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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/platform/fonts/shaping/font_features.h"
#include <hb.h>
#include "third_party/blink/renderer/platform/fonts/font.h"
#include "third_party/blink/renderer/platform/fonts/font_description.h"
namespace blink {
namespace {
constexpr FontFeatureRange kChws{{{'c', 'h', 'w', 's'}, 1}};
} // namespace
//
// Ensure `FontFeatureTag` is compatible with `hb_tag_t`.
//
static_assert(sizeof(FontFeatureTag) == sizeof(hb_tag_t));
static_assert(FontFeatureTag('1', '2', '3', '4').tag ==
HB_TAG('1', '2', '3', '4'));
//
// Ensure `FontFeatureRange` is compatible with `hb_feature_t`.
//
static_assert(sizeof(FontFeatureRange) == sizeof(hb_feature_t));
static_assert(offsetof(FontFeatureRange, tag) == offsetof(hb_feature_t, tag));
static_assert(offsetof(FontFeatureRange, value) ==
offsetof(hb_feature_t, value));
static_assert(offsetof(FontFeatureRange, start) ==
offsetof(hb_feature_t, start));
static_assert(offsetof(FontFeatureRange, end) == offsetof(hb_feature_t, end));
bool FontFeatureRange::IsInitial(base::span<const FontFeatureRange> features) {
return features.size() == 1 && features[0] == kChws;
}
template <wtf_size_t InlineCapacity>
void FontFeatureRange::FromFontDescription(
const FontDescription& description,
Vector<FontFeatureRange, InlineCapacity>& features) {
DCHECK(features.empty());
const bool is_horizontal = !description.IsVerticalAnyUpright();
constexpr FontFeatureRange no_kern{{{'k', 'e', 'r', 'n'}}};
constexpr FontFeatureRange no_vkrn{{{'v', 'k', 'r', 'n'}}};
switch (description.GetKerning()) {
case FontDescription::kNormalKerning:
// kern/vkrn are enabled by default in HarfBuzz
break;
case FontDescription::kNoneKerning:
features.push_back(is_horizontal ? no_kern : no_vkrn);
break;
case FontDescription::kAutoKerning:
break;
}
{
bool default_is_off = description.TextRendering() == blink::kOptimizeSpeed;
bool letter_spacing = description.LetterSpacing() != 0;
constexpr auto normal = FontDescription::kNormalLigaturesState;
constexpr auto enabled = FontDescription::kEnabledLigaturesState;
constexpr auto disabled = FontDescription::kDisabledLigaturesState;
// clig and liga are on by default in HarfBuzz
constexpr FontFeatureRange no_clig{{{'c', 'l', 'i', 'g'}}};
constexpr FontFeatureRange no_liga{{{'l', 'i', 'g', 'a'}}};
auto common = description.CommonLigaturesState();
if (letter_spacing ||
(common == disabled || (common == normal && default_is_off))) {
features.push_back(no_liga);
features.push_back(no_clig);
}
// dlig is off by default in HarfBuzz
constexpr FontFeatureRange dlig{{{'d', 'l', 'i', 'g'}, 1}};
auto discretionary = description.DiscretionaryLigaturesState();
if (!letter_spacing && discretionary == enabled) {
features.push_back(dlig);
}
// hlig is off by default in HarfBuzz
constexpr FontFeatureRange hlig{{{'h', 'l', 'i', 'g'}, 1}};
auto historical = description.HistoricalLigaturesState();
if (!letter_spacing && historical == enabled) {
features.push_back(hlig);
}
// calt is on by default in HarfBuzz
constexpr FontFeatureRange no_calt{{{'c', 'a', 'l', 't'}}};
auto contextual = description.ContextualLigaturesState();
if (letter_spacing ||
(contextual == disabled || (contextual == normal && default_is_off))) {
features.push_back(no_calt);
}
}
static constexpr FontFeatureRange hwid{{{'h', 'w', 'i', 'd'}, 1}};
static constexpr FontFeatureRange twid{{{'t', 'w', 'i', 'd'}, 1}};
static constexpr FontFeatureRange qwid{{{'q', 'w', 'i', 'd'}, 1}};
switch (description.WidthVariant()) {
case kHalfWidth:
features.push_back(hwid);
break;
case kThirdWidth:
features.push_back(twid);
break;
case kQuarterWidth:
features.push_back(qwid);
break;
case kRegularWidth:
break;
}
// font-variant-east-asian:
const FontVariantEastAsian east_asian = description.VariantEastAsian();
if (!east_asian.IsAllNormal()) [[unlikely]] {
static constexpr FontFeatureRange jp78{{{'j', 'p', '7', '8'}, 1}};
static constexpr FontFeatureRange jp83{{{'j', 'p', '8', '3'}, 1}};
static constexpr FontFeatureRange jp90{{{'j', 'p', '9', '0'}, 1}};
static constexpr FontFeatureRange jp04{{{'j', 'p', '0', '4'}, 1}};
static constexpr FontFeatureRange smpl{{{'s', 'm', 'p', 'l'}, 1}};
static constexpr FontFeatureRange trad{{{'t', 'r', 'a', 'd'}, 1}};
switch (east_asian.Form()) {
case FontVariantEastAsian::kNormalForm:
break;
case FontVariantEastAsian::kJis78:
