Android EditText 換行和對齊問題研究
阿新 • • 發佈：2019-01-23
1.原生方法換行Android textview換行屬性有BreakStrategy和hyphenationFrequencyandroid:breakStrategyBreak strategy (control over paragraph layout).Must be one of the following constant values.
對於TextView預設值是high_quality，對於EditText預設值是simple連字元android:hyphenationFrequencyFrequency of automatic hyphenation.Must be one of the following constant values.
當breakStrategy的值不是simple時改策略的normal和full有效。這兩個屬性是Android6.0引入的，實現在frameworks/minikin/libs/minikin目錄下，java通過jni呼叫so庫。但是按照icu的規範，英文單詞是儘可能的不中斷的，標點符號不會在行尾或者行首，所以即使設定high_quality和full的值，視覺上看起來也沒啥大變化。對齊android:justificationMode
| Constant | Value | Description |
| balanced | 2 | Line breaking strategy balances line lengths. |
| high_quality | 1 | Line breaking uses high-quality strategy, including hyphenation. |
| simple | 0 | Line breaking uses simple strategy. |
| Constant | Value | Description |
| full | 2 | |
| none | 0 | Standard amount of hyphenation, useful for running text and for screens with limited space for text. |
| normal | 1 | Less frequent hyphenation, useful for informal use cases, such as chat messages. |
4.4版本刪除程式碼在StaticLayout.java
// From the Unicode Line Breaking Algorithm (at least approximately)
//delete by lgy
// boolean isLineBreak = isSpaceOrTab ||
// // / is class SY and - is class HY, except when followed by a digit
// ((c == CHAR_SLASH || c == CHAR_HYPHEN) &&
// (j + 1 >= spanEnd || !Character.isDigit(chs[j + 1 - paraStart]))) ||
// // Ideographs are class ID: breakpoints when adjacent, except for NS
// // (non-starters), which can be broken after but not before
// (c >= CHAR_FIRST_CJK && isIdeographic(c, true) &&
// j + 1 < spanEnd && isIdeographic(chs[j + 1 - paraStart], false));
//
// if (isLineBreak) {
// okWidth = w;
// ok = j + 1;
//
// if (fitTop < okTop)
// okTop = fitTop;
// if (fitAscent < okAscent)
// okAscent = fitAscent;
// if (fitDescent > okDescent)
// okDescent = fitDescent;
// if (fitBottom > okBottom)
// okBottom = fitBottom;
// }