gecko-dev/gfx/thebes/gfxGraphiteShaper.cpp

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C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "gfxGraphiteShaper.h"
#include "nsString.h"
#include "gfxContext.h"
#include "gfxFontConstants.h"
#include "gfxTextRun.h"
#include "graphite2/Font.h"
#include "graphite2/Segment.h"
#include "harfbuzz/hb.h"
#define FloatToFixed(f) (65536 * (f))
#define FixedToFloat(f) ((f) * (1.0 / 65536.0))
// Right shifts of negative (signed) integers are undefined, as are overflows
// when converting unsigned to negative signed integers.
// (If speed were an issue we could make some 2's complement assumptions.)
#define FixedToIntRound(f) \
((f) > 0 ? ((32768 + (f)) >> 16) : -((32767 - (f)) >> 16))
using namespace mozilla; // for AutoSwap_* types
/*
* Creation and destruction; on deletion, release any font tables we're holding
*/
gfxGraphiteShaper::gfxGraphiteShaper(gfxFont* aFont)
: gfxFontShaper(aFont),
mGrFace(mFont->GetFontEntry()->GetGrFace()),
mGrFont(nullptr),
mFallbackToSmallCaps(false) {
mCallbackData.mFont = aFont;
}
gfxGraphiteShaper::~gfxGraphiteShaper() {
if (mGrFont) {
gr_font_destroy(mGrFont);
}
mFont->GetFontEntry()->ReleaseGrFace(mGrFace);
}
/*static*/
float gfxGraphiteShaper::GrGetAdvance(const void* appFontHandle,
uint16_t glyphid) {
const CallbackData* cb = static_cast<const CallbackData*>(appFontHandle);
return FixedToFloat(cb->mFont->GetGlyphWidth(glyphid));
}
static inline uint32_t MakeGraphiteLangTag(uint32_t aTag) {
uint32_t grLangTag = aTag;
// replace trailing space-padding with NULs for graphite
uint32_t mask = 0x000000FF;
while ((grLangTag & mask) == ' ') {
grLangTag &= ~mask;
mask <<= 8;
}
return grLangTag;
}
struct GrFontFeatures {
gr_face* mFace;
gr_feature_val* mFeatures;
};
static void AddFeature(const uint32_t& aTag, uint32_t& aValue, void* aUserArg) {
GrFontFeatures* f = static_cast<GrFontFeatures*>(aUserArg);
const gr_feature_ref* fref = gr_face_find_fref(f->mFace, aTag);
if (fref) {
gr_fref_set_feature_value(fref, aValue, f->mFeatures);
}
}
bool gfxGraphiteShaper::ShapeText(DrawTarget* aDrawTarget,
const char16_t* aText, uint32_t aOffset,
uint32_t aLength, Script aScript,
bool aVertical, RoundingFlags aRounding,
gfxShapedText* aShapedText) {
// some font back-ends require this in order to get proper hinted metrics
if (!mFont->SetupCairoFont(aDrawTarget)) {
return false;
}
const gfxFontStyle* style = mFont->GetStyle();
if (!mGrFont) {
if (!mGrFace) {
return false;
}
if (mFont->ProvidesGlyphWidths()) {
gr_font_ops ops = {
sizeof(gr_font_ops), &GrGetAdvance,
nullptr // vertical text not yet implemented
};
mGrFont = gr_make_font_with_ops(mFont->GetAdjustedSize(), &mCallbackData,
&ops, mGrFace);
} else {
mGrFont = gr_make_font(mFont->GetAdjustedSize(), mGrFace);
}
if (!mGrFont) {
return false;
}
// determine whether petite-caps falls back to small-caps
if (style->variantCaps != NS_FONT_VARIANT_CAPS_NORMAL) {
