GRAPHICS: Add mask mode to FloodFill class and document the class.

2 files changed, 87 insertions, 7 deletions

diff --git a/graphics/surface.cpp b/graphics/surface.cpp
index 2fe6a73010..c5d4cf0cbd 100644
--- a/graphics/surface.cpp
+++ b/graphics/surface.cpp
@@ -505,6 +505,9 @@ FloodFill::FloodFill(Graphics::Surface *surface, uint32 oldColor, uint32 fillCol
 	_w = surface->w;
 	_h = surface->h;
 
+	_mask = nullptr;
+	_maskMode = false;
+
 	_visited = (byte *)calloc(_w * _h, 1);
 }
 
@@ -517,28 +520,45 @@ FloodFill::~FloodFill() {
 	}
 
 	free(_visited);
+
+	if (_mask)
+		delete _mask;
 }
 
 void FloodFill::addSeed(int x, int y) {
 	if (x >= 0 && x < _w && y >= 0 && y < _h) {
 		if (!_visited[y * _w + x]) {
 			_visited[y * _w + x] = 1;
-			void *p = _surface->getBasePtr(x, y);
+			void *src = _surface->getBasePtr(x, y);
+			void *dst;
 			bool changed = false;
 
+			if (_maskMode)
+				dst = _mask->getBasePtr(x, y);
+			else
+				dst = src;
+
 			if (_surface->format.bytesPerPixel == 1) {
-				if (*((byte *)p) == _oldColor) {
-					*((byte *)p) = _fillColor;
+				if (*((byte *)src) == _oldColor) {
+					*((byte *)dst) = _maskMode ? 255 : _fillColor;
 					changed = true;
 				}
 			} else if (_surface->format.bytesPerPixel == 2) {
-				if (READ_UINT16(p) == _oldColor) {
-					WRITE_UINT16(p, _fillColor);
+				if (READ_UINT16(src) == _oldColor) {
+					if (!_maskMode)
+						WRITE_UINT16(src, _fillColor);
+					else
+						*((byte *)dst) = 255;
+
 					changed = true;
 				}
 			} else if (_surface->format.bytesPerPixel == 4) {
-				if (READ_UINT32(p) == _oldColor) {
-					WRITE_UINT32(p, _fillColor);
+				if (READ_UINT32(src) == _oldColor) {
+					if (!_maskMode)
+						WRITE_UINT32(src, _fillColor);
+					else
+						*((byte *)dst) = 255;
+
 					changed = true;
 				}
 			} else {
@@ -567,4 +587,12 @@ void FloodFill::fill() {
 	}
 }
 
+void FloodFill::fillMask() {
+	_mask = new Graphics::Surface();
+	_mask->create(_w, _h, Graphics::PixelFormat::createFormatCLUT8()); // Uses calloc()
+	_maskMode = true;
+
+	fill();
+}
+
 } // End of namespace Graphics
diff --git a/graphics/surface.h b/graphics/surface.h
index e5685bf997..414a734683 100644
--- a/graphics/surface.h
+++ b/graphics/surface.h
@@ -343,19 +343,71 @@ struct SharedPtrSurfaceDeleter {
 	}
 };
 
+/**
+ * Stack-based flood fill algorithm for arbitrary Surfaces.
+ *
+ * It could be used in 2 ways. One is to fill the pixels of oldColor
+ * with fillColor. Second is when the surface stays intact but another
+ * surface with mask is created, where filled colors are marked with 255.
+ *
+ * Before running fill() or fillMask(), the initial pixels must be addSeed
+ * with addSeed() method.
+ */
 class FloodFill {
 public:
+	/**
+	 * Construct a simple Surface object.
+	 *
+	 * @param surface Input surface
+	 * @param oldColor Color on the surface to change
+	 * @param fillColor Color to fill with
+	 */
 	FloodFill(Surface *surface, uint32 oldColor, uint32 fillColor);
 	~FloodFill();
+
+	/**
+	 * Add pixels to the fill queue.
+	 *
+	 * @param x The x coordinate of the pixel.
+	 * @param y The x coordinate of the pixel.
+	 */
 	void addSeed(int x, int y);
+
+	/**
+	 * Fill the surface as requested.
+	 *
+	 * It uses pixels which were added with addSeed() method.
+	 *
+	 * @see addSeed
+	 */
 	void fill();
 
+	/**
+	 * Fill the mask. The mask is a CLUT8 Surface with pixels 0 and 255.
+	 * 255 means that the pixel has been filled.
+	 *
+	 * It uses pixels which were added with addSeed() method.
+	 *
+	 * @see addSeed
+	 */
+	void fillMask();
+
+	/**
+	 * Get the resulting mask.
+	 *
+	 * @see fillMask
+	 */
+	Surface *getMask() { return _mask; }
+
 private:
 	Common::List<Common::Point *> _queue;
 	Surface *_surface;
+	Surface *_mask;
 	uint32 _oldColor, _fillColor;
 	byte *_visited;
 	int _w, _h;
+
+	bool _maskMode;
 };
 
 } // End of namespace Graphics