native_render: HiDPI glyph pages, sharp UI upscaling, 4x MSAA

- CGraphicFontTexture rasterises glyph pages at the swapchain density
  (UISetFontOversample, MT_FONT_OVERSAMPLE) with anti-aliased coverage;
  metrics, packing and UVs stay the 40250 1x values. Default 1 keeps the
  verbatim bilevel path (Godot unchanged).
- native.frag: sharp-bilinear sampling for magnified UI textures.
- Multisampled colour/depth with a resolve into the swapchain (MT_MSAA,
  default 4); stats line reports msaa=N.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

extension/src/platform/EterLib/GrpFontTexture.cpp

@@ -5,6 +5,38 @@
 #include "EterBase/Stl.h"
 
 #include "EterLib/Util.h"
+#include "UIRenderCommands.h"
+
+#include <unordered_map>
+
+// PORT: HiDPI glyph pages (UISetFontOversample). With a scale s > 1 the page DIB and texture are
+// s times larger and each glyph is drawn with an s-times font into the s-scaled cell, while the
+// 40250 metrics (width, height, advance), the packing and therefore the page UVs stay the logical
+// 1x values: text layout is unchanged, only the texels get finer.
+namespace {
+int g_font_oversample = 1;
+bool g_font_oversample_latched = false;
+// The 1x HFONT a CGraphicFontTexture measures with -> its s-times twin that draws.
+std::unordered_map<HFONT, HFONT> g_oversampled_fonts;
+
+int FontOversample()
+{
+	g_font_oversample_latched = true;
+	return g_font_oversample;
+}
+}  // namespace
+
+void UISetFontOversample(int scale)
+{
+	if (g_font_oversample_latched)
+		return;
+	g_font_oversample = scale < 1 ? 1 : (scale > 4 ? 4 : scale);
+}
+
+int UIFontOversample()
+{
+	return g_font_oversample;
+}
 
 CGraphicFontTexture::CGraphicFontTexture()
 {
@@ -49,6 +81,13 @@ void CGraphicFontTexture::Destroy()
 
 		while(i != m_fontMap.end())
 		{
+			TFontMap::mapped_type hFont = i->second;
+			auto hi = g_oversampled_fonts.find(hFont);
+			if (hi != g_oversampled_fonts.end())
+			{
+				DeleteObject((HGDIOBJ)hi->second);
+				g_oversampled_fonts.erase(hi);
+			}
 			DeleteObject((HGDIOBJ)i->second);
 			++i;
 		}
@@ -86,7 +125,8 @@ bool CGraphicFontTexture::Create(const char* c_szFontName, int fontSize, bool bI
 	if (GetMaxTextureHeight() > 512)
 		height = 512;
 	
-	if (!m_dib.Create(ms_hDC, width, height))
+	const int s = FontOversample();
+	if (!m_dib.Create(ms_hDC, width * s, height * s))
 		return false;
 
 	HDC hDC = m_dib.GetDCHandle();
@@ -139,6 +179,13 @@ HFONT CGraphicFontTexture::GetFont(WORD codePage)
 		hFont = CreateFontIndirect(&logFont);
 
 		m_fontMap.insert(TFontMap::value_type(codePage, hFont));
+
+		if (const int s = FontOversample(); s > 1 && hFont)
+		{
+			logFont.lfHeight = m_fontSize * s;
+			if (HFONT hHiFont = CreateFontIndirect(&logFont))
+				g_oversampled_fonts[hFont] = hHiFont;
+		}
 	}
 
 	return hFont;
@@ -210,7 +257,8 @@ CGraphicFontTexture::TCharacterInfomation* CGraphicFontTexture::GetCharacterInfo
 CGraphicFontTexture::TCharacterInfomation* CGraphicFontTexture::UpdateCharacterInfomation(TCharacterKey code)
 {
 	HDC hDC = m_dib.GetDCHandle();
-	SelectObject(hDC, GetFont(code.first));
+	HFONT hFont = GetFont(code.first);
+	SelectObject(hDC, hFont);
 
 	wchar_t keyValue = code.second;
 
@@ -232,8 +280,9 @@ CGraphicFontTexture::TCharacterInfomation* CGraphicFontTexture::UpdateCharacterI
 
 	LONG lAdvance = ceilf( stABC.abcfA + stABC.abcfB + stABC.abcfC );
 
-	int width = m_dib.GetWidth();
-	int height = m_dib.GetHeight();
+	const int s = FontOversample();
+	int width = m_dib.GetWidth() / s;
+	int height = m_dib.GetHeight() / s;
 
 	if (m_x + size.cx >= (width - 1))
 	{
@@ -255,6 +304,26 @@ CGraphicFontTexture::TCharacterInfomation* CGraphicFontTexture::UpdateCharacterI
 		}
 	}
 
+	auto hi = s > 1 ? g_oversampled_fonts.find(hFont) : g_oversampled_fonts.end();
+	if (hi != g_oversampled_fonts.end())
+	{
+		// Draw with the s-times font into the s-scaled cell and keep its anti-aliasing as
+		// A4R4G4B4 white with coverage alpha (1x keeps 40250's bilevel threshold below).
+		SelectObject(hDC, hi->second);
+		TextOutW(hDC, m_x * s, m_y * s, &keyValue, 1);
+		SelectObject(hDC, hFont);
+
+		const int nDIBWidth = m_dib.GetWidth();
+		DWORD* pdwRow = (DWORD*)m_dib.GetPointer() + nDIBWidth * (m_y * s) + m_x * s;
+		for (int y = 0; y < size.cy * s; ++y, pdwRow += nDIBWidth)
+			for (int x = 0; x < size.cx * s; ++x)
+			{
+				const DWORD alpha = ((pdwRow[x] & 0xff) * 15 + 127) / 255;
+				pdwRow[x] = alpha ? ((alpha << 12) | 0x0fff) : 0;
+			}
+	}
+	else
+	{
 	TextOutW(hDC, m_x, m_y, &keyValue, 1);
 		
 	int nChrX;
@@ -276,6 +345,7 @@ CGraphicFontTexture::TCharacterInfomation* CGraphicFontTexture::UpdateCharacterI
 			pdwDIBRow[nChrX]=(pdwDIBRow[nChrX]&0xff) ? 0xffff : 0;
 		}
 	}
+	}
 
 	float rhwidth = 1.0f / float(width);
 	float rhheight = 1.0f / float(height);

extension/src/platform/EterLib/UIRenderCommands.h

@@ -72,3 +72,10 @@ void UIRenderAdd(UIRenderCommand command);
 const std::vector<UIRenderCommand>& UIRenderCommands();
 void UIRenderSetClip(float x, float y, float width, float height);
 void UIRenderRestoreClip();
+
+// HiDPI text: CGraphicFontTexture rasterises its glyph pages at this multiple of the logical font
+// size (the swapchain's pixels per UI pixel) while keeping the 40250 glyph metrics and page UVs in
+// logical pixels. 1 (the default) is the verbatim 40250 path. Latched when the first font page is
+// created, so set it before the game creates fonts.
+void UISetFontOversample(int scale);
+int UIFontOversample();