[Skia] Create the font manager on demand when first needed

https://bugs.webkit.org/show_bug.cgi?id=271396

Reviewed by Adrian Perez de Castro.

We are creating the font manager in FontCache::platformInit(), but
that's only called once for all the instances. This makes all offscreen
canvas tests rendering text to crash, because the FontCache in the
worker thread doesn't have a font manager.

* Source/WebCore/platform/graphics/FontCache.h:
(WebCore::FontCache::fontManager const): Deleted.
* Source/WebCore/platform/graphics/skia/FontCacheSkia.cpp:
(WebCore::FontCache::platformInit):
(WebCore::FontCache::fontManager const):
(WebCore::FontCache::systemFallbackForCharacterCluster):
(WebCore::FontCache::systemFontFamilies):
(WebCore::FontCache::createFontPlatformData):
* Source/WebCore/platform/graphics/skia/FontCustomPlatformDataSkia.cpp:
(WebCore::FontCustomPlatformData::create):

Canonical link: https://commits.webkit.org/276483@main

Source/WebCore/platform/graphics/FontCache.h

@@ -199,7 +199,7 @@ class FontCache {
 
 #if USE(SKIA)
     static Vector<hb_feature_t> computeFeatures(const FontDescription&, const FontCreationContext&);
-    SkFontMgr* fontManager() const { return m_fontManager.get(); }
+    SkFontMgr& fontManager() const;
     SkiaHarfBuzzFontCache& harfBuzzFontCache() { return m_harfBuzzFontCache; }
 #endif
 
@@ -268,7 +268,7 @@ class FontCache {
 #endif
 
 #if USE(SKIA)
-    sk_sp<SkFontMgr> m_fontManager;
+    mutable sk_sp<SkFontMgr> m_fontManager;
     SkiaHarfBuzzFontCache m_harfBuzzFontCache;
 #endif
 

Source/WebCore/platform/graphics/skia/FontCacheSkia.cpp

@@ -39,7 +39,14 @@ namespace WebCore {
 
 void FontCache::platformInit()
 {
-    m_fontManager = SkFontMgr_New_FontConfig(FcConfigReference(nullptr));
+}
+
+SkFontMgr& FontCache::fontManager() const
+{
+    if (!m_fontManager)
+        m_fontManager = SkFontMgr_New_FontConfig(FcConfigReference(nullptr));
+    RELEASE_ASSERT(m_fontManager);
+    return *m_fontManager.get();
 }
 
 RefPtr<Font> FontCache::systemFallbackForCharacterCluster(const FontDescription& description, const Font&, IsForPlatformFont, PreferColoredFont, StringView stringView)
@@ -61,19 +68,20 @@ RefPtr<Font> FontCache::systemFallbackForCharacterCluster(const FontDescription&
 
     // FIXME: handle synthetic properties.
     auto features = computeFeatures(description, { });
-    auto typeface = m_fontManager->matchFamilyStyleCharacter(nullptr, { }, bcp47.data(), bcp47.size(), baseCharacter);
+    auto typeface = fontManager().matchFamilyStyleCharacter(nullptr, { }, bcp47.data(), bcp47.size(), baseCharacter);
     FontPlatformData alternateFontData(WTFMove(typeface), description.computedSize(), false /* syntheticBold */, false /* syntheticOblique */, description.orientation(), description.widthVariant(), description.textRenderingMode(), WTFMove(features));
     return fontForPlatformData(alternateFontData);
 }
 
 Vector<String> FontCache::systemFontFamilies()
 {
-    int count = m_fontManager->countFamilies();
+    auto& manager = fontManager();
+    int count = manager.countFamilies();
     Vector<String> fontFamilies;
     fontFamilies.reserveInitialCapacity(count);
     for (int i = 0; i < count; ++i) {
         SkString familyName;
-        m_fontManager->getFamilyName(i, &familyName);
+        manager.getFamilyName(i, &familyName);
         fontFamilies.append(String::fromUTF8(familyName.data()));
     }
     return fontFamilies;
@@ -319,7 +327,7 @@ static SkFontStyle skiaFontStyle(const FontDescription& fontDescription)
 std::unique_ptr<FontPlatformData> FontCache::createFontPlatformData(const FontDescription& fontDescription, const AtomString& family, const FontCreationContext& fontCreationContext)
 {
     auto familyName = getFamilyNameStringFromFamily(family);
-    auto typeface = m_fontManager->matchFamilyStyle(familyName.utf8().data(), skiaFontStyle(fontDescription));
+    auto typeface = fontManager().matchFamilyStyle(familyName.utf8().data(), skiaFontStyle(fontDescription));
     if (!typeface)
         return nullptr;
 

Source/WebCore/platform/graphics/skia/FontCustomPlatformDataSkia.cpp

@@ -101,7 +101,7 @@ FontPlatformData FontCustomPlatformData::fontPlatformData(const FontDescription&
 
 RefPtr<FontCustomPlatformData> FontCustomPlatformData::create(SharedBuffer& buffer, const String& itemInCollection)
 {
-    sk_sp<SkTypeface> typeface = FontCache::forCurrentThread().fontManager()->makeFromData(buffer.createSkData());
+    sk_sp<SkTypeface> typeface = FontCache::forCurrentThread().fontManager().makeFromData(buffer.createSkData());
     if (!typeface)
         return nullptr;