Implement Rect::IntersectLine

SDL2pp/Rect.cc

@@ -197,6 +197,14 @@ Optional<Rect> Rect::GetIntersection(const Rect& rect) const {
 		);
 }
 
+bool Rect::IntersectLine(int& x1, int& y1, int& x2, int& y2) const {
+	return SDL_IntersectRectAndLine(this, &x1, &y1, &x2, &y2) == SDL_TRUE;
+}
+
+bool Rect::IntersectLine(Point& p1, Point& p2) const {
+	return SDL_IntersectRectAndLine(this, &p1.x, &p1.y, &p2.x, &p2.y) == SDL_TRUE;
+}
+
 Rect Rect::operator+(const Point& offset) const {
 	return Rect(x + offset.x, y + offset.y, w, h);
 }

SDL2pp/Rect.hh

@@ -376,6 +376,45 @@ public:
 	////////////////////////////////////////////////////////////
 	Optional<Rect> GetIntersection(const Rect& rect) const;
 
+	////////////////////////////////////////////////////////////
+	/// \brief Calculate the intersection of a rectangle and line segment
+	///
+	/// \param[in,out] x1 Starting X-coordinate of the line
+	/// \param[in,out] y1 Starting Y-coordinate of the line
+	/// \param[in,out] x2 Ending X-coordinate of the line
+	/// \param[in,out] y2 Ending Y-coordinate of the line
+	///
+	/// \returns True if there is an intersection, false otherwise
+	///
+	/// This function is used to clip a line segment to a
+	/// rectangle. A line segment contained entirely within the
+	/// rectangle or that does not intersect will remain unchanged.
+	/// A line segment that crosses the rectangle at either or both
+	/// ends will be clipped to the boundary of the rectangle and
+	/// the new coordinates saved in x1, y1, x2, and/or y2 as
+	/// necessary.
+	///
+	////////////////////////////////////////////////////////////
+	bool IntersectLine(int& x1, int& y1, int& x2, int& y2) const;
+
+	////////////////////////////////////////////////////////////
+	/// \brief Calculate the intersection of a rectangle and line segment
+	///
+	/// \param[in,out] p1 Starting coordinates of the line
+	/// \param[in,out] p2 Ending coordinates of the line
+	///
+	/// \returns True if there is an intersection, false otherwise
+	///
+	/// This function is used to clip a line segment to a
+	/// rectangle. A line segment contained entirely within the
+	/// rectangle or that does not intersect will remain unchanged.
+	/// A line segment that crosses the rectangle at either or both
+	/// ends will be clipped to the boundary of the rectangle and
+	/// the new coordinates saved in p1 and/or p2 as necessary.
+	///
+	////////////////////////////////////////////////////////////
+	bool IntersectLine(Point& p1, Point& p2) const;
+
 	////////////////////////////////////////////////////////////
 	/// \brief Get rectangle moved by a given offset
 	///

tests/test_pointrect.cc

@@ -240,6 +240,23 @@ BEGIN_TEST()
 		EXPECT_TRUE(Rect(30, 40, 1, 1).Union(Rect(10, 20, 1, 1)) == Rect::FromCorners(10, 20, 30, 40));
 	}
 
+	{
+		// Rect/line intersections
+		Rect rect = Rect::FromCorners(10, 10, 20, 20);
+
+		Point p1(0, 0), p2(30, 30);
+		EXPECT_TRUE(rect.IntersectLine(p1, p2));
+		EXPECT_TRUE(p1 == Point(10, 10));
+		EXPECT_TRUE(p2 == Point(20, 20));
+
+		int x1 = 30, y1 = 0, x2 = 0, y2 = 30;
+		EXPECT_TRUE(rect.IntersectLine(x1, y1, x2, y2));
+		EXPECT_TRUE(x1 == 20);
+		EXPECT_TRUE(y1 == 10);
+		EXPECT_TRUE(x2 == 10);
+		EXPECT_TRUE(y2 == 20);
+	}
+
 	{
 		// Rect extend
 		EXPECT_TRUE(Rect(10, 20, 30, 40).GetExtension(0) == Rect(10, 20, 30, 40));