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gecko-dev/gfx/thebes/gfxHarfBuzzShaper.cpp

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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Corporation code.
*
* The Initial Developer of the Original Code is
* the Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2009-2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Jonathan Kew <jfkthame@gmail.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "prtypes.h"
#include "prmem.h"
#include "nsString.h"
#include "nsBidiUtils.h"
#include "nsMathUtils.h"
#include "gfxTypes.h"
#include "gfxContext.h"
#include "gfxPlatform.h"
#include "gfxHarfBuzzShaper.h"
#include "gfxFontUtils.h"
#include "gfxUnicodeProperties.h"
#include "harfbuzz/hb-unicode.h"
#include "harfbuzz/hb-ot.h"
#include "cairo.h"
#include "nsUnicodeRange.h"
#include "nsCRT.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
*/
gfxHarfBuzzShaper::gfxHarfBuzzShaper(gfxFont *aFont)
: gfxFontShaper(aFont),
mHBFace(nsnull),
mKernTable(nsnull),
mHmtxTable(nsnull),
mNumLongMetrics(0),
mCmapTable(nsnull),
mCmapFormat(-1),
mSubtableOffset(0),
mUVSTableOffset(0),
mUseFontGetGlyph(aFont->ProvidesGetGlyph()),
mUseFontGlyphWidths(PR_FALSE)
{
}
gfxHarfBuzzShaper::~gfxHarfBuzzShaper()
{
hb_blob_destroy(mCmapTable);
hb_blob_destroy(mHmtxTable);
hb_blob_destroy(mKernTable);
hb_face_destroy(mHBFace);
}
/*
* HarfBuzz callback access to font table data
*/
// callback for HarfBuzz to get a font table (in hb_blob_t form)
// from the shaper (passed as aUserData)
static hb_blob_t *
HBGetTable(hb_tag_t aTag, void *aUserData)
{
gfxHarfBuzzShaper *shaper = static_cast<gfxHarfBuzzShaper*>(aUserData);
return shaper->GetFont()->GetFontTable(aTag);
}
/*
* HarfBuzz font callback functions; user_data is a ptr to a
* FontCallbackData struct
*/
struct FontCallbackData {
FontCallbackData(gfxHarfBuzzShaper *aShaper, gfxContext *aContext)
: mShaper(aShaper), mContext(aContext)
{ }
gfxHarfBuzzShaper *mShaper;
gfxContext *mContext;
};
#define UNICODE_BMP_LIMIT 0x10000
hb_codepoint_t
gfxHarfBuzzShaper::GetGlyph(hb_codepoint_t unicode,
hb_codepoint_t variation_selector) const
{
if (mUseFontGetGlyph) {
return mFont->GetGlyph(unicode, variation_selector);
}
// we only instantiate a harfbuzz shaper if there's a cmap available
NS_ASSERTION(mFont->GetFontEntry()->HasCmapTable(),
"we cannot be using this font!");
NS_ASSERTION(mCmapTable && (mCmapFormat > 0) && (mSubtableOffset > 0),
"cmap data not correctly set up, expect disaster");
const PRUint8* data = (const PRUint8*)hb_blob_lock(mCmapTable);
hb_codepoint_t gid;
switch (mCmapFormat) {
case 4:
gid = unicode < UNICODE_BMP_LIMIT ?
gfxFontUtils::MapCharToGlyphFormat4(data + mSubtableOffset, unicode) : 0;
break;
case 12:
gid = gfxFontUtils::MapCharToGlyphFormat12(data + mSubtableOffset, unicode);
break;
default:
NS_WARNING("unsupported cmap format, glyphs will be missing");
gid = 0;
break;
}
if (gid && variation_selector && mUVSTableOffset) {
hb_codepoint_t varGID =
gfxFontUtils::MapUVSToGlyphFormat14(data + mUVSTableOffset,
unicode, variation_selector);
if (varGID) {
gid = varGID;
}
// else the variation sequence was not supported, use default mapping
// of the character code alone
}
hb_blob_unlock(mCmapTable);
return gid;
}
static hb_codepoint_t
HBGetGlyph(hb_font_t *font, hb_face_t *face, const void *user_data,
hb_codepoint_t unicode, hb_codepoint_t variation_selector)
{
const FontCallbackData *fcd =
static_cast<const FontCallbackData*>(user_data);
return fcd->mShaper->GetGlyph(unicode, variation_selector);
}
struct HMetricsHeader {
AutoSwap_PRUint32 tableVersionNumber;
AutoSwap_PRInt16 ascender;
AutoSwap_PRInt16 descender;
AutoSwap_PRInt16 lineGap;
AutoSwap_PRUint16 advanceWidthMax;
AutoSwap_PRInt16 minLeftSideBearing;
AutoSwap_PRInt16 minRightSideBearing;
AutoSwap_PRInt16 xMaxExtent;
AutoSwap_PRInt16 caretSlopeRise;
AutoSwap_PRInt16 caretSlopeRun;
AutoSwap_PRInt16 caretOffset;
AutoSwap_PRInt16 reserved[4];
