4 files changed, 61 insertions, 26 deletions

diff --git a/engines/sci/gui/gui.cpp b/engines/sci/gui/gui.cpp
index 31ff341aa6..3ca7794b0c 100644
--- a/engines/sci/gui/gui.cpp
+++ b/engines/sci/gui/gui.cpp
@@ -335,7 +335,7 @@ void SciGui::graphFillBox(Common::Rect rect, uint16 colorMask, int16 color, int1
 }
 
 void SciGui::graphDrawLine(Common::Point startPoint, Common::Point endPoint, int16 color, int16 priority, int16 control) {
-	_gfx->Draw_Line(startPoint.x, startPoint.y, endPoint.x, endPoint.y, color, priority, control);
+	_gfx->drawLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y, color, priority, control);
 	_screen->copyToScreen();
 }
 
diff --git a/engines/sci/gui/gui_gfx.cpp b/engines/sci/gui/gui_gfx.cpp
index 4c173f4e93..f6c5f62104 100644
--- a/engines/sci/gui/gui_gfx.cpp
+++ b/engines/sci/gui/gui_gfx.cpp
@@ -616,20 +616,9 @@ void SciGuiGfx::RestoreBits(GuiMemoryHandle memoryHandle) {
 	}
 }
 
-// Data passed to drawProc()
-struct LineData {
-	byte drawMask;
-	byte prio;
-	byte control;
-	SciGuiScreen *screen;
-};
-
-static void drawProc(int x, int y, int c, void *data) {
-	LineData *lineData = (LineData *)data;
-	lineData->screen->putPixel(x, y, lineData->drawMask, (byte)c, lineData->prio, lineData->control);
-}
-
-void SciGuiGfx::Draw_Line(int16 left, int16 top, int16 right, int16 bottom, byte color, byte priority, byte control) {
+// 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 SciGuiGfx::drawLine(int16 left, int16 top, int16 right, int16 bottom, byte color, byte priority, byte control) {
 	//set_drawing_flag
 	byte drawMask = _screen->getDrawingMask(color, priority, control);
 
@@ -639,13 +628,59 @@ void SciGuiGfx::Draw_Line(int16 left, int16 top, int16 right, int16 bottom, byte
 	top += _curPort->top;
 	bottom += _curPort->top;
 
-	LineData lineData;
-	lineData.drawMask = drawMask;
-	lineData.prio = priority;
-	lineData.control = control;
-	lineData.screen = _screen;
-
-	Graphics::drawLine(left, top, right, bottom, color, drawProc, &lineData);
+	// horizontal line
+	if (top == bottom) {
+		if (right < left)
+			SWAP(right, left);
+		for (int i = left; i <= right; i++)
+			_screen->putPixel(i, top, drawMask, color, priority, control);
+		return;
+	}
+	// vertical line
+	if (left == right) {
+		if (top > bottom)
+			SWAP(top, bottom);
+		for (int i = top; i <= bottom; i++)
+			_screen->putPixel(left, i, drawMask, color, priority, control);
+		return;
+	}
+	// sloped line - draw with Bresenham algorithm
+	int dy = bottom - top;
+	int dx = right - left;
+	int stepy = dy < 0 ? -1 : 1;
+	int stepx = dx < 0 ? -1 : 1;
+	dy = ABS(dy) << 1;
+	dx = ABS(dx) << 1;
+
+	// setting the 1st and last pixel
+	_screen->putPixel(left, top, drawMask, color, priority, control);
+	_screen->putPixel(right, bottom, drawMask, color, priority, control);
+	// drawing the line
+	if (dx > dy) { // going horizontal
+		int fraction = dy - (dx >> 1);
+		while (left != right) {
+			if (fraction >= 0) {
+				top += stepy;
+				fraction -= dx;
+			}
+			left += stepx;
+			fraction += dy;
+			_screen->putPixel(left, top, drawMask, color, priority, control);
+		}
+	} else { // going vertical
+		int fraction = dx - (dy >> 1);
+		while (top != bottom) {
+			if (fraction >= 0) {
+				left += stepx;
+				fraction -= dy;
+			}
+			top += stepy;
+			fraction += dx;
+			_screen->putPixel(left, top, drawMask, color, priority, control);
+		}
+	}
+	//g_sci->eventMgr->waitUntil(5);
+	//ShowBits(&_rThePort->rect,6);
 }
 
 // Bitmap for drawing sierra circles
diff --git a/engines/sci/gui/gui_gfx.h b/engines/sci/gui/gui_gfx.h
index 0c84d017e2..15302bf9a8 100644
--- a/engines/sci/gui/gui_gfx.h
+++ b/engines/sci/gui/gui_gfx.h
@@ -92,7 +92,7 @@ public:
 	GuiMemoryHandle SaveBits(const Common::Rect &rect, byte screenFlags);
 	void RestoreBits(GuiMemoryHandle memoryHandle);
 
-	void Draw_Line(int16 left, int16 top, int16 right, int16 bottom, byte color, byte prio, byte control);
+	void drawLine(int16 left, int16 top, int16 right, int16 bottom, byte color, byte prio, byte control);
 	void Draw_Box(Common::Rect box, byte color, byte prio, byte control);
 	void Draw_TexturedBox(Common::Rect box, byte color, byte prio, byte control, byte texture);
 	void Draw_Circle(Common::Rect box, byte size, byte color, byte prio, byte control);
diff --git a/engines/sci/gui/gui_picture.cpp b/engines/sci/gui/gui_picture.cpp
index d7b48865d4..0678fdfb83 100644
--- a/engines/sci/gui/gui_picture.cpp
+++ b/engines/sci/gui/gui_picture.cpp
@@ -352,7 +352,7 @@ void SciGuiPicture::drawVectorData(byte *data, int dataSize) {
 			while (vectorIsNonOpcode(data[curPos])) {
 				oldx = x; oldy = y;
 				vectorGetRelCoords(data, curPos, x, y);
-				_gfx->Draw_Line(oldx, oldy, x, y, pic_color, pic_priority, pic_control);
+				_gfx->drawLine(oldx, oldy, x, y, pic_color, pic_priority, pic_control);
 			}
 			break;
 		case PIC_OP_MEDIUM_LINES: // medium line
@@ -360,7 +360,7 @@ void SciGuiPicture::drawVectorData(byte *data, int dataSize) {
 			while (vectorIsNonOpcode(data[curPos])) {
 				oldx = x; oldy = y;
 				vectorGetRelCoordsMed(data, curPos, x, y);
-				_gfx->Draw_Line(oldx, oldy, x, y, pic_color, pic_priority, pic_control);
+				_gfx->drawLine(oldx, oldy, x, y, pic_color, pic_priority, pic_control);
 			}
 			break;
 		case PIC_OP_LONG_LINES: // long line
@@ -368,7 +368,7 @@ void SciGuiPicture::drawVectorData(byte *data, int dataSize) {
 			while (vectorIsNonOpcode(data[curPos])) {
 				oldx = x; oldy = y;
 				vectorGetAbsCoords(data, curPos, x, y);
-				_gfx->Draw_Line(oldx, oldy, x, y, pic_color, pic_priority, pic_control);
+				_gfx->drawLine(oldx, oldy, x, y, pic_color, pic_priority, pic_control);
 			}
 			break;