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SkUnicode_icu_bidi.cpp
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1/*
2 * Copyright 2022 Google LLC
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
8
12#include "src/base/SkUTF.h"
13
14#include <unicode/ubidi.h>
15#include <unicode/umachine.h>
16#include <unicode/utypes.h>
17
18#include <cstdint>
19#include <memory>
20#include <string>
21#include <utility>
22#include <vector>
23
24namespace {
25using SkUnicodeBidi = std::unique_ptr<UBiDi, SkBidiFactory::BidiCloseCallback>;
26
27class SkBidiIterator_icu : public SkBidiIterator {
28public:
29 SkBidiIterator_icu(SkUnicodeBidi bidi, sk_sp<SkBidiFactory> fact)
30 : fBidi(std::move(bidi)), fBidiFact(std::move(fact)) {}
31
32 Position getLength() override { return fBidiFact->bidi_getLength(fBidi.get()); }
33
34 Level getLevelAt(Position pos) override { return fBidiFact->bidi_getLevelAt(fBidi.get(), pos); }
35
36private:
37 SkUnicodeBidi fBidi;
38 sk_sp<SkBidiFactory> fBidiFact;
39};
40} // namespace
41
42std::unique_ptr<SkBidiIterator> SkBidiFactory::MakeIterator(const uint16_t utf16[],
43 int utf16Units,
45 UErrorCode status = U_ZERO_ERROR;
46 SkUnicodeBidi bidi(this->bidi_openSized(utf16Units, 0, &status), this->bidi_close_callback());
47 if (U_FAILURE(status)) {
48 SkDEBUGF("Bidi error: %s", this->errorName(status));
49 return nullptr;
50 }
51 SkASSERT(bidi);
52 uint8_t bidiLevel = (dir == SkBidiIterator::kLTR) ? UBIDI_LTR : UBIDI_RTL;
53 // The required lifetime of utf16 isn't well documented.
54 // It appears it isn't used after ubidi_setPara except through ubidi_getText.
55 this->bidi_setPara(bidi.get(), (const UChar*)utf16, utf16Units, bidiLevel, nullptr, &status);
56 if (U_FAILURE(status)) {
57 SkDEBUGF("Bidi error: %s", this->errorName(status));
58 return nullptr;
59 }
60 return std::unique_ptr<SkBidiIterator>(
61 new SkBidiIterator_icu(std::move(bidi), sk_ref_sp(this)));
62}
63
64std::unique_ptr<SkBidiIterator> SkBidiFactory::MakeIterator(const char utf8[],
65 int utf8Units,
67 // Convert utf8 into utf16 since ubidi only accepts utf16
68 if (!SkTFitsIn<int32_t>(utf8Units)) {
69 SkDEBUGF("Bidi error: text too long");
70 return nullptr;
71 }
72
73 // Getting the length like this seems to always set U_BUFFER_OVERFLOW_ERROR
74 int utf16Units = SkUTF::UTF8ToUTF16(nullptr, 0, utf8, utf8Units);
75 if (utf16Units < 0) {
76 SkDEBUGF("Bidi error: Invalid utf8 input");
77 return nullptr;
78 }
79 std::unique_ptr<uint16_t[]> utf16(new uint16_t[utf16Units]);
80 SkDEBUGCODE(int dstLen =) SkUTF::UTF8ToUTF16(utf16.get(), utf16Units, utf8, utf8Units);
81 SkASSERT(dstLen == utf16Units);
82
83 return MakeIterator(utf16.get(), utf16Units, dir);
84}
85
86/** Replaces invalid utf-8 sequences with REPLACEMENT CHARACTER U+FFFD. */
87static inline SkUnichar utf8_next(const char** ptr, const char* end) {
88 SkUnichar val = SkUTF::NextUTF8(ptr, end);
89 return val < 0 ? 0xFFFD : val;
90}
91
93 int utf8Units,
95 std::vector<SkUnicode::BidiRegion>* bidiRegions) const {
96 // Convert to UTF16 since for now bidi iterator only operates on utf16
97 auto utf16 = SkUnicode::convertUtf8ToUtf16(utf8, utf8Units);
98
99 // Create bidi iterator
100 UErrorCode status = U_ZERO_ERROR;
101 SkUnicodeBidi bidi(this->bidi_openSized(utf16.size(), 0, &status), this->bidi_close_callback());
102 if (U_FAILURE(status)) {
103 SkDEBUGF("Bidi error: %s", this->errorName(status));
104 return false;
105 }
106 SkASSERT(bidi);
107 uint8_t bidiLevel = (dir == SkUnicode::TextDirection::kLTR) ? UBIDI_LTR : UBIDI_RTL;
108 // The required lifetime of utf16 isn't well documented.
109 // It appears it isn't used after ubidi_setPara except through ubidi_getText.