AutoSwap_PRInt16 metricDataFormat;
AutoSwap_PRUint16 numberOfHMetrics;
};
struct HLongMetric {
AutoSwap_PRUint16 advanceWidth;
AutoSwap_PRInt16 lsb;
};
struct HMetrics {
HLongMetric metrics[1]; // actually numberOfHMetrics
// the variable-length metrics[] array is immediately followed by:
// AutoSwap_PRUint16 leftSideBearing[];
};
void
gfxHarfBuzzShaper::GetGlyphAdvance(gfxContext *aContext,
hb_codepoint_t glyph,
hb_position_t *x_advance,
hb_position_t *y_advance) const
{
if (mUseFontGlyphWidths) {
*x_advance = mFont->GetGlyphWidth(aContext, glyph);
return;
}
// font did not implement GetHintedGlyphWidth, so get an unhinted value
// directly from the font tables
NS_ASSERTION((mNumLongMetrics > 0) && mHmtxTable != nsnull,
"font is lacking metrics, we shouldn't be here");
if (glyph >= PRUint32(mNumLongMetrics)) {
glyph = mNumLongMetrics - 1;
}
// glyph must be valid now, because we checked during initialization
// that mNumLongMetrics is > 0, and that the hmtx table is large enough
// to contain mNumLongMetrics records
const HMetrics* hmtx =
reinterpret_cast<const HMetrics*>(hb_blob_lock(mHmtxTable));
*x_advance =
FloatToFixed(mFont->FUnitsToDevUnitsFactor() *
PRUint16(hmtx->metrics[glyph].advanceWidth));
hb_blob_unlock(mHmtxTable);
}
static void
HBGetGlyphAdvance(hb_font_t *font, hb_face_t *face, const void *user_data,
hb_codepoint_t glyph,
hb_position_t *x_advance, hb_position_t *y_advance)
{
const FontCallbackData *fcd =
static_cast<const FontCallbackData*>(user_data);
fcd->mShaper->GetGlyphAdvance(fcd->mContext, glyph, x_advance, y_advance);
}
static hb_bool_t
HBGetContourPoint(hb_font_t *font, hb_face_t *face, const void *user_data,
unsigned int point_index, hb_codepoint_t glyph,
hb_position_t *x, hb_position_t *y)
{
/* not yet implemented - no support for used of hinted contour points
to fine-tune anchor positions in GPOS AnchorFormat2 */
return false;
}
struct KernHeaderFmt0 {
AutoSwap_PRUint16 nPairs;
AutoSwap_PRUint16 searchRange;
AutoSwap_PRUint16 entrySelector;
AutoSwap_PRUint16 rangeShift;
};
struct KernPair {
AutoSwap_PRUint16 left;
AutoSwap_PRUint16 right;
AutoSwap_PRInt16 value;
};
// Find a kern pair in a Format 0 subtable.
// The aSubtable parameter points to the subtable itself, NOT its header,
// as the header structure differs between Windows and Mac (v0 and v1.0)
// versions of the 'kern' table.
// aSubtableLen is the length of the subtable EXCLUDING its header.
// If the pair <aFirstGlyph,aSecondGlyph> is found, the kerning value is
// added to aValue, so that multiple subtables can accumulate a total
// kerning value for a given pair.
static void
GetKernValueFmt0(const void* aSubtable,
PRUint32 aSubtableLen,
PRUint16 aFirstGlyph,
PRUint16 aSecondGlyph,
PRInt32& aValue,
PRBool aIsOverride = PR_FALSE,
PRBool aIsMinimum = PR_FALSE)
{
const KernHeaderFmt0* hdr =
reinterpret_cast<const KernHeaderFmt0*>(aSubtable);
const KernPair *lo = reinterpret_cast<const KernPair*>(hdr + 1);
const KernPair *hi = lo + PRUint16(hdr->nPairs);
const KernPair *limit = hi;
if (reinterpret_cast<const char*>(aSubtable) + aSubtableLen <
reinterpret_cast<const char*>(hi)) {
// subtable is not large enough to contain the claimed number
// of kern pairs, so just ignore it
return;
}
#define KERN_PAIR_KEY(l,r) (PRUint32((PRUint16(l) << 16) + PRUint16(r)))
PRUint32 key = KERN_PAIR_KEY(aFirstGlyph, aSecondGlyph);
while (lo < hi) {
const KernPair *mid = lo + (hi - lo) / 2;
if (KERN_PAIR_KEY(mid->left, mid->right) < key) {
lo = mid + 1;
} else {
hi = mid;
}
}
if (lo < limit && KERN_PAIR_KEY(lo->left, lo->right) == key) {
if (aIsOverride) {
aValue = PRInt16(lo->value);
} else if (aIsMinimum) {
aValue = PR_MAX(aValue, PRInt16(lo->value));
} else {
aValue += PRInt16(lo->value);
}
}
}
// Get kerning value from Apple (version 1.0) kern table,
// subtable format 2 (simple N x M array of kerning values)
// See http://developer.apple.com/fonts/TTRefMan/RM06/Chap6kern.html
// for details of version 1.0 format 2 subtable.
