|
1 // Copyright (c) 2003-2010 Nokia Corporation and/or its subsidiary(-ies). |
|
2 // All rights reserved. |
|
3 // This component and the accompanying materials are made available |
|
4 // under the terms of "Eclipse Public License v1.0" |
|
5 // which accompanies this distribution, and is available |
|
6 // at the URL "http://www.eclipse.org/legal/epl-v10.html". |
|
7 // |
|
8 // Initial Contributors: |
|
9 // Nokia Corporation - initial contribution. |
|
10 // |
|
11 // Contributors: |
|
12 // |
|
13 // Description: |
|
14 // |
|
15 |
|
16 |
|
17 #include <e32std.h> |
|
18 #include <e32svr.h> |
|
19 #include "LineBreak.h" |
|
20 #include "LineBreakImp.h" |
|
21 #include "GlyphSel.h" |
|
22 |
|
23 const TText16 KThaiCodePageStart = 0x0E00; |
|
24 const TText16 KThaiCodePageEnd = 0x0E5C; |
|
25 const TUint KNumThaiCharacters = KThaiCodePageEnd - KThaiCodePageStart; |
|
26 |
|
27 /** |
|
28 Ecanpsulates rules for when Thai character sequence line breaking. |
|
29 @internalComponent |
|
30 */ |
|
31 class ThaiLinebreakRules |
|
32 { |
|
33 public: |
|
34 enum TCharClassification |
|
35 { |
|
36 EOutOfRange, |
|
37 |
|
38 EConsOAng, |
|
39 EConsYoYak, |
|
40 EConsHoHip, |
|
41 EConsWoWean, |
|
42 EConsDigraph, |
|
43 EConsOther, |
|
44 |
|
45 EPostVowelA, |
|
46 EPostVowelAA, |
|
47 EPostVowelOther, |
|
48 EPreVowel, |
|
49 |
|
50 EDepMaiHanAkat, |
|
51 EDepSaraI, |
|
52 EDepOther, |
|
53 |
|
54 // marker for end |
|
55 EMaxClassification |
|
56 }; |
|
57 enum |
|
58 { |
|
59 KOutOfRangeFlag = 1 << EOutOfRange, |
|
60 KConsOAngFlag = 1 << EConsOAng, |
|
61 KConsYoYakFlag = 1 << EConsYoYak, |
|
62 KConsHoHipFlag = 1 << EConsHoHip, |
|
63 KConsWoWeanFlag = 1 << EConsWoWean, |
|
64 KConsDigraphFlag = 1 << EConsDigraph, |
|
65 KConsOtherFlag = 1 << EConsOther, |
|
66 KPostVowelAFlag = 1 << EPostVowelA, |
|
67 KPostVowelAAFlag = 1 << EPostVowelAA, |
|
68 KPostVowelOtherFlag = 1 << EPostVowelOther, |
|
69 KPreVowelFlag = 1 << EPreVowel, |
|
70 KDepMaiHanAkatFlag = 1 << EDepMaiHanAkat, |
|
71 KDepSaraIFlag = 1 << EDepSaraI, |
|
72 KDepOtherFlag = 1 << EDepOther, |
|
73 |
|
74 KSpecialDepFlags = KDepMaiHanAkatFlag | KDepSaraIFlag, |
|
75 KPostVowelFlags = KPostVowelAFlag | KPostVowelAAFlag | KPostVowelOtherFlag, |
|
76 KConsFlags = KConsOtherFlag | KConsDigraphFlag | KConsWoWeanFlag |
|
77 | KConsHoHipFlag | KConsYoYakFlag | KConsOAngFlag, |
|
78 KAllFlags = KOutOfRangeFlag | KConsOAngFlag | KConsYoYakFlag |
|
79 | KConsHoHipFlag | KConsWoWeanFlag | KConsDigraphFlag |
|
80 | KConsOtherFlag | KPostVowelAFlag | KPostVowelAAFlag |
|
81 | KPostVowelOtherFlag | KPreVowelFlag | KDepMaiHanAkatFlag |
|
82 | KDepSaraIFlag | KDepOtherFlag |
|
83 }; |
|
84 |
|
85 /** Returns the Thai linebreaking class of the character. */ |
|
