VideoCommon/BoundingBox: Make interface for querying bounding box data

Rather than expose the bounding box members directly, we can instead
provide an interface for code to use. This makes it nicer to transition
from global data, as the interface function names are already in
place.

Source/Core/VideoCommon/BoundingBox.h

@@ -11,21 +11,33 @@ class PointerWrap;
 // Bounding Box manager
 namespace BoundingBox
 {
-// Determines if bounding box is active
-extern bool active;
-
-// Bounding box current coordinates
-extern u16 coords[4];
-
-enum
+// Indicates a coordinate of the bounding box.
+enum class Coordinate
 {
-  LEFT = 0,
-  RIGHT = 1,
-  TOP = 2,
-  BOTTOM = 3
+  Left,    // The X coordinate of the left side of the bounding box.
+  Right,   // The X coordinate of the right side of the bounding box.
+  Top,     // The Y coordinate of the top of the bounding box.
+  Bottom,  // The Y coordinate of the bottom of the bounding box.
 };
 
+// Enables bounding box.
+void Enable();
+
+// Disables bounding box.
+void Disable();
+
+// Determines if bounding box is enabled.
+bool IsEnabled();
+
+// Gets a particular coordinate for the bounding box.
+u16 GetCoordinate(Coordinate coordinate);
+
+// Sets a particular coordinate for the bounding box.
+void SetCoordinate(Coordinate coordinate, u16 value);
+
+// Updates all bounding box coordinates.
+void Update(u16 left, u16 right, u16 top, u16 bottom);
+
 // Save state
 void DoState(PointerWrap& p);
-
-};  // end of namespace BoundingBox
+}  // namespace BoundingBox