MADS: Implemented MSurface::mergeFrom method

3 files changed, 53 insertions, 2 deletions

diff --git a/engines/mads/msurface.cpp b/engines/mads/msurface.cpp
index 2c9d093877..75aad01ee1 100644
--- a/engines/mads/msurface.cpp
+++ b/engines/mads/msurface.cpp
@@ -418,6 +418,50 @@ void MSurface::copyFrom(MSurface *src, const Common::Point &destPos, int depth,
 	}
 }
 
+void MSurface::mergeFrom(MSurface *src, const Common::Rect &srcBounds, const Common::Point &destPos) {
+	// Validation of the rectangle and position	
+	int destX = destPos.x, destY = destPos.y;
+	if ((destX >= w) || (destY >= h))
+		return;
+
+	Common::Rect copyRect = srcBounds;
+	if (destX < 0) {
+		copyRect.left += -destX;
+		destX = 0;
+	}
+	else if (destX + copyRect.width() > w) {
+		copyRect.right -= destX + copyRect.width() - w;
+	}
+	if (destY < 0) {
+		copyRect.top += -destY;
+		destY = 0;
+	}
+	else if (destY + copyRect.height() > h) {
+		copyRect.bottom -= destY + copyRect.height() - h;
+	}
+
+	if (!copyRect.isValidRect())
+		return;
+
+	// Copy the specified area
+
+	byte *data = src->getData();
+	byte *srcPtr = data + (src->getWidth() * copyRect.top + copyRect.left);
+	byte *destPtr = (byte *)pixels + (destY * getWidth()) + destX;
+
+	for (int rowCtr = 0; rowCtr < copyRect.height(); ++rowCtr) {
+		// Process each line of the area
+		for (int xCtr = 0; xCtr < copyRect.width(); ++xCtr) {
+			// Check for the range used for on-screen text, which should be kept intact
+			if (srcPtr[xCtr] < 8 || srcPtr[xCtr] > 15)
+				destPtr[xCtr] = srcPtr[xCtr];
+		}
+
+		srcPtr += src->getWidth();
+		destPtr += getWidth();
+	}
+}
+
 void MSurface::scrollX(int xAmount) {
 	if (xAmount == 0)
 		return;
diff --git a/engines/mads/msurface.h b/engines/mads/msurface.h
index 7cf2bbe15b..f590bac2e5 100644
--- a/engines/mads/msurface.h
+++ b/engines/mads/msurface.h
@@ -188,6 +188,14 @@ public:
 	}
 
 	/**
+	* Merges a sub-section of another surface into the current one.
+	* @param src			Source surface
+	* @param srcBounds		Area to copy/merge from
+	* @param destPos		Destination position to draw in current surface
+	*/
+	void mergeFrom(MSurface *src, const Common::Rect &srcBounds, const Common::Point &destPos);
+
+	/**
 	 * Scroll the screen horizontally by a given amount
 	 * @param xAmount	Horizontal amount
 	 */
diff --git a/engines/mads/user_interface.cpp b/engines/mads/user_interface.cpp
index 7b12ef4941..52b466a0aa 100644
--- a/engines/mads/user_interface.cpp
+++ b/engines/mads/user_interface.cpp
@@ -108,8 +108,7 @@ void UISlots::draw(bool updateFlag, bool delFlag) {
 
 			if (slot._flags >= IMG_ERASE) {
 				// Merge area
-				error("TODO: Create a sprite merge method");
-				userInterface._surface.copyTo(&userInterface, dirtyArea._bounds,
+				userInterface.mergeFrom(&userInterface._surface, dirtyArea._bounds,
 					Common::Point(dirtyArea._bounds.left, dirtyArea._bounds.top));
 			} else {
 				// Copy area