86 static TCharClassification Class(TInt aChar); |
|
87 /** Returns true if aChar is a combining character according to aBreaker. */ |
|
88 static TBool IsCombiningChar(TInt aChar, const MLineBreaker& aBreaker); |
|
89 /** Returns the Thai linebreaking class of the character at (*aChar), |
|
90 searching backwards for the base character if it is foreign and of type CM. |
|
91 @param aChar The position of the character within the string. |
|
92 @param aStart The start of the string. |
|
93 @param aBreaker The line breaker to query for line breaking class. |
|
94 */ |
|
95 static TCharClassification DerivedClass(const TText* aChar, |
|
96 const TText* aStart, const MLineBreaker& aBreaker); |
|
97 /** |
|
98 Gets the line break rule for the previous and current character pair |
|
99 @param aPrevClass Class of the previous character. |
|
100 @param aClass Class of the current character. |
|
101 @return the rule code corresponding to the input pair. |
|
102 */ |
|
103 static TBool BreakAllowedBetween( |
|
104 TCharClassification aPrevClass, TCharClassification aClass); |
|
105 /** Returns whether a line break is allowed before the SA character at |
|
106 (*aChar). |
|
107 @param aChar The position of the character within the string. |
|
108 @param aStart The start of the string. |
|
109 @param aBreaker The line breaker to query for line breaking class. |
|
110 */ |
|
111 static TBool BreakAllowedAt(const TText* aChar, |
|
112 const TText* aStart, const MLineBreaker& aBreaker); |
|
113 |
|
114 /** |
|
115 Classification of each character |
|
116 */ |
|
117 static const TUint8 KCharClassifications[KNumThaiCharacters]; |
|
118 |
|
119 /** |
|
120 Rules table of prev to next character |
|
121 */ |
|
122 static const TUint32 KRules[EMaxClassification]; |
|
123 }; |
|
124 |
|
125 const TUint8 ThaiLinebreakRules::KCharClassifications[KNumThaiCharacters] = |
|
126 { |
|
127 EOutOfRange, // 0x0E00 |
|
128 EConsOther, // 0x0E01 |
|
129 EConsOther, // 0x0E02 |
|
130 EConsOther, // 0x0E03 |
|
131 EConsOther, // 0x0E04 |
|
132 EConsOther, // 0x0E05 |
|
133 EConsOther, // 0x0E06 |
|
134 EConsDigraph, // 0x0E07 |
|
135 EConsOther, // 0x0E08 |
|
136 EConsOther, // 0x0E09 |
|
137 EConsOther, // 0x0E0A |
|
138 EConsOther, // 0x0E0B |
|
139 EConsOther, // 0x0E0C |
|
140 EConsOther, // 0x0E0D |
|
141 EConsOther, // 0x0E0E |
|
142 EConsOther, // 0x0E0F |
|
143 |
|
144 EConsOther, // 0x0E10 |
|
145 EConsOther, // 0x0E11 |
|
146 EConsOther, // 0x0E12 |
|
147 EConsOther, // 0x0E13 |
|
148 EConsOther, // 0x0E14 |
|
149 EConsOther, // 0x0E15 |
|
150 EConsOther, // 0x0E16 |
|
151 EConsOther, // 0x0E17 |
|
152 EConsOther, // 0x0E18 |
|
153 EConsDigraph, // 0x0E19 |
|
154 EConsOther, // 0x0E1A |
|
155 EConsOther, // 0x0E1B |
|
156 EConsOther, // 0x0E1C |
|
157 EConsOther, // 0x0E1D |
|
