Stop mapping all Unicode through CJK fonts and cut D2D working-set growth

Custom font fallback no longer covers the whole BMP/SIP, so Segoe UI Emoji
can paint color glyphs again; CJK still prefers Noto Sans SC then YaHei.
Drop GaussianBlur compatible targets during BeginDraw (they retained GPU
memory as the candidate window grew), grow the composition swapchain in
64px steps without shrinking, and reuse Card chrome plus cached text
formats instead of reallocating them every layout.

ui/src/Fonts.cpp

@@ -61,26 +61,57 @@ void ApplyUiFontFallback(IDWriteFactory *factory, IDWriteTextFormat *format)
     {
         return;
     }
-    ComPtr<IDWriteFontFallbackBuilder> builder;
-    if (FAILED(factory2->CreateFontFallbackBuilder(builder.GetAddressOf())))
+
+    static ComPtr<IDWriteFontFallback> cachedFallback;
+    static IDWriteFactory *cachedFactory = nullptr;
+    if (!cachedFallback || cachedFactory != factory)
     {
-        return;
-    }
-    WCHAR const *families[] = {L"Noto Sans SC", UiFontFallbackFamily()};
-    DWRITE_UNICODE_RANGE allText{0, 0x10FFFF};
-    if (FAILED(builder->AddMapping(&allText, 1, families, 2, nullptr, nullptr, nullptr, 1.0f)))
-    {
-        return;
-    }
-    ComPtr<IDWriteFontFallback> customFallback;
-    if (FAILED(builder->CreateFontFallback(customFallback.GetAddressOf())))
-    {
-        return;
+        ComPtr<IDWriteFontFallbackBuilder> builder;
+        if (FAILED(factory2->CreateFontFallbackBuilder(builder.GetAddressOf())))
+        {
+            return;
+        }
+
+        // Only CJK: mapping all of Unicode to Noto/YaHei replaces system fallback
+        // and makes Segoe UI Emoji (COLR) tofu.
+        static const DWRITE_UNICODE_RANGE kCjk[] = {
+            {0x2E80, 0x2EFF}, {0x2F00, 0x2FDF}, {0x3000, 0x303F}, {0x3040, 0x30FF},
+            {0x3100, 0x312F}, {0x31A0, 0x31BF}, {0x31C0, 0x31EF}, {0x3200, 0x32FF},
+            {0x3300, 0x33FF}, {0x3400, 0x4DBF}, {0x4E00, 0x9FFF}, {0xF900, 0xFAFF},
+            {0xFF00, 0xFFEF}, {0x20000, 0x2A6DF}, {0x2A700, 0x2B73F}, {0x2B740, 0x2B81F},
+            {0x2B820, 0x2CEAF}, {0x2CEB0, 0x2EBEF}, {0x30000, 0x3134F},
+        };
+        WCHAR const *cjkFamilies[] = {L"Noto Sans SC", UiFontFallbackFamily()};
+        if (FAILED(builder->AddMapping(kCjk, static_cast<UINT32>(sizeof(kCjk) / sizeof(kCjk[0])), cjkFamilies, 2,
+                                       nullptr, nullptr, nullptr, 1.0f)))
+        {
+            return;
+        }
+
+        if (FontFamilyExists(factory, L"Segoe UI Emoji"))
+        {
+            static const DWRITE_UNICODE_RANGE kEmoji[] = {
+                {0x200D, 0x200D}, {0x2600, 0x27BF}, {0xFE00, 0xFE0F}, {0x1F000, 0x1F02F},
+                {0x1F0A0, 0x1F0FF}, {0x1F300, 0x1FAFF}, {0x1F1E6, 0x1F1FF},
+            };
+            WCHAR const *emojiFamilies[] = {L"Segoe UI Emoji"};
+            builder->AddMapping(kEmoji, static_cast<UINT32>(sizeof(kEmoji) / sizeof(kEmoji[0])), emojiFamilies, 1,
+                                nullptr, nullptr, nullptr, 1.0f);
+        }
+
+        ComPtr<IDWriteFontFallback> customFallback;
+        if (FAILED(builder->CreateFontFallback(customFallback.GetAddressOf())))
+        {
+            return;
+        }
+        cachedFallback = customFallback;
+        cachedFactory = factory;
     }
+
     ComPtr<IDWriteTextFormat1> format1;
     if (SUCCEEDED(format->QueryInterface(IID_PPV_ARGS(&format1))))
     {
-        format1->SetFontFallback(customFallback.Get());
+        format1->SetFontFallback(cachedFallback.Get());
     }
 }
 } // namespace msimeui