/*
* Copyright 2009-2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/* migrated from chrome/src/skia/ext/SkFontHost_fontconfig_direct.cpp */
#include "SkAutoMalloc.h"
#include "SkBuffer.h"
#include "SkFixed.h"
#include "SkFontConfigInterface_direct.h"
#include "SkFontStyle.h"
#include "SkMutex.h"
#include "SkStream.h"
#include "SkString.h"
#include "SkTArray.h"
#include "SkTDArray.h"
#include "SkTemplates.h"
#include "SkTypeface.h"
#include <fontconfig/fontconfig.h>
#include <unistd.h>
#ifdef SK_DEBUG
# include "SkTLS.h"
#endif
namespace {
// Fontconfig is not threadsafe before 2.10.91. Before that, we lock with a global mutex.
// See https://bug.skia.org/1497 for background.
SK_DECLARE_STATIC_MUTEX(gFCMutex);
#ifdef SK_DEBUG
void* CreateThreadFcLocked() { return new bool(false); }
void DeleteThreadFcLocked(void* v) { delete static_cast<bool*>(v); }
# define THREAD_FC_LOCKED \
static_cast<bool*>(SkTLS::Get(CreateThreadFcLocked, DeleteThreadFcLocked))
#endif
struct FCLocker {
// Assume FcGetVersion() has always been thread safe.
FCLocker() {
if (FcGetVersion() < 21091) {
gFCMutex.acquire();
} else {
SkDEBUGCODE(bool* threadLocked = THREAD_FC_LOCKED);
SkASSERT(false == *threadLocked);
SkDEBUGCODE(*threadLocked = true);
}
}
~FCLocker() {
AssertHeld();
if (FcGetVersion() < 21091) {
gFCMutex.release();
} else {
SkDEBUGCODE(*THREAD_FC_LOCKED = false);
}
}
static void AssertHeld() { SkDEBUGCODE(
if (FcGetVersion() < 21091) {
gFCMutex.assertHeld();
} else {
SkASSERT(true == *THREAD_FC_LOCKED);
}
) }
};
} // namespace
size_t SkFontConfigInterface::FontIdentity::writeToMemory(void* addr) const {
size_t size = sizeof(fID) + sizeof(fTTCIndex);
size += sizeof(int32_t) + sizeof(int32_t) + sizeof(uint8_t); // weight, width, italic
size += sizeof(int32_t) + fString.size(); // store length+data
if (addr) {
SkWBuffer buffer(addr, size);
buffer.write32(fID);
buffer.write32(fTTCIndex);
buffer.write32(fString.size());
buffer.write32(fStyle.weight());
buffer.write32(fStyle.width());
buffer.write8(fStyle.slant());
buffer.write(fString.c_str(), fString.size());
buffer.padToAlign4();
SkASSERT(buffer.pos() == size);
}
return size;
}
size_t SkFontConfigInterface::FontIdentity::readFromMemory(const void* addr,
size_t size) {
SkRBuffer buffer(addr, size);
(void)buffer.readU32(&fID);
(void)buffer.readS32(&fTTCIndex);
uint32_t strLen, weight, width;
(void)buffer.readU32(&strLen);
(void)buffer.readU32(&weight);
(void)buffer.readU32(&width);
uint8_t u8;
(void)buffer.readU8(&u8);
SkFontStyle::Slant slant = (SkFontStyle::Slant)u8;
fStyle = SkFontStyle(weight, width, slant);
fString.resize(strLen);
(void)buffer.read(fString.writable_str(), strLen);
buffer.skipToAlign4();
return buffer.pos(); // the actual number of bytes read
}
#ifdef SK_DEBUG
static void make_iden(SkFontConfigInterface::FontIdentity* iden) {
