The QTextLayout handling is terribly slow on Qt 4.8.7, but some
caching has been added in Qt5 that makes it much faster. For some
reason, it is not that slow with Qt 4.8.1.
Caches are introduced for the three following methods
* width(doctring), controlled by CACHE_METRICS_WIDTH. This cache already
existed, but the code has been cleaned up
* getTextLayout, controlled by CACHE_METRICS_QTEXTLAYOUT (disabled by
default on Qt5, which does its own caching). This is used for pos2x
and x2pos and now for drawing of text too. The previous code used a
trivial caching scheme of the last used QTextLayout, but now they
are properly kept in a QCache. Moreover, the cacheEnabled() property
is enabled for these QTextLayout object (not sure what this does).
* breakAt, controlled by CACHE_METRICS_BREAKAT. This is the only user
of QTextLayout which did not have some kind of caching already.
For some weird reasons related to Argument-dependent look-up, the
qHash(docstring) function has to be defined in std namespace, since
lyx::docstring is actually std::basic_string<wchar_t>.
[NOTE: this version has profiling hooks, enabled by commenting out the line
#define DISABLE_PMPROF
that should eventually be removed.]
It may happen (for example with on the fly spell checking) that
GuiFontMetrics::pos2x is called with a negative pos value. Add a
special case for this situation.
Fixes bug #10506
An overlong word containing a hyphen could be broken anywhere, instead of after
the hyphen.
Example: compare the line breaking of
aaaaa-aaaaa-aaaaa-aaaaa
with
aaa aaaaa-aaaaa-aaaaa-aaaaa
(with a very narrow window)
This also improves Chinese text in some situations (#10299)
1) Distinguish expanding characters from separators, to fit with Qt's notion of
expanding character which comes from the Unicode std. CountExpanders() is moved
to FontMetrics to fix a discrepancy with the duplicate implementation from
598f7e4a.
2) Make these expanders stretch on-screen proportionally to the em of the font.
If a row mixes large and small text, LyX let us see which spaces are set in the
bigger font.
3) Now that the stretch is defined in ems, add a limit such that an expander
never stretches more than 1.5em to avoid weird and hard to read justified lines.
4) Add a return boolean to setSeparatorExtraWidth for future use.
This means that, when a string contains high-plane Unicode characters,
the length of a docstring and the corresponding QString will be
different: Qt will encode these characters using several 16bit
characters.
We have additionally to take into account QTBUG-25536, which implies
that sometimes qstring_to_ucs4(toqstr(s)) !=s. It is not clear whether
this bug can be a problem in other places.
Fixes bug #10443.
This fixes two particular problems
* with Qt5, it seems that QFontMetrics::width does not return the
correct value for some Arabic text; this patch uses QTextLayout
instead to compute a string width
* Likewise, the undocumented layout flags TextForceRightToLeft and
TextForceLeftToRight do not work with Arabic text; this patch uses
unicode override characters instead.
It might be that the two issues are related. In any case, they do not
happen with latin text where right-to-left direction is enforced. And
they do not happen with Qt4.
Additionally, remove some dead code in GuiFontMetrics::pos2x().
Fixes bug #10436.
* breakRow: remove wrong condition that would silently eat the contents of the
paragraph when the window is narrower than left margin
* breakRow: make sure that there is at least one element in each row
* breakAt: when force-breaking a row element, make sure it is not empty. Doing
so may create empty rows and therefore a endless loop.
Fixes bugs #9962 and #10001.
When an inset is separated from the adjacent string by a space, it is
reasonable to be able to break the string after the space.
Unfortunately, QTextLayout does not do that.
This patch reverts the workaround inserted in 71378268 and replaces it
with a different trick: the string is enlosed between a pair of
zero-width non breaking space characters, so that the leading/trailing
spaces are now normal spaces, where QTextLayout will agree to break
the string.
Fixes bug #9921 for good.
It is a bad idea to have a QObject variable that oulives the main QApplication object. See for example:
https://www.ics.com/designpatterns/book/globals.html
Here the QTextLayout object was static to the anonymous namespace getTextLayout function, and got destroyed after the freetype renderer had been disposed of by QApplication.
This causes segmentation faults when quitting LyX on some systems.
This patch moves the cache together with other GuiFontMetrics caches. It means that one will have one such QTextLayout per font type, but this will not change much.
This crude caching mecanism is useful in the particular case of a screen with many misspelling dotted lines. In this case, it is necessary to build a QTextLayout in order to know where to put the start/end of the spell line. Since rows typically contains text snippets longer than a word, we may be in a situation where the same QTextLayout is constructed repeatedly.
This commit is useful in this particular use case, and should not be costly in other cases. A better fix would be to remember the QTextLayout associated to each row element. This is a bit more work, so this fix should be sufficient for now.
Additionally, do not paint misspelled marks when painting is disabled.
Fixes bug #9890.
