Merge r245393 - [FreeType] Some character sequences with a variation …

…selector are not rendered https://bugs.webkit.org/show_bug.cgi?id=197838 Reviewed by Michael Catanzaro. We get the invalid glyph instead. See http://mts.io/2015/04/21/unicode-symbol-render-text-emoji/. In the table at the end the Emoji and Text columns are not correctly rendered. It happens also when copying an emoji from GtkEmojiChooser and pasting in WebKit text field, because GTK appends U+FE0F to all emojis to force the emoji style. We need to take into account the variation selector when checking if a font can render a combining sequence, using FT_Face_GetCharVariantIndex to get the right glyph in case of variation character present. * platform/graphics/Font.cpp: (WebCore::Font::platformSupportsCodePoint const): Add optional variation parameter. (WebCore::Font::canRenderCombiningCharacterSequence const): Take into account variation selector characters * platform/graphics/Font.h: * platform/graphics/cairo/FontCairoHarfbuzzNG.cpp: (WebCore::FontCascade::fontForCombiningCharacterSequence const): Check variation selectors 0xFE0E and 0xFE0F to decide whether to use the emoji or text style. * platform/graphics/cocoa/FontCocoa.mm: (WebCore::Font::platformSupportsCodePoint const): Return false when a variation character is passed so that characters are checked individually. * platform/graphics/freetype/SimpleFontDataFreeType.cpp: (WebCore::Font::platformSupportsCodePoint const): Use FT_Face_GetCharVariantIndex when a variation character is passed. * platform/graphics/harfbuzz/ComplexTextControllerHarfBuzz.cpp: (WebCore::harfBuzzFontFunctions): Do not return true when FT_Face_GetCharVariantIndex returns 0.
WebKit · May 17, 2019 · 3c196ef · 3c196ef
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diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
@@ -1,3 +1,32 @@
+2019-05-16  Carlos Garcia Campos  <cgarcia@igalia.com>
+
+        [FreeType] Some character sequences with a variation selector are not rendered
+        https://bugs.webkit.org/show_bug.cgi?id=197838
+
+        Reviewed by Michael Catanzaro.
+
+        We get the invalid glyph instead. See http://mts.io/2015/04/21/unicode-symbol-render-text-emoji/. In the table at
+        the end the Emoji and Text columns are not correctly rendered. It happens also when copying an emoji from
+        GtkEmojiChooser and pasting in WebKit text field, because GTK appends U+FE0F to all emojis to force the emoji
+        style. We need to take into account the variation selector when checking if a font can render a combining
+        sequence, using FT_Face_GetCharVariantIndex to get the right glyph in case of variation character present.
+
+        * platform/graphics/Font.cpp:
+        (WebCore::Font::platformSupportsCodePoint const): Add optional variation parameter.
+        (WebCore::Font::canRenderCombiningCharacterSequence const): Take into account variation selector characters
+        * platform/graphics/Font.h:
+        * platform/graphics/cairo/FontCairoHarfbuzzNG.cpp:
+        (WebCore::FontCascade::fontForCombiningCharacterSequence const): Check variation selectors 0xFE0E and 0xFE0F to
+        decide whether to use the emoji or text style.
+        * platform/graphics/cocoa/FontCocoa.mm:
+        (WebCore::Font::platformSupportsCodePoint const): Return false when a variation character is passed so that
+        characters are checked individually.
+        * platform/graphics/freetype/SimpleFontDataFreeType.cpp:
+        (WebCore::Font::platformSupportsCodePoint const): Use FT_Face_GetCharVariantIndex when a variation character is
+        passed.
+        * platform/graphics/harfbuzz/ComplexTextControllerHarfBuzz.cpp:
+        (WebCore::harfBuzzFontFunctions): Do not return true when FT_Face_GetCharVariantIndex returns 0.
+
 2019-03-16  Darin Adler  <darin@apple.com>
 
