[core] Added Map::{get,set}LatLngBounds

include/mbgl/map/map.hpp

@@ -111,6 +111,8 @@ class Map : private util::noncopyable {
     void resetZoom();
 
     // Bounds
+    void setLatLngBounds(const LatLngBounds&);
+    LatLngBounds getLatLngBounds() const;
     void setMinZoom(double);
     double getMinZoom() const;
     void setMaxZoom(double);

src/mbgl/map/map.cpp

@@ -666,6 +666,15 @@ void Map::resetZoom() {
 
 #pragma mark - Bounds
 
+LatLngBounds Map::getLatLngBounds() const {
+    return impl->transform.getState().getLatLngBounds();
+}
+
+void Map::setLatLngBounds(const LatLngBounds& bounds) {
+    impl->cameraMutated = true;
+    impl->transform.setLatLngBounds(bounds);
+    impl->onUpdate(Update::Repaint);
+}
 
 void Map::setMinZoom(const double minZoom) {
     impl->transform.setMinZoom(minZoom);

src/mbgl/map/transform.cpp

@@ -440,6 +440,12 @@ void Transform::setScale(double scale, optional<EdgeInsets> padding, const Anima
 
 #pragma mark - Bounds
 
+void Transform::setLatLngBounds(const LatLngBounds& bounds) {
+    if (bounds.valid()) {
+        state.setLatLngBounds(bounds);
+    }
+}
+
 void Transform::setMinZoom(const double minZoom) {
     if (std::isnan(minZoom)) return;
     state.setMinZoom(minZoom);

src/mbgl/map/transform.hpp

@@ -57,6 +57,7 @@ class Transform : private util::noncopyable {
 
     // Bounds
 
+    void setLatLngBounds(const LatLngBounds&);
     void setMinZoom(double);
     void setMaxZoom(double);
 

src/mbgl/map/transform_state.cpp

@@ -139,6 +139,15 @@ double TransformState::getScale() const {
 
 #pragma mark - Bounds
 
+void TransformState::setLatLngBounds(const LatLngBounds& bounds_) {
+    bounds = bounds_;
+    setLatLngZoom(getLatLng(LatLng::Unwrapped), getZoom());
+}
+
+LatLngBounds TransformState::getLatLngBounds() const {
+    return bounds;
+}
+
 void TransformState::setMinZoom(const double minZoom) {
     if (minZoom <= getMaxZoom()) {
         min_scale = zoomScale(util::clamp(minZoom, util::MIN_ZOOM, util::MAX_ZOOM));
@@ -321,16 +330,18 @@ void TransformState::moveLatLng(const LatLng& latLng, const ScreenCoordinate& an
 }
 
 void TransformState::setLatLngZoom(const LatLng &latLng, double zoom) {
+    const LatLng constrained = bounds.constrain(latLng);
+
     double newScale = zoomScale(zoom);
     const double newWorldSize = newScale * util::tileSize;
     Bc = newWorldSize / util::DEGREES_MAX;
     Cc = newWorldSize / util::M2PI;
 
     const double m = 1 - 1e-15;
-    const double f = util::clamp(std::sin(util::DEG2RAD * latLng.latitude), -m, m);
+    const double f = util::clamp(std::sin(util::DEG2RAD * constrained.latitude), -m, m);
 
     ScreenCoordinate point = {
-        -latLng.longitude * Bc,
+        -constrained.longitude * Bc,
         0.5 * Cc * std::log((1 + f) / (1 - f)),
     };
     setScalePoint(newScale, point);

src/mbgl/map/transform_state.hpp

@@ -51,6 +51,8 @@ class TransformState {
     double getZoomFraction() const;
 
     // Bounds
+    void setLatLngBounds(const LatLngBounds&);
+    LatLngBounds getLatLngBounds() const;
     void setMinZoom(double);
     double getMinZoom() const;
     void setMaxZoom(double);
@@ -80,6 +82,8 @@ class TransformState {
     bool rotatedNorth() const;
     void constrain(double& scale, double& x, double& y) const;
 
+    LatLngBounds bounds = LatLngBounds::world();
+
     // Limit the amount of zooming possible on the map.
     double min_scale = std::pow(2, 0);
     double max_scale = std::pow(2, 20);

test/map/transform.test.cpp

@@ -543,3 +543,42 @@ TEST(Transform, DefaultTransform) {
     ASSERT_FALSE(transform.resize({ max, max }));
     testConversions(nullIsland, center);
 }
+
+TEST(Transform, LatLngBounds) {
+    const LatLng nullIsland {};
+    const LatLng sanFrancisco { 37.7749, -122.4194 };
+
+    Transform transform;
+    transform.resize({ 1000, 1000 });
+    transform.setLatLngZoom({ 0, 0 }, transform.getState().getMaxZoom());
+
+    // Default bounds.
+    ASSERT_EQ(transform.getState().getLatLngBounds(), LatLngBounds::world());
+    ASSERT_EQ(transform.getLatLng(), nullIsland);
+
+    // Invalid bounds.
+    transform.setLatLngBounds(LatLngBounds::empty());
+    ASSERT_EQ(transform.getState().getLatLngBounds(), LatLngBounds::world());
+
+    transform.setLatLng(sanFrancisco);
+    ASSERT_EQ(transform.getLatLng(), sanFrancisco);
+
+    // Single location.
+    transform.setLatLngBounds(LatLngBounds::singleton(sanFrancisco));
+    ASSERT_EQ(transform.getLatLng(), sanFrancisco);
+
+    transform.setLatLngBounds(LatLngBounds::hull({ -90.0, -180.0 }, { 0.0, 180.0 }));
+    transform.setLatLng(sanFrancisco);
+    ASSERT_EQ(transform.getLatLng().latitude, 0.0);
+    ASSERT_EQ(transform.getLatLng().longitude, sanFrancisco.longitude);
+
+    transform.setLatLngBounds(LatLngBounds::hull({ -90.0, 0.0 }, { 90.0, 180.0 }));
+    transform.setLatLng(sanFrancisco);
+    ASSERT_EQ(transform.getLatLng().latitude, sanFrancisco.latitude);
+    ASSERT_EQ(transform.getLatLng().longitude, 0.0);
+
+    transform.setLatLngBounds(LatLngBounds::hull({ -90.0, 0.0 }, { 0.0, 180.0 }));
+    transform.setLatLng(sanFrancisco);
+    ASSERT_EQ(transform.getLatLng().latitude, 0.0);
+    ASSERT_EQ(transform.getLatLng().longitude, 0.0);
+}