This event is sent to SegmentListeners when a text content is to be modified. The segments field can be used in conjunction with the segmentsChars field or by itself. Setting only the segmentsChars field has no effect. When used by itself, the segments field specify text ranges that should be treated as separate segments.
The elements in the segments field specify the start offset of a segment relative to the start of the text. They must follow the following rules:
- elements must be in ascending order and must not have duplicates
- elements must not exceed the text length
In addition, the first element may be set to zero and the last element may be set to the end of the line but this is not required. The segments field may be left null if the entire text content doesn't require segmentation. A SegmentListener may be used when adjacent segments of right-to-left text should not be reordered relative to each other. For example, within a Java editor, you may wish multiple right-to-left string literals to be reordered differently than the bidi algorithm specifies. Example:
stored text = "R1R2R3" + "R4R5R6" R1 to R6 are right-to-left characters. The quotation marks are part of the text. The text is 13 characters long. segments = null: entire text content will be reordered and thus the two R2L segments swapped (as per the bidi algorithm). visual display (rendered on screen) = "R6R5R4" + "R3R2R1" segments = [0, 5, 8] "R1R2R3" will be reordered, followed by [blank]+[blank] and "R4R5R6". visual display = "R3R2R1" + "R6R5R4"
The segments and segementsChars fields can be used together to obtain different types of bidi reordering and text display. The application can use these two fields to insert Unicode Control Characters in specific offsets in the text, the character at segmentsChars[i] is inserted at the offset specified by segments[i]. When both fields are set, the rules for the segments field are less restrictive:
- elements must be in ascending order, duplicates are allowed
- elements must not exceed the text length
@since 3.8