blob: 0576a8340d5ebe32bdc43b3aea397669fe564e30 [file] [log] [blame]
/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "Minikin"
#include "FontLanguage.h"
#include <hb.h>
#include <string.h>
#include <unicode/uloc.h>
#include <algorithm>
namespace minikin {
#define SCRIPT_TAG(c1, c2, c3, c4) \
(((uint32_t)(c1)) << 24 | ((uint32_t)(c2)) << 16 | ((uint32_t)(c3)) << 8 | \
((uint32_t)(c4)))
// Check if a language code supports emoji according to its subtag
static bool isEmojiSubtag(const char* buf,
size_t bufLen,
const char* subtag,
size_t subtagLen) {
if (bufLen < subtagLen) {
return false;
}
if (strncmp(buf, subtag, subtagLen) != 0) {
return false; // no match between two strings
}
return (bufLen == subtagLen || buf[subtagLen] == '\0' ||
buf[subtagLen] == '-' || buf[subtagLen] == '_');
}
// Pack the three letter code into 15 bits and stored to 16 bit integer. The
// highest bit is 0. For the region code, the letters must be all digits in
// three letter case, so the number of possible values are 10. For the language
// code, the letters must be all small alphabets, so the number of possible
// values are 26. Thus, 5 bits are sufficient for each case and we can pack the
// three letter language code or region code to 15 bits.
//
// In case of two letter code, use fullbit(0x1f) for the first letter instead.
static uint16_t packLanguageOrRegion(const char* c,
size_t length,
uint8_t twoLetterBase,
uint8_t threeLetterBase) {
if (length == 2) {
return 0x7c00u | // 0x1fu << 10
(uint16_t)(c[0] - twoLetterBase) << 5 |
(uint16_t)(c[1] - twoLetterBase);
} else {
return ((uint16_t)(c[0] - threeLetterBase) << 10) |
(uint16_t)(c[1] - threeLetterBase) << 5 |
(uint16_t)(c[2] - threeLetterBase);
}
}
static size_t unpackLanguageOrRegion(uint16_t in,
char* out,
uint8_t twoLetterBase,
uint8_t threeLetterBase) {
uint8_t first = (in >> 10) & 0x1f;
uint8_t second = (in >> 5) & 0x1f;
uint8_t third = in & 0x1f;
if (first == 0x1f) {
out[0] = second + twoLetterBase;
out[1] = third + twoLetterBase;
return 2;
} else {
out[0] = first + threeLetterBase;
out[1] = second + threeLetterBase;
out[2] = third + threeLetterBase;
return 3;
}
}
// Find the next '-' or '_' index from startOffset position. If not found,
// returns bufferLength.
static size_t nextDelimiterIndex(const char* buffer,
size_t bufferLength,
size_t startOffset) {
for (size_t i = startOffset; i < bufferLength; ++i) {
if (buffer[i] == '-' || buffer[i] == '_') {
return i;
}
}
return bufferLength;
}
static inline bool isLowercase(char c) {
return 'a' <= c && c <= 'z';
}
static inline bool isUppercase(char c) {
return 'A' <= c && c <= 'Z';
}
static inline bool isDigit(char c) {
return '0' <= c && c <= '9';
}
// Returns true if the buffer is valid for language code.
static inline bool isValidLanguageCode(const char* buffer, size_t length) {
if (length != 2 && length != 3)
return false;
if (!isLowercase(buffer[0]))
return false;
if (!isLowercase(buffer[1]))
return false;
if (length == 3 && !isLowercase(buffer[2]))
return false;
return true;
}
// Returns true if buffer is valid for script code. The length of buffer must
// be 4.
static inline bool isValidScriptCode(const char* buffer) {
return isUppercase(buffer[0]) && isLowercase(buffer[1]) &&
isLowercase(buffer[2]) && isLowercase(buffer[3]);
}
// Returns true if the buffer is valid for region code.
