Use an enum for efb scale values.

Source/Core/VideoCommon/Src/EmuWindow.cpp

@@ -247,7 +247,7 @@ void OSDMenu(WPARAM wParam)
 		OSDChoice = 1;
 		// Toggle native resolution
 		g_Config.iEFBScale = g_Config.iEFBScale + 1;
-		if (g_Config.iEFBScale > 7) g_Config.iEFBScale = 0;
+		if (g_Config.iEFBScale > SCALE_4X) g_Config.iEFBScale = SCALE_AUTO;
 		break;
 	case '4':
 		OSDChoice = 2;

Source/Core/VideoCommon/Src/RenderBase.cpp

@@ -144,7 +144,7 @@ int Renderer::EFBToScaledX(int x)
 {
 	switch (g_ActiveConfig.iEFBScale)
 	{
-		case 0: // fractional
+	case SCALE_AUTO: // fractional
 			return (int)ssaa_multiplier * FramebufferManagerBase::ScaleToVirtualXfbWidth(x, s_backbuffer_width);
 
 		default:
@@ -156,7 +156,7 @@ int Renderer::EFBToScaledY(int y)
 {
 	switch (g_ActiveConfig.iEFBScale)
 	{
-		case 0: // fractional
+		case SCALE_AUTO: // fractional
 			return (int)ssaa_multiplier * FramebufferManagerBase::ScaleToVirtualXfbHeight(y, s_backbuffer_height);
 
 		default:
@@ -166,7 +166,7 @@ int Renderer::EFBToScaledY(int y)
 
 void Renderer::CalculateTargetScale(int x, int y, int &scaledX, int &scaledY)
 {
-	if (g_ActiveConfig.iEFBScale == 0 || g_ActiveConfig.iEFBScale == 1)
+	if (g_ActiveConfig.iEFBScale == SCALE_AUTO || g_ActiveConfig.iEFBScale == SCALE_AUTO_INTEGRAL)
 	{
 		scaledX = x;
 		scaledY = y;
@@ -283,28 +283,28 @@ void Renderer::DrawDebugText()
 	const char* res_text = "";
 	switch (g_ActiveConfig.iEFBScale)
 	{
-	case 0:
+	case SCALE_AUTO:
 		res_text = "Auto (fractional)";
 		break;
-	case 1:
+	case SCALE_AUTO_INTEGRAL:
 		res_text = "Auto (integral)";
 		break;
-	case 2:
+	case SCALE_1X:
 		res_text = "Native";
 		break;
-	case 3:
+	case SCALE_1_5X:
 		res_text = "1.5x";
 		break;
-	case 4:
+	case SCALE_2X:
 		res_text = "2x";
 		break;
-	case 5:
+	case SCALE_2_5X:
 		res_text = "2.5x";
 		break;
-	case 6:
+	case SCALE_3X:
 		res_text = "3x";
 		break;
-	case 7:
+	case SCALE_4X:
 		res_text = "4x";
 		break;
 	}

Source/Core/VideoCommon/Src/VideoConfig.cpp

@@ -79,7 +79,7 @@ void VideoConfig::Load(const char *ini_file)
 	iniFile.Get("Settings", "HackedBufferUpload", &bHackedBufferUpload, 0);
 
 	iniFile.Get("Settings", "MSAA", &iMultisampleMode, 0);
-	iniFile.Get("Settings", "EFBScale", &iEFBScale, 2); // native
+	iniFile.Get("Settings", "EFBScale", &iEFBScale, (int) SCALE_1X); // native
 
 	iniFile.Get("Settings", "DstAlphaPass", &bDstAlphaPass, false);
 
@@ -139,21 +139,21 @@ void VideoConfig::GameIniLoad(const char *ini_file)
 	iniFile.GetIfExists("Video_Settings", "MSAA", &iMultisampleMode);
 	int tmp = 0;
 	iniFile.GetIfExists("Video_Settings", "EFBScale", &tmp); // integral
-	if (tmp != -1)
+	if (tmp != SCALE_FORCE_INTEGRAL)
 		iEFBScale = tmp;
 	// Round down to multiple of native IR
 	else
 	{
 		switch (iEFBScale)
 		{
-		case 0:
+		case SCALE_AUTO:
-			iEFBScale = 1;
+			iEFBScale = SCALE_AUTO_INTEGRAL;
 			break;
-		case 3: // 1.5x
+		case SCALE_1_5X:
-			iEFBScale = 2;
+			iEFBScale = SCALE_1X;
 			break;
-		case 5: // 2.5x
+		case SCALE_2_5X:
-			iEFBScale = 4;
+			iEFBScale = SCALE_2X;
 			break;
 		default:
 			break;

Source/Core/VideoCommon/Src/VideoConfig.h

@@ -44,6 +44,18 @@ enum AspectMode {
 	ASPECT_STRETCH = 3,
 };
 
+enum EFBScale {
+	SCALE_FORCE_INTEGRAL = -1,
+	SCALE_AUTO,
+	SCALE_AUTO_INTEGRAL,
+	SCALE_1X,
+	SCALE_1_5X,
+	SCALE_2X,
+	SCALE_2_5X,
+	SCALE_3X,
+	SCALE_4X,
+};
+
 class IniFile;
 
 // NEVER inherit from this class.