1 files changed, 41 insertions, 7 deletions
diff --git a/engines/sci/gfx/gfx_support.cpp b/engines/sci/gfx/gfx_support.cpp
index 2529fde35b..22de7055c2 100644
--- a/engines/sci/gfx/gfx_support.cpp
+++ b/engines/sci/gfx/gfx_support.cpp
@@ -34,15 +34,49 @@
 
 namespace Sci {
 
-static void drawProc(int x, int y, int c, void *data) {
-	gfx_pixmap_t *pxm = (gfx_pixmap_t *)data;
-	byte *p = pxm->index_data;
-	uint8 col = c;
-	memcpy(p + (y * pxm->index_width + x), &col, 1);
-}
+#define LINEMACRO(startx, starty, deltalinear, deltanonlinear, linearvar, nonlinearvar, \
+                  linearend, nonlinearstart, linearmod, nonlinearmod) \
+	incrNE = ((deltalinear) > 0) ? (deltalinear) : -(deltalinear); \
+	incrNE <<= 1; \
+	deltanonlinear <<= 1; \
+	incrE = ((deltanonlinear) > 0) ? -(deltanonlinear) : (deltanonlinear);  \
+	d = nonlinearstart - 1;  \
+	while (linearvar != (linearend)) { \
+		memcpy(buffer + linewidth * (starty) + (startx), &color, pixelwidth); \
+		linearvar += linearmod; \
+		if ((d += incrE) < 0) { \
+			d += incrNE; \
+			nonlinearvar += nonlinearmod; \
+		}; \
+	}; \
+	memcpy(buffer + linewidth * (starty) + (startx), &color, pixelwidth);
+
+
+// Sierra's Bresenham line drawing
+// WARNING: Do not just blindly replace this with Graphics::drawLine(), as it seems to create issues with flood fill
+void gfx_draw_line_buffer(byte *buffer, int linewidth, int pixelwidth, Common::Point start, Common::Point end, unsigned int color) {
+	int incrE, incrNE, d;
+	int dx = ABS(end.x - start.x);
+	int dy = ABS(end.y - start.y);
+#ifdef SCUMM_BIG_ENDIAN
+	color = SWAP_BYTES_32(color);
+#endif
+
+	if (dx > dy) {
+		int sign1 = (end.x < start.x) ? -1 : 1;
+		int sign2 = (end.y < start.y) ? -1 : 1;
+		LINEMACRO(start.x, start.y, dx, dy, start.x, start.y, end.x, dx, sign1 * pixelwidth, sign2);
+	} else { // dx <= dy
+		int sign1 = (end.y < start.y) ? -1 : 1;
+		int sign2 = (end.x < start.x) ? -1 : 1;
+		LINEMACRO(start.x, start.y, dy, dx, start.y, start.x, end.y, dy, sign1, sign2 * pixelwidth);
+	}
+ }
+ 
+#undef LINEMACRO
 
 void gfx_draw_line_pixmap_i(gfx_pixmap_t *pxm, Common::Point start, Common::Point end, int color) {
-	Graphics::drawLine(start.x, start.y, end.x, end.y, color, drawProc, pxm);
+	gfx_draw_line_buffer(pxm->index_data, pxm->index_width, 1, start, end, color);
 }
 
 void gfx_draw_box_buffer(byte *buffer, int linewidth, rect_t zone, int color) {