#1833 soft-hyphen in text widget

[Anonymous]

Soft-hyphens '\u00AD' are not properly handled in text
widgets.
They are always shown as '-' (hyphen) but a soft-hyphen
should only appear if it is the last character in a line.

I.E
"abc\u00AD123" should be displayed as

abc123

or

abc-
123

but is always displayed as
abc-123

Tested on win/linux
8.4.6 / 8.4.7 / 8.5a2

[Donal K. Fellows]

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Issue originally raised on comp.lang.tcl

The word-break algorithm is also wrong ('-wrap word'
considers \u00AD to not be a potential break point)

This is probably also broken in multiline labels/buttons.

[Vince Darley]

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The bug in question is around here:

if (wrapMode != TEXT_WRAPMODE_WORD) {
chunkPtr->breakIndex = chunkPtr->numBytes;
} else {
for (count = bytesThatFit, p += bytesThatFit - 1; count > 0;
count--, p--) {
if (isspace(UCHAR(*p))) {
chunkPtr->breakIndex = count;
break;
}
}

in tkTextDisp.c (line 6668 onwards). That 'isspace(UCHAR)'
needs to be made utf aware and look for special characters
like \u00AD.

Code contributions (and new tests) appreciated. This is not
on my immediate to-do list.

[Vince Darley]

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I should add that my previous comment refers to where the
fix for word-wrapping at a soft-hyphen should go.

To make soft-hyphens not display when they're not at the end
of a line will require more changes both earlier on in the
same TkTextCharLayoutProc (or more likely in the helper
routine MeasureChars), and in CharDisplayProc. These
additional changes are non-trivial.

[Vince Darley]

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Note, even beyond this bug, shouldn't "word wrapping"
actually wrap at ordinary hyphens as well? Currently all of
Tk's word wrapping wraps only at whitespace.