158 EConsOther, // 0x0E1E |
|
159 EConsOther, // 0x0E1F |
|
160 |
|
161 EConsOther, // 0x0E20 |
|
162 EConsDigraph, // 0x0E21 |
|
163 EConsYoYak, // 0x0E22 |
|
164 EConsDigraph, // 0x0E23 |
|
165 EConsOther, // 0x0E24 |
|
166 EConsDigraph, // 0x0E25 |
|
167 EConsOther, // 0x0E26 |
|
168 EConsWoWean, // 0x0E27 |
|
169 EConsOther, // 0x0E28 |
|
170 EConsOther, // 0x0E29 |
|
171 EConsOther, // 0x0E2A |
|
172 EConsHoHip, // 0x0E2B |
|
173 EConsOther, // 0x0E2C |
|
174 EConsOAng, // 0x0E2D |
|
175 EConsOther, // 0x0E2E |
|
176 EOutOfRange, // 0x0E2F |
|
177 |
|
178 EPostVowelA, // 0x0E30 |
|
179 EDepMaiHanAkat, // 0x0E31 |
|
180 EPostVowelAA, // 0x0E32 |
|
181 EPostVowelOther,// 0x0E33 |
|
182 |
|
183 EDepSaraI, // 0x0E34 |
|
184 EDepOther, // 0x0E35 |
|
185 EDepOther, // 0x0E36 |
|
186 EDepOther, // 0x0E37 |
|
187 EDepOther, // 0x0E38 |
|
188 EDepOther, // 0x0E39 |
|
189 EDepOther, // 0x0E3A |
|
190 |
|
191 EOutOfRange, // 0x0E3B |
|
192 EOutOfRange, // 0x0E3C |
|
193 EOutOfRange, // 0x0E3D |
|
194 EOutOfRange, // 0x0E3E |
|
195 EOutOfRange, // 0x0E3F |
|
196 |
|
197 EPreVowel, // 0x0E40 |
|
198 EPreVowel, // 0x0E41 |
|
199 EPreVowel, // 0x0E42 |
|
200 EPreVowel, // 0x0E43 |
|
201 EPreVowel, // 0x0E44 |
|
202 |
|
203 EPostVowelOther,// 0x0E45 |
|
204 EOutOfRange, // 0x0E46 |
|
205 |
|
206 EDepOther, // 0x0E47 |
|
207 EDepOther, // 0x0E48 |
|
208 EDepOther, // 0x0E49 |
|
209 EDepOther, // 0x0E4A |
|
210 EDepOther, // 0x0E4B |
|
211 EDepOther, // 0x0E4C |
|
212 EDepOther, // 0x0E4D |
|
213 EDepOther, // 0x0E4E |
|
214 EOutOfRange, // 0x0E4F |
|
215 |
|
216 EOutOfRange, // 0x0E50 |
|
217 EOutOfRange, // 0x0E51 |
|
218 EOutOfRange, // 0x0E52 |
|
219 EOutOfRange, // 0x0E53 |
|
220 EOutOfRange, // 0x0E54 |
|
221 EOutOfRange, // 0x0E55 |
|
222 EOutOfRange, // 0x0E56 |
|
223 EOutOfRange, // 0x0E57 |
|
224 EOutOfRange, // 0x0E58 |
|
225 EOutOfRange, // 0x0E59 |
|
226 EOutOfRange, // 0x0E5A |
|
227 EOutOfRange // 0x0E5B |
|
228 }; |
|
229 |
|
230 const TUint32 KNormalBreaksBeforeCons = |
|
231 ThaiLinebreakRules::KPreVowelFlag |
|
232 | ThaiLinebreakRules::KConsOtherFlag |
|
233 | ThaiLinebreakRules::KConsDigraphFlag |
|
234 | ThaiLinebreakRules::KConsHoHipFlag |
|
235 | ThaiLinebreakRules::KOutOfRangeFlag; |
|
236 const TUint32 KNormalBreaksBeforePostVowel = |
|
237 ThaiLinebreakRules::KPreVowelFlag |
|
238 | ThaiLinebreakRules::KPostVowelFlags |
|
239 | ThaiLinebreakRules::KConsFlags |
|
240 | ThaiLinebreakRules::KOutOfRangeFlag; |
|
241 const TUint32 ThaiLinebreakRules::KRules[EMaxClassification] = |
|
242 { |
|
243 /* Prev Char EOutOfRange */ |
|
244 KAllFlags - KOutOfRangeFlag, |
|
245 /* Prev Char EConsOAng */ |
|
246 KNormalBreaksBeforeCons, |
|
247 /* Prev Char EConsYoYak */ |
|
248 KNormalBreaksBeforeCons, |
|
249 /* Prev Char EConsHoHip */ |
