TeX and CSS treat line heights in fundamentally different ways. In
TeX, every character is treated as a box of its precise height and
depth; the line height (\baselineskip) applies after characters have
been assembled into lines. In CSS, in contrast, every character
creates a "line box" corresponding to the accompanying font. When
characters of different fonts and sizes are placed into the same
span, the resulting line box contains the line boxes of all children.
This is unfortunate because, for example, we want `\frac{1}{2}` to
behave in vertical spacing contexts like it is exactly as tall and
deep as the visible fraction (which is the TeX behavior). Given CSS
constraints, though, in most contexts the fraction has extra vertical
space: the line boxes for the numerator and denominator create
padding. For small boxes, this isn't so bad. To really see the
problem put a tall rule in the denominator of a fraction, or check
out the VerticalSpacing screenshotter test, which has way more space
than it should.
Solving this problem in CSS is difficult. There is no easy way to get
rid of the extra line boxes.
But there is *a* way, namely tables. A table-cell with vertical-align
top, bottom, or middle is ignored for the purposes of line height
calculation.
So in this commit, makeVList puts its contents into a
vertical-align:bottom table-cell (to clear unwanted line boxes), with
an extra row used to represent depth.
Many Chrome screenshotter tests change. This is because Chrome rounds
table dimensions to integral numbers of pixels, while it uses
sub-pixel positioning for non-table displayed tabs. That makes many
vlists a fraction of a pixel wider than they used to be.
* Internal: Pass full `options` objects to makeSpan/makeSymbol.
Not just the current color. This will facilitate applying options
to built nodes in a standardized way, rather than changing all
callsites.
* Add style switching test: text and scriptstyle in the same group.
* Apply style-specific spacing using different CSS coding.
Specifically, infer style from a class on the *current* element,
rather than the parent element. Use "mtight" class to denote elements
with tight spacing (scriptstyle or scriptscriptstyle). Apply that
class automatically based on options.
* Fix#533, #534, #541.
- #534: Implement getTypeOfGroup for font groups.
- #533, #541: Improve the ways spaces are applied to lists. Since
CSS adjacency implements mathematical spacing, it's incorrect to
introduce "convenience spans" for spaces and display changes into
the generated HTML -- those spans break adjacency. Apply display
changes directly, and shift space spans into adjacent atoms.
Requires updates to two screenshotter tests, LimitControls and
SupSubLeftAlignReset. The new results for these tests are closer
to TeX output than the old results.
Also requires updates to Jasmine tests, since those assumed output
structures that have changed.
* Fix#136: Size commands generate fragments, not spans.
This is so the size commands don't hide the types of their enclosed
atoms. Addresses #136.
This slightly changes the vertical position of the Sizing test. Not
sure the vertical position matters, so change the test.