iden->fID = 10;
iden->fTTCIndex = 2;
iden->fString.set("Hello world");
iden->fStyle = SkFontStyle(300, 6, SkFontStyle::kItalic_Slant);
}
static void test_writeToMemory(const SkFontConfigInterface::FontIdentity& iden0,
int initValue) {
SkFontConfigInterface::FontIdentity iden1;
size_t size0 = iden0.writeToMemory(nullptr);
SkAutoMalloc storage(size0);
memset(storage.get(), initValue, size0);
size_t size1 = iden0.writeToMemory(storage.get());
SkASSERT(size0 == size1);
SkASSERT(iden0 != iden1);
size_t size2 = iden1.readFromMemory(storage.get(), size1);
SkASSERT(size2 == size1);
SkASSERT(iden0 == iden1);
}
static void fontconfiginterface_unittest() {
SkFontConfigInterface::FontIdentity iden0, iden1;
SkASSERT(iden0 == iden1);
make_iden(&iden0);
SkASSERT(iden0 != iden1);
make_iden(&iden1);
SkASSERT(iden0 == iden1);
test_writeToMemory(iden0, 0);
test_writeToMemory(iden0, 0);
}
#endif
///////////////////////////////////////////////////////////////////////////////
// Returns the string from the pattern, or nullptr
static const char* get_string(FcPattern* pattern, const char field[], int index = 0) {
const char* name;
if (FcPatternGetString(pattern, field, index, (FcChar8**)&name) != FcResultMatch) {
name = nullptr;
}
return name;
}
///////////////////////////////////////////////////////////////////////////////
namespace {
// Equivalence classes, used to match the Liberation and other fonts
// with their metric-compatible replacements. See the discussion in
// GetFontEquivClass().
enum FontEquivClass
{
OTHER,
SANS,
SERIF,
MONO,
SYMBOL,
PGOTHIC,
GOTHIC,
PMINCHO,
MINCHO,
SIMSUN,
NSIMSUN,
SIMHEI,
PMINGLIU,
MINGLIU,
PMINGLIUHK,
MINGLIUHK,
CAMBRIA,
CALIBRI,
};
// Match the font name against a whilelist of fonts, returning the equivalence
// class.
FontEquivClass GetFontEquivClass(const char* fontname)
{
// It would be nice for fontconfig to tell us whether a given suggested
// replacement is a "strong" match (that is, an equivalent font) or
// a "weak" match (that is, fontconfig's next-best attempt at finding a
// substitute). However, I played around with the fontconfig API for
// a good few hours and could not make it reveal this information.
//
// So instead, we hardcode. Initially this function emulated
// /etc/fonts/conf.d/30-metric-aliases.conf
// from my Ubuntu system, but we're better off being very conservative.
// Arimo, Tinos and Cousine are a set of fonts metric-compatible with
// Arial, Times New Roman and Courier New with a character repertoire
// much larger than Liberation. Note that Cousine is metrically
// compatible with Courier New, but the former is sans-serif while
// the latter is serif.
struct FontEquivMap {
FontEquivClass clazz;
const char name[40];
};
static const FontEquivMap kFontEquivMap[] = {
{ SANS, "Arial" },
