[FreeType] Some character sequences with a variation selector are not rendered
authorcarlosgc@webkit.org <carlosgc@webkit.org@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Thu, 16 May 2019 09:31:16 +0000 (09:31 +0000)
committercarlosgc@webkit.org <carlosgc@webkit.org@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Thu, 16 May 2019 09:31:16 +0000 (09:31 +0000)
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.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@245393 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/ChangeLog
Source/WebCore/platform/graphics/Font.cpp
Source/WebCore/platform/graphics/Font.h
Source/WebCore/platform/graphics/cairo/FontCairoHarfbuzzNG.cpp
Source/WebCore/platform/graphics/cocoa/FontCocoa.mm
Source/WebCore/platform/graphics/freetype/SimpleFontDataFreeType.cpp
Source/WebCore/platform/graphics/harfbuzz/ComplexTextControllerHarfBuzz.cpp

index b8354e0..1757f4f 100644 (file)
@@ -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.
+
 2019-05-16  Greg Hughes  <ghughes@apple.com>
 
         Updated screenHasInvertedColors to use AppKit when available
index cc94d6c..a743e9c 100644 (file)
@@ -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;
     }
index 11df1e6..3ca9788 100644 (file)
@@ -175,7 +175,7 @@ public:
     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;
 
index 0704635..a0882f7 100644 (file)
@@ -115,11 +115,18 @@ 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) {
@@ -127,12 +134,16 @@ const Font* FontCascade::fontForCombiningCharacterSequence(const UChar* original
         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();
     }
 
index 89c2571..7007af4 100644 (file)
@@ -613,8 +613,11 @@ Path Font::platformPathForGlyph(Glyph glyph) const
     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;
index c915429..cd082ca 100644 (file)
@@ -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;
 }
index 360ffa1..69c8c90 100644 (file)
@@ -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);