
-    vec2<double> project() const;
+    PrecisionPoint project() const;
 };
 
 struct ProjectedMeters {

src/mbgl/annotation/point_annotation_impl.cpp

@@ -13,7 +13,7 @@ void PointAnnotationImpl::updateLayer(const TileID& tileID, AnnotationTileLayer&
     featureProperties.emplace("sprite", point.icon.empty() ? std::string("default_marker") : point.icon);
 
     const uint16_t extent = 4096;
-    const vec2<double> pp = point.position.project();
+    const mbgl::PrecisionPoint pp = point.position.project();
     const uint32_t z2 = 1 << tileID.z;
     const uint32_t x = pp.x * z2;
     const uint32_t y = pp.y * z2;

src/mbgl/map/map.cpp

@@ -156,8 +156,8 @@ void Map::easeTo(CameraOptions options) {
 
 #pragma mark - Position
 
-void Map::moveBy(double dx, double dy, const Duration& duration) {
-    transform->moveBy(dx, dy, duration);
+void Map::moveBy(const PrecisionPoint& point, const Duration& duration) {
+    transform->moveBy(point, duration);
     update(Update::Repaint);
 }
 

src/mbgl/map/transform.cpp

@@ -87,21 +87,20 @@ void Transform::easeTo(CameraOptions options) {
     _easeTo(options, new_scale, angle, xn, yn);
 }
 
-void Transform::moveBy(const double dx, const double dy, const Duration& duration) {
-    if (std::isnan(dx) || std::isnan(dy)) {
+void Transform::moveBy(const PrecisionPoint& point, const Duration& duration) {
+    if (!point.isValid()) {
         return;
     }
 
-    _moveBy(dx, dy, duration);
+    _moveBy(point, duration);
 }
 
-void Transform::_moveBy(const double dx, const double dy, const Duration& duration) {
-    
-    double x = state.x + std::cos(state.angle) * dx + std::sin( state.angle) * dy;
-    double y = state.y + std::cos(state.angle) * dy + std::sin(-state.angle) * dx;
+void Transform::_moveBy(const PrecisionPoint& point, const Duration& duration) {
+    double x = state.x + std::cos(state.angle) * point.x + std::sin( state.angle) * point.y;
+    double y = state.y + std::cos(state.angle) * point.y + std::sin(-state.angle) * point.x;
 
     state.constrain(state.scale, y);
-    
+
     CameraOptions options;
     options.duration = duration;
     _easeTo(options, state.scale, state.angle, x, y);

src/mbgl/map/transform.hpp

@@ -27,7 +27,7 @@ public:
     void easeTo(const CameraOptions options);
 
     // Position
-    void moveBy(double dx, double dy, const Duration& = Duration::zero());
+    void moveBy(const PrecisionPoint&, const Duration& = Duration::zero());
     void setLatLng(LatLng latLng, const Duration& = Duration::zero());
     void setLatLng(LatLng latLng, vec2<double> point, const Duration& duration = Duration::zero());
     void setLatLngZoom(LatLng latLng, double zoom, const Duration& = Duration::zero());
@@ -66,7 +66,7 @@ public:
     bool isPanning() const { return state.isPanning(); }
 
 private:
-    void _moveBy(double dx, double dy, const Duration& = Duration::zero());
+    void _moveBy(const PrecisionPoint&, const Duration& = Duration::zero());
     void _setScale(double scale, double cx, double cy, const Duration& = Duration::zero());
     void _setScaleXY(double new_scale, double xn, double yn, const Duration& = Duration::zero());
     void _easeTo(CameraOptions options, const double new_scale, const double new_angle,

src/mbgl/renderer/painter.cpp

@@ -372,7 +372,7 @@ void Painter::renderBackground(const BackgroundLayer& layer) {
         patternShader->u_opacity = properties.opacity;
 
         LatLng latLng = state.getLatLng();
-        vec2<double> center = state.latLngToPoint(latLng);
+        PrecisionPoint center = state.latLngToPoint(latLng);
         float scale = 1 / std::pow(2, zoomFraction);
 
         std::array<float, 2> sizeA = imagePosA.size;

src/mbgl/util/geo.cpp

@@ -12,7 +12,7 @@ LatLng::LatLng(const TileID& id) {
     latitude = 180.0 / M_PI * std::atan(0.5 * (std::exp(n) - std::exp(-n)));
 }
 
-vec2<double> LatLng::project() const {
+PrecisionPoint LatLng::project() const {
     // Clamp to the latitude limits of Mercator.
     const double constrainedLatitude = ::fmin(::fmax(latitude, -util::LATITUDE_MAX), util::LATITUDE_MAX);