struct KernHeaderVersion1Fmt2 {
KernTableSubtableHeaderVersion1 header;
AutoSwap_PRUint16 rowWidth;
AutoSwap_PRUint16 leftOffsetTable;
AutoSwap_PRUint16 rightOffsetTable;
AutoSwap_PRUint16 array;
};
struct KernClassTableHdr {
AutoSwap_PRUint16 firstGlyph;
AutoSwap_PRUint16 nGlyphs;
AutoSwap_PRUint16 offsets[1]; // actually an array of nGlyphs entries
};
static PRInt16
GetKernValueVersion1Fmt2(const void* aSubtable,
PRUint32 aSubtableLen,
PRUint16 aFirstGlyph,
PRUint16 aSecondGlyph)
{
if (aSubtableLen < sizeof(KernHeaderVersion1Fmt2)) {
return 0;
}
const char* base = reinterpret_cast<const char*>(aSubtable);
const char* subtableEnd = base + aSubtableLen;
const KernHeaderVersion1Fmt2* h =
reinterpret_cast<const KernHeaderVersion1Fmt2*>(aSubtable);
PRUint32 offset = h->array;
const KernClassTableHdr* leftClassTable =
reinterpret_cast<const KernClassTableHdr*>(base +
PRUint16(h->leftOffsetTable));
if (reinterpret_cast<const char*>(leftClassTable) +
sizeof(KernClassTableHdr) > subtableEnd) {
return 0;
}
if (aFirstGlyph >= PRUint16(leftClassTable->firstGlyph)) {
aFirstGlyph -= PRUint16(leftClassTable->firstGlyph);
if (aFirstGlyph < PRUint16(leftClassTable->nGlyphs)) {
if (reinterpret_cast<const char*>(leftClassTable) +
sizeof(KernClassTableHdr) +
aFirstGlyph * sizeof(PRUint16) >= subtableEnd) {
return 0;
}
offset = PRUint16(leftClassTable->offsets[aFirstGlyph]);
}
}
const KernClassTableHdr* rightClassTable =
reinterpret_cast<const KernClassTableHdr*>(base +
PRUint16(h->rightOffsetTable));
if (reinterpret_cast<const char*>(rightClassTable) +
sizeof(KernClassTableHdr) > subtableEnd) {
return 0;
}
if (aSecondGlyph >= PRUint16(rightClassTable->firstGlyph)) {
aSecondGlyph -= PRUint16(rightClassTable->firstGlyph);
if (aSecondGlyph < PRUint16(rightClassTable->nGlyphs)) {
if (reinterpret_cast<const char*>(rightClassTable) +
sizeof(KernClassTableHdr) +
aSecondGlyph * sizeof(PRUint16) >= subtableEnd) {
return 0;
}
offset += PRUint16(rightClassTable->offsets[aSecondGlyph]);
}
}
const AutoSwap_PRInt16* pval =
reinterpret_cast<const AutoSwap_PRInt16*>(base + offset);
if (reinterpret_cast<const char*>(pval + 1) >= subtableEnd) {
return 0;
}
return *pval;
}
// Get kerning value from Apple (version 1.0) kern table,
// subtable format 3 (simple N x M array of kerning values)
// See http://developer.apple.com/fonts/TTRefMan/RM06/Chap6kern.html
// for details of version 1.0 format 3 subtable.
struct KernHeaderVersion1Fmt3 {
KernTableSubtableHeaderVersion1 header;
AutoSwap_PRUint16 glyphCount;
PRUint8 kernValueCount;
PRUint8 leftClassCount;
PRUint8 rightClassCount;
PRUint8 flags;
};
static PRInt16
GetKernValueVersion1Fmt3(const void* aSubtable,
PRUint32 aSubtableLen,
PRUint16 aFirstGlyph,
PRUint16 aSecondGlyph)
{
// check that we can safely read the header fields
if (aSubtableLen < sizeof(KernHeaderVersion1Fmt3)) {
return 0;
}
const KernHeaderVersion1Fmt3* hdr =
reinterpret_cast<const KernHeaderVersion1Fmt3*>(aSubtable);
if (hdr->flags != 0) {
return 0;
}
PRUint16 glyphCount = hdr->glyphCount;
// check that table is large enough for the arrays
if (sizeof(KernHeaderVersion1Fmt3) +
hdr->kernValueCount * sizeof(PRInt16) +
glyphCount + glyphCount +
hdr->leftClassCount * hdr->rightClassCount > aSubtableLen) {
return 0;
}
if (aFirstGlyph >= glyphCount || aSecondGlyph >= glyphCount) {
// glyphs are out of range for the class tables
return 0;
}
// get pointers to the four arrays within the subtable
const AutoSwap_PRInt16* kernValue =
reinterpret_cast<const AutoSwap_PRInt16*>(hdr + 1);
const PRUint8* leftClass =
reinterpret_cast<const PRUint8*>(kernValue + hdr->kernValueCount);
const PRUint8* rightClass = leftClass + glyphCount;
const PRUint8* kernIndex = rightClass + glyphCount;
PRUint8 lc = leftClass[aFirstGlyph];
PRUint8 rc = rightClass[aSecondGlyph];
if (lc >= hdr->leftClassCount || rc >= hdr->rightClassCount) {
return 0;
}
PRUint8 ki = kernIndex[leftClass[aFirstGlyph] * hdr->rightClassCount +
rightClass[aSecondGlyph]];
if (ki >= hdr->kernValueCount) {
return 0;
}
return kernValue[ki];
}
#define KERN0_COVERAGE_HORIZONTAL 0x0001
#define KERN0_COVERAGE_MINIMUM 0x0002
#define KERN0_COVERAGE_CROSS_STREAM 0x0004
#define KERN0_COVERAGE_OVERRIDE 0x0008
#define KERN0_COVERAGE_RESERVED 0x00F0
#define KERN1_COVERAGE_VERTICAL 0x8000
#define KERN1_COVERAGE_CROSS_STREAM 0x4000
#define KERN1_COVERAGE_VARIATION 0x2000
#define KERN1_COVERAGE_RESERVED 0x1F00
hb_position_t
gfxHarfBuzzShaper::GetKerning(PRUint16 aFirstGlyph,
PRUint16 aSecondGlyph) const
{
// We want to ignore any kern pairs involving <space>, because we are
// handling words in isolation, the only space characters seen here are
// the ones artificially added by the textRun code.