static inline bool isValidRegionCode(const char* buffer, size_t length) {
return (length == 2 && isUppercase(buffer[0]) && isUppercase(buffer[1])) ||
(length == 3 && isDigit(buffer[0]) && isDigit(buffer[1]) &&
isDigit(buffer[2]));
}
// Parse BCP 47 language identifier into internal structure
FontLanguage::FontLanguage(const char* buf, size_t length) : FontLanguage() {
size_t firstDelimiterPos = nextDelimiterIndex(buf, length, 0);
if (isValidLanguageCode(buf, firstDelimiterPos)) {
mLanguage = packLanguageOrRegion(buf, firstDelimiterPos, 'a', 'a');
} else {
// We don't understand anything other than two-letter or three-letter
// language codes, so we skip parsing the rest of the string.
return;
}
if (firstDelimiterPos == length) {
mHbLanguage = hb_language_from_string(getString().c_str(), -1);
return; // Language code only.
}
size_t nextComponentStartPos = firstDelimiterPos + 1;
size_t nextDelimiterPos =
nextDelimiterIndex(buf, length, nextComponentStartPos);
size_t componentLength = nextDelimiterPos - nextComponentStartPos;
if (componentLength == 4) {
// Possibly script code.
const char* p = buf + nextComponentStartPos;
if (isValidScriptCode(p)) {
mScript = SCRIPT_TAG(p[0], p[1], p[2], p[3]);
mSubScriptBits = scriptToSubScriptBits(mScript);
}
if (nextDelimiterPos == length) {
mHbLanguage = hb_language_from_string(getString().c_str(), -1);
mEmojiStyle = resolveEmojiStyle(buf, length, mScript);
return; // No region code.
}
nextComponentStartPos = nextDelimiterPos + 1;
nextDelimiterPos = nextDelimiterIndex(buf, length, nextComponentStartPos);
componentLength = nextDelimiterPos - nextComponentStartPos;
}
if (componentLength == 2 || componentLength == 3) {
// Possibly region code.
const char* p = buf + nextComponentStartPos;
if (isValidRegionCode(p, componentLength)) {
mRegion = packLanguageOrRegion(p, componentLength, 'A', '0');
}
}
mHbLanguage = hb_language_from_string(getString().c_str(), -1);
mEmojiStyle = resolveEmojiStyle(buf, length, mScript);
}
// static
FontLanguage::EmojiStyle FontLanguage::resolveEmojiStyle(const char* buf,
size_t length,
uint32_t script) {
// First, lookup emoji subtag.
// 10 is the length of "-u-em-text", which is the shortest emoji subtag,
// unnecessary comparison can be avoided if total length is smaller than 10.
const size_t kMinSubtagLength = 10;
if (length >= kMinSubtagLength) {
static const char kPrefix[] = "-u-em-";
const char* pos =
std::search(buf, buf + length, kPrefix, kPrefix + strlen(kPrefix));
if (pos != buf + length) { // found
pos += strlen(kPrefix);
const size_t remainingLength = length - (pos - buf);
if (isEmojiSubtag(pos, remainingLength, "emoji", 5)) {
return EMSTYLE_EMOJI;
} else if (isEmojiSubtag(pos, remainingLength, "text", 4)) {
return EMSTYLE_TEXT;
} else if (isEmojiSubtag(pos, remainingLength, "default", 7)) {
return EMSTYLE_DEFAULT;
}
}
}
// If no emoji subtag was provided, resolve the emoji style from script code.
if (script == SCRIPT_TAG('Z', 's', 'y', 'e')) {
return EMSTYLE_EMOJI;
} else if (script == SCRIPT_TAG('Z', 's', 'y', 'm')) {
return EMSTYLE_TEXT;
}
return EMSTYLE_EMPTY;
}
// static
uint8_t FontLanguage::scriptToSubScriptBits(uint32_t script) {
uint8_t subScriptBits = 0u;
switch (script) {
case SCRIPT_TAG('B', 'o', 'p', 'o'):
subScriptBits = kBopomofoFlag;
break;
case SCRIPT_TAG('H', 'a', 'n', 'g'):
subScriptBits = kHangulFlag;
break;
case SCRIPT_TAG('H', 'a', 'n', 'b'):
// Bopomofo is almost exclusively used in Taiwan.
