| // Copyright 2021 The Chromium Authors. All rights reserved. |
| // 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 "third_party/blink/renderer/platform/fonts/font.h" |
| |
| namespace blink { |
| |
| namespace { |
| |
| constexpr hb_feature_t CreateFeature(hb_tag_t tag, uint32_t value = 0) { |
| return {tag, value, 0 /* start */, static_cast<unsigned>(-1) /* end */}; |
| } |
| |
| constexpr hb_feature_t CreateFeature(char c1, |
| char c2, |
| char c3, |
| char c4, |
| uint32_t value = 0) { |
| return CreateFeature(HB_TAG(c1, c2, c3, c4), value); |
| } |
| |
| } // namespace |
| |
| base::Optional<unsigned> FontFeatures::FindValueForTesting(hb_tag_t tag) const { |
| for (const hb_feature_t& feature : features_) { |
| if (feature.tag == tag) |
| return feature.value; |
| } |
| return base::nullopt; |
| } |
| |
| void FontFeatures::Initialize(const FontDescription& description) { |
| DCHECK(IsEmpty()); |
| const bool is_horizontal = !description.IsVerticalAnyUpright(); |
| |
| constexpr hb_feature_t no_kern = CreateFeature('k', 'e', 'r', 'n'); |
| constexpr hb_feature_t no_vkrn = CreateFeature('v', 'k', 'r', 'n'); |
| switch (description.GetKerning()) { |
| case FontDescription::kNormalKerning: |
| // kern/vkrn are enabled by default in HarfBuzz |
| break; |
| case FontDescription::kNoneKerning: |
| Append(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 hb_feature_t no_clig = CreateFeature('c', 'l', 'i', 'g'); |
| constexpr hb_feature_t no_liga = CreateFeature('l', 'i', 'g', 'a'); |
| auto common = description.CommonLigaturesState(); |
| if (letter_spacing || |
| (common == disabled || (common == normal && default_is_off))) { |
| Append(no_liga); |
| Append(no_clig); |
| } |
| // dlig is off by default in HarfBuzz |
| constexpr hb_feature_t dlig = CreateFeature('d', 'l', 'i', 'g', 1); |
| auto discretionary = description.DiscretionaryLigaturesState(); |
| if (!letter_spacing && discretionary == enabled) { |
| Append(dlig); |
| } |
| // hlig is off by default in HarfBuzz |
| constexpr hb_feature_t hlig = CreateFeature('h', 'l', 'i', 'g', 1); |
| auto historical = description.HistoricalLigaturesState(); |
| if (!letter_spacing && historical == enabled) { |
| Append(hlig); |
| } |
| // calt is on by default in HarfBuzz |
| constexpr hb_feature_t no_calt = CreateFeature('c', 'a', 'l', 't'); |
| auto contextual = description.ContextualLigaturesState(); |
| if (letter_spacing || |
| (contextual == disabled || (contextual == normal && default_is_off))) { |
| Append(no_calt); |
| } |
| } |
| |
| static constexpr hb_feature_t hwid = CreateFeature('h', 'w', 'i', 'd', 1); |
| static constexpr hb_feature_t twid = CreateFeature('t', 'w', 'i', 'd', 1); |
| static constexpr hb_feature_t qwid = CreateFeature('q', 'w', 'i', 'd', 1); |
| switch (description.WidthVariant()) { |
| case kHalfWidth: |
| Append(hwid); |
| break; |
| case kThirdWidth: |
| Append(twid); |
| break; |
| case kQuarterWidth: |
| Append(qwid); |
| break; |
| case kRegularWidth: |
| break; |
| } |
| |
| // font-variant-east-asian: |
| const FontVariantEastAsian east_asian = description.VariantEastAsian(); |
| if (UNLIKELY(!east_asian.IsAllNormal())) { |
| static constexpr hb_feature_t jp78 = CreateFeature('j', 'p', '7', '8', 1); |
| static constexpr hb_feature_t jp83 = CreateFeature('j', 'p', '8', '3', 1); |
| static constexpr hb_feature_t jp90 = CreateFeature('j', 'p', '9', '0', 1); |
| static constexpr hb_feature_t jp04 = CreateFeature('j', 'p', '0', '4', 1); |
| static constexpr hb_feature_t smpl = CreateFeature('s', 'm', 'p', 'l', 1); |
| static constexpr hb_feature_t trad = CreateFeature('t', 'r', 'a', 'd', 1); |