features.push_back(jp78);
break;
case FontVariantEastAsian::kJis83:
features.push_back(jp83);
break;
case FontVariantEastAsian::kJis90:
features.push_back(jp90);
break;
case FontVariantEastAsian::kJis04:
features.push_back(jp04);
break;
case FontVariantEastAsian::kSimplified:
features.push_back(smpl);
break;
case FontVariantEastAsian::kTraditional:
features.push_back(trad);
break;
default:
NOTREACHED();
}
static constexpr FontFeatureRange fwid{{{'f', 'w', 'i', 'd'}, 1}};
static constexpr FontFeatureRange pwid{{{'p', 'w', 'i', 'd'}, 1}};
switch (east_asian.Width()) {
case FontVariantEastAsian::kNormalWidth:
break;
case FontVariantEastAsian::kFullWidth:
features.push_back(fwid);
break;
case FontVariantEastAsian::kProportionalWidth:
features.push_back(pwid);
break;
default:
NOTREACHED();
}
static constexpr FontFeatureRange ruby{{{'r', 'u', 'b', 'y'}, 1}};
if (east_asian.Ruby())
features.push_back(ruby);
}
// font-variant-numeric:
static constexpr FontFeatureRange lnum{{{'l', 'n', 'u', 'm'}, 1}};
if (description.VariantNumeric().NumericFigureValue() ==
FontVariantNumeric::kLiningNums)
features.push_back(lnum);
static constexpr FontFeatureRange onum{{{'o', 'n', 'u', 'm'}, 1}};
if (description.VariantNumeric().NumericFigureValue() ==
FontVariantNumeric::kOldstyleNums)
features.push_back(onum);
static constexpr FontFeatureRange pnum{{{'p', 'n', 'u', 'm'}, 1}};
if (description.VariantNumeric().NumericSpacingValue() ==
FontVariantNumeric::kProportionalNums)
features.push_back(pnum);
static constexpr FontFeatureRange tnum{{{'t', 'n', 'u', 'm'}, 1}};
if (description.VariantNumeric().NumericSpacingValue() ==
FontVariantNumeric::kTabularNums)
features.push_back(tnum);
static constexpr FontFeatureRange afrc{{{'a', 'f', 'r', 'c'}, 1}};
if (description.VariantNumeric().NumericFractionValue() ==
FontVariantNumeric::kStackedFractions)
features.push_back(afrc);
static constexpr FontFeatureRange frac{{{'f', 'r', 'a', 'c'}, 1}};
if (description.VariantNumeric().NumericFractionValue() ==
FontVariantNumeric::kDiagonalFractions)
features.push_back(frac);
static constexpr FontFeatureRange ordn{{{'o', 'r', 'd', 'n'}, 1}};
if (description.VariantNumeric().OrdinalValue() ==
FontVariantNumeric::kOrdinalOn)
features.push_back(ordn);
static constexpr FontFeatureRange zero{{{'z', 'e', 'r', 'o'}, 1}};
if (description.VariantNumeric().SlashedZeroValue() ==
FontVariantNumeric::kSlashedZeroOn)
features.push_back(zero);
const FontFeatureTag chws_or_vchw = is_horizontal
? FontFeatureTag{'c', 'h', 'w', 's'}
: FontFeatureTag{'v', 'c', 'h', 'w'};
bool default_enable_chws =
ShouldTrimAdjacent(description.GetTextSpacingTrim());
const FontFeatureSettings* settings = description.FeatureSettings();
if (settings) [[unlikely]] {
// TODO(drott): crbug.com/450619 Implement feature resolution instead of
// just appending the font-feature-settings.
const FontFeatureTag halt_or_vhal =
is_horizontal ? FontFeatureTag{'h', 'a', 'l', 't'}
: FontFeatureTag{'v', 'h', 'a', 'l'};
const FontFeatureTag palt_or_vpal =
is_horizontal ? FontFeatureTag{'p', 'a', 'l', 't'}
: FontFeatureTag{'v', 'p', 'a', 'l'};
for (const FontFeature& setting : *settings) {
const FontFeatureRange feature{
{setting.Tag(), static_cast<uint32_t>(setting.Value())}};
features.push_back(feature);
// `chws` should not be appended if other glyph-width GPOS feature exists.
if (default_enable_chws &&
(feature.tag == chws_or_vchw ||
(feature.value &&
(feature.tag == halt_or_vhal || feature.tag == palt_or_vpal))))
default_enable_chws = false;
}
}
if (default_enable_chws)
features.push_back(FontFeatureRange{{chws_or_vchw, 1}});
const FontDescription::FontVariantPosition variant_position =
description.VariantPosition();
if (variant_position == FontDescription::kSubVariantPosition) {
constexpr FontFeatureRange feature{{{'s', 'u', 'b', 's'}, 1}};
features.push_back(feature);
}
if (variant_position == FontDescription::kSuperVariantPosition) {
constexpr FontFeatureRange feature{{{'s', 'u', 'p', 's'}, 1}};
features.push_back(feature);
}
}
//
// Explicitly instantiate template functions.
//
template PLATFORM_EXPORT void FontFeatureRange::FromFontDescription(
const FontDescription&,
Vector<FontFeatureRange, FontFeatureRange::kInitialSize>&);
template PLATFORM_EXPORT void FontFeatureRange::FromFontDescription(
const FontDescription&,
FontFeatures&);
} // namespace blink
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