This is better because it implements a LRU cache. Indeed, while editing in particular, width of many different strings has to be computed. This is different from the previous situation where only width of single characters was computed and cached.
* GuiFontMetrics::pos2x, x2pos: add support for inter-word spacing.
* GuiPainter::text: idem
* Row::Element::countSeparators:
Row::countSeparators: new methods that count spaces in strings.
Row::setSeparatorExtraWidth: new method (code lifted from TextMetrics.cpp).
* TextMetrics::computeRowMetrics: rely on the above methods.
* RowPainter::paintMispelledMarked: pass only a Row::Element object reference
RowPainter::paintStringAndSel: idem; do not rely on values returned by
Painter::text (trailing spaces do not honor wordspacing value).
The goal of this commit is to make painting faster by reducing the
number of strings to paint. To this end, it is necessary to include
spaces in row elements.
Also importantly, this commit should fix existing problems with line
breaking in chinese text.
* TextMetrics::breakRow: do not do anything special for word separators.
* Row::add: when adding a character to a row element, keep the string
width updated. If need be, it is possible to tweak this by updating
every 10 characters, for example.
* GuiFontMetrics::breakAt (new): use QTextLayout to break text either
at word boundary or at an arbitrary width.
* Row::Element::breakAt: use the above method.
* Row::shortenIfNeeded: simplify now that because there is no need for
handling separator elements. This will be taken care of by the
improved breakAt.
Two things remain to be done:
* remove all traces of separator row element
* re-implement text justification.
The computation of length on screen depend in particular of the computation of the size of an em. Many places of the code used to rely on the width of the M character, which is not really correct:
http://en.wikipedia.org/wiki/Em_%28typography%29
In digital typography, the best value to use is the point size of the font.
* Implement FontMetrics::em(), which returns the value in pixels of the EM unit.
Convert code to use it.
* Introduce Length::inPixel(MetricsBase const &), which takes the textwidth and em information from the MetricsBase object. Convert code to use it.
* Fix several places where Length::inPixel is used without a proper em value.
* add mathed_font_em() helper function. It should eventually be removed like some other functions in MathSupport.
* Add dummy implementation of FontMetrics to tex2lyx for linking purposes.
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.
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
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.
This has the advantage of simplifying our code and to produce the
correct output: the small capitals should have the exact same width as
the lower case letters.
The slanted fonts are also translated to oblique on Qt side, but this
does not seems to have an effect in my testing. It may be that proper
oblique fonts need to be installed.
each failure.
There are several places I was not sure what to do. These are marked
by comments beginning "LASSERT:" so they can be found easily. At the
moment, they are at:
Author.cpp:105: // LASSERT: What should we do here?
Author.cpp:121: // LASSERT: What should we do here?
Buffer.cpp:4525: // LASSERT: Is it safe to continue here, or should we just return?
Cursor.cpp:345: // LASSERT: Is it safe to continue here, or should we return?
Cursor.cpp:403: // LASSERT: Is it safe to continue here, or should we return?
Cursor.cpp:1143: // LASSERT: There have been several bugs around this code, that seem
CursorSlice.cpp:83: // LASSERT: This should only ever be called from an InsetMath.
CursorSlice.cpp:92: // LASSERT: This should only ever be called from an InsetMath.
LayoutFile.cpp:303: // LASSERT: Why would this fail?
Text.cpp:995: // LASSERT: Is it safe to continue here?
The stmaryrd package adds support for lots of math symbols, using a font
designed to accompany the computer modern fonts. The changes in detail:
- Fix generate_symbols_list.py to work with stmaryrd.sty. It loooks like it
was automatically translated from a perl version and never used.
- Generate the new symbols in lib/symbols using generate_symbols_list.py and
add some manual adjustments
- Generate stmary10.ttf by a simple ttf export from stmary10.sfd with fontforge
- Add license info for stmary10.ttf
- Create a test file with all symbols from stmaryrd.sty. Actually it would be
nice to have this for the other fonts as well.
- The mechanics: lyx2lyx, tex2lyx, font machinery etc.
When creating the QFontMetrics object, we should specify a QPaintDevice. 0 is a paint device which is screen-compatible or pixmap-compatible. This makes sure that the correct DPI is used in font metrics calculations.
see also:
http://bugreports.qt.nokia.com/browse/QTBUG-16331.
git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@37030 a592a061-630c-0410-9148-cb99ea01b6c8
http://bugzilla.lyx.org/show_bug.cgi?id=3759
It also simplifies and fix the smallcaps case which was not correct WRT unicode. Even though I don't know if toUpper() means something in the non ucs2 range.
FYI, I used toqstr() to do the ucs4 -> ucs2 conversion when needed. This helper method works only with Qt >= 4.2.
* GuiFontMetrics::smallcapsWidth(): changed to work with single ucs4 characters.
* GuiFontMetrics::xxx(): make sure that font metrics works with characters not in the ucs2 range.
git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@18593 a592a061-630c-0410-9148-cb99ea01b6c8
