1 // Copyright (c) 2002-2009 Nokia Corporation and/or its subsidiary(-ies). |
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2 // All rights reserved. |
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3 // This component and the accompanying materials are made available |
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4 // under the terms of "Eclipse Public License v1.0" |
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5 // which accompanies this distribution, and is available |
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6 // at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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7 // |
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8 // Initial Contributors: |
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9 // Nokia Corporation - initial contribution. |
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10 // |
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11 // Contributors: |
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12 // |
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13 // Description: |
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14 // |
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15 |
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16 #include "BidiCopy.h" |
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17 #include <e32std.h> |
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18 #include "mglyphs.inl" |
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19 |
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20 TInt BidiCopy::Mirror(TInt a) |
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21 /** |
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22 Find the mirror image of a character. |
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23 @internalComponent |
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24 */ |
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25 { |
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26 TInt current = MirrorStart(a); |
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27 unsigned long v = mGlyphArray[current]; |
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28 TInt key = v >> 16; |
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29 // 1st easy-out: no steps at all for any at this key |
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30 if (key == 0) |
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31 return a; |
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32 // 2nd easy-out: no steps at all but we have found it |
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33 if (key == a) |
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34 return v & 0xFFFF; |
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35 TInt step = MirrorStep(a); |
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36 do { |
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37 current += step; |
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38 current &= (KMirrorTableSize-1); |
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39 key = mGlyphArray[current] >> 16; |
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40 if (key == a) |
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41 return mGlyphArray[current] & 0xFFFF; |
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42 } while (key != 0); |
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43 return a; |
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44 } |
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45 |
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46 void BidiCopy::ReverseCodes(TText* aText, TInt aLength) |
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47 /** |
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48 Reverse the contents of aText[0..aLength], so that aText[0] holds the |
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49 value previously found in aText[aLength - 1], aText[1] holds the value |
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50 previously held in aText[aLength - 2] and so on. |
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51 @internalComponent |
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52 */ |
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53 { |
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54 TText *text = aText; // backup |
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55 |
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56 // reverse int16 by int16 (note: high surrogate + low surrogate will be reverse to low surrogate + high surrogate) |
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57 TText* end = aText + aLength - 1; |
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58 while (aText < end) |
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59 { |
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60 TText t = *aText; |
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61 *aText = *end; |
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62 *end = t; |
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63 ++aText; |
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64 --end; |
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65 } |
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66 |
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67 CorrectSurrogatePairs(text, aLength); |
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68 } |
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69 |
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70 void BidiCopy::DeleteUnreversedSurrogates(TText* aText, TInt aLength) |
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71 /** |
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72 Replaces all surrogates with 0xFFFF that are not paired up the wrong |
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73 way round. |
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74 @internalComponent |
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75 */ |
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76 { |
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77 if (aLength < 1) |
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78 return; |
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79 TText* end = aText + aLength; |
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80 while (aText < end) |
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81 { |
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82 if ((aText[0] & 0xF800) == 0xD800) |
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83 { |
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84 if ((aText[0] & 0xFC00) == 0xD800 |
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85 && aText + 1 != end |
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86 && (aText[1] & 0xFC00) == 0xDC00) |
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87 ++aText; |
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88 else |
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89 aText[0] = 0xFFFF; |
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90 } |
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91 ++aText; |
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92 } |
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93 } |
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94 |
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95 void BidiCopy::CorrectSurrogatePairs(TText* aText, TInt aLength) |
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96 /** |
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97 Corrects all reversed surrogate pairs. Assumes that no unpaired |
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98 surrogates are present. |
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99 @internalComponent |
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100 */ |
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101 { |
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102 TText* end = aText + aLength; |
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103 while (aText < end) |
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104 { |
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105 if ((aText[0] & 0xF800) == 0xD800) |
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106 { |
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107 // Surrogate pair discovered. |
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108 // Do we need to swap it? |
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109 ASSERT(aText + 1 < end); |
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110 ASSERT((aText[1] & 0xF800) == 0xD800); |
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111 if ((aText[0] & 0xFC00) == 0xDC00) |
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112 { |
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113 ASSERT((aText[1] & 0xFC00) == 0xD800); |
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114 TText t = aText[0]; |
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115 aText[0] = aText[1]; |
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116 aText[1] = t; |
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117 } |