| switch (east_asian.Form()) { |
| case FontVariantEastAsian::kNormalForm: |
| break; |
| case FontVariantEastAsian::kJis78: |
| Append(jp78); |
| break; |
| case FontVariantEastAsian::kJis83: |
| Append(jp83); |
| break; |
| case FontVariantEastAsian::kJis90: |
| Append(jp90); |
| break; |
| case FontVariantEastAsian::kJis04: |
| Append(jp04); |
| break; |
| case FontVariantEastAsian::kSimplified: |
| Append(smpl); |
| break; |
| case FontVariantEastAsian::kTraditional: |
| Append(trad); |
| break; |
| default: |
| NOTREACHED(); |
| } |
| static constexpr hb_feature_t fwid = CreateFeature('f', 'w', 'i', 'd', 1); |
| static constexpr hb_feature_t pwid = CreateFeature('p', 'w', 'i', 'd', 1); |
| switch (east_asian.Width()) { |
| case FontVariantEastAsian::kNormalWidth: |
| break; |
| case FontVariantEastAsian::kFullWidth: |
| Append(fwid); |
| break; |
| case FontVariantEastAsian::kProportionalWidth: |
| Append(pwid); |
| break; |
| default: |
| NOTREACHED(); |
| } |
| static constexpr hb_feature_t ruby = CreateFeature('r', 'u', 'b', 'y', 1); |
| if (east_asian.Ruby()) |
| Append(ruby); |
| } |
| |
| // font-variant-numeric: |
| static constexpr hb_feature_t lnum = CreateFeature('l', 'n', 'u', 'm', 1); |
| if (description.VariantNumeric().NumericFigureValue() == |
| FontVariantNumeric::kLiningNums) |
| Append(lnum); |
| |
| static constexpr hb_feature_t onum = CreateFeature('o', 'n', 'u', 'm', 1); |
| if (description.VariantNumeric().NumericFigureValue() == |
| FontVariantNumeric::kOldstyleNums) |
| Append(onum); |
| |
| static constexpr hb_feature_t pnum = CreateFeature('p', 'n', 'u', 'm', 1); |
| if (description.VariantNumeric().NumericSpacingValue() == |
| FontVariantNumeric::kProportionalNums) |
| Append(pnum); |
| static constexpr hb_feature_t tnum = CreateFeature('t', 'n', 'u', 'm', 1); |
| if (description.VariantNumeric().NumericSpacingValue() == |
| FontVariantNumeric::kTabularNums) |
| Append(tnum); |
| |
| static constexpr hb_feature_t afrc = CreateFeature('a', 'f', 'r', 'c', 1); |
| if (description.VariantNumeric().NumericFractionValue() == |
| FontVariantNumeric::kStackedFractions) |
| Append(afrc); |
| static constexpr hb_feature_t frac = CreateFeature('f', 'r', 'a', 'c', 1); |
| if (description.VariantNumeric().NumericFractionValue() == |
| FontVariantNumeric::kDiagonalFractions) |
| Append(frac); |
| |
| static constexpr hb_feature_t ordn = CreateFeature('o', 'r', 'd', 'n', 1); |
| if (description.VariantNumeric().OrdinalValue() == |
| FontVariantNumeric::kOrdinalOn) |
| Append(ordn); |
| |
| static constexpr hb_feature_t zero = CreateFeature('z', 'e', 'r', 'o', 1); |
| if (description.VariantNumeric().SlashedZeroValue() == |
| FontVariantNumeric::kSlashedZeroOn) |
| Append(zero); |
| |
| const hb_tag_t chws_or_vchw = |
| is_horizontal ? HB_TAG('c', 'h', 'w', 's') : HB_TAG('v', 'c', 'h', 'w'); |
| bool default_enable_chws = true; |
| |
| const FontFeatureSettings* settings = description.FeatureSettings(); |
| if (UNLIKELY(settings)) { |
| // TODO(drott): crbug.com/450619 Implement feature resolution instead of |
| // just appending the font-feature-settings. |
| const hb_tag_t halt_or_vhal = |
| is_horizontal ? HB_TAG('h', 'a', 'l', 't') : HB_TAG('v', 'h', 'a', 'l'); |
| const hb_tag_t palt_or_vpal = |
| is_horizontal ? HB_TAG('p', 'a', 'l', 't') : HB_TAG('v', 'p', 'a', 'l'); |
| for (const FontFeature& setting : *settings) { |
| const hb_feature_t feature = |
| CreateFeature(setting.Tag(), setting.Value()); |
| Append(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) |
| Append(CreateFeature(chws_or_vchw, 1)); |
| } |
| |
| } // namespace blink |
