2 files changed, 128 insertions, 33 deletions

diff --git a/src/tilearea.cpp b/src/tilearea.cpp
index 7572f9f63..046e22221 100644
--- a/src/tilearea.cpp
+++ b/src/tilearea.cpp
@@ -18,8 +18,11 @@
  * @param start the start of the area
  * @param end   the end of the area
  */
-TileArea::TileArea(TileIndex start, TileIndex end)
+OrthogonalTileArea::OrthogonalTileArea(TileIndex start, TileIndex end)
 {
+	assert(start < MapSize());
+	assert(end < MapSize());
+
 	uint sx = TileX(start);
 	uint sy = TileY(start);
 	uint ex = TileX(end);
@@ -37,7 +40,7 @@ TileArea::TileArea(TileIndex start, TileIndex end)
  * Add a single tile to a tile area; enlarge if needed.
  * @param to_add The tile to add
  */
-void TileArea::Add(TileIndex to_add)
+void OrthogonalTileArea::Add(TileIndex to_add)
 {
 	if (this->tile == INVALID_TILE) {
 		this->tile = to_add;
@@ -69,7 +72,7 @@ void TileArea::Add(TileIndex to_add)
  * @param ta the other tile area to check against.
  * @return true if they intersect.
  */
-bool TileArea::Intersects(const TileArea &ta) const
+bool OrthogonalTileArea::Intersects(const OrthogonalTileArea &ta) const
 {
 	if (ta.w == 0 || this->w == 0) return false;
 
@@ -98,7 +101,7 @@ bool TileArea::Intersects(const TileArea &ta) const
  * @param tile Tile to test for.
  * @return True if the tile is inside the area.
  */
-bool TileArea::Contains(TileIndex tile) const
+bool OrthogonalTileArea::Contains(TileIndex tile) const
 {
 	if (this->w == 0) return false;
 
@@ -115,7 +118,7 @@ bool TileArea::Contains(TileIndex tile) const
 /**
  * Clamp the tile area to map borders.
  */
-void TileArea::ClampToMap()
+void OrthogonalTileArea::ClampToMap()
 {
 	assert(this->tile < MapSize());
 	this->w = min(this->w, MapSizeX() - TileX(this->tile));
@@ -123,42 +126,70 @@ void TileArea::ClampToMap()
 }
 
 /**
- * Construct the iterator.
- * @param corner1 Tile from where to begin iterating.
- * @param corner2 Tile where to end the iterating.
+ * Create a diagonal tile area from two corners.
+ * @param start First corner of the area.
+ * @param end Second corner of the area.
  */
-DiagonalTileIterator::DiagonalTileIterator(TileIndex corner1, TileIndex corner2) : TileIterator(corner2), base_x(TileX(corner2)), base_y(TileY(corner2)), a_cur(0), b_cur(0)
+DiagonalTileArea::DiagonalTileArea(TileIndex start, TileIndex end) : tile(start)
 {
-	assert(corner1 < MapSize());
-	assert(corner2 < MapSize());
-
-	int dist_x = TileX(corner1) - TileX(corner2);
-	int dist_y = TileY(corner1) - TileY(corner2);
-	this->a_max = dist_x + dist_y;
-	this->b_max = dist_y - dist_x;
+	assert(start < MapSize());
+	assert(end < MapSize());
 
 	/* Unfortunately we can't find a new base and make all a and b positive because
 	 * the new base might be a "flattened" corner where there actually is no single
 	 * tile. If we try anyway the result is either inaccurate ("one off" half of the
 	 * time) or the code gets much more complex;
 	 *
-	 * We also need to increment here to have equality as marker for the end of a row or
-	 * column. Like that it's shorter than having another if/else in operator++
-	 */
-	if (this->a_max > 0) {
-		this->a_max++;
+	 * We also need to increment/decrement a and b here to have one-past-end semantics
+	 * for a and b, just the way the orthogonal tile area does it for w and h. */
+
+	this->a = TileY(end) + TileX(end) - TileY(start) - TileX(start);
+	this->b = TileY(end) - TileX(end) - TileY(start) + TileX(start);
+	if (this->a > 0) {
+		this->a++;
 	} else {
-		this->a_max--;
+		this->a--;
 	}
 
-	if (this->b_max > 0) {
-		this->b_max++;
+	if (this->b > 0) {
+		this->b++;
 	} else {
-		this->b_max--;
+		this->b--;
 	}
 }
 
 /**
+ * Does this tile area contain a tile?
+ * @param tile Tile to test for.
+ * @return True if the tile is inside the area.
+ */
+bool DiagonalTileArea::Contains(TileIndex tile) const
+{
+	int a = TileY(tile) + TileX(tile);
+	int b = TileY(tile) - TileX(tile);
+
+	int start_a = TileY(this->tile) + TileX(this->tile);
+	int start_b = TileY(this->tile) - TileX(this->tile);
+
+	int end_a = start_a + this->a;
+	int end_b = start_b + this->b;
+
+	/* Swap if necessary, preserving the "one past end" semantics. */
+	if (start_a > end_a) {
+		int tmp = start_a;
+		start_a = end_a + 1;
+		end_a = tmp + 1;
+	}
+	if (start_b > end_b) {
+		int tmp = start_b;
+		start_b = end_b + 1;
+		end_b = tmp + 1;
+	}
+
+	return (a >= start_a && a < end_a && b >= start_b && b < end_b);
+}
+
+/**
  * Move ourselves to the next tile in the rectangle on the map.
  */
 TileIterator &DiagonalTileIterator::operator++()
diff --git a/src/tilearea_type.h b/src/tilearea_type.h
index 7fabc50c4..45bfb3d4c 100644
--- a/src/tilearea_type.h
+++ b/src/tilearea_type.h
@@ -15,7 +15,7 @@
 #include "map_func.h"
 
