[core] Group Map LatLngBounds, min and max zoom methods

Group bounds, minimum and maximum zoom related methods together using
the new BoundOptions.

v2: Document that getBounds() initializes all optional fields.
  - Add test for getBounds() on a map with default values.

2 files changed, 40 insertions, 7 deletions

diff --git a/include/mbgl/map/bound_options.hpp b/include/mbgl/map/bound_options.hpp
new file mode 100644
index 0000000000..69d353a301
--- /dev/null
+++ b/include/mbgl/map/bound_options.hpp
@@ -0,0 +1,30 @@
+#pragma once
+
+#include <mbgl/util/geo.hpp>
+#include <mbgl/util/optional.hpp>
+
+namespace mbgl {
+
+/**
+ * @brief Holds options to limit what parts of a map are visible. All fields are
+ * optional.
+ */
+struct BoundOptions {
+    /// Sets the latitude and longitude bounds to which the camera center are constrained
+    BoundOptions& withLatLngBounds(LatLngBounds b) { bounds = b; return *this; }
+    /// Sets the minimum zoom level
+    BoundOptions& withMinZoom(double z) { minZoom = z; return *this; }
+    /// Sets the maximum zoom level
+    BoundOptions& withMaxZoom(double z) { maxZoom = z; return *this; }
+
+    /// Constrain the center of the camera to be within these bounds.
+    optional<LatLngBounds> bounds;
+
+    /// Maximum zoom level allowed.
+    optional<double> maxZoom;
+
+    /// Minimum zoom level allowed.
+    optional<double> minZoom;
+};
+
+}  // namespace mbgl
diff --git a/include/mbgl/map/map.hpp b/include/mbgl/map/map.hpp
index 93e5190f99..b4f60a19ba 100644
--- a/include/mbgl/map/map.hpp
+++ b/include/mbgl/map/map.hpp
@@ -2,6 +2,7 @@
 
 #include <mbgl/util/optional.hpp>
 #include <mbgl/util/chrono.hpp>
+#include <mbgl/map/bound_options.hpp>
 #include <mbgl/map/map_observer.hpp>
 #include <mbgl/map/map_options.hpp>
 #include <mbgl/map/mode.hpp>
@@ -76,13 +77,15 @@ public:
     CameraOptions cameraForGeometry(const Geometry<double>&, const EdgeInsets&, optional<double> bearing = {}, optional<double> pitch = {}) const;
     LatLngBounds latLngBoundsForCamera(const CameraOptions&) const;
 
-    // Bounds
-    void setLatLngBounds(LatLngBounds);
-    LatLngBounds getLatLngBounds() const;
-    void setMinZoom(double);
-    double getMinZoom() const;
-    void setMaxZoom(double);
-    double getMaxZoom() const;
+    /// @name Bounds
+    /// @{
+
+    void setBounds(const BoundOptions& options);
+
+    /// Returns the current map bound options. All optional fields in BoundOptions are set.
+    BoundOptions getBounds() const;
+
+    /// @}
 
     // North Orientation
     void setNorthOrientation(NorthOrientation);