PRUint32 spaceGlyph = mFont->GetSpaceGlyph();
if (aFirstGlyph == spaceGlyph || aSecondGlyph == spaceGlyph) {
return 0;
}
if (!mKernTable) {
mKernTable = mFont->GetFontTable(TRUETYPE_TAG('k','e','r','n'));
if (!mKernTable) {
mKernTable = hb_blob_create_empty();
}
}
PRUint32 len = hb_blob_get_length(mKernTable);
if (len < sizeof(KernTableVersion0)) {
return 0;
}
PRInt32 value = 0;
const char* base = reinterpret_cast<const char*>(hb_blob_lock(mKernTable));
// First try to interpret as "version 0" kern table
// (see http://www.microsoft.com/typography/otspec/kern.htm)
const KernTableVersion0* kern0 =
reinterpret_cast<const KernTableVersion0*>(base);
if (PRUint16(kern0->version) == 0) {
PRUint16 nTables = kern0->nTables;
PRUint32 offs = sizeof(KernTableVersion0);
for (PRUint16 i = 0; i < nTables; ++i) {
if (offs + sizeof(KernTableSubtableHeaderVersion0) > len) {
break;
}
const KernTableSubtableHeaderVersion0* st0 =
reinterpret_cast<const KernTableSubtableHeaderVersion0*>
(base + offs);
PRUint16 subtableLen = PRUint16(st0->length);
if (offs + subtableLen > len) {
break;
}
offs += subtableLen;
PRUint16 coverage = st0->coverage;
if (!(coverage & KERN0_COVERAGE_HORIZONTAL)) {
// we only care about horizontal kerning (for now)
continue;
}
if (coverage &
(KERN0_COVERAGE_CROSS_STREAM | KERN0_COVERAGE_RESERVED)) {
// we don't support cross-stream kerning, and
// reserved bits should be zero;
// ignore the subtable if not
continue;
}
PRUint8 format = (coverage >> 8);
switch (format) {
case 0:
GetKernValueFmt0(st0 + 1, subtableLen - sizeof(*st0),
aFirstGlyph, aSecondGlyph, value,
(coverage & KERN0_COVERAGE_OVERRIDE) != 0,
(coverage & KERN0_COVERAGE_MINIMUM) != 0);
break;
default:
// TODO: implement support for other formats,
// if they're ever used in practice
#if DEBUG
{
char buf[1024];
sprintf(buf, "unknown kern subtable in %s: "
"ver 0 format %d\n",
NS_ConvertUTF16toUTF8(mFont->GetName()).get(),
format);
NS_WARNING(buf);
}
#endif
break;
}
}
} else {
// It wasn't a "version 0" table; check if it is Apple version 1.0
// (see http://developer.apple.com/fonts/TTRefMan/RM06/Chap6kern.html)
const KernTableVersion1* kern1 =
reinterpret_cast<const KernTableVersion1*>(base);
if (PRUint32(kern1->version) == 0x00010000) {
PRUint32 nTables = kern1->nTables;
PRUint32 offs = sizeof(KernTableVersion1);
for (PRUint32 i = 0; i < nTables; ++i) {
if (offs + sizeof(KernTableSubtableHeaderVersion1) > len) {
break;
}
const KernTableSubtableHeaderVersion1* st1 =
reinterpret_cast<const KernTableSubtableHeaderVersion1*>
(base + offs);
PRUint32 subtableLen = PRUint32(st1->length);
offs += subtableLen;
PRUint16 coverage = st1->coverage;
if (coverage &
(KERN1_COVERAGE_VERTICAL |
KERN1_COVERAGE_CROSS_STREAM |
KERN1_COVERAGE_VARIATION |
KERN1_COVERAGE_RESERVED)) {
// we only care about horizontal kerning (for now),
// we don't support cross-stream kerning,
// we don't support variations,
// reserved bits should be zero;
// ignore the subtable if not
continue;
}
PRUint8 format = (coverage & 0xff);
switch (format) {
case 0:
GetKernValueFmt0(st1 + 1, subtableLen - sizeof(*st1),
aFirstGlyph, aSecondGlyph, value);
break;
case 2:
value = GetKernValueVersion1Fmt2(st1, subtableLen,
aFirstGlyph, aSecondGlyph);
break;
case 3:
value = GetKernValueVersion1Fmt3(st1, subtableLen,
aFirstGlyph, aSecondGlyph);
break;
default:
// TODO: implement support for other formats.
// Note that format 1 cannot be supported here,
// as it requires the full glyph array to run the FSM,
// not just the current glyph pair.
