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Class Bidi
java.lang.Object └ java.text.Bidi
public final class Bidi
This class implements the Unicode Bidirectional Algorithm.
Since:A Bidi object provides information on the bidirectional reordering of the text used to create it. This is required, for example, to properly display Arabic or Hebrew text. These languages are inherently mixed directional, as they order numbers from left-to-right while ordering most other text from right-to-left.
Once created, a Bidi object can be queried to see if the text it represents is all left-to-right or all right-to-left. Such objects are very lightweight and this text is relatively easy to process.
If there are multiple runs of text, information about the runs can be accessed by indexing to get the start, limit, and level of a run. The level represents both the direction and the 'nesting level' of a directional run. Odd levels are right-to-left, while even levels are left-to-right. So for example level 0 represents left-to-right text, while level 1 represents right-to-left text, and level 2 represents left-to-right text embedded in a right-to-left run.
1.4
Fields
static int | DIRECTION_DEFAULT_LEFT_TO_RIGHT | |
Constant indicating that the base direction depends on the first strong directional character in the text according to the Unicode Bidirectional Algorithm. If no strong directional character is present, the base direction is left-to-right. |
static int | DIRECTION_DEFAULT_RIGHT_TO_LEFT | |
Constant indicating that the base direction depends on the first strong directional character in the text according to the Unicode Bidirectional Algorithm. If no strong directional character is present, the base direction is right-to-left. |
static int | DIRECTION_LEFT_TO_RIGHT | |
Constant indicating base direction is left-to-right. |
static int | DIRECTION_RIGHT_TO_LEFT | |
Constant indicating base direction is right-to-left. |
Constructors
public | Bidi (String paragraph, int flags) | |
Create Bidi from the given paragraph of text and base direction. |
public | Bidi (AttributedCharacterIterator paragraph) | |
Create Bidi from the given paragraph of text. The RUN_DIRECTION attribute in the text, if present, determines the base direction (left-to-right or right-to-left). If not present, the base direction is computes using the Unicode Bidirectional Algorithm, defaulting to left-to-right i ... more > |
public | Bidi (char text, int textStart, byte embeddings, int embStart, int paragraphLength, int flags) | |
Create Bidi from the given text, embedding, and direction information. The embeddings array may be null. If present, the values represent embedding level information. Negative values from -1 to -61 indicate overrides at the absolute value of the level. Positive values from 1 to 61 in ... more > |
Methods
boolean | baseIsLeftToRight () | |
Return true if the base direction is left-to-right. |
| createLineBidi (int lineStart, int lineLimit) | ||
Create a Bidi object representing the bidi information on a line of text within the paragraph represented by the current Bidi. This call is not required if the entire paragraph fits on one line. |
int | getBaseLevel () | |
Return the base level (0 if left-to-right, 1 if right-to-left). |
int | getLength () | |
Return the length of text in the line. |
int | getLevelAt (int offset) | |
Return the resolved level of the character at offset. If offset is = the length of the line, return the base direction level. |
int | getRunCount () | |
Return the number of level runs. |
int | getRunLevel (int run) | |
Return the level of the nth logical run in this line. |
int | getRunLimit (int run) | |
Return the index of the character past the end of the nth logical run in this line, as an offset from the start of the line. For example, this will return the length of the line for the last run on the line. |
int | getRunStart (int run) | |
Return the index of the character at the start of the nth logical run in this line, as an offset from the start of the line. |
boolean | isLeftToRight () | |
Return true if the line is all left-to-right text and the base direction is left-to-right. |
boolean | isMixed () | |
Return true if the line is not left-to-right or right-to-left. This means it either has mixed runs of left-to-right and right-to-left text, or the base direction differs from the direction of the only run of text. |
boolean | isRightToLeft () | |
Return true if the line is all right-to-left text, and the base direction is right-to-left. |
static void | reorderVisually (byte levels, int levelStart, Object objects, int objectStart, int count) | |
Reorder the objects in the array into visual order based on their levels. This is a utility function to use when you have a collection of objects representing runs of text in logical order, each run containing text at a single level. The elements at index from objectStart up to object ... more > |
static boolean | requiresBidi (char text, int start, int limit) | |
Return true if the specified text requires bidi analysis. If this returns false, the text will display left-to-right. Clients can then avoid constructing a Bidi object. Text in the Arabic Presentation Forms area of Unicode is presumed to already be shaped and ordered for display, and ... more > |
| toString () | ||
Display the bidi internal state, used in debugging. |
Inherited methods
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