switch (style->variantCaps) {
case NS_FONT_VARIANT_CAPS_ALLPETITE:
case NS_FONT_VARIANT_CAPS_PETITECAPS:
bool synLower, synUpper;
mFont->SupportsVariantCaps(aScript, style->variantCaps,
mFallbackToSmallCaps, synLower, synUpper);
break;
default:
break;
}
}
}
gfxFontEntry* entry = mFont->GetFontEntry();
uint32_t grLang = 0;
if (style->languageOverride) {
grLang = MakeGraphiteLangTag(style->languageOverride);
} else if (entry->mLanguageOverride) {
grLang = MakeGraphiteLangTag(entry->mLanguageOverride);
} else if (style->explicitLanguage) {
nsAutoCString langString;
style->language->ToUTF8String(langString);
grLang = GetGraphiteTagForLang(langString);
}
gr_feature_val* grFeatures = gr_face_featureval_for_lang(mGrFace, grLang);
// insert any merged features into Graphite feature list
GrFontFeatures f = {mGrFace, grFeatures};
MergeFontFeatures(style, mFont->GetFontEntry()->mFeatureSettings,
aShapedText->DisableLigatures(),
mFont->GetFontEntry()->FamilyName(), mFallbackToSmallCaps,
AddFeature, &f);
// Graphite shaping doesn't map U+00a0 (nbsp) to space if it is missing
// from the font, so check for that possibility. (Most fonts double-map
// the space glyph to both 0x20 and 0xA0, so this won't often be needed;
// so we don't copy the text until we know it's required.)
nsAutoString transformed;
const char16_t NO_BREAK_SPACE = 0x00a0;
if (!entry->HasCharacter(NO_BREAK_SPACE)) {
nsDependentSubstring src(aText, aLength);
if (src.FindChar(NO_BREAK_SPACE) != kNotFound) {
transformed = src;
transformed.ReplaceChar(NO_BREAK_SPACE, ' ');
aText = transformed.BeginReading();
}
}
size_t numChars =
gr_count_unicode_characters(gr_utf16, aText, aText + aLength, nullptr);
gr_bidirtl grBidi = gr_bidirtl(
aShapedText->IsRightToLeft() ? (gr_rtl | gr_nobidi) : gr_nobidi);
gr_segment* seg = gr_make_seg(mGrFont, mGrFace, 0, grFeatures, gr_utf16,
aText, numChars, grBidi);
gr_featureval_destroy(grFeatures);
if (!seg) {
return false;
}
nsresult rv = SetGlyphsFromSegment(aShapedText, aOffset, aLength, aText, seg,
aRounding);
gr_seg_destroy(seg);
return NS_SUCCEEDED(rv);
}
#define SMALL_GLYPH_RUN \
256 // avoid heap allocation of per-glyph data arrays
// for short (typical) runs up to this length
struct Cluster {
uint32_t baseChar; // in UTF16 code units, not Unicode character indices
uint32_t baseGlyph;
uint32_t nChars; // UTF16 code units
uint32_t nGlyphs;
Cluster() : baseChar(0), baseGlyph(0), nChars(0), nGlyphs(0) {}
};
nsresult gfxGraphiteShaper::SetGlyphsFromSegment(
gfxShapedText* aShapedText, uint32_t aOffset, uint32_t aLength,
const char16_t* aText, gr_segment* aSegment, RoundingFlags aRounding) {
typedef gfxShapedText::CompressedGlyph CompressedGlyph;
int32_t dev2appUnits = aShapedText->GetAppUnitsPerDevUnit();
bool rtl = aShapedText->IsRightToLeft();
uint32_t glyphCount = gr_seg_n_slots(aSegment);
// identify clusters; graphite may have reordered/expanded/ligated glyphs.
