Fixes for the backupBackground method when X < 0

svn-id: r40590

2 files changed, 7 insertions, 3 deletions

diff --git a/engines/cruise/backgroundIncrust.cpp b/engines/cruise/backgroundIncrust.cpp
index 8d4bb70128..776aa6305d 100644
--- a/engines/cruise/backgroundIncrust.cpp
+++ b/engines/cruise/backgroundIncrust.cpp
@@ -52,7 +52,11 @@ void backupBackground(backgroundIncrustStruct *pIncrust, int X, int Y, int width
 	pIncrust->ptr = (uint8*)malloc(width * height);
 	for (int i = 0; i < height; i++) {
 		for (int j = 0; j < width; j++) {
-			pIncrust->ptr[i * width + j] = pBackground[(i+Y) * 320 + j + X];
+			int xp = j + X;
+			int yp = i + Y;
+
+			pIncrust->ptr[i * width + j] = ((xp < 0) || (yp < 0) || (xp >= 320) || (yp >= 200)) ?
+				0 : pBackground[yp * 320 + xp];
 		}
 	}
 }
diff --git a/engines/cruise/backgroundIncrust.h b/engines/cruise/backgroundIncrust.h
index 81b53815d9..92db79cf13 100644
--- a/engines/cruise/backgroundIncrust.h
+++ b/engines/cruise/backgroundIncrust.h
@@ -35,8 +35,8 @@ struct backgroundIncrustStruct {
 	uint16 objectIdx;
 	int16 type;
 	uint16 overlayIdx;
-	uint16 X;
-	uint16 Y;
+	int16 X;
+	int16 Y;
 	uint16 field_E;
 	uint16 scale;
 	uint16 backgroundIdx;