[CSS Fonts] Implement ic-height for font-size-adjust

https://bugs.webkit.org/show_bug.cgi?id=264064

Reviewed by NOBODY (OOPS!).

This change brings the ic-height metric support for font-size-adjust [1] into
ports using OpenType. As initializing glyphs' vertical data is expensive, we defer
it until the vertical data is requested. If a used font does not provide height
of the cjk water glyph, we use its width as a fallback [2] because the glyph usually
has the same width and height.

[1] https://www.w3.org/TR/css-fonts-5/#valdef-font-size-adjust-ic-height
[2] w3c/csswg-drafts#8792

Test: imported/w3c/web-platform-tests/css/css-fonts/font-size-adjust-ic-height.html

* LayoutTests/imported/w3c/web-platform-tests/css/css-fonts/font-size-adjust-ic-height-expected.html: Added.
* LayoutTests/imported/w3c/web-platform-tests/css/css-fonts/font-size-adjust-ic-height-ref.html: Added.
* LayoutTests/imported/w3c/web-platform-tests/css/css-fonts/font-size-adjust-ic-height.html: Added.
* Source/WebCore/platform/graphics/Font.cpp:
(WebCore::m_shouldNotBeUsedForArabic):
(WebCore::Font::platformGlyphInit):
(WebCore::Font::platformGlyphVerticalDataInit):
(WebCore::Font::heightForGlyph const):
* Source/WebCore/platform/graphics/Font.h:
(WebCore::Font::widthForGlyph const):
* Source/WebCore/platform/graphics/FontMetrics.h:
(WebCore::FontMetrics::ideogramHeight const):
(WebCore::FontMetrics::reset):
* Source/WebCore/platform/graphics/FontSizeAdjust.h:
(WebCore::FontSizeAdjust::resolve const):
* Source/WebCore/rendering/RenderFileUploadControl.cpp:
(WebCore::RenderFileUploadControl::paintControl):
* Source/WebCore/style/StyleFontSizeFunctions.cpp:
(WebCore::Style::adjustedFontSize):

Author: shivamidow

LayoutTests/imported/w3c/web-platform-tests/css/css-fonts/font-size-adjust-ic-height-expected.html

@@ -0,0 +1,25 @@
+>
+<meta charset="UTF-8">
+<title>font-size-adjust with the ic-height metrictitle>
+<link rel="author" title="ChangSeok Oh" href="mailto:[email protected]" />
+<style>
+@font-face {
+  font-family: IcTestFullWidth;
+  src: url(../css-values/resources/IcTestFullWidth.woff2);
+}
+div {
+  font-family: IcTestFullWidth;
+  background: green;
+  color: green;
+  writing-mode: vertical-rl;
+  text-orientation: upright;
+}
+.valueRef {
+  font-size: 200px;
+}
+.fromFontRef {
+  font-size: 100px;
+}
+style>
+<div class="valueRef">水div>
+<div class="fromFontRef">水div>

LayoutTests/imported/w3c/web-platform-tests/css/css-fonts/font-size-adjust-ic-height-ref.html

@@ -0,0 +1,25 @@
+>
+<meta charset="UTF-8">
+<title>font-size-adjust with the ic-height metrictitle>
+<link rel="author" title="ChangSeok Oh" href="mailto:[email protected]" />
+<style>
+@font-face {
+  font-family: IcTestFullWidth;
+  src: url(../css-values/resources/IcTestFullWidth.woff2);
+}
+div {
+  font-family: IcTestFullWidth;
+  background: green;
+  color: green;
+  writing-mode: vertical-rl;
+  text-orientation: upright;
+}
+.valueRef {
+  font-size: 200px;
+}
+.fromFontRef {
+  font-size: 100px;
+}
+style>
+<div class="valueRef">水div>
+<div class="fromFontRef">水div>

LayoutTests/imported/w3c/web-platform-tests/css/css-fonts/font-size-adjust-ic-height.html

@@ -0,0 +1,32 @@
+>
+<meta charset="UTF-8">
+<title>font-size-adjust with the ic-height metrictitle>
+<link rel="author" title="ChangSeok Oh" href="mailto:[email protected]" />
+<link rel="help" href="https://www.w3.org/TR/css-fonts-5/#valdef-font-size-adjust-ic-height" />
+<link rel="match" href="font-size-adjust-ic-height-ref.html" />
+<meta name="assert" content="Test checks whether font-size-adjust with the ic-height metric adjusts font size.">
+<style>
+@font-face {
+  font-family: IcTestFullWidth;
+  src: url(../css-values/resources/IcTestFullWidth.woff2);
+}
+div {
+  font-family: IcTestFullWidth;
+  font-size: 100px;
+  background: green;
+  color: green;
+  writing-mode: vertical-rl;
+  text-orientation: upright;
+}
+.value {
+  /* The IcTestFullWidth font has an aspect value of 1.0 for ic-height.
+     Therefore, an ic-height 2.0 means a 200% scaling up. */
+  font-size-adjust: ic-height 2.0;
+}
+.fromFont {
+  /* Likewise, ic-height from-font means 100% of the specified font size. */
+  font-size-adjust: ic-height from-font;
+}
+style>
+<div class="value">水div>
+<div class="fromFont">水div>