{ SANS, "Arimo" },
{ SANS, "Liberation Sans" },
{ SERIF, "Times New Roman" },
{ SERIF, "Tinos" },
{ SERIF, "Liberation Serif" },
{ MONO, "Courier New" },
{ MONO, "Cousine" },
{ MONO, "Liberation Mono" },
{ SYMBOL, "Symbol" },
{ SYMBOL, "Symbol Neu" },
// ＭＳ Ｐゴシック
{ PGOTHIC, "MS PGothic" },
{ PGOTHIC, "\xef\xbc\xad\xef\xbc\xb3 \xef\xbc\xb0"
"\xe3\x82\xb4\xe3\x82\xb7\xe3\x83\x83\xe3\x82\xaf" },
{ PGOTHIC, "Noto Sans CJK JP" },
{ PGOTHIC, "IPAPGothic" },
{ PGOTHIC, "MotoyaG04Gothic" },
// ＭＳ ゴシック
{ GOTHIC, "MS Gothic" },
{ GOTHIC, "\xef\xbc\xad\xef\xbc\xb3 "
"\xe3\x82\xb4\xe3\x82\xb7\xe3\x83\x83\xe3\x82\xaf" },
{ GOTHIC, "Noto Sans Mono CJK JP" },
{ GOTHIC, "IPAGothic" },
{ GOTHIC, "MotoyaG04GothicMono" },
// ＭＳ Ｐ明朝
{ PMINCHO, "MS PMincho" },
{ PMINCHO, "\xef\xbc\xad\xef\xbc\xb3 \xef\xbc\xb0"
"\xe6\x98\x8e\xe6\x9c\x9d"},
{ PMINCHO, "Noto Serif CJK JP" },
{ PMINCHO, "IPAPMincho" },
{ PMINCHO, "MotoyaG04Mincho" },
// ＭＳ 明朝
{ MINCHO, "MS Mincho" },
{ MINCHO, "\xef\xbc\xad\xef\xbc\xb3 \xe6\x98\x8e\xe6\x9c\x9d" },
{ MINCHO, "Noto Serif CJK JP" },
{ MINCHO, "IPAMincho" },
{ MINCHO, "MotoyaG04MinchoMono" },
// 宋体
{ SIMSUN, "Simsun" },
{ SIMSUN, "\xe5\xae\x8b\xe4\xbd\x93" },
{ SIMSUN, "Noto Serif CJK SC" },
{ SIMSUN, "MSung GB18030" },
{ SIMSUN, "Song ASC" },
// 新宋体
{ NSIMSUN, "NSimsun" },
{ NSIMSUN, "\xe6\x96\xb0\xe5\xae\x8b\xe4\xbd\x93" },
{ NSIMSUN, "Noto Serif CJK SC" },
{ NSIMSUN, "MSung GB18030" },
{ NSIMSUN, "N Song ASC" },
// 黑体
{ SIMHEI, "Simhei" },
{ SIMHEI, "\xe9\xbb\x91\xe4\xbd\x93" },
{ SIMHEI, "Noto Sans CJK SC" },
{ SIMHEI, "MYingHeiGB18030" },
{ SIMHEI, "MYingHeiB5HK" },
// 新細明體
{ PMINGLIU, "PMingLiU"},
{ PMINGLIU, "\xe6\x96\xb0\xe7\xb4\xb0\xe6\x98\x8e\xe9\xab\x94" },
{ PMINGLIU, "Noto Serif CJK TC"},
{ PMINGLIU, "MSung B5HK"},
// 細明體
{ MINGLIU, "MingLiU"},
{ MINGLIU, "\xe7\xb4\xb0\xe6\x98\x8e\xe9\xab\x94" },
{ MINGLIU, "Noto Serif CJK TC"},
{ MINGLIU, "MSung B5HK"},
// 新細明體
{ PMINGLIUHK, "PMingLiU_HKSCS"},
{ PMINGLIUHK, "\xe6\x96\xb0\xe7\xb4\xb0\xe6\x98\x8e\xe9\xab\x94_HKSCS" },
{ PMINGLIUHK, "Noto Serif CJK TC"},
{ PMINGLIUHK, "MSung B5HK"},
// 細明體
{ MINGLIUHK, "MingLiU_HKSCS"},
{ MINGLIUHK, "\xe7\xb4\xb0\xe6\x98\x8e\xe9\xab\x94_HKSCS" },
{ MINGLIUHK, "Noto Serif CJK TC"},
{ MINGLIUHK, "MSung B5HK"},
// Cambria
{ CAMBRIA, "Cambria" },
{ CAMBRIA, "Caladea" },
// Calibri
{ CALIBRI, "Calibri" },
{ CALIBRI, "Carlito" },
};
static const size_t kFontCount =
sizeof(kFontEquivMap)/sizeof(kFontEquivMap[0]);
// TODO(jungshik): If this loop turns out to be hot, turn
// the array to a static (hash)map to speed it up.
for (size_t i = 0; i < kFontCount; ++i) {
if (strcasecmp(kFontEquivMap[i].name, fontname) == 0)
return kFontEquivMap[i].clazz;
}
return OTHER;
}
// Return true if |font_a| and |font_b| are visually and at the metrics
// level interchangeable.
