53fe735f08e1b8933458ece9ff2ea8f2a9f91362
[jvcard.git] / TerminalTextUtils.java
1 /*
2 * This file is part of lanterna (http://code.google.com/p/lanterna/).
3 *
4 * lanterna is free software: you can redistribute it and/or modify
5 * it under the terms of the GNU Lesser General Public License as published by
6 * the Free Software Foundation, either version 3 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public License
15 * along with this program. If not, see <http://www.gnu.org/licenses/>.
16 *
17 * Copyright (C) 2010-2015 Martin
18 */
19 package com.googlecode.lanterna;
20
21 import java.util.ArrayList;
22 import java.util.Arrays;
23 import java.util.LinkedList;
24 import java.util.List;
25
26 /**
27 * This class contains a number of utility methods for analyzing characters and strings in a terminal context. The main
28 * purpose is to make it easier to work with text that may or may not contain double-width text characters, such as CJK
29 * (Chinese, Japanese, Korean) and other special symbols. This class assumes those are all double-width and in case the
30 * terminal (-emulator) chooses to draw them (somehow) as single-column then all the calculations in this class will be
31 * wrong. It seems safe to assume what this class considers double-width really is taking up two columns though.
32 *
33 * @author Martin
34 */
35 public class TerminalTextUtils {
36 private TerminalTextUtils() {
37 }
38
39 /**
40 * Given a character, is this character considered to be a CJK character?
41 * Shamelessly stolen from
42 * <a href="http://stackoverflow.com/questions/1499804/how-can-i-detect-japanese-text-in-a-java-string">StackOverflow</a>
43 * where it was contributed by user Rakesh N
44 * @param c Character to test
45 * @return {@code true} if the character is a CJK character
46 *
47 */
48 public static boolean isCharCJK(final char c) {
49 Character.UnicodeBlock unicodeBlock = Character.UnicodeBlock.of(c);
50 return (unicodeBlock == Character.UnicodeBlock.HIRAGANA)
51 || (unicodeBlock == Character.UnicodeBlock.KATAKANA)
52 || (unicodeBlock == Character.UnicodeBlock.KATAKANA_PHONETIC_EXTENSIONS)
53 || (unicodeBlock == Character.UnicodeBlock.HANGUL_COMPATIBILITY_JAMO)
54 || (unicodeBlock == Character.UnicodeBlock.HANGUL_JAMO)
55 || (unicodeBlock == Character.UnicodeBlock.HANGUL_SYLLABLES)
56 || (unicodeBlock == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS)
57 || (unicodeBlock == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A)
58 || (unicodeBlock == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_B)
59 || (unicodeBlock == Character.UnicodeBlock.CJK_COMPATIBILITY_FORMS)
60 || (unicodeBlock == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS)
61 || (unicodeBlock == Character.UnicodeBlock.CJK_RADICALS_SUPPLEMENT)
62 || (unicodeBlock == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION)
63 || (unicodeBlock == Character.UnicodeBlock.ENCLOSED_CJK_LETTERS_AND_MONTHS)
64 || (unicodeBlock == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS && c < 0xFF61); //The magic number here is the separating index between full-width and half-width
65 }
66
67 /**
68 * Checks if a character is expected to be taking up two columns if printed to a terminal. This will generally be
69 * {@code true} for CJK (Chinese, Japanese and Korean) characters.
70 * @param c Character to test if it's double-width when printed to a terminal
71 * @return {@code true} if this character is expected to be taking up two columns when printed to the terminal,
72 * otherwise {@code false}
73 */
74 public static boolean isCharDoubleWidth(final char c) {
75 return isCharCJK(c);
76 }
77
78 /**
79 * @deprecated Call {@code getColumnWidth(s)} instead
80 */
81 @Deprecated
82 public static int getTrueWidth(String s) {
83 return getColumnWidth(s);
84 }
85
86 /**
87 * Given a string, returns how many columns this string would need to occupy in a terminal, taking into account that
88 * CJK characters takes up two columns.