|
250 KNormalBreaksBeforeCons - KConsDigraphFlag, |
|
251 /* Prev Char EConsWoWean */ |
|
252 KNormalBreaksBeforeCons - KConsDigraphFlag - KConsHoHipFlag, |
|
253 /* Prev Char EConsDigraph */ |
|
254 KNormalBreaksBeforeCons, |
|
255 /* Prev Char EConsOther */ |
|
256 KNormalBreaksBeforeCons, |
|
257 /* Prev Char EPostVowelA */ |
|
258 KNormalBreaksBeforePostVowel, |
|
259 /* Prev Char EPostVowelAA */ |
|
260 KNormalBreaksBeforePostVowel - KPostVowelAFlag, |
|
261 /* Prev Char EPostVowelOther */ |
|
262 KNormalBreaksBeforePostVowel, |
|
263 /* Prev Char EPreVowel */ |
|
264 KPreVowelFlag | KPostVowelFlags | KOutOfRangeFlag, |
|
265 /* Prev Char EDepMaiHanAkat */ |
|
266 KSpecialDepFlags | KPreVowelFlag | KPostVowelAAFlag |
|
267 | KPostVowelAFlag | KOutOfRangeFlag, |
|
268 /* Prev Char EDepSaraI */ |
|
269 KSpecialDepFlags | KPreVowelFlag | KPostVowelAAFlag |
|
270 | KPostVowelAFlag | KOutOfRangeFlag, |
|
271 /* Prev Char EDepOther */ |
|
272 KSpecialDepFlags | KPreVowelFlag | KPostVowelAAFlag |
|
273 | KPostVowelAFlag | KConsOtherFlag | KConsDigraphFlag |
|
274 | KConsWoWeanFlag | KConsHoHipFlag | KOutOfRangeFlag |
|
275 }; |
|
276 |
|
277 ThaiLinebreakRules::TCharClassification ThaiLinebreakRules::Class(TInt a) |
|
278 { |
|
279 return static_cast<TCharClassification>( |
|
280 (KThaiCodePageStart <= a && a < KThaiCodePageEnd) ? |
|
281 KCharClassifications[a - KThaiCodePageStart] : |
|
282 EOutOfRange); |
|
283 } |
|
284 |
|
285 TBool ThaiLinebreakRules::IsCombiningChar(TInt aChar, |
|
286 const MLineBreaker& aBreaker) |
|
287 { |
|
288 TUint dummy1, dummy2; |
|
289 return aBreaker.LineBreakClass(aChar, dummy1, dummy2) == MLineBreaker::ECmLineBreakClass; |
|
290 } |
|
291 |
|
292 ThaiLinebreakRules::TCharClassification ThaiLinebreakRules::DerivedClass( |
|
293 const TText* aChar, const TText* aStart, const MLineBreaker& aBreaker) |
|
294 { |
|
295 ThaiLinebreakRules::TCharClassification c = Class(*aChar); |
|
296 while (c == EOutOfRange && aChar != aStart |
|
297 && IsCombiningChar(*aChar, aBreaker)) |
|
298 { |
|
299 --aChar; |
|
300 c = Class(*aChar); |
|
301 } |
|
302 return c; |
|
303 } |
|
304 |
|
305 TBool ThaiLinebreakRules::BreakAllowedBetween( |
|
306 ThaiLinebreakRules::TCharClassification aClass, |
|
307 ThaiLinebreakRules::TCharClassification aNextClass) |
|
308 { |
|
309 return KRules[aClass] & (1 << aNextClass); |
|
310 } |
|
311 |
|
312 TBool ThaiLinebreakRules::BreakAllowedAt(const TText* aChar, |
|
313 const TText* aStart, const MLineBreaker& aBreaker) |
|
314 { |
|
315 __ASSERT_DEBUG(aStart < aChar, User::Invariant()); |
|
316 TCharClassification c = Class(*aChar); |
|
317 if (c == EOutOfRange && IsCombiningChar(*aChar, aBreaker)) |
|
318 return EFalse; |
|
319 return BreakAllowedBetween(DerivedClass(aChar - 1, aStart, aBreaker), c); |