bool IsMetricCompatibleReplacement(const char* font_a, const char* font_b)
{
FontEquivClass class_a = GetFontEquivClass(font_a);
FontEquivClass class_b = GetFontEquivClass(font_b);
return class_a != OTHER && class_a == class_b;
}
// Normally we only return exactly the font asked for. In last-resort
// cases, the request either doesn't specify a font or is one of the
// basic font names like "Sans", "Serif" or "Monospace". This function
// tells you whether a given request is for such a fallback.
bool IsFallbackFontAllowed(const SkString& family) {
const char* family_cstr = family.c_str();
return family.isEmpty() ||
strcasecmp(family_cstr, "sans") == 0 ||
strcasecmp(family_cstr, "serif") == 0 ||
strcasecmp(family_cstr, "monospace") == 0;
}
// Retrieves |is_bold|, |is_italic| and |font_family| properties from |font|.
static int get_int(FcPattern* pattern, const char object[], int missing) {
int value;
if (FcPatternGetInteger(pattern, object, 0, &value) != FcResultMatch) {
return missing;
}
return value;
}
static int map_range(SkFixed value,
SkFixed old_min, SkFixed old_max,
SkFixed new_min, SkFixed new_max)
{
SkASSERT(old_min < old_max);
SkASSERT(new_min <= new_max);
return new_min + SkMulDiv(value - old_min, new_max - new_min, old_max - old_min);
}
struct MapRanges {
SkFixed old_val;
SkFixed new_val;
};
static SkFixed map_ranges_fixed(SkFixed val, MapRanges const ranges[], int rangesCount) {
// -Inf to [0]
if (val < ranges[0].old_val) {
return ranges[0].new_val;
}
// Linear from [i] to [i+1]
for (int i = 0; i < rangesCount - 1; ++i) {
if (val < ranges[i+1].old_val) {
return map_range(val, ranges[i].old_val, ranges[i+1].old_val,
ranges[i].new_val, ranges[i+1].new_val);
}
}
// From [n] to +Inf
// if (fcweight < Inf)
return ranges[rangesCount-1].new_val;
}
static int map_ranges(int val, MapRanges const ranges[], int rangesCount) {
return SkFixedRoundToInt(map_ranges_fixed(SkIntToFixed(val), ranges, rangesCount));
}
template<int n> struct SkTFixed {
static_assert(-32768 <= n && n <= 32767, "SkTFixed_n_not_in_range");
static const SkFixed value = static_cast<SkFixed>(n << 16);
};
static SkFontStyle skfontstyle_from_fcpattern(FcPattern* pattern) {
typedef SkFontStyle SkFS;
static const MapRanges weightRanges[] = {
{ SkTFixed<FC_WEIGHT_THIN>::value, SkTFixed<SkFS::kThin_Weight>::value },
{ SkTFixed<FC_WEIGHT_EXTRALIGHT>::value, SkTFixed<SkFS::kExtraLight_Weight>::value },
{ SkTFixed<FC_WEIGHT_LIGHT>::value, SkTFixed<SkFS::kLight_Weight>::value },
{ SkTFixed<FC_WEIGHT_REGULAR>::value, SkTFixed<SkFS::kNormal_Weight>::value },
{ SkTFixed<FC_WEIGHT_MEDIUM>::value, SkTFixed<SkFS::kMedium_Weight>::value },
{ SkTFixed<FC_WEIGHT_DEMIBOLD>::value, SkTFixed<SkFS::kSemiBold_Weight>::value },
