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% language=uk
\environment details-environment
\startcomponent details-tuningformulas
\startchapter[title={Tuning math formulas}]
Because of its look and feel, a math formula can look too widely spaced when put
on a grid. There are a few ways to control this. First of all, the default grid
option bound to math is already more tolerant. But you can control it locally
too. Take the following formula:
\startbuffer
\startformula
a = b^c
\stopformula
\stopbuffer
\blank \fakeline \getbuffer \fakeline \blank
This has been entered as:
\typebuffer
and because it is just a line of math it comes out as expected. The next code
\startbuffer
\startformula
a = \frac {a} {b}
\stopformula
\stopbuffer
\typebuffer
produces a higher line:
\blank \fakeline \getbuffer \fakeline \blank
as does:
\startbuffer
\startformula
a = \frac {\frac {b} {c}} {\frac {d} {e}}
\stopformula
\stopbuffer
\typebuffer
\blank \fakeline \getbuffer \fakeline \blank
We will now demonstrate three ways to compensate fo rexcessive spacing. The first
variant just sets a grid parameter:
\startbuffer
\startformula[grid=math:-halfline]
a = \frac {\frac {b} {c}} {\frac {d} {e}}
\stopformula
\stopbuffer
\typebuffer
\blank \fakeline \getbuffer \fakeline \blank
You can also pass this as an option. Only a few such grid related options are
defined: \type {halfline}, \type {line}, \type {-halfline} and \type {-grid}.
\startbuffer
\startformula[-halfline]
a = \frac {\frac {b} {c}} {\frac {d} {e}}
\stopformula
\stopbuffer
\typebuffer
\blank \fakeline \getbuffer \fakeline \blank
If you need to compensate frequently you can consider defining an instance:
\startbuffer
\defineformula[tight][grid=math:-halfline]
\starttightformula
a = \frac {\frac {b} {c}} {\frac {d} {e}}
\stoptightformula
\stopbuffer
\typebuffer
\blank \fakeline \getbuffer \fakeline \blank
The result can be somewhat unexpected at the top and bottom of a page. When we
subtract half a line from the height we can end up above the text area. This is
where the \type {split} directive comes in. So, the compensations are actually
defined as
\starttabulate[|TCT{blue}|T|]
\NC math \NC \theexpandedsnapperset{math} \NC \NR
\NC math:line \NC \theexpandedsnapperset{math:line} \NC \NR
\NC math:halfline \NC \theexpandedsnapperset{math:halfline} \NC \NR
\NC math:-line \NC \theexpandedsnapperset{math:-line} \NC \NR
\NC math:-halfline \NC \theexpandedsnapperset{math:-halfline} \NC \NR
\stoptabulate
You can define your own variants building on top of an existing one:
\starttyping
\definegridsnapping[math:my][math,....]
\stoptyping
We demonstrate the effect of the \type {split} directive here. It triggers a
check at the page boundaries but you need to keep in mind that this is not always
robust as such boundaries themselves can be triggered by and inject anything.
\startbuffer[a]
\dorecurse {15} {
\startformula[grid={math,-halfline}]
a = \frac {\frac {b} {c}} {\frac {d} {e}}
(\hbox{top #1 default})
\stopformula
\blank[samepage]
\fakeline
}
\stopbuffer
\startbuffer[b]
\dorecurse {15} {
\startformula[grid={math,-halfline,split}]
a = \frac {\frac {b} {c}} {\frac {d} {e}}
(\hbox{top #1 compensated})
\stopformula
\blank[samepage]
\fakeline
}
\stopbuffer
\getbuffer[a]
\getbuffer[b]
As said, the compensation is achieved with the \type {page} directive. The
previous pages were rendered using:
\typebuffer[a]
and
\typebuffer[b]
In order to get a consistent result we keep the depth of the formula the same but
effectively shift it down a bit, still honouring the grid. So what about the
bottom.
We can decide that the snapped formula doesn't fit and force a new page but we
can also accept that it sticks out to the bottom, which is less worse than the
top|-|of|-|the|-|page case.
\startbuffer[a]
\dorecurse{45}{\fakeline}
\startformula[grid={math,-halfline}]
a = \frac {\frac {b} {c}} {\frac {d} {e}}
(\hbox{bottom default})
\stopformula
\stopbuffer
\startbuffer[b]
\dorecurse{45}{\fakeline}
\startformula[grid={math,-halfline,split}]
a = \frac {\frac {b} {c}} {\frac {d} {e}}
(\hbox{bottom compensated})
\stopformula
\stopbuffer
\page \getbuffer[a] % fits on the page
\page \getbuffer[b] % forces a new page
These mechanisms might be improved over time but as we don't use it frequently
that might take a while.
The following formula was posted at the \CONTEXT\ mailing list in a grid snapping
thread and we will use it to demonstrate how you can mess a bit with the
snapping.
\startbuffer
g(x_{*}) = \lim_{n\to\infty} g(a_{n}) \leq 0 \leq \lim_{n\to\infty} g(b_{n}) = g(x_{*})
\stopbuffer
\typebuffer
We show the given grid parameter as well as its expansion into the low level grid
directives.
\unexpanded\def\SampleFormula#1%
{\definegridsnapping[math:temp][#1]
\blank
\type{grid=#1} \hfill expanded: \normalexpanded{\type{\theexpandedsnapperset{math:temp}}}
\blank[samepage]
\fakeline
\blank[samepage]
\startformula[grid={#1}]
\getbuffer
\stopformula
\blank[samepage]
\fakeline
\blank}
\SampleFormula{math}
\SampleFormula{low,halfline}
\SampleFormula{math,nodepth}
\stopchapter
\stopcomponent
|