 /** Represents the covered area of e.g. a rail station */
-struct TileArea {
+struct OrthogonalTileArea {
 	TileIndex tile; ///< The base tile of the area
 	uint16 w;       ///< The width of the area
 	uint16 h;       ///< The height of the area
@@ -26,10 +26,11 @@ struct TileArea {
 	 * @param w the width
 	 * @param h the height
 	 */
-	TileArea(TileIndex tile = INVALID_TILE, uint8 w = 0, uint8 h = 0) : tile(tile), w(w), h(h) {}
-
-	TileArea(TileIndex start, TileIndex end);
+	OrthogonalTileArea(TileIndex tile = INVALID_TILE, uint8 w = 0, uint8 h = 0) : tile(tile), w(w), h(h)
+	{
+	}
 
+	OrthogonalTileArea(TileIndex start, TileIndex end);
 
 	void Add(TileIndex to_add);
 
@@ -43,7 +44,7 @@ struct TileArea {
 		this->h    = 0;
 	}
 
-	bool Intersects(const TileArea &ta) const;
+	bool Intersects(const OrthogonalTileArea &ta) const;
 
 	bool Contains(TileIndex tile) const;
 
@@ -59,6 +60,41 @@ struct TileArea {
 	}
 };
 
+/** Represents a diagonal tile area. */
+struct DiagonalTileArea {
+
+	TileIndex tile; ///< Base tile of the area
+	int16 a;        ///< Extent in diagonal "x" direction (may be negative to signify the area stretches to the left)
+	int16 b;        ///< Extent in diagonal "y" direction (may be negative to signify the area stretches upwards)
+
+	/**
+	 * Construct this tile area with some set values.
+	 * @param tile The base tile.
+	 * @param a The "x" extent.
+	 * @param b The "y" estent.
+	 */
+	DiagonalTileArea(TileIndex tile = INVALID_TILE, int8 a = 0, int8 b = 0) : tile(tile), a(a), b(b)
+	{
+	}
+
+	DiagonalTileArea(TileIndex start, TileIndex end);
+
+	/**
+	 * Clears the TileArea by making the tile invalid and setting a and b to 0.
+	 */
+	void Clear()
+	{
+		this->tile = INVALID_TILE;
+		this->a    = 0;
+		this->b    = 0;
+	}
+
+	bool Contains(TileIndex tile) const;
+};
+
+/** Shorthand for the much more common orthogonal tile area. */
+typedef OrthogonalTileArea TileArea;
+
 /** Base class for tile iterators. */
 class TileIterator {
 protected:
@@ -68,7 +104,7 @@ protected:
 	 * Initialise the iterator starting at this tile.
 	 * @param tile The tile we start iterating from.
 	 */
-	TileIterator(TileIndex tile) : tile(tile)
+	TileIterator(TileIndex tile = INVALID_TILE) : tile(tile)
 	{
 	}
 
@@ -110,8 +146,18 @@ public:
 	 * Construct the iterator.
 	 * @param ta Area, i.e. begin point and width/height of to-be-iterated area.
 	 */
-	OrthogonalTileIterator(const TileArea &ta) : TileIterator(ta.w == 0 || ta.h == 0 ? INVALID_TILE : ta.tile), w(ta.w), x(ta.w), y(ta.h)
+	OrthogonalTileIterator(const OrthogonalTileArea &ta) : TileIterator(ta.w == 0 || ta.h == 0 ? INVALID_TILE : ta.tile), w(ta.w), x(ta.w), y(ta.h)
+	{
+	}
+
+	/**
+	 * Construct the iterator.
+	 * @param corner1 Tile from where to begin iterating.
+	 * @param corner2 Tile where to end the iterating.
+	 */
+	OrthogonalTileIterator(TileIndex corner1, TileIndex corner2)
 	{
+		*this = OrthogonalTileIterator(OrthogonalTileArea(corner1, corner2));
 	}
 
 	/**
@@ -149,7 +195,25 @@ private:
 	int b_max;   ///< The (rotated) y coordinate of the end of the iteration.
 
 public:
-	DiagonalTileIterator(TileIndex begin, TileIndex end);
+
+	/**
+	 * Construct the iterator.
+	 * @param ta Area, i.e. begin point and (diagonal) width/height of to-be-iterated area.
+	 */
+	DiagonalTileIterator(const DiagonalTileArea &ta) :
+		TileIterator(ta.tile), base_x(TileX(ta.tile)), base_y(TileY(ta.tile)), a_cur(0), b_cur(0), a_max(ta.a), b_max(ta.b)
+	{
+	}
+
+	/**
+	 * Construct the iterator.
+	 * @param corner1 Tile from where to begin iterating.
+	 * @param corner2 Tile where to end the iterating.
+	 */
+	DiagonalTileIterator(TileIndex corner1, TileIndex corner2)
+	{
+		*this = DiagonalTileIterator(DiagonalTileArea(corner1, corner2));
+	}
 
 	TileIterator& operator ++();