{ SkTFixed<FC_WEIGHT_BOLD>::value, SkTFixed<SkFS::kBold_Weight>::value },
{ SkTFixed<FC_WEIGHT_EXTRABOLD>::value, SkTFixed<SkFS::kExtraBold_Weight>::value },
{ SkTFixed<FC_WEIGHT_BLACK>::value, SkTFixed<SkFS::kBlack_Weight>::value },
{ SkTFixed<FC_WEIGHT_EXTRABLACK>::value, SkTFixed<SkFS::kExtraBlack_Weight>::value },
};
int weight = map_ranges(get_int(pattern, FC_WEIGHT, FC_WEIGHT_REGULAR),
weightRanges, SK_ARRAY_COUNT(weightRanges));
static const MapRanges widthRanges[] = {
{ SkTFixed<FC_WIDTH_ULTRACONDENSED>::value, SkTFixed<SkFS::kUltraCondensed_Width>::value },
{ SkTFixed<FC_WIDTH_EXTRACONDENSED>::value, SkTFixed<SkFS::kExtraCondensed_Width>::value },
{ SkTFixed<FC_WIDTH_CONDENSED>::value, SkTFixed<SkFS::kCondensed_Width>::value },
{ SkTFixed<FC_WIDTH_SEMICONDENSED>::value, SkTFixed<SkFS::kSemiCondensed_Width>::value },
{ SkTFixed<FC_WIDTH_NORMAL>::value, SkTFixed<SkFS::kNormal_Width>::value },
{ SkTFixed<FC_WIDTH_SEMIEXPANDED>::value, SkTFixed<SkFS::kSemiExpanded_Width>::value },
{ SkTFixed<FC_WIDTH_EXPANDED>::value, SkTFixed<SkFS::kExpanded_Width>::value },
{ SkTFixed<FC_WIDTH_EXTRAEXPANDED>::value, SkTFixed<SkFS::kExtraExpanded_Width>::value },
{ SkTFixed<FC_WIDTH_ULTRAEXPANDED>::value, SkTFixed<SkFS::kUltraExpanded_Width>::value },
};
int width = map_ranges(get_int(pattern, FC_WIDTH, FC_WIDTH_NORMAL),
widthRanges, SK_ARRAY_COUNT(widthRanges));
SkFS::Slant slant = SkFS::kUpright_Slant;
switch (get_int(pattern, FC_SLANT, FC_SLANT_ROMAN)) {
case FC_SLANT_ROMAN: slant = SkFS::kUpright_Slant; break;
case FC_SLANT_ITALIC : slant = SkFS::kItalic_Slant ; break;
case FC_SLANT_OBLIQUE: slant = SkFS::kOblique_Slant; break;
default: SkASSERT(false); break;
}
return SkFontStyle(weight, width, slant);
}
static void fcpattern_from_skfontstyle(SkFontStyle style, FcPattern* pattern) {
typedef SkFontStyle SkFS;
static const MapRanges weightRanges[] = {
{ SkTFixed<SkFS::kThin_Weight>::value, SkTFixed<FC_WEIGHT_THIN>::value },
{ SkTFixed<SkFS::kExtraLight_Weight>::value, SkTFixed<FC_WEIGHT_EXTRALIGHT>::value },
{ SkTFixed<SkFS::kLight_Weight>::value, SkTFixed<FC_WEIGHT_LIGHT>::value },
{ SkTFixed<SkFS::kNormal_Weight>::value, SkTFixed<FC_WEIGHT_REGULAR>::value },
{ SkTFixed<SkFS::kMedium_Weight>::value, SkTFixed<FC_WEIGHT_MEDIUM>::value },
{ SkTFixed<SkFS::kSemiBold_Weight>::value, SkTFixed<FC_WEIGHT_DEMIBOLD>::value },
{ SkTFixed<SkFS::kBold_Weight>::value, SkTFixed<FC_WEIGHT_BOLD>::value },
{ SkTFixed<SkFS::kExtraBold_Weight>::value, SkTFixed<FC_WEIGHT_EXTRABOLD>::value },
{ SkTFixed<SkFS::kBlack_Weight>::value, SkTFixed<FC_WEIGHT_BLACK>::value },
{ SkTFixed<SkFS::kExtraBlack_Weight>::value, SkTFixed<FC_WEIGHT_EXTRABLACK>::value },
};
int weight = map_ranges(style.weight(), weightRanges, SK_ARRAY_COUNT(weightRanges));
static const MapRanges widthRanges[] = {