89 * @param s String to check length
90 * @return Number of actual terminal columns the string would occupy
91 */
92 public static int getColumnWidth(String s) {
93 return getColumnIndex(s, s.length());
94 }
95
96 /**
97 * Given a string and a character index inside that string, find out what the column index of that character would
98 * be if printed in a terminal. If the string only contains non-CJK characters then the returned value will be same
99 * as {@code stringCharacterIndex}, but if there are CJK characters the value will be different due to CJK
100 * characters taking up two columns in width. If the character at the index in the string is a CJK character itself,
101 * the returned value will be the index of the left-side of character.
102 * @param s String to translate the index from
103 * @param stringCharacterIndex Index within the string to get the terminal column index of
104 * @return Index of the character inside the String at {@code stringCharacterIndex} when it has been writted to a
105 * terminal
106 * @throws StringIndexOutOfBoundsException if the index given is outside the String length or negative
107 */
108 public static int getColumnIndex(String s, int stringCharacterIndex) throws StringIndexOutOfBoundsException {
109 int index = 0;
110 for(int i = 0; i < stringCharacterIndex; i++) {
111 if(isCharCJK(s.charAt(i))) {
112 index++;
113 }
114 index++;
115 }
116 return index;
117 }
118
119 /**
120 * This method does the reverse of getColumnIndex, given a String and imagining it has been printed out to the
121 * top-left corner of a terminal, in the column specified by {@code columnIndex}, what is the index of that
122 * character in the string. If the string contains no CJK characters, this will always be the same as
123 * {@code columnIndex}. If the index specified is the right column of a CJK character, the index is the same as if
124 * the column was the left column. So calling {@code getStringCharacterIndex("英", 0)} and
125 * {@code getStringCharacterIndex("英", 1)} will both return 0.
126 * @param s String to translate the index to
127 * @param columnIndex Column index of the string written to a terminal
128 * @return The index in the string of the character in terminal column {@code columnIndex}
129 */
130 public static int getStringCharacterIndex(String s, int columnIndex) {
131 int index = 0;
132 int counter = 0;
133 while(counter < columnIndex) {
134 if(isCharCJK(s.charAt(index++))) {
135 counter++;
136 if(counter == columnIndex) {
137 return index - 1;
138 }
139 }
140 counter++;
141 }
142 return index;
143 }
144
145 /**
146 * Given a string that may or may not contain CJK characters, returns the substring which will fit inside
147 * <code>availableColumnSpace</code> columns. This method does not handle special cases like tab or new-line.
148 * <p>
149 * Calling this method is the same as calling {@code fitString(string, 0, availableColumnSpace)}.
150 * @param string The string to fit inside the availableColumnSpace
151 * @param availableColumnSpace Number of columns to fit the string inside
152 * @return The whole or part of the input string which will fit inside the supplied availableColumnSpace
153 */
154 public static String fitString(String string, int availableColumnSpace) {
155 return fitString(string, 0, availableColumnSpace);
156 }
157
158 /**
159 * Given a string that may or may not contain CJK characters, returns the substring which will fit inside
160 * <code>availableColumnSpace</code> columns. This method does not handle special cases like tab or new-line.
161 * <p>
162 * This overload has a {@code fromColumn} parameter that specified where inside the string to start fitting. Please
163 * notice that {@code fromColumn} is not a character index inside the string, but a column index as if the string
164 * has been printed from the left-most side of the terminal. So if the string is "日本語", fromColumn set to 1 will
165 * not starting counting from the second character ("本") in the string but from the CJK filler character belonging
166 * to "日". If you want to count from a particular character index inside the string, please pass in a substring
167 * and use fromColumn set to 0.
168 * @param string The string to fit inside the availableColumnSpace
169 * @param fromColumn From what column of the input string to start fitting (see description above!)
