From e9399b612136c5e9c4ce0d5c46b84c67ed3377e9 Mon Sep 17 00:00:00 2001
From: ysj1173886760 <1173886760@qq.com>
Date: Mon, 16 Aug 2021 16:34:31 +0800
Subject: [PATCH] DIRECTOR: add comment on invertChannel.

---
 engines/director/window.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/engines/director/window.cpp b/engines/director/window.cpp
index d2a2656e617..141855490ae 100644
--- a/engines/director/window.cpp
+++ b/engines/director/window.cpp
@@ -100,13 +100,14 @@ void Window::invertChannel(Channel *channel, const Common::Rect &destRect) {
 			byte *src = (byte *)_composeSurface->getBasePtr(srcRect.left, srcRect.top + i);
 			const byte *msk = mask ? (const byte *)mask->getBasePtr(xoff, yoff + i) : nullptr;
 
+			// if this will cause efficiency problem, then we shall cache the inverted color in wm
 			for (int j = 0; j < srcRect.width(); j++, src++)
 				if (!mask || (msk && !(*msk++))) {
 					byte r, g, b;
 					g_director->_wm->decomposeColor(*src, r, g, b);
-					r = 255 - r;
-					g = 255 - g;
-					b = 255 - b;
+					r = ~r;
+					g = ~g;
+					b = ~b;
 					*src = g_director->_wm->findBestColor(r, g, b);
 				}
 		}