{ SkTFixed<SkFS::kUltraCondensed_Width>::value, SkTFixed<FC_WIDTH_ULTRACONDENSED>::value },
{ SkTFixed<SkFS::kExtraCondensed_Width>::value, SkTFixed<FC_WIDTH_EXTRACONDENSED>::value },
{ SkTFixed<SkFS::kCondensed_Width>::value, SkTFixed<FC_WIDTH_CONDENSED>::value },
{ SkTFixed<SkFS::kSemiCondensed_Width>::value, SkTFixed<FC_WIDTH_SEMICONDENSED>::value },
{ SkTFixed<SkFS::kNormal_Width>::value, SkTFixed<FC_WIDTH_NORMAL>::value },
{ SkTFixed<SkFS::kSemiExpanded_Width>::value, SkTFixed<FC_WIDTH_SEMIEXPANDED>::value },
{ SkTFixed<SkFS::kExpanded_Width>::value, SkTFixed<FC_WIDTH_EXPANDED>::value },
{ SkTFixed<SkFS::kExtraExpanded_Width>::value, SkTFixed<FC_WIDTH_EXTRAEXPANDED>::value },
{ SkTFixed<SkFS::kUltraExpanded_Width>::value, SkTFixed<FC_WIDTH_ULTRAEXPANDED>::value },
};
int width = map_ranges(style.width(), widthRanges, SK_ARRAY_COUNT(widthRanges));
int slant = FC_SLANT_ROMAN;
switch (style.slant()) {
case SkFS::kUpright_Slant: slant = FC_SLANT_ROMAN ; break;
case SkFS::kItalic_Slant : slant = FC_SLANT_ITALIC ; break;
case SkFS::kOblique_Slant: slant = FC_SLANT_OBLIQUE; break;
default: SkASSERT(false); break;
}
FcPatternAddInteger(pattern, FC_WEIGHT, weight);
FcPatternAddInteger(pattern, FC_WIDTH , width);
FcPatternAddInteger(pattern, FC_SLANT , slant);
}
} // anonymous namespace
///////////////////////////////////////////////////////////////////////////////
#define kMaxFontFamilyLength 2048
#ifdef SK_FONT_CONFIG_INTERFACE_ONLY_ALLOW_SFNT_FONTS
const char* kFontFormatTrueType = "TrueType";
const char* kFontFormatCFF = "CFF";
#endif
SkFontConfigInterfaceDirect::SkFontConfigInterfaceDirect() {
FCLocker lock;
FcInit();
SkDEBUGCODE(fontconfiginterface_unittest();)
}
SkFontConfigInterfaceDirect::~SkFontConfigInterfaceDirect() {
}
bool SkFontConfigInterfaceDirect::isAccessible(const char* filename) {
if (access(filename, R_OK) != 0) {
return false;
}
return true;
}
bool SkFontConfigInterfaceDirect::isValidPattern(FcPattern* pattern) {
#ifdef SK_FONT_CONFIG_INTERFACE_ONLY_ALLOW_SFNT_FONTS
const char* font_format = get_string(pattern, FC_FONTFORMAT);
if (font_format
&& strcmp(font_format, kFontFormatTrueType) != 0
&& strcmp(font_format, kFontFormatCFF) != 0)
{
return false;
}
#endif
// fontconfig can also return fonts which are unreadable
const char* c_filename = get_string(pattern, FC_FILE);
if (!c_filename) {
return false;
}
return this->isAccessible(c_filename);
}
// Find matching font from |font_set| for the given font family.
FcPattern* SkFontConfigInterfaceDirect::MatchFont(FcFontSet* font_set,
const char* post_config_family,
const SkString& family) {
// Older versions of fontconfig have a bug where they cannot select
// only scalable fonts so we have to manually filter the results.