170 * @param availableColumnSpace Number of columns to fit the string inside
171 * @return The whole or part of the input string which will fit inside the supplied availableColumnSpace
172 */
173 public static String fitString(String string, int fromColumn, int availableColumnSpace) {
174 if(availableColumnSpace <= 0) {
175 return "";
176 }
177
178 StringBuilder bob = new StringBuilder();
179 int column = 0;
180 int index = 0;
181 while(index < string.length() && column < fromColumn) {
182 char c = string.charAt(index++);
183 column += TerminalTextUtils.isCharCJK(c) ? 2 : 1;
184 }
185 if(column > fromColumn) {
186 bob.append(" ");
187 availableColumnSpace--;
188 }
189
190 while(availableColumnSpace > 0 && index < string.length()) {
191 char c = string.charAt(index++);
192 availableColumnSpace -= TerminalTextUtils.isCharCJK(c) ? 2 : 1;
193 if(availableColumnSpace < 0) {
194 bob.append(' ');
195 }
196 else {
197 bob.append(c);
198 }
199 }
200 return bob.toString();
201 }
202
203 /**
204 * This method will calculate word wrappings given a number of lines of text and how wide the text can be printed.
205 * The result is a list of new rows where word-wrapping was applied.
206 * @param maxWidth Maximum number of columns that can be used before word-wrapping is applied, if <= 0 then the
207 * lines will be returned unchanged
208 * @param lines Input text
209 * @return The input text word-wrapped at {@code maxWidth}; this may contain more rows than the input text
210 */
211 public static List<String> getWordWrappedText(int maxWidth, String... lines) {
212 //Bounds checking
213 if(maxWidth <= 0) {
214 return Arrays.asList(lines);
215 }
216
217 List<String> result = new ArrayList<String>();
218 LinkedList<String> linesToBeWrapped = new LinkedList<String>(Arrays.asList(lines));
219 while(!linesToBeWrapped.isEmpty()) {
220 String row = linesToBeWrapped.removeFirst();
221 int rowWidth = getColumnWidth(row);
222 if(rowWidth <= maxWidth) {
223 result.add(row);
224 }
225 else {
226 //Now search in reverse and find the first possible line-break
227 final int characterIndexMax = getStringCharacterIndex(row, maxWidth);
228 int characterIndex = characterIndexMax;
229 while(characterIndex >= 0 &&
230 !Character.isSpaceChar(row.charAt(characterIndex)) &&
231 !isCharCJK(row.charAt(characterIndex))) {
232 characterIndex--;
233 }
234 // right *after* a CJK is also a "nice" spot to break the line!
235 if (characterIndex >= 0 && characterIndex < characterIndexMax &&
236 isCharCJK(row.charAt(characterIndex))) {
237 characterIndex++; // with these conditions it fits!
238 }
239
240 if(characterIndex < 0) {
241 //Failed! There was no 'nice' place to cut so just cut it at maxWidth
242 characterIndex = Math.max(characterIndexMax, 1); // at least 1 char
243 result.add(row.substring(0, characterIndex));
244 linesToBeWrapped.addFirst(row.substring(characterIndex));
245 }
246 else {
247 // characterIndex == 0 only happens, if either
248 // - first char is CJK and maxWidth==1 or
249 // - first char is whitespace
250 // either way: put it in row before break to prevent infinite loop.
251 characterIndex = Math.max( characterIndex, 1); // at least 1 char
252
253 //Ok, split the row, add it to the result and continue processing the second half on a new line
254 result.add(row.substring(0, characterIndex));
255 while(characterIndex < row.length() &&
256 Character.isSpaceChar(row.charAt(characterIndex))) {
257 characterIndex++;
258 };
259 if (characterIndex < row.length()) { // only if rest contains non-whitespace
260 linesToBeWrapped.addFirst(row.substring(characterIndex));
261 }
262 }
263 }
264 }
265 return result;
266 }
267 }