Source/WebCore/platform/graphics/Font.cpp

@@ -1,6 +1,7 @@
 /*
  * Copyright (C) 2005-2023 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov
+ * Copyright (C) 2023 ChangSeok Oh 
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -89,12 +90,8 @@ Font::Font(const FontPlatformData& platformData, Origin origin, IsInterstitial i
     platformInit();
     platformGlyphInit();
     platformCharWidthInit();
-#if ENABLE(OPENTYPE_VERTICAL)
-    if (platformData.orientation() == FontOrientation::Vertical && orientationFallback == IsOrientationFallback::No) {
-        m_verticalData = FontCache::forCurrentThread().verticalData(platformData);
-        m_hasVerticalGlyphs = m_verticalData.get() && m_verticalData->hasVerticalMetrics();
-    }
-#endif
+    if (platformData.orientation() == FontOrientation::Vertical && orientationFallback == IsOrientationFallback::No)
+        platformGlyphVerticalDataInit();
 }
 
 // Estimates of avgCharWidth and maxCharWidth for platforms that don't support accessing these values from the font.
@@ -158,6 +155,19 @@ void Font::platformGlyphInit()
     if (auto* page = glyphPage(GlyphPage::pageNumberForCodePoint(cjkWater))) {
         auto glyph = page->glyphDataForCharacter(cjkWater).glyph;
         m_fontMetrics.setIdeogramWidth(widthForGlyph(glyph));
+        m_fontMetrics.setIdeogramHeightCallback([this, weakThis = WeakPtr { *this }, glyph] {
+            if (!weakThis)
+                return 0.0f;
+
+            platformGlyphVerticalDataInit();
+
+            auto advanceHeight = heightForGlyph(glyph);
+            // FIXME: Vertical glyph data is often missing in fonts, but a fallback
+            // behavior is not standardized yet. Gecko uses average character width instead,
+            // so we implement it until a standard fallback is defined.
+            // See https://github.com/w3c/csswg-drafts/issues/8792
+            return advanceHeight.has_value() ? advanceHeight.value() : platformWidthForGlyph(glyph);
+        });
     } else
         m_fontMetrics.setIdeogramWidth(platformData().size());
 
@@ -168,6 +178,18 @@ void Font::platformGlyphInit()
     determinePitch();
 }
 
+void Font::platformGlyphVerticalDataInit()
+{
+#if ENABLE(OPENTYPE_VERTICAL)
+    // Initializing vertical data is expensive. We limit it if only necessary.
+    if (m_verticalData)
+        return;
+
+    m_verticalData = FontCache::forCurrentThread().verticalData(m_platformData);
+    m_hasVerticalGlyphs = m_verticalData.get() && m_verticalData->hasVerticalMetrics();
+#endif
+}
+
 Font::~Font()
 {
     SystemFallbackFontCache::forCurrentThread().remove(this);
@@ -617,6 +639,16 @@ bool Font::canRenderCombiningCharacterSequence(StringView stringView) const
     return true;
 }
 
+std::optional<float> Font::heightForGlyph(Glyph glyph) const
+{
+#if ENABLE(OPENTYPE_VERTICAL)
+    if (m_verticalData)
+        return m_verticalData->advanceHeight(this, glyph);
+#endif
+    UNUSED_PARAM(glyph);
+    return std::nullopt;
+}
+
 Path Font::pathForGlyph(Glyph glyph) const
 {
     if (m_glyphPathMap) {

Source/WebCore/platform/graphics/Font.h

@@ -156,6 +156,7 @@ class Font : public RefCounted, public CanMakeWeakPtr, public CanMak
         Exclude
     };
     float widthForGlyph(Glyph, SyntheticBoldInclusion = SyntheticBoldInclusion::Incorporate) const;
+    std::optional<float> heightForGlyph(Glyph) const;
 
     Path pathForGlyph(Glyph) const;
 
@@ -237,6 +238,7 @@ class Font : public RefCounted, public CanMakeWeakPtr, public CanMak
 
     void platformInit();
     void platformGlyphInit();
+    void platformGlyphVerticalDataInit();
     void platformCharWidthInit();
     void platformDestroy();
 
@@ -406,11 +408,10 @@ ALWAYS_INLINE float Font::widthForGlyph(Glyph glyph, SyntheticBoldInclusion Synt
     if (width != cGlyphSizeUnknown)
         return width + (SyntheticBoldInclusion == SyntheticBoldInclusion::Incorporate ? syntheticBoldOffset() : 0);
 
-#if ENABLE(OPENTYPE_VERTICAL)
-    if (m_verticalData)
-        width = m_verticalData->advanceHeight(this, glyph);
-    else
-#endif
+    if (m_platformData.orientation() == FontOrientation::Vertical && !isTextOrientationFallback()) {
+        auto height = heightForGlyph(glyph);
+        width = height.has_value() ? height.value() : platformWidthForGlyph(glyph);
+    } else
         width = platformWidthForGlyph(glyph);
 
     m_glyphToWidthMap.setMetricsForGlyph(glyph, width);

