AtlasEngine: Fix bugs around bitmap font rendering (#14014)

This commit fixes several issues:
* Some fonts set a line-gap even though they behave as if they
  don't want any line-gaps. Since Terminals don't really have
  any gaps anyways, it'll now not be taken into account anymore.
* Center alignment breaks bitmap glyphs which expect left-alignment.
* Automatic "opsz" axis makes Terminus TTF's italic glyphs look quite
  weird. I disabled this feature as we might not need it anyways.

A complete fix depends on #14013
Closes #14006

## Validation Steps Performed
* Use Terminus TTF at 13.5pt
* Print UTF-8-demo.txt
* No gaps between block characters ✅

src/renderer/atlas/AtlasEngine.api.cpp

@@ -620,17 +620,20 @@ void AtlasEngine::_resolveFontMetrics(const wchar_t* requestedFaceName, const Fo
     const auto designUnitsPerPx = fontSizeInPx / static_cast<float>(metrics.designUnitsPerEm);
     const auto ascent = static_cast<float>(metrics.ascent) * designUnitsPerPx;
     const auto descent = static_cast<float>(metrics.descent) * designUnitsPerPx;
-    const auto lineGap = static_cast<float>(metrics.lineGap) * designUnitsPerPx;
     const auto underlinePosition = static_cast<float>(-metrics.underlinePosition) * designUnitsPerPx;
     const auto underlineThickness = static_cast<float>(metrics.underlineThickness) * designUnitsPerPx;
     const auto strikethroughPosition = static_cast<float>(-metrics.strikethroughPosition) * designUnitsPerPx;
     const auto strikethroughThickness = static_cast<float>(metrics.strikethroughThickness) * designUnitsPerPx;
 
     const auto advanceWidth = static_cast<float>(glyphMetrics.advanceWidth) * designUnitsPerPx;
 
-    const auto halfGap = lineGap / 2.0f;
-    const auto baseline = std::roundf(ascent + halfGap);
-    const auto lineHeight = std::roundf(baseline + descent + halfGap);
+    // NOTE: Line-gaps shouldn't be taken into account for lineHeight calculations.
+    // Terminals don't really have "gaps" between lines and instead the expectation
+    // is that two full block characters above each other don't leave any gaps
+    // between the lines. "Terminus TTF" for instance sets a line-gap of 90 units
+    // even though its font bitmap only covers the ascend/descend height.
+    const auto baseline = std::roundf(ascent);
+    const auto lineHeight = std::roundf(baseline + descent);
     const auto underlinePos = std::roundf(baseline + underlinePosition);
     const auto underlineWidth = std::max(1.0f, std::roundf(underlineThickness));
     const auto strikethroughPos = std::roundf(baseline + strikethroughPosition);

src/renderer/atlas/AtlasEngine.cpp

@@ -1102,7 +1102,6 @@ void AtlasEngine::_recreateFontDependentResources()
                 auto& textFormat = _r.textFormats[italic][bold];
 
                 THROW_IF_FAILED(_sr.dwriteFactory->CreateTextFormat(_api.fontMetrics.fontName.c_str(), _api.fontMetrics.fontCollection.get(), fontWeight, fontStyle, DWRITE_FONT_STRETCH_NORMAL, _api.fontMetrics.fontSizeInDIP, L"", textFormat.put()));
-                THROW_IF_FAILED(textFormat->SetTextAlignment(DWRITE_TEXT_ALIGNMENT_CENTER));
                 THROW_IF_FAILED(textFormat->SetWordWrapping(DWRITE_WORD_WRAPPING_NO_WRAP));
 
                 // DWRITE_LINE_SPACING_METHOD_UNIFORM:
@@ -1111,11 +1110,16 @@ void AtlasEngine::_recreateFontDependentResources()
                 // We want that. Otherwise fallback fonts might be rendered with an incorrect baseline and get cut off vertically.
                 THROW_IF_FAILED(textFormat->SetLineSpacing(DWRITE_LINE_SPACING_METHOD_UNIFORM, _r.cellSizeDIP.y, _api.fontMetrics.baselineInDIP));
 
-                if (const auto textFormat3 = textFormat.try_query<IDWriteTextFormat3>())
-                {
-                    THROW_IF_FAILED(textFormat3->SetAutomaticFontAxes(DWRITE_AUTOMATIC_FONT_AXES_OPTICAL_SIZE));
+                // NOTE: SetTextAlignment(DWRITE_TEXT_ALIGNMENT_CENTER) breaks certain
+                // bitmap fonts which expect glyphs to be laid out left-aligned.
+
+                // NOTE: SetAutomaticFontAxes(DWRITE_AUTOMATIC_FONT_AXES_OPTICAL_SIZE) breaks certain
+                // fonts making them look fairly unslightly. With no option to easily disable this
+                // feature in Windows Terminal, it's better left disabled by default.
 
-                    if (!_api.fontAxisValues.empty())
+                if (!_api.fontAxisValues.empty())
+                {
+                    if (const auto textFormat3 = textFormat.try_query<IDWriteTextFormat3>())
                     {
                         // The wght axis defaults to the font weight.
                         _api.fontAxisValues[0].value = bold || standardAxes[0].value == -1.0f ? static_cast<float>(fontWeight) : standardAxes[0].value;