7 files changed, 74 insertions, 2 deletions
diff --git a/include/mbgl/map/map.hpp b/include/mbgl/map/map.hpp
index b740c3462e..908beb6b29 100644
--- a/include/mbgl/map/map.hpp
+++ b/include/mbgl/map/map.hpp
@@ -111,6 +111,8 @@ public:
     void resetZoom();
 
     // Bounds
+    void setLatLngBounds(const LatLngBounds&);
+    LatLngBounds getLatLngBounds() const;
     void setMinZoom(double);
     double getMinZoom() const;
     void setMaxZoom(double);
diff --git a/src/mbgl/map/map.cpp b/src/mbgl/map/map.cpp
index f42c11bdbb..261d2f149f 100644
--- a/src/mbgl/map/map.cpp
+++ b/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);
diff --git a/src/mbgl/map/transform.cpp b/src/mbgl/map/transform.cpp
index b8c3c3fefb..469db09e0a 100644
--- a/src/mbgl/map/transform.cpp
+++ b/src/mbgl/map/transform.cpp
@@ -435,6 +435,12 @@ 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);
diff --git a/src/mbgl/map/transform.hpp b/src/mbgl/map/transform.hpp
index 4b97e07b52..a4a08f4ad9 100644
--- a/src/mbgl/map/transform.hpp
+++ b/src/mbgl/map/transform.hpp
@@ -57,6 +57,7 @@ public:
 
     // Bounds
 
+    void setLatLngBounds(const LatLngBounds&);
     void setMinZoom(double);
     void setMaxZoom(double);
 
diff --git a/src/mbgl/map/transform_state.cpp b/src/mbgl/map/transform_state.cpp
index 3336c71125..764845bc8c 100644
--- a/src/mbgl/map/transform_state.cpp
+++ b/src/mbgl/map/transform_state.cpp
@@ -142,6 +142,15 @@ 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));
@@ -324,16 +333,18 @@ 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);
diff --git a/src/mbgl/map/transform_state.hpp b/src/mbgl/map/transform_state.hpp
index 4a0218e10e..b8baefdba1 100644
--- a/src/mbgl/map/transform_state.hpp
+++ b/src/mbgl/map/transform_state.hpp
@@ -51,6 +51,8 @@ public:
     double getZoomFraction() const;
 
     // Bounds
+    void setLatLngBounds(const LatLngBounds&);
+    LatLngBounds getLatLngBounds() const;
     void setMinZoom(double);
     double getMinZoom() const;
     void setMaxZoom(double);
@@ -84,6 +86,8 @@ private:
     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);
diff --git a/test/map/transform.test.cpp b/test/map/transform.test.cpp
index a8869b41bf..caee0ba23d 100644
--- a/test/map/transform.test.cpp
+++ b/test/map/transform.test.cpp
@@ -534,3 +534,42 @@ TEST(Transform, DefaultTransform) {
     ASSERT_DOUBLE_EQ(point.x, center.x);
     ASSERT_DOUBLE_EQ(point.y, center.y);
 }
+
+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);
+}