#if DEBUG
{
char buf[1024];
sprintf(buf, "unknown kern subtable in %s: "
"ver 0 format %d\n",
NS_ConvertUTF16toUTF8(mFont->GetName()).get(),
format);
NS_WARNING(buf);
}
#endif
break;
}
}
}
}
hb_blob_unlock(mKernTable);
if (value != 0) {
return FloatToFixed(mFont->FUnitsToDevUnitsFactor() * value);
}
return 0;
}
static hb_position_t
HBGetKerning(hb_font_t *font, hb_face_t *face, const void *user_data,
hb_codepoint_t first_glyph, hb_codepoint_t second_glyph)
{
const FontCallbackData *fcd =
static_cast<const FontCallbackData*>(user_data);
return fcd->mShaper->GetKerning(first_glyph, second_glyph);
}
/*
* HarfBuzz unicode property callbacks
*/
static hb_codepoint_t
HBGetMirroring(hb_codepoint_t aCh)
{
return gfxUnicodeProperties::GetMirroredChar(aCh);
}
static hb_category_t
HBGetGeneralCategory(hb_codepoint_t aCh)
{
return hb_category_t(gfxUnicodeProperties::GetGeneralCategory(aCh));
}
static hb_script_t
HBGetScript(hb_codepoint_t aCh)
{
return hb_script_t(gfxUnicodeProperties::GetScriptCode(aCh));
}
static unsigned int
HBGetCombiningClass(hb_codepoint_t aCh)
{
return gfxUnicodeProperties::GetCombiningClass(aCh);
}
static unsigned int
HBGetEastAsianWidth(hb_codepoint_t aCh)
{
return gfxUnicodeProperties::GetEastAsianWidth(aCh);
}
/*
* gfxFontShaper override to initialize the text run using HarfBuzz
*/
static hb_font_funcs_t * sHBFontFuncs = nsnull;
static hb_unicode_funcs_t * sHBUnicodeFuncs = nsnull;
PRBool
gfxHarfBuzzShaper::InitTextRun(gfxContext *aContext,
gfxTextRun *aTextRun,
const PRUnichar *aString,
PRUint32 aRunStart,
PRUint32 aRunLength,
PRInt32 aRunScript)
{
// some font back-ends require this in order to get proper hinted metrics
mFont->SetupCairoFont(aContext);
if (!mHBFace) {
mUseFontGlyphWidths = mFont->ProvidesGlyphWidths();
// set up the harfbuzz face etc the first time we use the font
if (!sHBFontFuncs) {
// static function callback pointers, initialized by the first
// harfbuzz shaper used
sHBFontFuncs = hb_font_funcs_create();
hb_font_funcs_set_glyph_func(sHBFontFuncs, HBGetGlyph);
hb_font_funcs_set_glyph_advance_func(sHBFontFuncs,
HBGetGlyphAdvance);
hb_font_funcs_set_contour_point_func(sHBFontFuncs,
HBGetContourPoint);
hb_font_funcs_set_kerning_func(sHBFontFuncs, HBGetKerning);
sHBUnicodeFuncs = hb_unicode_funcs_create();
hb_unicode_funcs_set_mirroring_func(sHBUnicodeFuncs,
HBGetMirroring);
hb_unicode_funcs_set_script_func(sHBUnicodeFuncs, HBGetScript);
hb_unicode_funcs_set_general_category_func(sHBUnicodeFuncs,
HBGetGeneralCategory);
hb_unicode_funcs_set_combining_class_func(sHBUnicodeFuncs,
HBGetCombiningClass);
hb_unicode_funcs_set_eastasian_width_func(sHBUnicodeFuncs,
HBGetEastAsianWidth);
}
mHBFace = hb_face_create_for_tables(HBGetTable, nsnull, this);
if (!mUseFontGetGlyph) {
// get the cmap table and find offset to our subtable
mCmapTable = mFont->GetFontTable(TRUETYPE_TAG('c','m','a','p'));
if (!mCmapTable) {
NS_WARNING("failed to load cmap, glyphs will be missing");
return PR_FALSE;
}
const PRUint8* data = (const PRUint8*)hb_blob_lock(mCmapTable);
PRBool symbol;
mCmapFormat = gfxFontUtils::
FindPreferredSubtable(data, hb_blob_get_length(mCmapTable),
&mSubtableOffset, &mUVSTableOffset,
&symbol);
hb_blob_unlock(mCmapTable);
}
if (!mUseFontGlyphWidths) {
// if font doesn't implement GetGlyphWidth, we will be reading
// the hmtx table directly;
// read mNumLongMetrics from hhea table without caching its blob,
// and preload/cache the hmtx table
hb_blob_t *hheaTable =
mFont->GetFontTable(TRUETYPE_TAG('h','h','e','a'));
if (hheaTable &&
hb_blob_get_length(hheaTable) >= sizeof(HMetricsHeader)) {
const HMetricsHeader* hhea =
reinterpret_cast<const HMetricsHeader*>
(hb_blob_lock(hheaTable));
mNumLongMetrics = hhea->numberOfHMetrics;
hb_blob_unlock(hheaTable);
if (mNumLongMetrics > 0 &&
PRInt16(hhea->metricDataFormat) == 0) {
// no point reading hmtx if number of entries is zero!
