With this merge, the way paragraphs are typeset changes. Paragraphs
are first tolenized as row elements, and these elements are then
broken into separate rows as needed to fit the margins. This allows to
reduce the amount of metrics computation and make LyX much faster in
the case of large insets.
Moreover, the code relies more on RofFlags enum, which desribes how an
inset or a row element should be typset. This aspect will be extended
in the future.
Some user for whom performance is very bad (which I cannot reproduce
unfortunately) have reported a 4-fold speedup. In general cases, the
speedup will be less impressive but still noticeable.
Related to bugs #12297 and #5861.
Increase the maximal size of the breakString cache (to compute where
to break lines) from 512kB to 10MB. This has a big impact of cache
hits on large file like the example in #12297, which is now 99%. On
this example the time taken by breakString decreases from 33.5us to
2.4us.
The string width cache has been increased fro 512kB to 1MB, but this
does not make such a big difference.
Additionally, comments and variable names have been improved.
Related to bug #12297.
Add new row flags Flush and FlushBefore to let insets indicate whether
they cause flushing of current row (eg. newline) or of previous row
(e.g. display insets).
Replace FontMetrics::breakAt, which returned the next break point,
with FontMetrics::breakString, which returns a vector of break points.
To this end, an additional parameter gives the available width for
next rows.
Rename various variables and methods accordingly. Factor the code in
breakString_helper to be more manageable.
Adapt Row::Element::splitAt to return a bool on sucess and provide
remaining row elements in a vector. The width noted above has been
added as parameters.
Rename the helper function splitFrom to moveElements and rewrite the
code to be more efficient.
Remove type of row element INVALID, which is not needed anymore.
The code in TextMetrics::breakParagraph is now much simpler.
In Row::finalize, remove the code that computed inconditionnally the
current element size, and make sure that this width will be computed
in all code paths of Row::Element::splitAt.
In TextMetrics::breakParagraph, get rid of the fragile `pos' local
variable, which was not correctly updated. Rely on the endpos of the
last element in row instead.
Rewrite cleanupRow to rely on the endpos of last the row element to
set row endpos, instead of a `pos' parameter.
Instead of having breakParagraph decide when breaking a row is
necessary, let Row::shortenIfNeeded set the row_flag of the last
element to request a row break. This was already done in splitAt.
This is in preparation of splitAt splitting in more than two elements.
Move to Row::Element::rtrim the code in Row::shortenIfNeeded that
removes trailing spaces from last element in row, so that it can be
called when actually breaking a row.
Fixes bug found by Kornel.
In this case, the extra element returned should empty but valid. The
row flag BreakAfter is set to indicate that we have a break there
(this principle will be used more generally in a forthcoming commit).
To detect that we cut at the trailing space, it is necessary to rely
on the difference between QTextLine::horizontalAdvance() and
QTextLine::naturalTextWidth() when the flag
QTextOption::IncludeTrailingSpaces is used: the trailing space is
taken into account in the later, but not in the former.
Somme comments have been added to make code intent clearer.
At least with Qt 4.8.7 on Ubuntu 16.04, QTextLine::lineWidth() can
return a bogus value, at least with Courier font. One hypothesis is
that the invisible characters that we use in breakAt_helper are given
a non-null width.
Work around it, although the exact bug has not been pinpointed.
Change semantics of Row::shortenIfNeeded: instead of breaking the row
and returning a boolean, it returns the list of row elements that have
been removed (or broken) from the row. The logic of the method remains
the same.
Use shortenIfNeeded in breakParagraph. This was the last missing block.
Remove Row::breakAt and the old breakRow. Only bugs remain now :)
To this end, add the helper function needsRowBreak which computes the
effect of two consecutive row flags. This function implements the
priorities described in RowFlags.h.
This function is called with the relevant flags, or NoBreak* when at
boundaries and updates need_new_row.
Some common code is factored in a new cleanupRow() helper.
Remove the code that computed the width every 30 characters (yay!).
Make sure that finalizeLast() is called after inserting a row element in
a row in breakParagraph.
Still many features missing:
- handle insets that break rows (display math, newline, ...)
- handle rows that are too long by replacing the single call to
breakAt with a call to a reworked Row::shortenIfNeeded.
- some easy things at the end of breakRow (bidi text, etc.).
Move the enum definition RowFlags in its own include file, to avoid
loading Inset.h. Document it more thoroughly.
Rename RowAfter to AlwaysBreakAfter.
Add CanBreakInside (rows that can be themselves broken). This allow to
differentiate elements before bodyPos() and allows to remove a
parameter to shortenIfNeeded().
Make the Inset::rowFlags() method return int instead of RowFlags, as
should be done for all the bitwise flags. Remove the hand-made bitwise
operators.
Set R::E::row_flags when creating elements.
* INSET elements use the inset's rowFLags();
* virtual element forbid breaking before them, and inherit the *After
flags from the previous element of the row;
* STRING elements usr CanBreakInside, except before bodyPos.
More stuff may be added later.
This contains large parts of breakRow, but creates a unique row for the paragraph.
The parts taken or not in redoParagraph are annotated.
The new method is not used yet.
Move declaration of RowList to Row.h
Move initialization of POD members of Row and Row::Element to declaration.
Make method isVirtual() depend on type.
Add new row element type INVALID and method isValid()
Make methods R::E::left/right_pos inline.
Add method R::E::splitAt() that returns an element containing the
remaining stuff, or an invalid element if nothing was split. breakAt
is now a simple wrapper around this function.
Add method R::push_back().
Since we intend to break the row element in two, it is not good to
truncate the string too early.
Moreover, the row element width is now set at this point, even if no
breaking occurs.
When inserting € in a math cell, it is put in a text inset and the
cursor leaves the inset. However, inserting ¤ then leads to
\text{€}\text{¤}.
Therefore, try to see if there is a previous \text inset that can be
recycled and insert the new inset there in this case, leading to
\text{€¤}.
Fixes bug #11979.
This allows to simplify the code in Lexer and to remove the dependency
on Formats class.
As a consequence, a pair of dummy definitions of isZippedFile can be removed.
