This branch implements string-wise metrics computation. The goal is to
have both good metrics computation (and font with proper kerning and
ligatures) and better performance than what we have with
force_paint_single_char. Moreover there has been some code
factorization in TextMetrics, where the same row-breaking algorithm
was basically implemented 3 times.
Globally, the new code is a bit shorter than the existing one, and it
is much cleaner. There is still a lot of potential for code removal,
especially in the RowPainter, which should be rewritten to use the new
Row information.
The bugs fixed and caused by this branch are tracked at ticket #9003:
http://www.lyx.org/trac/ticket/9003
What is done:
* Make TextMetrics methods operate on Row objects: breakRow and
setRowHeight instead of rowBreakPoint and rowHeight.
* Change breakRow operation to operate at strings level to compute
metrics The list of elements is stored in the row object in visual
ordering, not logical. This will eventually allow to get rid of the
Bidi class.
* rename getColumnNearX to getPosNearX (and change code accordingly).
It does not make sense to return a position relative to the start of
row, since nobody needs this.
* Re-implement cursorX and getPosNearX using row elements.
* Get rid of lyxrc.force_paint_single_char. This was a workaround that
is not necessary anymore.
* Implement proper string metrics computation (with cache). Remove
useless workarounds which disable kerning and ligatures.
* Draw also RtL text string-wise. This speeds-up drawing.
* Do not cut strings at selection boundary in RowPainter. This avoids
ligature/kerning breaking in latin text, and bad rendering problems
in Arabic.
* Remove homebrew Arabic and Hebrew support from Encoding.cpp. We now
rely on Qt to do handle complex scripts.
* Get rid of LyXRC::rtl_support, which does not have a real use case.
* Fix display of [] and {} delimiters in Arabic scripts.
Actually the workaround that is used to show parenthesis in the right direction
is not needed any more, since this is part of the unicode bidi writing algorithm.
This fixes at the same time the use of [] or as delimiters in arabic, which was wrong on screen.
Note that there is a problem with hebrew, but this will require a fileformat change.
The use of RLO/LRO overrides to force text orientation was really hackish and the way it was done caused dropped letters in Mac OS X (for some unknown reasons).
This new approach is much cleaner, except that it relies on features not advertised in documentation
but present at least from Qt 4.5 to Qt 5.3:
* TextFlag enum values TextForceLeftToRight and TextForceRightToLeft, which are strong versions
of QPainter::setLayoutDirection; they are passed as a parameter of QPainter::drawText.
* QTextLayout::setFlags method, which is required to pass the above flags to QTextLayout.
The unicode override method is still used to draw strings Mac OS X because, for some reason, the direction was not really enforced in this case.
This can only be done where splitting of string is identical in row breaking and display. It will be possible to reintroduce this when row painting uses the tokenized row information.
The option --enable-qt5 allows configuring for Qt5. The default is Qt4.
Nothing special is done with respect to Qt4, apart from pulling in the
correct libraries. Indeed, other than the core and gui libraries, now
also the concurrent and widgets libraries are needed.
For Windows: AcroRd32 and gsview (both 32 and 64 bit versions).
For Unix: qpdfview.
Qpdfview is a nice alternative to Okular for KDE users and a superior
alternative to Evince for Gnome users, due to its complete synctex
support. It only depends on Qt libraries for the graphical interface.
Forthcoming versions of cygwin will use a different mechanism for
obtaining passwd/group information based on /etc/nsswitch.conf.
Thus, it will not be guaranteed that the files /etc/passwd and
/etc/group even exist. The recommended way for obtaining those
info is by using the getent command, which already works in
current versions.
The conversion from floating point to string performed by
boost:lexical_cast does not allow specifying a precision and,
for example, values such as 0.9 are resturned as 0.899999976.
The standard C++ way for performing the conversion is using
std::ostringstream which is exempt from this problem, even if
less efficient. For the sake of accuracy, boost::lexical_cast
is ditched in favor of the ostrinsgstream implementation.