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118 ++aText; |
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119 } |
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120 ++aText; |
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121 } |
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122 } |
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123 |
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124 void BidiCopy::CorrectGroups(TText* aText, TInt aLength) |
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125 /** |
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126 Correct all reversed groups (non-combiner followed by combining |
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127 characters). Surrogate pairs may be reversed by this operation. |
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128 Assumes that no unpaired surrogates are present. |
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129 Leading and trailing 0xFFFFs are left alone. |
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130 @internalComponent |
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131 */ |
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132 { |
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133 TText *end = aText + aLength; |
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134 // Ignore leading 0xFFFFs. This helps Tagma's |
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135 // RTmTextCache::GetDisplayedText with its sentinels. |
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136 while (aText < end && *aText == 0xFFFF) |
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137 ++aText; |
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138 TText* groupStart = aText; |
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139 while (aText < end) |
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140 { |
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141 TText* next = aText + 1; |
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142 TInt c = aText[0]; |
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143 if ((c & 0xFC00) == 0xD800) |
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144 { |
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145 ASSERT(aText + 1 < end); |
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146 ASSERT((aText[1] & 0xFC00) == 0xDC00); |
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147 c = (c << 10) + (aText[1] & 0x3FF) |
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148 + (0x10000 - 0xD800*0x400); |
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149 ++next; |
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150 } |
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151 // ignore non-characters |
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152 if ((c & 0xFFFE) != 0xFFFE) |
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153 { |
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154 // non-marks represent the end of groups that may need to |
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155 // be reversed |
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156 TChar ch = c; |
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157 if ((ch.GetCategory() & 0xFFFFFFF0) != TChar::EMarkGroup) |
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158 { |
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159 if (aText != groupStart) |
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160 ReverseCodes(groupStart, aText - groupStart + 1); |
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161 groupStart = next; |
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162 } |
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163 } |
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164 aText = next; |
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165 } |
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166 } |
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167 |
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168 void BidiCopy::SubstituteMirrorImages(TText* aText, TInt aLength) |
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169 /** |
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170 Reverse all mirror image characters. Will not change characters |
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171 in the basic multilingual plane for surrogate pairs. Assumes |
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172 that no unpaired surrogates are present. |
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173 @internalComponent |
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174 */ |
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175 { |
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176 TText *end = aText + aLength; |
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177 while (aText < end) |
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178 { |
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179 TText* next = aText + 1; |
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180 TInt c = aText[0]; |
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181 if ((c & 0xFC00) == 0xD800) |
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182 { |
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183 ASSERT(aText + 1 < end); |
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184 ASSERT((aText[1] & 0xFC00) == 0xDC00); |
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185 c = (c << 10) + (aText[1] & 0x3FF) |
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186 + (0x10000 - 0xD800*0x400); |
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187 ++next; |
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188 } |
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189 TInt m = Mirror(c); |
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190 if (m != c) |
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191 { |
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192 if (m <= 0xFFFF) |
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193 { |
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194 aText[0] = static_cast<TText>(m); |
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195 if (0xFFFF < c) |
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196 aText[1] = 0xFFFF; |
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197 } |
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198 else if (0xFFFF < c) |
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199 { |
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200 aText[0] = static_cast<TText>((c >> 10) + 0xD760); |
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201 aText[1] = static_cast<TText>((c & 0x3FF) + 0xDC00); |
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202 } |
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203 } |
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204 aText = next; |
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205 } |
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206 } |
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207 |
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208 TText* BidiCopy::CopyMirror(TText* aDestination, const TText* aSource, TInt length) |
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209 /** |
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210 Copy some text, substituting mirrored characters. |
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211 |
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212 @return aDestination + number of TText codes output. |
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213 @internalComponent |
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214 */ |
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215 { |
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216 for (; length; --length, ++aDestination, ++aSource) |
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217 *aDestination = static_cast<TText>(Mirror(*aSource)); |
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218 return aDestination; |
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219 } |
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220 |
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221 TText* BidiCopy::OutputTChar(TText* aDestination, TInt aToOutput) |
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222 /** |
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223 Write out the input character as UTF16. |
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224 |
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225 @return aDestination + number of TText codes output. |
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226 @internalComponent |
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227 */ |
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228 { |
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229 if (aToOutput > 0xFFFF) |
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230 { |
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231 TInt c = aToOutput; |
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232 aDestination[0] = static_cast<TText>((c >> 10) + 0xD760); |
