Merge branch 'master' into jgrpp

# Conflicts:
#	src/company_cmd.cpp
#	src/core/geometry_func.cpp
#	src/date.cpp
#	src/genworld_gui.cpp
#	src/gfx.cpp
#	src/object_gui.cpp
#	src/openttd.cpp
#	src/settings_type.h
#	src/video/allegro_v.cpp
#	src/video/dedicated_v.cpp
#	src/video/null_v.cpp
#	src/video/sdl2_v.cpp
#	src/video/sdl_v.cpp
#	src/video/win32_v.cpp

src/core/geometry_func.cpp

@@ -40,3 +40,25 @@ Dimension adddim(const Dimension &d1, const Dimension &d2)
 	d.height = d1.height + d2.height;
 	return d;
 }
+
+/**
+ * Compute the bounding rectangle around two rectangles.
+ * @param r1 First rectangle.
+ * @param r2 Second rectangle.
+ * @return The bounding rectangle, the smallest rectangle that contains both arguments.
+ */
+Rect BoundingRect(const Rect &r1, const Rect &r2)
+{
+	/* If either the first or the second is empty, return the other. */
+	if (IsEmptyRect(r1)) return r2;
+	if (IsEmptyRect(r2)) return r1;
+
+	Rect r;
+
+	r.top    = std::min(r1.top,    r2.top);
+	r.bottom = std::max(r1.bottom, r2.bottom);
+	r.left   = std::min(r1.left,   r2.left);
+	r.right  = std::max(r1.right,  r2.right);
+
+	return r;
+}

src/core/geometry_func.hpp

@@ -15,4 +15,16 @@
 Dimension maxdim(const Dimension &d1, const Dimension &d2);
 Dimension adddim(const Dimension &d1, const Dimension &d2);
 
+/**
+ * Check if a rectangle is empty.
+ * @param r Rectangle to check.
+ * @return True if and only if the rectangle doesn't define space.
+ */
+static inline bool IsEmptyRect(const Rect &r)
+{
+	return (r.left | r.top | r.right | r.bottom) == 0;
+}
+
+Rect BoundingRect(const Rect &r1, const Rect &r2);
+
 #endif /* GEOMETRY_FUNC_HPP */