// in that case, we won't be able to use this font
// (this method will return FALSE below if mHmtx is null)
mHmtxTable =
mFont->GetFontTable(TRUETYPE_TAG('h','m','t','x'));
if (hb_blob_get_length(mHmtxTable) <
mNumLongMetrics * sizeof(HLongMetric)) {
// hmtx table is not large enough for the claimed
// number of entries: invalid, do not use.
hb_blob_destroy(mHmtxTable);
mHmtxTable = nsnull;
}
}
}
hb_blob_destroy(hheaTable);
}
}
if ((!mUseFontGetGlyph && mCmapFormat <= 0) ||
(!mUseFontGlyphWidths && !mHmtxTable)) {
// unable to shape with this font
return PR_FALSE;
}
FontCallbackData fcd(this, aContext);
hb_font_t *font = hb_font_create();
hb_font_set_funcs(font, sHBFontFuncs, nsnull, &fcd);
hb_font_set_ppem(font, mFont->GetAdjustedSize(), mFont->GetAdjustedSize());
PRUint32 scale = FloatToFixed(mFont->GetAdjustedSize()); // 16.16 fixed-point
hb_font_set_scale(font, scale, scale);
// aRunStart and aRunLength define the section of the textRun and of
// aString that is to be drawn with this particular font
PRBool disableLigatures =
(aTextRun->GetFlags() &
gfxTextRunFactory::TEXT_DISABLE_OPTIONAL_LIGATURES) != 0;
nsAutoTArray<hb_feature_t,20> features;
// Ligature features are enabled by default in the generic shaper,
// so we explicitly turn them off if necessary (for letter-spacing)
if (disableLigatures) {
hb_feature_t ligaOff = { HB_TAG('l','i','g','a'), 0, 0, -1 };
hb_feature_t cligOff = { HB_TAG('c','l','i','g'), 0, 0, -1 };
features.AppendElement(ligaOff);
features.AppendElement(cligOff);
}
// css features need to be merged with the existing ones, if any
const gfxFontStyle *style = aTextRun->GetFontGroup()->GetStyle();
const nsTArray<gfxFontFeature> *cssFeatures = &style->featureSettings;
if (cssFeatures->IsEmpty()) {
cssFeatures = &mFont->GetFontEntry()->mFeatureSettings;
}
for (PRUint32 i = 0; i < cssFeatures->Length(); ++i) {
PRUint32 j;
for (j = 0; j < features.Length(); ++j) {
if (cssFeatures->ElementAt(i).mTag == features[j].tag) {
features[j].value = cssFeatures->ElementAt(i).mValue;
break;
}
}
if (j == features.Length()) {
const gfxFontFeature& f = cssFeatures->ElementAt(i);
hb_feature_t hbf = { f.mTag, f.mValue, 0, -1 };
features.AppendElement(hbf);
}
}
hb_buffer_t *buffer = hb_buffer_create(aRunLength);
hb_buffer_set_unicode_funcs(buffer, sHBUnicodeFuncs);
hb_buffer_set_direction(buffer,
aTextRun->IsRightToLeft() ?
HB_DIRECTION_RTL : HB_DIRECTION_LTR);
// For unresolved "common" or "inherited" runs, default to Latin for now.
// (Should we somehow use the language or locale to try and infer
// a better default?)
hb_buffer_set_script(buffer,
aRunScript <= HB_SCRIPT_INHERITED ? HB_SCRIPT_LATIN
: hb_script_t(aRunScript));
hb_language_t language;
if (style->languageOverride) {
language = hb_ot_tag_to_language(style->languageOverride);
} else if (mFont->GetFontEntry()->mLanguageOverride) {
language =
hb_ot_tag_to_language(mFont->GetFontEntry()->mLanguageOverride);
} else {
nsCString langString;
style->language->ToUTF8String(langString);
language = hb_language_from_string(langString.get());
}
hb_buffer_set_language(buffer, language);
hb_buffer_add_utf16(buffer, reinterpret_cast<const uint16_t*>(aString + aRunStart),
aRunLength, 0, aRunLength);
hb_shape(font, mHBFace, buffer, features.Elements(), features.Length());
if (aTextRun->IsRightToLeft()) {
hb_buffer_reverse(buffer);
}
#ifdef DEBUG
nsresult rv =
#endif
SetGlyphsFromRun(aContext, aTextRun, buffer, aRunStart, aRunLength);
NS_WARN_IF_FALSE(NS_SUCCEEDED(rv), "failed to store glyphs into textrun");
hb_buffer_destroy(buffer);
hb_font_destroy(font);
return PR_TRUE;
}
/**
* Work out whether cairo will snap inter-glyph spacing to pixels.
*
* Layout does not align text to pixel boundaries, so, with font drawing
* backends that snap glyph positions to pixels, it is important that
* inter-glyph spacing within words is always an integer number of pixels.
* This ensures that the drawing backend snaps all of the word's glyphs in the
* same direction and so inter-glyph spacing remains the same.
*/
static void
GetRoundOffsetsToPixels(gfxContext *aContext,
PRBool *aRoundX, PRBool *aRoundY)
{
*aRoundX = PR_FALSE;
// Could do something fancy here for ScaleFactors of
// AxisAlignedTransforms, but we leave things simple.
// Not much point rounding if a matrix will mess things up anyway.
if (aContext->CurrentMatrix().HasNonTranslation()) {
*aRoundY = PR_FALSE;
return;
}
// All raster backends snap glyphs to pixels vertically.
// Print backends set CAIRO_HINT_METRICS_OFF.