         Improve normalization code, including moving from unorm.h to unorm2.h

diff --git a/Source/WebCore/platform/graphics/Font.cpp b/Source/WebCore/platform/graphics/Font.cpp
@@ -33,6 +33,7 @@
 #if PLATFORM(COCOA)
 #include <pal/spi/cocoa/CoreTextSPI.h>
 #endif
+#include "CharacterProperties.h"
 #include "FontCache.h"
 #include "FontCascade.h"
 #include "OpenTypeMathData.h"
@@ -641,9 +642,9 @@ bool Font::variantCapsSupportsCharacterForSynthesis(FontVariantCaps fontVariantC
     }
 }
 
-bool Font::platformSupportsCodePoint(UChar32 character) const
+bool Font::platformSupportsCodePoint(UChar32 character, Optional<UChar32> variation) const
 {
-    return glyphForCharacter(character);
+    return variation ? false : glyphForCharacter(character);
 }
 #endif
 
@@ -671,7 +672,23 @@ bool Font::canRenderCombiningCharacterSequence(const UChar* characters, size_t l
 {
     ASSERT(isMainThread());
 
-    for (UChar32 codePoint : StringView(characters, length).codePoints()) {
+    auto codePoints = StringView(characters, length).codePoints();
+    auto it = codePoints.begin();
+    auto end = codePoints.end();
+    while (it != end) {
+        auto codePoint = *it;
+        ++it;
+
+        if (it != end && isVariationSelector(*it)) {
+            if (!platformSupportsCodePoint(codePoint, *it)) {
+                // Try the characters individually.
+                if (!supportsCodePoint(codePoint) || !supportsCodePoint(*it))
+                    return false;
+            }
+            ++it;
+            continue;
+        }
+
         if (!supportsCodePoint(codePoint))
             return false;
     }

diff --git a/Source/WebCore/platform/graphics/Font.h b/Source/WebCore/platform/graphics/Font.h
@@ -175,7 +175,7 @@ class Font : public RefCounted<Font> {
     GlyphData glyphDataForCharacter(UChar32) const;
     Glyph glyphForCharacter(UChar32) const;
     bool supportsCodePoint(UChar32) const;
-    bool platformSupportsCodePoint(UChar32) const;
+    bool platformSupportsCodePoint(UChar32, Optional<UChar32> variation = WTF::nullopt) const;
 
     RefPtr<Font> systemFallbackFontForCharacter(UChar32, const FontDescription&, IsForPlatformFont) const;
 

diff --git a/Source/WebCore/platform/graphics/cairo/FontCairoHarfbuzzNG.cpp b/Source/WebCore/platform/graphics/cairo/FontCairoHarfbuzzNG.cpp
@@ -115,24 +115,35 @@ const Font* FontCascade::fontForCombiningCharacterSequence(const UChar* original
         return nullptr;
 
     bool isEmoji = characterSequenceIsEmoji(iterator, character, clusterLength);
+    bool preferColoredFont = isEmoji;
+    // U+FE0E forces text style.
+    // U+FE0F forces emoji style.
+    if (characters[length - 1] == 0xFE0E)
+        preferColoredFont = false;
+    else if (characters[length - 1] == 0xFE0F)
+        preferColoredFont = true;
 
     const Font* baseFont = glyphDataForCharacter(character, false, NormalVariant).font;
     if (baseFont
         && (clusterLength == length || baseFont->canRenderCombiningCharacterSequence(characters, length))
-        && (!isEmoji || baseFont->platformData().isColorBitmapFont()))
+        && (!preferColoredFont || baseFont->platformData().isColorBitmapFont()))
         return baseFont;
 
     for (unsigned i = 0; !fallbackRangesAt(i).isNull(); ++i) {
         const Font* fallbackFont = fallbackRangesAt(i).fontForCharacter(character);
         if (!fallbackFont || fallbackFont == baseFont)
             continue;
 