AutoTArray<Cluster, SMALL_GLYPH_RUN> clusters;
AutoTArray<uint16_t, SMALL_GLYPH_RUN> gids;
AutoTArray<float, SMALL_GLYPH_RUN> xLocs;
AutoTArray<float, SMALL_GLYPH_RUN> yLocs;
if (!clusters.SetLength(aLength, fallible) ||
!gids.SetLength(glyphCount, fallible) ||
!xLocs.SetLength(glyphCount, fallible) ||
!yLocs.SetLength(glyphCount, fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
// walk through the glyph slots and check which original character
// each is associated with
uint32_t gIndex = 0; // glyph slot index
uint32_t cIndex = 0; // current cluster index
for (const gr_slot* slot = gr_seg_first_slot(aSegment); slot != nullptr;
slot = gr_slot_next_in_segment(slot), gIndex++) {
uint32_t before =
gr_cinfo_base(gr_seg_cinfo(aSegment, gr_slot_before(slot)));
uint32_t after = gr_cinfo_base(gr_seg_cinfo(aSegment, gr_slot_after(slot)));
gids[gIndex] = gr_slot_gid(slot);
xLocs[gIndex] = gr_slot_origin_X(slot);
yLocs[gIndex] = gr_slot_origin_Y(slot);
// if this glyph has a "before" character index that precedes the
// current cluster's char index, we need to merge preceding
// clusters until it gets included
while (before < clusters[cIndex].baseChar && cIndex > 0) {
clusters[cIndex - 1].nChars += clusters[cIndex].nChars;
clusters[cIndex - 1].nGlyphs += clusters[cIndex].nGlyphs;
--cIndex;
}
// if there's a gap between the current cluster's base character and
// this glyph's, extend the cluster to include the intervening chars
if (gr_slot_can_insert_before(slot) && clusters[cIndex].nChars &&
before >= clusters[cIndex].baseChar + clusters[cIndex].nChars) {
NS_ASSERTION(cIndex < aLength - 1, "cIndex at end of word");
Cluster& c = clusters[cIndex + 1];
c.baseChar = clusters[cIndex].baseChar + clusters[cIndex].nChars;
c.nChars = before - c.baseChar;
c.baseGlyph = gIndex;
c.nGlyphs = 0;
++cIndex;
}
// increment cluster's glyph count to include current slot
NS_ASSERTION(cIndex < aLength, "cIndex beyond word length");
++clusters[cIndex].nGlyphs;
// bump |after| index if it falls in the middle of a surrogate pair
if (NS_IS_HIGH_SURROGATE(aText[after]) && after < aLength - 1 &&
NS_IS_LOW_SURROGATE(aText[after + 1])) {
after++;
}
// extend cluster if necessary to reach the glyph's "after" index
if (clusters[cIndex].baseChar + clusters[cIndex].nChars < after + 1) {
clusters[cIndex].nChars = after + 1 - clusters[cIndex].baseChar;
}
}
CompressedGlyph* charGlyphs = aShapedText->GetCharacterGlyphs() + aOffset;
bool roundX = bool(aRounding & RoundingFlags::kRoundX);
bool roundY = bool(aRounding & RoundingFlags::kRoundY);
// now put glyphs into the textrun, one cluster at a time
for (uint32_t i = 0; i <= cIndex; ++i) {
const Cluster& c = clusters[i];
float adv; // total advance of the cluster
if (rtl) {
if (i == 0) {
adv = gr_seg_advance_X(aSegment) - xLocs[c.baseGlyph];
} else {
adv = xLocs[clusters[i - 1].baseGlyph] - xLocs[c.baseGlyph];
}
} else {
if (i == cIndex) {
adv = gr_seg_advance_X(aSegment) - xLocs[c.baseGlyph];
} else {
adv = xLocs[clusters[i + 1].baseGlyph] - xLocs[c.baseGlyph];
}
}
// Check for default-ignorable char that didn't get filtered, combined,
// etc by the shaping process, and skip it.