Source/WebCore/platform/graphics/FontMetrics.h

@@ -22,6 +22,7 @@
 
 #include "FontBaseline.h"
 #include <optional>
+#include <wtf/Function.h>
 #include <wtf/MathExtras.h>
 
 namespace WebCore {
@@ -30,6 +31,8 @@ class FontMetrics {
 public:
     static const unsigned defaultUnitsPerEm = 1000;
 
+    using IdeogramHeightCallback = Function<float()>;
+
     unsigned unitsPerEm() const { return m_unitsPerEm; }
     void setUnitsPerEm(unsigned unitsPerEm) { m_unitsPerEm = unitsPerEm; }
 
@@ -126,6 +129,14 @@ class FontMetrics {
     float ideogramWidth() const { return m_ideogramWidth; }
     void setIdeogramWidth(float ideogramWidth) { m_ideogramWidth = ideogramWidth; }
 
+    float ideogramHeight() const
+    {
+        if (!m_ideogramHeight && m_ideogramHeightCallback)
+            m_ideogramHeight = m_ideogramHeightCallback();
+        return m_ideogramHeight.has_value() ? m_ideogramHeight.value() : 0;
+    };
+    void setIdeogramHeightCallback(IdeogramHeightCallback&& callback) { m_ideogramHeightCallback = WTFMove(callback); }
+
     float underlinePosition() const { return m_underlinePosition; }
     void setUnderlinePosition(float underlinePosition) { m_underlinePosition = underlinePosition; }
 
@@ -151,6 +162,7 @@ class FontMetrics {
         m_xHeight = 0;
         m_zeroWidth = std::nullopt;
         m_ideogramWidth = 0;
+        m_ideogramHeight = std::nullopt;
         m_underlinePosition = 0;
         m_underlineThickness = 0;
     }
@@ -175,6 +187,9 @@ class FontMetrics {
     float m_xHeight { 0 };
     float m_underlinePosition { 0 };
     float m_underlineThickness { 0 };
+
+    mutable std::optional<float> m_ideogramHeight;
+    IdeogramHeightCallback m_ideogramHeightCallback;
 };
 
 static inline float scaleEmToUnits(float x, unsigned unitsPerEm)

Source/WebCore/platform/graphics/FontSizeAdjust.h

@@ -56,12 +56,14 @@ struct FontSizeAdjust {
             if (fontMetrics.zeroWidth())
                 metricValue = fontMetrics.zeroWidth();
             break;
-        // FIXME: Are ic-height and ic-width the same? Gecko treats them the same.
         case FontSizeAdjust::Metric::IcWidth:
-        case FontSizeAdjust::Metric::IcHeight:
             if (fontMetrics.ideogramWidth() > 0)
                 metricValue = fontMetrics.ideogramWidth();
             break;
+        case FontSizeAdjust::Metric::IcHeight:
+            if (fontMetrics.ideogramHeight() > 0)
+                metricValue = fontMetrics.ideogramHeight();
+            break;
         case FontSizeAdjust::Metric::ExHeight:
         default:
             if (fontMetrics.hasXHeight())

Source/WebCore/rendering/RenderFileUploadControl.cpp

@@ -185,7 +185,7 @@ void RenderFileUploadControl::paintControl(PaintInfo& paintInfo, const LayoutPoi
                         textVisualRect.setLocation(buttonTextRenderer->localToContainerPoint(textVisualRect.location(), this));
                         textVisualRect.moveBy(roundPointToDevicePixels(paintOffset, document().deviceScaleFactor()));
 
-                        auto metrics = textBox->style().fontCascade().metricsOfPrimaryFont();
+                        const auto& metrics = textBox->style().fontCascade().metricsOfPrimaryFont();
 
                         if (!isHorizontalWritingMode) {
                             if (isFlippedBlocksWritingMode)

Source/WebCore/style/StyleFontSizeFunctions.cpp

@@ -202,10 +202,10 @@ float adjustedFontSize(float size, const FontSizeAdjust& sizeAdjust, const FontM
         return metrics.hasCapHeight() ? adjustedFontSize(size, *sizeAdjust.value, metrics.floatCapHeight()) : size;
     case FontSizeAdjust::Metric::ChWidth:
         return metrics.zeroWidth() ? adjustedFontSize(size, *sizeAdjust.value, *metrics.zeroWidth()) : size;
-    // FIXME: Are ic-height and ic-width the same? Gecko treats them the same.
     case FontSizeAdjust::Metric::IcWidth:
-    case FontSizeAdjust::Metric::IcHeight:
         return metrics.ideogramWidth() > 0 ? adjustedFontSize(size, *sizeAdjust.value, metrics.ideogramWidth()) : size;
+    case FontSizeAdjust::Metric::IcHeight:
+        return metrics.ideogramHeight() > 0 ? adjustedFontSize(size, *sizeAdjust.value, metrics.ideogramHeight()) : size;
     case FontSizeAdjust::Metric::ExHeight:
     default:
         return metrics.hasXHeight() ? adjustedFontSize(size, *sizeAdjust.value, metrics.xHeight()) : size;