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233 aDestination[1] = static_cast<TText>((c & 0x3FF) + 0xDC00); |
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234 return aDestination + 2; |
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235 } |
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236 *aDestination = static_cast<TText>(aToOutput); |
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237 return aDestination + 1; |
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238 } |
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239 |
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240 TText* BidiCopy::CopyBackwards(TText* aDestination, |
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241 const TText* aSource, TInt aLength) |
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242 /** |
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243 Copy the text backwards without substituting mirrored characters, |
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244 checking for surrogate pairs or combining characters. |
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245 |
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246 @return aDestination + number of TText codes output. |
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247 @internalComponent |
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248 */ |
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249 { |
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250 TText *end = aDestination + aLength; |
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251 while (aDestination != end) |
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252 { |
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253 *--end = *aSource++; |
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254 } |
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255 return aDestination + aLength; |
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256 } |
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257 |
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258 TText* BidiCopy::CopyBackwardsWithMirroring(TText* aDestination, |
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259 const TText* aSource, TInt aLength) |
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260 /** |
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261 Copy the text backwards to the output without checking for surrogate |
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262 pairs or combining characters, substituting mirrored characters. |
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263 |
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264 @return aDestination + number of TText codes output. |
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265 @internalComponent |
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266 */ |
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267 { |
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268 TText *end = aDestination + aLength; |
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269 while (aDestination != end) |
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270 { |
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271 *--end = static_cast<TText>(Mirror(*aSource++)); |
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272 } |
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273 return aDestination + aLength; |
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274 } |
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275 |
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276 TText* BidiCopy::CopyGroupsBackwards(TText* aDestination, |
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277 const TText* aSource, TInt aLength) |
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278 /** |
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279 Copy the text backwards, substituting mirrored characters and correctly |
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280 handling all surrogate pairs and combining characters. |
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281 |
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282 @return aDestination + number of TText codes output. |
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283 @internalComponent |
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284 */ |
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285 { |
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286 TText* retval = CopyBackwards(aDestination, aSource, aLength); |
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287 DeleteUnreversedSurrogates(aDestination, aLength); |
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288 SubstituteMirrorImages(aDestination, aLength); |
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289 CorrectGroups(aDestination, aLength); |
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290 CorrectSurrogatePairs(aDestination, aLength); |
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291 return retval; |
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292 } |
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293 |
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294 TBool BidiCopy::ImplicitDirectionalityIsRightToLeft( |
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295 const TText* aText, TInt aLength, TBool* aFound) |
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296 /** |
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297 Find out if the implicit directionality of a piece of text is right to |
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298 left. |
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299 |
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300 @param aText Text to be examined, or the first portion of text to be examined. |
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301 @param aLength Length of the text. |
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302 @param aFound If non-null, returns ETrue if the directionality could be |
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303 determined from aText. If not, and there is more text beyond, the function |
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304 should be called with the next portion of text until aFound returns ETrue |
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305 or there is no more text. |
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306 @return ETrue if the directionality is right to left. If the directionality |
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307 cannot be determined solely from this text, EFalse is returned. This is the |
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308 implicit directionality of text that is composed entirely of neutrals. |
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309 @internalComponent |
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310 */ |
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311 { |
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312 if (aFound) |
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313 *aFound = ETrue; |
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314 const TText* end = aText + aLength; |
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315 TInt lastUtf16 = 0; |
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316 while (aText != end) |
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317 { |
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318 TInt code = *aText++; |
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319 if ((code & 0xFFFFFC00) == 0xD800 |
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320 && (lastUtf16 & 0xFFFFFC00) == 0xDC00) |
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321 { |
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322 code = (code << 10) + (lastUtf16 & 0x3FF) |
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323 + (0x10000 - 0xD800*0x400); |
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324 } |
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325 lastUtf16 = code; |
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326 TChar c = code; |
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327 switch(c.GetBdCategory()) |
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328 { |
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329 case TChar::ELeftToRight: |
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330 return EFalse; |
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331 case TChar::ERightToLeft: |
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332 case TChar::ERightToLeftArabic: |
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333 return ETrue; |
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334 default: |
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335 break; |
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336 } |
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337 } |
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338 if (aFound) |
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339 *aFound = EFalse; |
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340 return EFalse; |
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341 } |
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