Add OpenTypeCapsSupport class

third_party/WebKit/Source/platform/fonts/opentype/OpenTypeCapsSupport.cpp

+// Copyright 2015 The Chromium Authors. All rights reserved.

[eae, 2016/04/12 15:20:12]

2016

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "platform/fonts/opentype/OpenTypeCapsSupport.h"
+
+namespace blink {
+
+OpenTypeCapsSupport::OpenTypeCapsSupport()
+    : m_harfBuzzFace(nullptr)
+    , m_requestedCaps(FontDescription::CapsNormal)
+    , m_fontSupport(FontSupport::Full)
+    , m_capsSynthesis(CapsSynthesis::None)
+{
+}
+
+OpenTypeCapsSupport::OpenTypeCapsSupport(const HarfBuzzFace* harfBuzzFace,
+    FontDescription::FontVariantCaps requestedCaps,
+    hb_script_t script)
+    : m_harfBuzzFace(harfBuzzFace)
+    , m_requestedCaps(requestedCaps)
+    , m_fontSupport(FontSupport::Full)
+    , m_capsSynthesis(CapsSynthesis::None)
+{
+    if (requestedCaps != FontDescription::CapsNormal)
+        determineFontSupport(script);
+}
+
+FontDescription::FontVariantCaps OpenTypeCapsSupport::fontFeatureToUse(
+    SmallCapsIterator::SmallCapsBehavior sourceTextCase)
+{
+    if (m_fontSupport == FontSupport::Full)
+        return m_requestedCaps;
+
+    if (m_fontSupport == FontSupport::Fallback) {
+        if (m_requestedCaps == FontDescription::FontVariantCaps::AllPetiteCaps)
+            return FontDescription::FontVariantCaps::AllSmallCaps;
+
+        if (m_requestedCaps == FontDescription::FontVariantCaps::PetiteCaps
+            || (m_requestedCaps == FontDescription::FontVariantCaps::Unicase
+            && sourceTextCase == SmallCapsIterator::SmallCapsSameCase))
+            return FontDescription::FontVariantCaps::SmallCaps;
+    }
+
+    return FontDescription::FontVariantCaps::CapsNormal;
+}
+
+bool OpenTypeCapsSupport::needsRunCaseSplitting()
+{
+    // Lack of titling case support is ignored, titling case is not synthesized.
+    return m_fontSupport != FontSupport::Full
+        && m_requestedCaps != FontDescription::TitlingCaps;
+}
+
+bool OpenTypeCapsSupport::needsSyntheticFont(
+    SmallCapsIterator::SmallCapsBehavior runCase)
+{
+    if (m_fontSupport == FontSupport::Full)
+        return false;
+
+    if (m_requestedCaps == FontDescription::TitlingCaps)
+        return false;
+
+    if (m_fontSupport == FontSupport::None) {
+        if (runCase == SmallCapsIterator::SmallCapsUppercaseNeeded
+            && (m_capsSynthesis == CapsSynthesis::LowerToSmallCaps
+            || m_capsSynthesis == CapsSynthesis::BothToSmallCaps))
+            return true;
+
+        if (runCase == SmallCapsIterator::SmallCapsSameCase
+            && (m_capsSynthesis == CapsSynthesis::UpperToSmallCaps
+            || m_capsSynthesis == CapsSynthesis::BothToSmallCaps)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+CaseMapIntend OpenTypeCapsSupport::needsCaseChange(
+    SmallCapsIterator::SmallCapsBehavior runCase)
+{
+    CaseMapIntend caseMapIntend = CaseMapIntend::KeepSameCase;
+
+    if (m_fontSupport == FontSupport::Full)
+        return caseMapIntend;
+
+    switch (runCase) {
+    case SmallCapsIterator::SmallCapsSameCase:
+        caseMapIntend = m_fontSupport == FontSupport::Fallback
+            && (m_capsSynthesis == CapsSynthesis::BothToSmallCaps
+            || m_capsSynthesis == CapsSynthesis::UpperToSmallCaps)
+            ? CaseMapIntend::LowerCase
+            : CaseMapIntend::KeepSameCase;
+        break;
+    case SmallCapsIterator::SmallCapsUppercaseNeeded:
+        caseMapIntend = m_fontSupport != FontSupport::Fallback
+            && (m_capsSynthesis == CapsSynthesis::LowerToSmallCaps
+            || m_capsSynthesis == CapsSynthesis::BothToSmallCaps)
+            ? CaseMapIntend::UpperCase
+            : CaseMapIntend::KeepSameCase;
+        break;
+    default:
+        break;
+    }
+    return caseMapIntend;
+}
+
+void OpenTypeCapsSupport::determineFontSupport(hb_script_t script)
+{
+    switch (m_requestedCaps) {
+    case FontDescription::SmallCaps:
+        if (!supportsOpenTypeFeature(script, HB_TAG('s', 'm', 'c', 'p'))) {
+            m_fontSupport = FontSupport::None;
+            m_capsSynthesis = CapsSynthesis::LowerToSmallCaps;
+        }
+        break;
+    case FontDescription::AllSmallCaps:
+        if (!(supportsOpenTypeFeature(script, HB_TAG('s', 'm', 'c', 'p'))
+            && supportsOpenTypeFeature(
+                script,
+                HB_TAG('c', '2', 's', 'c')))) {
+            m_fontSupport = FontSupport::None;
+            m_capsSynthesis = CapsSynthesis::BothToSmallCaps;
+        }
+        break;
+    case FontDescription::PetiteCaps:
+        if (!supportsOpenTypeFeature(script, HB_TAG('p', 'c', 'a', 'p'))) {
+            if (supportsOpenTypeFeature(script, HB_TAG('s', 'm', 'c', 'p'))) {
+                m_fontSupport = FontSupport::Fallback;
+            } else {
+                m_fontSupport = FontSupport::None;
+                m_capsSynthesis = CapsSynthesis::LowerToSmallCaps;
+            }
+        }
+        break;
+    case FontDescription::AllPetiteCaps:
+        if (!(supportsOpenTypeFeature(script, HB_TAG('p', 'c', 'a', 'p'))
+            && supportsOpenTypeFeature(
+            script,
+            HB_TAG('c', '2', 'p', 'c')))) {
+            if (supportsOpenTypeFeature(script, HB_TAG('s', 'm', 'c', 'p'))
+                && supportsOpenTypeFeature(
+                script,
+                HB_TAG('c', '2', 's', 'c'))) {
+                m_fontSupport = FontSupport::Fallback;
+            } else {
+                m_fontSupport = FontSupport::None;
+                m_capsSynthesis = CapsSynthesis::BothToSmallCaps;
+            }
+        }
+        break;
+    case FontDescription::Unicase:
+        if (!supportsOpenTypeFeature(script, HB_TAG('u', 'n', 'i', 'c'))) {
+            m_capsSynthesis = CapsSynthesis::UpperToSmallCaps;
+            if (supportsOpenTypeFeature(script, HB_TAG('s', 'm', 'c', 'p'))) {
+                m_fontSupport = FontSupport::Fallback;
+            } else {
+                m_fontSupport = FontSupport::None;
+            }
+        }
+        break;
+    case FontDescription::TitlingCaps:
+        if (!supportsOpenTypeFeature(script, HB_TAG('t', 'i', 't', 'l'))) {
+            m_fontSupport = FontSupport::None;
+        }
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+    }
+}
+
+} // namespace blink