*aRoundY = PR_TRUE;
cairo_t *cr = aContext->GetCairo();
cairo_scaled_font_t *scaled_font = cairo_get_scaled_font(cr);
// Sometimes hint metrics gets set for us, most notably for printing.
cairo_font_options_t *font_options = cairo_font_options_create();
cairo_scaled_font_get_font_options(scaled_font, font_options);
cairo_hint_metrics_t hint_metrics =
cairo_font_options_get_hint_metrics(font_options);
cairo_font_options_destroy(font_options);
switch (hint_metrics) {
case CAIRO_HINT_METRICS_OFF:
*aRoundY = PR_FALSE;
return;
case CAIRO_HINT_METRICS_DEFAULT:
// Here we mimic what cairo surface/font backends do. Printing
// surfaces have already been handled by hint_metrics. The
// fallback show_glyphs implementation composites pixel-aligned
// glyph surfaces, so we just pick surface/font combinations that
// override this.
switch (cairo_scaled_font_get_type(scaled_font)) {
#if CAIRO_HAS_DWRITE_FONT // dwrite backend is not in std cairo releases yet
case CAIRO_FONT_TYPE_DWRITE:
// show_glyphs is implemented on the font and so is used for
// all surface types.
return;
#endif
case CAIRO_FONT_TYPE_QUARTZ:
// Quartz surfaces implement show_glyphs for Quartz fonts
if (cairo_surface_get_type(cairo_get_target(cr)) ==
CAIRO_SURFACE_TYPE_QUARTZ) {
return;
}
default:
break;
}
// fall through:
case CAIRO_HINT_METRICS_ON:
break;
}
*aRoundX = PR_TRUE;
return;
}
#define SMALL_GLYPH_RUN 128 // some testing indicates that 90%+ of text runs
// will fit without requiring separate allocation
// for charToGlyphArray
nsresult
gfxHarfBuzzShaper::SetGlyphsFromRun(gfxContext *aContext,
gfxTextRun *aTextRun,
hb_buffer_t *aBuffer,
PRUint32 aTextRunOffset,
PRUint32 aRunLength)
{
PRInt32 numGlyphs = hb_buffer_get_length(aBuffer);
if (numGlyphs == 0)
return NS_OK;
const hb_glyph_info_t *ginfo = hb_buffer_get_glyph_infos(aBuffer);
nsAutoTArray<gfxTextRun::DetailedGlyph,1> detailedGlyphs;
static const PRInt32 NO_GLYPH = -1;
nsAutoTArray<PRInt32,SMALL_GLYPH_RUN> charToGlyphArray;
if (!charToGlyphArray.SetLength(aRunLength))
return NS_ERROR_OUT_OF_MEMORY;
PRInt32 *charToGlyph = charToGlyphArray.Elements();
for (PRUint32 offset = 0; offset < aRunLength; ++offset) {
charToGlyph[offset] = NO_GLYPH;
}
for (PRInt32 i = 0; i < numGlyphs; ++i) {
PRUint32 loc = ginfo[i].cluster;
if (loc < aRunLength) {
charToGlyph[loc] = i;
}
}
PRInt32 glyphStart = 0; // looking for a clump that starts at this glyph
PRInt32 charStart = 0; // and this char index within the range of the run
PRBool roundX;
PRBool roundY;
GetRoundOffsetsToPixels(aContext, &roundX, &roundY);
// This is signed to avoid promotion to unsigned.
PRInt32 dev2appUnits = aTextRun->GetAppUnitsPerDevUnit();
// factor to convert 16.16 fixed-point pixels to app units
// (only used if not rounding)
double hb2appUnits = FixedToFloat(aTextRun->GetAppUnitsPerDevUnit());
// keep track of y-position to set glyph offsets if needed
nscoord yPos = 0;
const hb_glyph_position_t *posInfo = hb_buffer_get_glyph_positions(aBuffer);
while (glyphStart < numGlyphs) {
PRBool inOrder = PR_TRUE;
PRInt32 charEnd = ginfo[glyphStart].cluster;
PRInt32 glyphEnd = glyphStart;
PRInt32 charLimit = aRunLength;
while (charEnd < charLimit) {
// This is normally executed once for each iteration of the outer loop,
// but in unusual cases where the character/glyph association is complex,
// the initial character range might correspond to a non-contiguous
// glyph range with "holes" in it. If so, we will repeat this loop to
// extend the character range until we have a contiguous glyph sequence.
charEnd += 1;
while (charEnd != charLimit && charToGlyph[charEnd] == NO_GLYPH) {
charEnd += 1;
}
// find the maximum glyph index covered by the clump so far
for (PRInt32 i = charStart; i < charEnd; ++i) {
if (charToGlyph[i] != NO_GLYPH) {
glyphEnd = PR_MAX(glyphEnd, charToGlyph[i] + 1);
// update extent of glyph range
}
}
if (glyphEnd == glyphStart + 1) {
// for the common case of a single-glyph clump,
// we can skip the following checks
break;
}
if (glyphEnd == glyphStart) {
// no glyphs, try to extend the clump
continue;
}
// check whether all glyphs in the range are associated with the characters
// in our clump; if not, we have a discontinuous range, and should extend it
// unless we've reached the end of the text
PRBool allGlyphsAreWithinCluster = PR_TRUE;
PRInt32 prevGlyphCharIndex = charStart - 1;
for (PRInt32 i = glyphStart; i < glyphEnd; ++i) {
PRInt32 glyphCharIndex = ginfo[i].cluster;
if (glyphCharIndex < charStart || glyphCharIndex >= charEnd) {
allGlyphsAreWithinCluster = PR_FALSE;
break;
}
if (glyphCharIndex <= prevGlyphCharIndex) {
inOrder = PR_FALSE;
}
prevGlyphCharIndex = glyphCharIndex;
}
if (allGlyphsAreWithinCluster) {
break;
}
}
NS_ASSERTION(glyphStart < glyphEnd,
"character/glyph clump contains no glyphs!");
NS_ASSERTION(charStart != charEnd,
"character/glyph clump contains no characters!");
// Now charStart..charEnd is a ligature clump, corresponding to glyphStart..glyphEnd;
// Set baseCharIndex to the char we'll actually attach the glyphs to (1st of ligature),
// and endCharIndex to the limit (position beyond the last char),
// adjusting for the offset of the stringRange relative to the textRun.