-        if (fallbackFont->canRenderCombiningCharacterSequence(characters, length) && (!isEmoji || fallbackFont->platformData().isColorBitmapFont()))
+        if (fallbackFont->canRenderCombiningCharacterSequence(characters, length) && (!preferColoredFont || fallbackFont->platformData().isColorBitmapFont()))
             return fallbackFont;
     }
 
-    if (auto systemFallback = FontCache::singleton().systemFallbackForCharacters(m_fontDescription, baseFont, IsForPlatformFont::No, isEmoji ? FontCache::PreferColoredFont::Yes : FontCache::PreferColoredFont::No, characters, length)) {
-        if (systemFallback->canRenderCombiningCharacterSequence(characters, length) && (!isEmoji || systemFallback->platformData().isColorBitmapFont()))
+    if (auto systemFallback = FontCache::singleton().systemFallbackForCharacters(m_fontDescription, baseFont, IsForPlatformFont::No, preferColoredFont ? FontCache::PreferColoredFont::Yes : FontCache::PreferColoredFont::No, characters, length)) {
+        if (systemFallback->canRenderCombiningCharacterSequence(characters, length) && (!preferColoredFont || systemFallback->platformData().isColorBitmapFont()))
+            return systemFallback.get();
+
+        // In case of emoji, if fallback font is colored try again without the variation selector character.
+        if (isEmoji && characters[length - 1] == 0xFE0F && systemFallback->platformData().isColorBitmapFont() && systemFallback->canRenderCombiningCharacterSequence(characters, length - 1))
             return systemFallback.get();
     }
 

diff --git a/Source/WebCore/platform/graphics/cocoa/FontCocoa.mm b/Source/WebCore/platform/graphics/cocoa/FontCocoa.mm
@@ -613,8 +613,11 @@ static int extractNumber(CFNumberRef number)
     return adoptCF(CGPathCreateMutableCopy(result.get()));
 }
 
-bool Font::platformSupportsCodePoint(UChar32 character) const
+bool Font::platformSupportsCodePoint(UChar32 character, Optional<UChar32> variation) const
 {
+    if (variation)
+        return false;
+
     UniChar codeUnits[2];
     CGGlyph glyphs[2];
     CFIndex count = 0;

diff --git a/Source/WebCore/platform/graphics/freetype/SimpleFontDataFreeType.cpp b/Source/WebCore/platform/graphics/freetype/SimpleFontDataFreeType.cpp
@@ -201,11 +201,11 @@ bool Font::variantCapsSupportsCharacterForSynthesis(FontVariantCaps fontVariantC
     }
 }
 
-bool Font::platformSupportsCodePoint(UChar32 character) const
+bool Font::platformSupportsCodePoint(UChar32 character, Optional<UChar32> variation) const
 {
     CairoFtFaceLocker cairoFtFaceLocker(m_platformData.scaledFont());
     if (FT_Face face = cairoFtFaceLocker.ftFace())
-        return !!FcFreeTypeCharIndex(face, character);
+        return variation ? !!FT_Face_GetCharVariantIndex(face, character, variation.value()) : !!FcFreeTypeCharIndex(face, character);
 
     return false;
 }

diff --git a/Source/WebCore/platform/graphics/harfbuzz/ComplexTextControllerHarfBuzz.cpp b/Source/WebCore/platform/graphics/harfbuzz/ComplexTextControllerHarfBuzz.cpp
@@ -78,7 +78,7 @@ static hb_font_funcs_t* harfBuzzFontFunctions()
             CairoFtFaceLocker cairoFtFaceLocker(scaledFont);
             if (FT_Face ftFace = cairoFtFaceLocker.ftFace()) {
                 *glyph = FT_Face_GetCharVariantIndex(ftFace, unicode, variation);
-                return true;
+                return !!*glyph;
             }
             return false;
             }, nullptr, nullptr);