subScriptBits = kHanFlag | kBopomofoFlag;
break;
case SCRIPT_TAG('H', 'a', 'n', 'i'):
subScriptBits = kHanFlag;
break;
case SCRIPT_TAG('H', 'a', 'n', 's'):
subScriptBits = kHanFlag | kSimplifiedChineseFlag;
break;
case SCRIPT_TAG('H', 'a', 'n', 't'):
subScriptBits = kHanFlag | kTraditionalChineseFlag;
break;
case SCRIPT_TAG('H', 'i', 'r', 'a'):
subScriptBits = kHiraganaFlag;
break;
case SCRIPT_TAG('H', 'r', 'k', 't'):
subScriptBits = kKatakanaFlag | kHiraganaFlag;
break;
case SCRIPT_TAG('J', 'p', 'a', 'n'):
subScriptBits = kHanFlag | kKatakanaFlag | kHiraganaFlag;
break;
case SCRIPT_TAG('K', 'a', 'n', 'a'):
subScriptBits = kKatakanaFlag;
break;
case SCRIPT_TAG('K', 'o', 'r', 'e'):
subScriptBits = kHanFlag | kHangulFlag;
break;
}
return subScriptBits;
}
std::string FontLanguage::getString() const {
if (isUnsupported()) {
return "und";
}
char buf[16];
size_t i = unpackLanguageOrRegion(mLanguage, buf, 'a', 'a');
if (mScript != 0) {
buf[i++] = '-';
buf[i++] = (mScript >> 24) & 0xFFu;
buf[i++] = (mScript >> 16) & 0xFFu;
buf[i++] = (mScript >> 8) & 0xFFu;
buf[i++] = mScript & 0xFFu;
}
if (mRegion != INVALID_CODE) {
buf[i++] = '-';
i += unpackLanguageOrRegion(mRegion, buf + i, 'A', '0');
}
return std::string(buf, i);
}
bool FontLanguage::isEqualScript(const FontLanguage& other) const {
return other.mScript == mScript;
}
// static
bool FontLanguage::supportsScript(uint8_t providedBits, uint8_t requestedBits) {
return requestedBits != 0 && (providedBits & requestedBits) == requestedBits;
}
bool FontLanguage::supportsHbScript(hb_script_t script) const {
static_assert(
SCRIPT_TAG('J', 'p', 'a', 'n') == HB_TAG('J', 'p', 'a', 'n'),
"The Minikin script and HarfBuzz hb_script_t have different encodings.");
if (script == mScript)
return true;
return supportsScript(mSubScriptBits, scriptToSubScriptBits(script));
}
int FontLanguage::calcScoreFor(const FontLanguages& supported) const {
bool languageScriptMatch = false;
bool subtagMatch = false;
bool scriptMatch = false;
for (size_t i = 0; i < supported.size(); ++i) {
if (mEmojiStyle != EMSTYLE_EMPTY &&
mEmojiStyle == supported[i].mEmojiStyle) {
subtagMatch = true;
if (mLanguage == supported[i].mLanguage) {
return 4;
}
}
if (isEqualScript(supported[i]) ||
supportsScript(supported[i].mSubScriptBits, mSubScriptBits)) {
scriptMatch = true;
if (mLanguage == supported[i].mLanguage) {
languageScriptMatch = true;
}
}
}
if (supportsScript(supported.getUnionOfSubScriptBits(), mSubScriptBits)) {
scriptMatch = true;
if (mLanguage == supported[0].mLanguage &&
supported.isAllTheSameLanguage()) {
return 3;
}
}
if (languageScriptMatch) {
return 3;
} else if (subtagMatch) {
return 2;
} else if (scriptMatch) {
return 1;
}
return 0;
}
FontLanguages::FontLanguages(std::vector<FontLanguage>&& languages)
: mLanguages(std::move(languages)) {
if (mLanguages.empty()) {
return;
}
const FontLanguage& lang = mLanguages[0];
mIsAllTheSameLanguage = true;
mUnionOfSubScriptBits = lang.mSubScriptBits;
for (size_t i = 1; i < mLanguages.size(); ++i) {
mUnionOfSubScriptBits |= mLanguages[i].mSubScriptBits;
if (mIsAllTheSameLanguage && lang.mLanguage != mLanguages[i].mLanguage) {
mIsAllTheSameLanguage = false;
}
}
}
#undef SCRIPT_TAG
} // namespace minikin