Bug 27593
| Summary: | [Qt] Hyphenation is broken (no hyphens visible) for QtWebkit | ||
|---|---|---|---|
| Product: | WebKit | Reporter: | Alexei Puzikov <puzikov> |
| Component: | Text | Assignee: | Nobody <webkit-unassigned> |
| Status: | RESOLVED WORKSFORME | ||
| Severity: | Normal | CC: | cmarcelo, jesus, joseph.wild, jturcotte, kinbot, kovid, laszlo.gombos, pierre.rossi, vestbo |
| Priority: | P2 | Keywords: | Qt, QtTriaged |
| Version: | 420+ | ||
| Hardware: | All | ||
| OS: | All | ||
Alexei Puzikov
Steps to reproduce:
1. With any QtWebkit-based browser or example (tested with Arora+Qt4.5.2 and Browser demo from the same Qt) browse to http://www.cs.tut.fi/~jkorpela/shytest.html
2. Resize browser window.
3. Observe that words are hyphenated/broken, but no hyphens are visible.
Works OK with:
Safari, Konqueror, Firefox
| Attachments | ||
|---|---|---|
| Add attachment proposed patch, testcase, etc. |
Tor Arne Vestbø
Confirmed in WebKit trunk (r48110), against Qt 4.6 (77fd77d6), on Mac OS 10.5
Alexey Proskuryakov
*** Bug 29576 has been marked as a duplicate of this bug. ***
Alexey Proskuryakov
*** Bug 29573 has been marked as a duplicate of this bug. ***
Alexey Proskuryakov
*** Bug 35838 has been marked as a duplicate of this bug. ***
Jesus Sanchez-Palencia
Reproduced on Snow Leopard with Qt 4.7 trunk (HEAD 03f8f1df0d88f5ffe0b3120cffce614cbeefdb70) and WebKit trunk (r59155).
Joe Wild
https://bugs.webkit.org/show_bug.cgi?id=27593
3. 27593 Nor P2 All webkit-unassigned@lists.web... NEW [Qt] Hyphenation
is broken (no hyphens visible) for QtWebkit
From what I can tell the Qt line text breaking code does not honor the
soft hypen (&Shy;).
Below is a edited call stack. I replaced soft hyphen char with
"\xAD". Basically, it shows the WebCore line breaking calling into
the Qt TextBreakIterator and then into Qt
QTextBoundaryFinder::toNextBoundary(),
#0 WebCore::textBreakFollowing (bi=0x340bfe0, pos=19)
/Source/WebCore/platform/text/qt/TextBreakIteratorQt.cpp:12
int textBreakFollowing(TextBreakIterator* bi, int pos)
{
bi->setPosition(pos);
int newpos = bi->toNextBoundary();
DEBUG() << "textBreakFollowing" << pos << newpos;
return newpos;
}
#1 WebCore::lineBreakIterator
/Source/WebCore/platform/text/qt/TextBreakIteratorQt.cpp:95
#2 WebCore::nextBreakablePosition
#3 WebCore::isBreakable
/Source/WebCore/rendering/break_lines.h:33
#4 WebCore::RenderBlock::findNextLineBreak
/Source/WebCore/rendering/RenderBlockLineLayout.cpp:1725
#5 WebCore::RenderBlock::layoutInlineChildren
/Source/WebCore/rendering/RenderBlockLineLayout.cpp:681
#6 WebCore::RenderBlock::layoutBlock
/Source/WebCore/rendering/RenderBlock.cpp:1222
Since I don't have Qt enabled for debugging, I traced that by looking
at the source.
The QTextBoundaryFinder::toNextBoundary() for Line skips anything <
HB_Break which means it will only return the position for HB_Break or
HB_ForcedBreak. HB_SoftHyphen is ignored. This routine returns when
it encounters the next whitespace ignoring any soft hyphens.
int QTextBoundaryFinder::toNextBoundary()
{
...
case Line:
Q_ASSERT(pos);
while (pos < length && d->attributes[pos-1].lineBreakType < HB_Break)
++pos;
break;
toNextBoundary uses harfbuzz.
./3rdparty/harfbuzz/src/harfbuzz-shaper.h:
typedef enum {
HB_NoBreak,
HB_SoftHyphen,
HB_Break,
HB_ForcedBreak
} HB_LineBreakType;
So is this as simple as changing the condition to < HB_SoftHyphen or
is there a deeper problem. Need to investigate.
Joe Wild
When I enable ICU in WebKit with the following, the test case passes.
build-webkit --qt --debug --qmakearg=CONFIG+=text_breaking_with_icu
This further points to this code
./src/corelib/tools/qtextboundaryfinder.cpp
int QTextBoundaryFinder::toNextBoundary()
which is not called when ICU is enabled.
There is a corresponding Qt error
https://qtrequirements.europe.nokia.com/browse/QT-4657
which I need to get reopened. I think we closed the wrong error.
Pierre Rossi
This seems to work well these days. Could be a side effect of fixing QTextBoundaryFinder. :)