FcPattern* match = nullptr;
for (int i = 0; i < font_set->nfont; ++i) {
FcPattern* current = font_set->fonts[i];
if (this->isValidPattern(current)) {
match = current;
break;
}
}
if (match && !IsFallbackFontAllowed(family)) {
bool acceptable_substitute = false;
for (int id = 0; id < 255; ++id) {
const char* post_match_family = get_string(match, FC_FAMILY, id);
if (!post_match_family)
break;
acceptable_substitute =
(strcasecmp(post_config_family, post_match_family) == 0 ||
// Workaround for Issue 12530:
// requested family: "Bitstream Vera Sans"
// post_config_family: "Arial"
// post_match_family: "Bitstream Vera Sans"
// -> We should treat this case as a good match.
strcasecmp(family.c_str(), post_match_family) == 0) ||
IsMetricCompatibleReplacement(family.c_str(), post_match_family);
if (acceptable_substitute)
break;
}
if (!acceptable_substitute)
return nullptr;
}
return match;
}
bool SkFontConfigInterfaceDirect::matchFamilyName(const char familyName[],
SkFontStyle style,
FontIdentity* outIdentity,
SkString* outFamilyName,
SkFontStyle* outStyle) {
SkString familyStr(familyName ? familyName : "");
if (familyStr.size() > kMaxFontFamilyLength) {
return false;
}
FCLocker lock;
FcPattern* pattern = FcPatternCreate();
if (familyName) {
FcPatternAddString(pattern, FC_FAMILY, (FcChar8*)familyName);
}
fcpattern_from_skfontstyle(style, pattern);
FcPatternAddBool(pattern, FC_SCALABLE, FcTrue);
FcConfigSubstitute(nullptr, pattern, FcMatchPattern);
FcDefaultSubstitute(pattern);
// Font matching:
// CSS often specifies a fallback list of families:
// font-family: a, b, c, serif;
// However, fontconfig will always do its best to find *a* font when asked
// for something so we need a way to tell if the match which it has found is
// "good enough" for us. Otherwise, we can return nullptr which gets piped up
// and lets WebKit know to try the next CSS family name. However, fontconfig
// configs allow substitutions (mapping "Arial -> Helvetica" etc) and we
// wish to support that.
//
// Thus, if a specific family is requested we set @family_requested. Then we
// record two strings: the family name after config processing and the
// family name after resolving. If the two are equal, it's a good match.
//
// So consider the case where a user has mapped Arial to Helvetica in their
// config.
// requested family: "Arial"
// post_config_family: "Helvetica"
// post_match_family: "Helvetica"
// -> good match
//
// and for a missing font:
// requested family: "Monaco"
// post_config_family: "Monaco"
// post_match_family: "Times New Roman"
// -> BAD match
//
// However, we special-case fallback fonts; see IsFallbackFontAllowed().
const char* post_config_family = get_string(pattern, FC_FAMILY);
if (!post_config_family) {
// we can just continue with an empty name, e.g. default font
post_config_family = "";
}
FcResult result;
FcFontSet* font_set = FcFontSort(nullptr, pattern, 0, nullptr, &result);
if (!font_set) {
FcPatternDestroy(pattern);
return false;
}
FcPattern* match = this->MatchFont(font_set, post_config_family, familyStr);
if (!match) {
FcPatternDestroy(pattern);
FcFontSetDestroy(font_set);
return false;
}
FcPatternDestroy(pattern);
// From here out we just extract our results from 'match'
post_config_family = get_string(match, FC_FAMILY);
if (!post_config_family) {
FcFontSetDestroy(font_set);
return false;
}
const char* c_filename = get_string(match, FC_FILE);
if (!c_filename) {
FcFontSetDestroy(font_set);
return false;
}
int face_index = get_int(match, FC_INDEX, 0);
FcFontSetDestroy(font_set);
if (outIdentity) {
outIdentity->fTTCIndex = face_index;
outIdentity->fString.set(c_filename);
}
if (outFamilyName) {
outFamilyName->set(post_config_family);
}
if (outStyle) {
*outStyle = skfontstyle_from_fcpattern(match);
}
return true;
}
SkStreamAsset* SkFontConfigInterfaceDirect::openStream(const FontIdentity& identity) {
return SkStream::MakeFromFile(identity.fString.c_str()).release();
}