AtlasEngine: Implement remaining underlines and builtin glyphs for D2D (

#17278)

This implements builtin glyphs for our Direct2D renderer, as well as
dashed and curly underlines. With this in place the only two features
it doesn't support are inverted cursors and VT soft fonts.
This allows us to remove the `_hack*` members introduced in a6a0e44.

The implementation of dashed underlines is trivial, while curly
underlines use quadratic bezier curves. Caching the curve as a sprite
is possible, however I feel like that can be done in the future.

Builtin glyphs on the other hand require a cache, because otherwise
filling the entire viewport with shaded glyphs would result in poor
performance. This is why it's built on top of `ID2D1SpriteBatch`.
Unfortunately the API causes an eager flush of other pending graphics
instructions, which is why there's still a decent perf hit.

Finally, as a little extra, this fixes the rounded powerline glyph
shapes being slightly cut off. The fix is to simply don't round the
position and radius of the ellipsis/semi-circle.

Closes #17224

## Validation Steps Performed
* RenderingTests.exe updated ✅
* All supported builtin glyphs look sorta right at different sizes ✅

src/renderer/atlas/AtlasEngine.cpp

@@ -74,9 +74,8 @@ try
         _handleSettingsUpdate();
     }
 
-    if (ATLAS_DEBUG_DISABLE_PARTIAL_INVALIDATION || _hackTriggerRedrawAll)
+    if constexpr (ATLAS_DEBUG_DISABLE_PARTIAL_INVALIDATION)
     {
-        _hackTriggerRedrawAll = false;
         _api.invalidatedRows = invalidatedRowsAll;
         _api.scrollOffset = 0;
     }
@@ -703,8 +702,6 @@ void AtlasEngine::_recreateFontDependentResources()
             _api.textFormatAxes[i] = { fontAxisValues.data(), fontAxisValues.size() };
         }
     }
-
-    _hackWantsBuiltinGlyphs = _p.s->font->builtinGlyphs && !_hackIsBackendD2D;
 }
 
 void AtlasEngine::_recreateCellCountDependentResources()
@@ -765,18 +762,13 @@ void AtlasEngine::_flushBufferLine()
     // This would seriously blow us up otherwise.
     Expects(_api.bufferLineColumn.size() == _api.bufferLine.size() + 1);
 
+    const auto builtinGlyphs = _p.s->font->builtinGlyphs;
     const auto beg = _api.bufferLine.data();
     const auto len = _api.bufferLine.size();
     size_t segmentBeg = 0;
     size_t segmentEnd = 0;
     bool custom = false;
 
-    if (!_hackWantsBuiltinGlyphs)
-    {
-        _mapRegularText(0, len);
-        return;
-    }
-
     while (segmentBeg < len)
     {
         segmentEnd = segmentBeg;
@@ -789,7 +781,7 @@ void AtlasEngine::_flushBufferLine()
                 codepoint = til::combine_surrogates(codepoint, beg[i++]);
             }
 
-            const auto c = BuiltinGlyphs::IsBuiltinGlyph(codepoint) || BuiltinGlyphs::IsSoftFontChar(codepoint);
+            const auto c = (builtinGlyphs && BuiltinGlyphs::IsBuiltinGlyph(codepoint)) || BuiltinGlyphs::IsSoftFontChar(codepoint);
             if (custom != c)
             {
                 break;

src/renderer/atlas/AtlasEngine.h

@@ -127,18 +127,6 @@ namespace Microsoft::Console::Render::Atlas
         std::unique_ptr<IBackend> _b;
         RenderingPayload _p;
 
-        // _p.s->font->builtinGlyphs is the setting which decides whether we should map box drawing glyphs to
-        // our own builtin versions. There's just one problem: BackendD2D doesn't have this functionality.
-        // But since AtlasEngine shapes the text before it's handed to the backends, it would need to know
-        // whether BackendD2D is in use, before BackendD2D even exists. These two flags solve the issue
-        // by triggering a complete, immediate redraw whenever the backend type changes.
-        //
-        // The proper solution is to move text shaping into the backends.
-        // Someone just needs to write a generic "TextBuffer to DWRITE_GLYPH_RUN" function.
-        bool _hackIsBackendD2D = false;
-        bool _hackWantsBuiltinGlyphs = true;
-        bool _hackTriggerRedrawAll = false;
-
         struct ApiState
         {
             GenerationalSettings s = DirtyGenerationalSettings();

src/renderer/atlas/AtlasEngine.r.cpp

@@ -77,7 +77,7 @@ CATCH_RETURN()
 
 [[nodiscard]] bool AtlasEngine::RequiresContinuousRedraw() noexcept
 {
-    return ATLAS_DEBUG_CONTINUOUS_REDRAW || (_b && _b->RequiresContinuousRedraw()) || _hackTriggerRedrawAll;
+    return ATLAS_DEBUG_CONTINUOUS_REDRAW || (_b && _b->RequiresContinuousRedraw());
 }
 
 void AtlasEngine::WaitUntilCanRender() noexcept
@@ -282,21 +282,15 @@ void AtlasEngine::_recreateBackend()
     {
     case GraphicsAPI::Direct2D:
         _b = std::make_unique<BackendD2D>();
-        _hackIsBackendD2D = true;
         break;
     default:
         _b = std::make_unique<BackendD3D>(_p);
-        _hackIsBackendD2D = false;
         break;
     }
 
     // This ensures that the backends redraw their entire viewports whenever a new swap chain is created,
     // EVEN IF we got called when no actual settings changed (i.e. rendering failure, etc.).
     _p.MarkAllAsDirty();
-
-    const auto hackWantsBuiltinGlyphs = _p.s->font->builtinGlyphs && !_hackIsBackendD2D;
-    _hackTriggerRedrawAll = _hackWantsBuiltinGlyphs != hackWantsBuiltinGlyphs;
-    _hackWantsBuiltinGlyphs = hackWantsBuiltinGlyphs;
 }
 
 void AtlasEngine::_handleSwapChainUpdate()