110 this->bidi_setPara(
111 bidi.get(), (const UChar*)utf16.c_str(), utf16.size(), bidiLevel, nullptr, &status);
112 if (U_FAILURE(status)) {
113 SkDEBUGF("Bidi error: %s", this->errorName(status));
114 return false;
115 }
116
117 // Iterate through bidi regions and the result positions into utf8
118 const char* start8 = utf8;
119 const char* end8 = utf8 + utf8Units;
120 SkUnicode::BidiLevel currentLevel = 0;
121
122 SkUnicode::Position pos8 = 0;
123 SkUnicode::Position pos16 = 0;
124 SkUnicode::Position end16 = this->bidi_getLength(bidi.get());
125
126 if (end16 == 0) {
127 return true;
128 }
129 if (this->bidi_getDirection(bidi.get()) != UBIDI_MIXED) {
130 // The entire paragraph is unidirectional.
131 bidiRegions->emplace_back(0, utf8Units, this->bidi_getLevelAt(bidi.get(), 0));
132 return true;
133 }
134
135 while (pos16 < end16) {
136 auto level = this->bidi_getLevelAt(bidi.get(), pos16);
137 if (pos16 == 0) {
138 currentLevel = level;
139 } else if (level != currentLevel) {
140 SkUnicode::Position end = start8 - utf8;
141 bidiRegions->emplace_back(pos8, end, currentLevel);
142 currentLevel = level;
143 pos8 = end;
144 }
145 SkUnichar u = utf8_next(&start8, end8);
146 pos16 += SkUTF::ToUTF16(u);
147 }
148 SkUnicode::Position end = start8 - utf8;
149 if (end != pos8) {
150 bidiRegions->emplace_back(pos8, end, currentLevel);
151 }
152 return true;
153}
SkPoint pos
#define SkASSERT(cond)
Definition: SkAssert.h:116
#define SkDEBUGF(...)
Definition: SkDebug.h:24
sk_sp< T > sk_ref_sp(T *obj)
Definition: SkRefCnt.h:381
std::unique_ptr< SkBidiIterator > SkUnicodeBidi
SkDEBUGCODE(SK_SPI) SkThreadID SkGetThreadID()
int32_t SkUnichar
Definition: SkTypes.h:175
static SkUnichar utf8_next(const char **ptr, const char *end)
bool ExtractBidi(const char utf8[], int utf8Units, SkUnicode::TextDirection dir, std::vector< SkUnicode::BidiRegion > *bidiRegions) const
virtual void bidi_setPara(UBiDi *bidi, const UChar *text, int32_t length, UBiDiLevel paraLevel, UBiDiLevel *embeddingLevels, UErrorCode *status) const =0
virtual SkBidiIterator::Level bidi_getLevelAt(const UBiDi *bidi, int pos) const =0
virtual SkBidiIterator::Position bidi_getLength(const UBiDi *bidi) const =0
std::unique_ptr< SkBidiIterator > MakeIterator(const uint16_t utf16[], int utf16Units, SkBidiIterator::Direction dir) const
virtual UBiDi * bidi_openSized(int32_t maxLength, int32_t maxRunCount, UErrorCode *pErrorCode) const =0
virtual BidiCloseCallback bidi_close_callback() const =0
virtual UBiDiDirection bidi_getDirection(const UBiDi *bidi) const =0
virtual const char * errorName(UErrorCode status) const =0
virtual Level getLevelAt(Position)=0
virtual Position getLength()=0
static std::u16string convertUtf8ToUtf16(const char *utf8, int utf8Units)
Definition: SkUnicode.cpp:32
size_t Position
Definition: SkUnicode.h:98
uint8_t BidiLevel
Definition: SkUnicode.h:99
glong glong end
SK_SPI int UTF8ToUTF16(uint16_t dst[], int dstCapacity, const char src[], size_t srcByteLength)
Definition: SkUTF.cpp:259
SK_SPI SkUnichar NextUTF8(const char **ptr, const char *end)
Definition: SkUTF.cpp:118
SK_SPI size_t ToUTF16(SkUnichar uni, uint16_t utf16[2]=nullptr)
Definition: SkUTF.cpp:243
DEF_SWITCHES_START aot vmservice shared library Name of the *so containing AOT compiled Dart assets for launching the service isolate vm snapshot The VM snapshot data that will be memory mapped as read only SnapshotAssetPath must be present isolate snapshot The isolate snapshot data that will be memory mapped as read only SnapshotAssetPath must be present cache dir Path to the cache directory This is different from the persistent_cache_path in embedder which is used for Skia shader cache icu native lib Path to the library file that exports the ICU data vm service The hostname IP address on which the Dart VM Service should be served If not defaults to or::depending on whether ipv6 is specified vm service A custom Dart VM Service port The default is to pick a randomly available open port disable vm Disable the Dart VM Service The Dart VM Service is never available in release mode disable vm service Disable mDNS Dart VM Service publication Bind to the IPv6 localhost address for the Dart VM Service Ignored if vm service host is set endless trace Enable an endless trace buffer The default is a ring buffer This is useful when very old events need to viewed For during application launch Memory usage will continue to grow indefinitely however Start app with an specific route defined on the framework flutter assets dir
Definition: switches.h:145
Definition: ref_ptr.h:256