From a9da116ceb318d3223bb515cad46f613dfdc0d36 Mon Sep 17 00:00:00 2001
From: Fabio Battaglia
Date: Tue, 17 Mar 2009 08:03:29 +0000
Subject: sword1: optimize drawing routine for screen 54

svn-id: r39477
---
 engines/sword1/screen.cpp | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/engines/sword1/screen.cpp b/engines/sword1/screen.cpp
index 15df92b021..72ce14b427 100644
--- a/engines/sword1/screen.cpp
+++ b/engines/sword1/screen.cpp
@@ -376,17 +376,28 @@ void Screen::draw(void) {
 		if(SwordEngine::isPsx()) {
 			if (!_psxCache.decodedBackground)
 				_psxCache.decodedBackground = psxShrinkedBackgroundToIndexed(_layerBlocks[0], _scrnSizeX, _scrnSizeY);
-			src = _psxCache.decodedBackground;
-		}
-
+			memcpy(_screenBuf, _psxCache.decodedBackground, _scrnSizeX * _scrnSizeY);
+		} else {
+#if 0
 		for (uint16 cnty = 0; cnty < _scrnSizeY; cnty++)
 			for (uint16 cntx = 0; cntx < _scrnSizeX; cntx++) {
-				if (*src)
+				if (*(src + cnty * _scrnSizeX + cntx))
 					if (!(SwordEngine::isMac()) || *src != 255) // see bug #1701058
-						*dest = *src;
-				dest++;
-				src++;
+						*(dest + cnty * _scrnSizeX + cntx) = *(src + cnty * _scrnSizeX + cntx);
 			}
+#endif
+
+			uint16 scrnScrlY = MIN((uint32)_oldScrollY, Logic::_scriptVars[SCROLL_OFFSET_Y]);
+			uint16 scrnHeight = SCREEN_DEPTH + ABS((int32)_oldScrollY - (int32)Logic::_scriptVars[SCROLL_OFFSET_Y]);
+
+			// In this background to create transparency we have to iterate through all pixels, avoid checking those out of screen
+			for (uint16 cnty = scrnScrlY; (cnty < _scrnSizeY) && (cnty < scrnHeight + scrnScrlY); cnty++)
+				for (uint16 cntx = 0; cntx < _scrnSizeX; cntx++) {
+					if (*(src + cnty * _scrnSizeX + cntx))
+						if (!(SwordEngine::isMac()) || *src != 255) // see bug #1701058
+							*(dest + cnty * _scrnSizeX + cntx) = *(src + cnty * _scrnSizeX + cntx);
+				}
+	}
 
 	} else if (!(SwordEngine::isPsx())) {
 		memcpy(_screenBuf, _layerBlocks[0], _scrnSizeX * _scrnSizeY);
-- 
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