uint32_t offs = c.baseChar;
NS_ASSERTION(offs < aLength, "unexpected offset");
if (c.nGlyphs == 1 && c.nChars == 1 &&
aShapedText->FilterIfIgnorable(aOffset + offs, aText[offs])) {
continue;
}
uint32_t appAdvance = roundX ? NSToIntRound(adv) * dev2appUnits
: NSToIntRound(adv * dev2appUnits);
if (c.nGlyphs == 1 && CompressedGlyph::IsSimpleGlyphID(gids[c.baseGlyph]) &&
CompressedGlyph::IsSimpleAdvance(appAdvance) &&
charGlyphs[offs].IsClusterStart() && yLocs[c.baseGlyph] == 0) {
charGlyphs[offs].SetSimpleGlyph(appAdvance, gids[c.baseGlyph]);
} else {
// not a one-to-one mapping with simple metrics: use DetailedGlyph
AutoTArray<gfxShapedText::DetailedGlyph, 8> details;
float clusterLoc;
for (uint32_t j = c.baseGlyph; j < c.baseGlyph + c.nGlyphs; ++j) {
gfxShapedText::DetailedGlyph* d = details.AppendElement();
d->mGlyphID = gids[j];
d->mOffset.y = roundY ? NSToIntRound(-yLocs[j]) * dev2appUnits
: -yLocs[j] * dev2appUnits;
if (j == c.baseGlyph) {
d->mAdvance = appAdvance;
clusterLoc = xLocs[j];
} else {
float dx =
rtl ? (xLocs[j] - clusterLoc) : (xLocs[j] - clusterLoc - adv);
d->mOffset.x =
roundX ? NSToIntRound(dx) * dev2appUnits : dx * dev2appUnits;
d->mAdvance = 0;
}
}
bool isClusterStart = charGlyphs[offs].IsClusterStart();
aShapedText->SetGlyphs(
aOffset + offs,
CompressedGlyph::MakeComplex(isClusterStart, true, details.Length()),
details.Elements());
}
for (uint32_t j = c.baseChar + 1; j < c.baseChar + c.nChars; ++j) {
NS_ASSERTION(j < aLength, "unexpected offset");
CompressedGlyph& g = charGlyphs[j];
NS_ASSERTION(!g.IsSimpleGlyph(), "overwriting a simple glyph");
g.SetComplex(g.IsClusterStart(), false, 0);
}
}
return NS_OK;
}
#undef SMALL_GLYPH_RUN
// for language tag validation - include list of tags from the IANA registry
#include "gfxLanguageTagList.cpp"
nsTHashtable<nsUint32HashKey>* gfxGraphiteShaper::sLanguageTags;
/*static*/
uint32_t gfxGraphiteShaper::GetGraphiteTagForLang(const nsCString& aLang) {
int len = aLang.Length();
if (len < 2) {
return 0;
}
// convert primary language subtag to a left-packed, NUL-padded integer
// for the Graphite API
uint32_t grLang = 0;
for (int i = 0; i < 4; ++i) {
grLang <<= 8;
if (i < len) {
uint8_t ch = aLang[i];
if (ch == '-') {
// found end of primary language subtag, truncate here
len = i;
continue;
}
if (ch < 'a' || ch > 'z') {
// invalid character in tag, so ignore it completely
return 0;
}
grLang += ch;
}
}
// valid tags must have length = 2 or 3
if (len < 2 || len > 3) {
return 0;
}
if (!sLanguageTags) {
// store the registered IANA tags in a hash for convenient validation
sLanguageTags =
new nsTHashtable<nsUint32HashKey>(ArrayLength(sLanguageTagList));
for (const uint32_t* tag = sLanguageTagList; *tag != 0; ++tag) {
sLanguageTags->PutEntry(*tag);
}
}
// only accept tags known in the IANA registry
if (sLanguageTags->GetEntry(grLang)) {
return grLang;
}
return 0;
}
/*static*/
void gfxGraphiteShaper::Shutdown() {
#ifdef NS_FREE_PERMANENT_DATA
if (sLanguageTags) {
sLanguageTags->Clear();
delete sLanguageTags;
sLanguageTags = nullptr;
}
#endif
}