In C++11 another option would be using std::to_string, but I
think it is not as efficient as the boost way and not worth
implementing through #ifdef's.
Incidentally, this patch would have also fixed#9190 and all
similar cases involving the use of convert<string>(float|double).
When a font is scaled by a certain percentage in the document settings,
LyX was outputting a ridiculous parameter value. For example, if the
font is scaled 90%, the corresponding parameter was "scaled=0.899999976".
The patch avoids this and, in the previous case, one gets "scaled=0.9".
This is not only cosmetic, because in roundtrip conversions the parameter
would be continuosly changing.
This commit and b60b505f should be backported to the 2.1.x branch, where
reimporting with tex2lyx an exported document produces wrong results
(also in version 2.1.0).
This variable was introduced to guard against any bad consequence of the then-new right-to-left
languages support. Let's be bold and get rid of it altogether!
Now right to left support is always enabled.
This commits (tries to) reintroduce properly the code that was reverted at the beginning of this branch. This had to be done because these patches interefered with the big refactoring of TextMetrics.cpp.
This commit reintroduces the changes to TextMetrics.cpp contained in c668ebf6, c85dbfea9 and 061509bf.
This is handled by Qt now.
Note that a small optimization (do not draw text that is to the left
of WorkArea) is removed because it cannot be guaranteed to be exact
anymore. It was probably not very useful anyway, and would become
useless once the RowPainter is rewritten to use Row information.
Update 00README_STR_METRICS_BRANCH.
The display of partially-selected word is now done in a new Painter::text method
which displays the string twice with different clip settings. This allows to
catter for the case where Color_selectiontext is not black.
Morover, the code that uses unicode override characters to force the
direction of a string is moved to lstrings.h.
Fixes: #9116
Moreover, breaks row at insets when there is no suitable separator.
Also make the code of Row::shorten_if_needed somewhat simpler by using
iterators and factoring the code.
Fixes: #9120
The old implementation of Row::Element::pos2x and x2pos did not work
correctly with Arabic text, because characters can have shapes that
depend on context.
This new implementation leverages QTextLayout in a simplified way,
since only one word is added to the layout.
This allows to make Row::Element::x2pos more readable.
Fixes: #9115.
Do not cut strings at separators in RowPainter when text is not
justified. This speeds-up painting by reducing the number of strings
to draw.
Do also a modest cleanup of paintChar (remove dubious optimization).
Instead of relying on character range (Hebrew or Arabic) or character
direction, use RLO unicode character (Right-to-Left override) to force
painting in the direction indicated by the current font. This should
be as close as we can to the old LyX behavior (and requires less
code).
If this code works as intended, it will be possible to remove a lot of
code from Encodings.cpp.
We rely on Qt built-in unicode support for handling Arabic and Hebrew
compose characters. This allows to avoid to use our homegrown
machinery.
This should provide a nice speedup at a low cost and
will eventually allow us to get rid of:
* most of our Arabic/Hebrew machinery in Encodings.cpp,
* Paragraph::transformChar,
* and probably more.
All these problems are related to what happens at the extreme points of rows
* since VIRTUAL elements have a width but no contents, they have to
be treated specially at some places. It would have been better to
avoid testing for them explicitly, but I did not find a way.
* Improve and cleanup the code in breakRow and fix in passing a crash
when clicking on the right of an incomplete MARGIN_MANUAL
paragraph.
* improve the computation of row width in TextMetrics::computeRowMetrics.
* handle properly the case where a position if not found on the row
in both cursorX and getPosNearX (actually, this happens when
selecting).
* Some code cleanup and comments.
The fact that the bug was still present in the features/str-metrics
branch comes from a goof in the initial implementation of 'virtual'
row elements (completion and end-of-par markers). Now that this is
corrected, everything works as it should.
The fact that the bug is present in master is due to some other reason
that is not useful to investigate now.
