test(render): force deterministic font rasterization

Force ANTIALIASED_QUALITY for render tests by setting
FW_FONT_QUALITY=4 in the render test assembly setup and
reading that override in the native LOGFONT creation
paths. This keeps local and CI rasterization aligned
without changing production rendering.

Also remove the RootSite per-channel pixel tolerance
now that tests render deterministically again, so
snapshot failures remain strict and actionable.

Author: johnml1135

Src/Common/Controls/DetailControls/DetailControlsTests/RenderTestAssemblySetup.cs

@@ -18,6 +18,11 @@ public sealed class RenderTestAssemblySetup
 		[OneTimeSetUp]
 		public void OneTimeSetup()
 		{
+			// Force grayscale antialiasing (ANTIALIASED_QUALITY=4) for deterministic
+			// rendering across dev machines and CI (Windows Server 2025).
+			// The native VwGraphics reads this env var when creating GDI fonts.
+			Environment.SetEnvironmentVariable("FW_FONT_QUALITY", "4");
+
 			try
 			{
 				SetProcessDpiAwarenessContext(DpiAwarenessContextUnaware);

Src/Common/RootSite/RootSiteTests/RenderBaselineVerifier.cs

@@ -10,8 +10,6 @@ internal static class RenderBaselineVerifier
 	{
 		private const string UpdateBaselinesEnvVar = "FW_UPDATE_RENDER_BASELINES";
 		private const int MaxAllowedPixelDifferences = 4;
-		private const int PerChannelTolerance = 8;
-		private const int AlphaTolerance = 8;
 
 		internal static string GetSourceFileDirectory([CallerFilePath] string sourceFile = "")
 		{
@@ -111,7 +109,7 @@ private static int CountDifferentPixels(Bitmap expectedBitmap, Bitmap actualBitm
 					var expected = expectedBitmap.GetPixel(x, y);
 					var actual = actualBitmap.GetPixel(x, y);
 
-					if (!PixelsAreEquivalent(expected, actual))
+					if (expected != actual)
 						differentPixelCount++;
 				}
 			}
@@ -156,14 +154,6 @@ private static int ScaleDiffChannel(int expected, int actual)
 		{
 			return Math.Min(255, Math.Abs(expected - actual) * 4);
 		}
-
-		private static bool PixelsAreEquivalent(Color expected, Color actual)
-		{
-			return Math.Abs(expected.A - actual.A) <= AlphaTolerance &&
-				Math.Abs(expected.R - actual.R) <= PerChannelTolerance &&
-				Math.Abs(expected.G - actual.G) <= PerChannelTolerance &&
-				Math.Abs(expected.B - actual.B) <= PerChannelTolerance;
-		}
 	}
 
 	internal sealed class RenderBaselineVerificationResult

Src/Common/RootSite/RootSiteTests/RenderTestAssemblySetup.cs

@@ -18,6 +18,11 @@ public sealed class RenderTestAssemblySetup
 		[OneTimeSetUp]
 		public void OneTimeSetup()
 		{
+			// Force grayscale antialiasing (ANTIALIASED_QUALITY=4) for deterministic
+			// rendering across dev machines and CI (Windows Server 2025).
+			// The native VwGraphics reads this env var when creating GDI fonts.
+			Environment.SetEnvironmentVariable("FW_FONT_QUALITY", "4");
+
 			try
 			{
 				SetProcessDpiAwarenessContext(DpiAwarenessContextUnaware);

Src/views/VwPropertyStore.cpp

@@ -43,6 +43,25 @@ static int g_rgnFontSizes[] = {
 	// kvfsSmaller and kvfsLarger don't have absolute values
 static int knDefaultFontSize = 10000;   // 10 point default
 
+// Returns the lfQuality value to use for LOGFONT creation.
+// If the FW_FONT_QUALITY env var is set to a valid value (0-6), that value is used.
+// This allows tests to force ANTIALIASED_QUALITY (4) for deterministic rendering.
+static BYTE GetFontQualityOverride()
+{
+	static BYTE s_quality = []() -> BYTE {
+		wchar_t buf[16] = {};
+		DWORD len = ::GetEnvironmentVariableW(L"FW_FONT_QUALITY", buf, _countof(buf));
+		if (len > 0 && len < _countof(buf))
+		{
+			int val = _wtoi(buf);
+			if (val >= 0 && val <= 6)
+				return static_cast<BYTE>(val);
+		}
+		return DRAFT_QUALITY;
+	}();
+	return s_quality;
+}
+
 // The order of these is signficant--it is the order the font properties are recorded in
 // for each writing system, in the wsStyle string.
 // A copy of this list is in VwPropertyStore.cpp -- the two lists must be kept in sync.
@@ -358,7 +377,7 @@ int VwPropertyStore::AdjustedLineHeight(VwPropertyStore * pzvpsLeaf, int * pdymp
 	lf.lfCharSet = DEFAULT_CHARSET;			// let name determine it; WS should specify valid
 	lf.lfOutPrecision = OUT_TT_ONLY_PRECIS;	// only work with TrueType fonts
 	lf.lfClipPrecision = CLIP_DEFAULT_PRECIS; // ??
-	lf.lfQuality = DRAFT_QUALITY; // I (JohnT) don't think this matters for TrueType fonts.
+	lf.lfQuality = GetFontQualityOverride();
 	lf.lfPitchAndFamily = 0; // must be zero for EnumFontFamiliesEx
 	wcscpy_s(lf.lfFaceName, LF_FACESIZE, pchrp->szFaceName);
 	qzvpsWithWsAndFont->Unlock();

Src/views/lib/VwGraphics.cpp

@@ -28,6 +28,25 @@ DEFINE_THIS_FILE
 	Local Constants and static variables
 ***********************************************************************************************/
 
+// Returns the lfQuality value to use for LOGFONT creation.
+// If the FW_FONT_QUALITY env var is set to a valid value (0-6), that value is used.
+// This allows tests to force ANTIALIASED_QUALITY (4) for deterministic rendering.
+static BYTE GetFontQualityOverride()
+{
+	static BYTE s_quality = []() -> BYTE {
+		wchar_t buf[16] = {};
+		DWORD len = ::GetEnvironmentVariableW(L"FW_FONT_QUALITY", buf, _countof(buf));
+		if (len > 0 && len < _countof(buf))
+		{
+			int val = _wtoi(buf);
+			if (val >= 0 && val <= 6)
+				return static_cast<BYTE>(val);
+		}
+		return DRAFT_QUALITY;
+	}();
+	return s_quality;
+}
+
 /***********************************************************************************************
 	Two local classes, copied from AfGfx.h. Maybe we should move them to somewhere they
 	can be shared more easily?
@@ -1247,7 +1266,7 @@ STDMETHODIMP VwGraphics::SetupGraphics(LgCharRenderProps * pchrp)
 			lf.lfCharSet = DEFAULT_CHARSET;			// let name determine it; WS should specify valid
 			lf.lfOutPrecision = OUT_TT_ONLY_PRECIS;	// only work with TrueType fonts
 			lf.lfClipPrecision = CLIP_DEFAULT_PRECIS; // ??
-			lf.lfQuality = DRAFT_QUALITY; // I (JohnT) don't think this matters for TrueType fonts.
+			lf.lfQuality = GetFontQualityOverride();
 			lf.lfPitchAndFamily = 0; // must be zero for EnumFontFamiliesEx
 			#ifdef UNICODE
 					// ENHANCE: test this path if ever needed.