LibGfx: Add BoundingBox helper class

This is a small helper class to compute the bounding box of a set of
points.

Userland/Libraries/LibGfx/BoundingBox.h

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2023, MacDue <macdue@dueutil.tech>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibGfx/Point.h>
+#include <LibGfx/Rect.h>
+
+namespace Gfx {
+
+template<typename T>
+class BoundingBox {
+public:
+    constexpr BoundingBox() = default;
+
+    constexpr void add_point(T x, T y)
+    {
+        if (m_has_no_points) {
+            m_min_x = m_max_x = x;
+            m_min_y = m_max_y = y;
+            m_has_no_points = false;
+        } else {
+            m_min_x = min(m_min_x, x);
+            m_min_y = min(m_min_y, y);
+            m_max_x = max(m_max_x, x);
+            m_max_y = max(m_max_y, y);
+        }
+    }
+
+    constexpr T x() const { return m_min_x; }
+    constexpr T y() const { return m_min_y; }
+    constexpr T width() const { return m_max_x - m_min_x; }
+    constexpr T height() const { return m_max_y - m_min_y; }
+
+    void add_point(Point<T> point)
+    {
+        add_point(point.x(), point.y());
+    }
+
+    constexpr Rect<T> to_rect() const
+    {
+        return Rect<T> { x(), y(), width(), height() };
+    }
+
+    constexpr operator Rect<T>() const
+    {
+        return to_rect();
+    }
+
+private:
+    T m_min_x { 0 };
+    T m_min_y { 0 };
+    T m_max_x { 0 };
+    T m_max_y { 0 };
+    bool m_has_no_points { true };
+};
+
+using FloatBoundingBox = BoundingBox<float>;
+using IntBoundingBox = BoundingBox<int>;
+
+}