From a8e8f6d409f2ae3d61541e8a64fba83e0adab327 Mon Sep 17 00:00:00 2001
From: Drake Arconis <drake@alchemyviewer.org>
Date: Mon, 1 Jan 2018 07:47:48 -0500
Subject: [PATCH] Fix gamma corruption

---
 indra/llwindow/llwindowwin32.cpp | 25 +++++++++++++++++++++----
 indra/llwindow/llwindowwin32.h   |  5 +++--
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/indra/llwindow/llwindowwin32.cpp b/indra/llwindow/llwindowwin32.cpp
index 346ebc0c9..97049b98a 100644
--- a/indra/llwindow/llwindowwin32.cpp
+++ b/indra/llwindow/llwindowwin32.cpp
@@ -422,6 +422,10 @@ LLWindowWin32::LLWindowWin32(LLWindowCallbacks* callbacks,
 
 	LL_INFOS() << "Desired FSAA Samples = " << mFSAASamples << LL_ENDL;
 
+	memset(mCurrentGammaRamp, 0, sizeof(mCurrentGammaRamp));
+	memset(mPrevGammaRamp, 0, sizeof(mPrevGammaRamp));
+	mCustomGammaSet = FALSE;
+
 	// Initialize the keyboard
 	gKeyboard = new LLKeyboardWin32();
 	gKeyboard->setCallbacks(callbacks);
@@ -3019,13 +3023,26 @@ F32 LLWindowWin32::getGamma()
 
 BOOL LLWindowWin32::restoreGamma()
 {
-	return SetDeviceGammaRamp(mhDC, mPrevGammaRamp);
+	if (mCustomGammaSet != FALSE)
+	{
+		mCustomGammaSet = FALSE;
+		return SetDeviceGammaRamp(mhDC, mPrevGammaRamp);
+	}
+	return TRUE;
 }
 
 BOOL LLWindowWin32::setGamma(const F32 gamma)
 {
 	mCurrentGamma = gamma;
 
+	//Get the previous gamma ramp to restore later.
+	if (mCustomGammaSet == FALSE)
+	{
+		if (GetDeviceGammaRamp(mhDC, mPrevGammaRamp) == FALSE)
+			return FALSE;
+		mCustomGammaSet = TRUE;
+	}
+
 	LL_DEBUGS("Window") << "Setting gamma to " << gamma << LL_ENDL;
 
 	for ( int i = 0; i < 256; ++i )
@@ -3037,9 +3054,9 @@ BOOL LLWindowWin32::setGamma(const F32 gamma)
 		if ( value > 0xffff )
 			value = 0xffff;
 
-		mCurrentGammaRamp [ 0 * 256 + i ] = 
-			mCurrentGammaRamp [ 1 * 256 + i ] = 
-				mCurrentGammaRamp [ 2 * 256 + i ] = ( WORD )value;
+		mCurrentGammaRamp[0][i] =
+			mCurrentGammaRamp[1][i] =
+			mCurrentGammaRamp[2][i] = (WORD) value;
 	};
 
 	return SetDeviceGammaRamp ( mhDC, mCurrentGammaRamp );
diff --git a/indra/llwindow/llwindowwin32.h b/indra/llwindow/llwindowwin32.h
index 46f2200f7..4f8693dbe 100644
--- a/indra/llwindow/llwindowwin32.h
+++ b/indra/llwindow/llwindowwin32.h
@@ -189,8 +189,9 @@ protected:
 	F32			mCurrentGamma;
 	U32			mFSAASamples;
 	S32			mVsyncMode;
-	WORD		mPrevGammaRamp[256*3];
-	WORD		mCurrentGammaRamp[256*3];
+	WORD		mPrevGammaRamp[3][256];
+	WORD		mCurrentGammaRamp[3][256];
+	BOOL		mCustomGammaSet;
 
 	LPWSTR		mIconResource;
 	BOOL		mMousePositionModified;