|
320 } |
|
321 |
|
322 /** |
|
323 Returns whether a line break is possible within a run of characters all having |
|
324 the class ESaLineBreakClass (Complex content). Languages with Unicocde |
|
325 characters having such a class include: Thai, Lao, Myanmar and Khmer. This |
|
326 default implementation of the GetLineBreakInContext() method only supports the |
|
327 Thai script. Breaks are determined in Thai based on a simple understanding of |
|
328 syllable boundaries. When characters from the other unsupported Sa class |
|
329 languages are found the method exits with EFalse. |
|
330 @param aText |
|
331 The text to be searched, which is a contiguous run of characters of class SA |
|
332 (or CM attatched to SA). The break position may be restricted further by |
|
333 aMinBreakPos and aMaxBreakPos, but more text is provided for extra context |
|
334 should it be needed. |
|
335 @param aMinBreakPos |
|
336 The start of the text to be considered for line breaks. |
|
337 @param aMaxBreakPos |
|
338 The end of the text to be considered for line breaks. |
|
339 @param aForwards |
|
340 ETrue if aBreakPos is to be set with the first legal break position, |
|
341 EFalse if aBreakPos is to be set with the last legal break position. |
|
342 @param aBreakPos |
|
343 If break position found on exit its value is >= Min and <= Max |
|
344 positions supplied. |
|
345 @return TBool |
|
346 ETrue if and only if a legal break was found, EFalse otherwise. |
|
347 @publishedAll |
|
348 @released |
|
349 */ |
|
350 EXPORT_C TBool MLineBreaker::GetLineBreakInContext(const TDesC16& aText, |
|
351 TInt aMinBreakPos, TInt aMaxBreakPos, TBool aForwards, |
|
352 TInt& aBreakPos) const |
|
353 { |
|
354 __ASSERT_DEBUG (0 <= aMinBreakPos && aMaxBreakPos <= aText.Length(), |
|
355 Panic(ELineBreakPanic_InvalidInputParam)); |
|
356 |
|
357 TInt length = aText.Length(); |
|
358 |
|
359 if (aMinBreakPos < 1) |
|
360 aMinBreakPos = 1; |
|
361 if (length - 1 < aMaxBreakPos) |
|
362 aMaxBreakPos = length - 1; |
|
363 if (aMaxBreakPos < aMinBreakPos) |
|
364 return EFalse; |
|
365 |
|
366 const TText16* text = aText.Ptr(); |
|
367 |
|
368 if (*text == KZeroWidthSpace) |
|
369 { |
|
370 aBreakPos = aMinBreakPos; |
|
371 return ETrue; |
|
372 } |
|
373 else if (*(text+length-1) == KZeroWidthSpace) |
|
374 return EFalse; |
|
375 |
|
376 TInt start = aForwards? aMinBreakPos : aMaxBreakPos; |
|
377 TInt end = aForwards? aMaxBreakPos + 1 : aMinBreakPos - 1; |
|
378 TInt direction = aForwards? 1 : -1; |
|
379 for (TInt i = start; i != end; i += direction) |
|
380 { |
|
381 if (ThaiLinebreakRules::BreakAllowedAt(text + i, text, *this)) |
|
382 { |
|
383 aBreakPos = i; |
|
384 return ETrue; |
|
385 } |
|
386 } |
|
387 return EFalse; |
|
388 } |