PRInt32 baseCharIndex, endCharIndex;
while (charEnd < PRInt32(aRunLength) && charToGlyph[charEnd] == NO_GLYPH)
charEnd++;
baseCharIndex = charStart;
endCharIndex = charEnd;
// Then we check if the clump falls outside our actual string range;
// if so, just go to the next.
if (baseCharIndex >= PRInt32(aRunLength)) {
glyphStart = glyphEnd;
charStart = charEnd;
continue;
}
// Ensure we won't try to go beyond the valid length of the textRun's text
endCharIndex = NS_MIN<PRInt32>(endCharIndex, aRunLength);
// Now we're ready to set the glyph info in the textRun
PRInt32 glyphsInClump = glyphEnd - glyphStart;
// Check for default-ignorable char that didn't get filtered, combined,
// etc by the shaping process, and remove from the run.
// (This may be done within harfbuzz eventually.)
if (glyphsInClump == 1 && baseCharIndex + 1 == endCharIndex &&
aTextRun->FilterIfIgnorable(aTextRunOffset + baseCharIndex)) {
glyphStart = glyphEnd;
charStart = charEnd;
continue;
}
// Check if it's a simple one-to-one mapping
hb_position_t x_advance = posInfo[glyphStart].x_advance;
nscoord advance =
roundX ? dev2appUnits * FixedToIntRound(x_advance)
: NS_floor(hb2appUnits * x_advance + 0.5);
if (glyphsInClump == 1 &&
gfxTextRun::CompressedGlyph::IsSimpleGlyphID(ginfo[glyphStart].codepoint) &&
gfxTextRun::CompressedGlyph::IsSimpleAdvance(advance) &&
aTextRun->IsClusterStart(aTextRunOffset + baseCharIndex) &&
posInfo[glyphStart].x_offset == 0 &&
posInfo[glyphStart].y_offset == 0 && yPos == 0)
{
gfxTextRun::CompressedGlyph g;
aTextRun->SetSimpleGlyph(aTextRunOffset + baseCharIndex,
g.SetSimpleGlyph(advance,
ginfo[glyphStart].codepoint));
} else {
// collect all glyphs in a list to be assigned to the first char;
// there must be at least one in the clump, and we already measured
// its advance, hence the placement of the loop-exit test and the
// measurement of the next glyph
while (1) {
gfxTextRun::DetailedGlyph* details =
detailedGlyphs.AppendElement();
details->mGlyphID = ginfo[glyphStart].codepoint;
// Rounding offsets independently of advances on the assumption
// that clusters use offsets and rounding of offsets should
// not accumulate, and that advances are typically between
// clusters.
hb_position_t x_offset = posInfo[glyphStart].x_offset;
details->mXOffset =
roundX ? dev2appUnits * FixedToIntRound(x_offset)
: NS_floor(hb2appUnits * x_offset + 0.5);
hb_position_t y_offset = posInfo[glyphStart].y_offset;
details->mYOffset = yPos -
(roundY ? dev2appUnits * FixedToIntRound(y_offset)
: NS_floor(hb2appUnits * y_offset + 0.5));
details->mAdvance = advance;
hb_position_t y_advance = posInfo[glyphStart].y_advance;
if (y_advance != 0) {
yPos -=
roundY ? dev2appUnits * FixedToIntRound(y_advance)
: NS_floor(hb2appUnits * y_advance + 0.5);
}
if (++glyphStart >= glyphEnd) {
break;
}
x_advance = posInfo[glyphStart].x_advance;
advance =
roundX ? dev2appUnits * FixedToIntRound(x_advance)
: NS_floor(hb2appUnits * x_advance + 0.5);
}
gfxTextRun::CompressedGlyph g;
g.SetComplex(aTextRun->IsClusterStart(aTextRunOffset + baseCharIndex),
PR_TRUE, detailedGlyphs.Length());
aTextRun->SetGlyphs(aTextRunOffset + baseCharIndex,
g, detailedGlyphs.Elements());
detailedGlyphs.Clear();
}
// the rest of the chars in the group are ligature continuations,
// no associated glyphs
while (++baseCharIndex != endCharIndex &&
baseCharIndex < PRInt32(aRunLength)) {
gfxTextRun::CompressedGlyph g;
g.SetComplex(inOrder &&
aTextRun->IsClusterStart(aTextRunOffset + baseCharIndex),
PR_FALSE, 0);
aTextRun->SetGlyphs(aTextRunOffset + baseCharIndex, g, nsnull);
}
glyphStart = glyphEnd;
charStart = charEnd;
}
return NS_OK;
}
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