@Section
    @Title { Changing the appearance of cells }
    @Tag { tbl_cell }
@Begin
@PP
The @Code "@Cell" symbol offers a few options for changing the appearance
tables. @RawIndex { tables }
tables.paint @SubIndex { @Code "paint" option }
paint. @RawIndex { @Code "paint" option }
paint.in.tables @SubIndex { in tables }
tables. @RawIndex { tables }
tables.font @SubIndex { @Code "font" option }
font.option. @RawIndex { @Code "font" option }
font.option.in.tables @SubIndex { in tables }
tables. @RawIndex { tables }
tables.break @SubIndex { @Code "break" option }
break. @RawIndex { @Code "break" option }
break.tables @SubIndex { in tables }
of entries placed in it.  Like all options, these
appear immediately after the @Code "@Cell" symbol, with their values in braces:
@ID @OneRow @Code @Verbatim {
@Tbl
   aformat { @Cell paint { lightgrey } font { Italic } break { clines } A }
{
@Rowa A {
IMPORTANT
Do not throw stones at this notice
}
}
}
The result here is
@CD
@Tbl
   aformat { @Cell paint { lightgrey } font { Italic } break { clines } A | @Cell B }
{
@Rowa A {
IMPORTANT
Do not throw stones at this notice
}
}
with a light grey background, Italic font, and
@Code "clines" paragraph breaking style.  The paint colour
may be any colour from Section {@NumberOf colour}.
@PP
Wherever there is a @Code paint option in the standard packages, there
is a neighbouring @Code texture option, which causes the paint to be
tables. @RawIndex { tables }
tables.texture @SubIndex { @Code "texture" option }
texture.option. @RawIndex { @Code "texture" option }
texture.option.in.tables @SubIndex { in tables }
applied according to a given texture.  For a list of available
textures, consult Section {@NumberOf textures}; for how the @Code texture
option works, consult the description of the @Code texture option to the
@Code "@Box" symbol in Section {@NumberOf boxes} (all @Code texture
options work in the same way).  Here's an example:
@ID @OneRow @Code @Verbatim {
@Tbl
    width { 2f }
    height { 2f }
    aformat {
@Cell paint { black } texture { brickwork } A | @Cell B |
@Cell paint { black } texture { brickwork } C | @Cell D }
    bformat {
@Cell A | @Cell paint { black } texture { brickwork } B |
@Cell C | @Cell paint { black } texture { brickwork } D }
{
@Rowa
@Rowb
@Rowa
@Rowb
}
}
produces
@FootNote { If you can't see any textures here, the fault is probably
with your PostScript viewer.  See Section {@NumberOf textures}. }
@CD @OneRow
@Tbl
    width { 2f }
    height { 2f }
    aformat {
@Cell paint { black } texture { brickwork } A | @Cell B |
@Cell paint { black } texture { brickwork } C | @Cell D }
    bformat {
@Cell A | @Cell paint { black } texture { brickwork } B |
@Cell C | @Cell paint { black } texture { brickwork } D }
{
@Rowa
@Rowb
@Rowa
@Rowb
}
Another option, {@Code background}, allows an arbitrary object to be
tables. @RawIndex { tables }
tables.background @SubIndex { @Code "background" option }
background.tables @Index { @Code "background" option (tables) }
placed in the background of the cell, in front of any paint but behind
the entry.
@PP
Later sections introduce other @Code "@Cell" options, for
fixed-width columns, indented entries, margins, and rules.  It is also
possible to combine other symbols from Lout with cell formatting, by
placing them between the @Code "@Cell" symbol and its following letter,
rotated.entries @Index { rotated entries in tables }
like this:
@ID @OneRow @Code @Verbatim {
@Tbl
    aformat { @Cell 90d @Rotate @S A | @Cell @B grey @Colour B }
{
@Rowa
    A { Col A }
    B { Col B }
}
}
Think of the @Code "A" as standing for the value of the @Code "A"
option of the @Code "@Rowa" symbol (which it does), and you'll see
that this is just Lout's usual rule of symbols applying to the
object that follows them.  The result here is
@CD @Tbl
    aformat { @Cell 90d @Rotate @S A | @Cell @B grey @Colour B }
{
@Rowa
    A { Col A }
    B { Col B }
}
In simple cases @Code "@B" is easier than {@Code "font { Bold }"};
the latter is useful as a default value, as we will see in a moment.
Note the difference between a coloured background, obtained with
{@Code "paint"}, and a coloured entry, obtained using the @Code "@Colour"
symbol.
@PP
When an entry in a table consists of several paragraphs, it will usually
be best to enclose it in {@Code "@OneRow"}, since otherwise @Code "@Tbl"
is likely to take each paragraph as a separate row, leading to incorrect
vertical spacing.  A convenient way to do this is
@ID @Code "aformat { @Cell @OneRow A | @Cell @OneRow B }"
and so on.
@PP
@Code "@Tbl" offers many places where you can set cell options.  The meaning
of the option is the same wherever you set it;
what changes is the extent of its application.  Taking the @Code "paint"
option as a representative example, the most specific place to set it
is at a @Code "@Cell" symbol as above; then it affects only that cell
in rows formatted using that format.  Alternatively,
@ID @OneRow @Code @Verbatim {
@Tbl
    apaint { lightgrey }
    aformat { @Cell A | @Cell B }
}
will paint every cell in the {@Code "aformat"}.  And
@ID @OneRow @Code @Verbatim {
@Rowa
    paint { lightgrey }
    A { ... }
}
will paint every cell in a particular row.  To paint the entire table, use
@ID @OneRow @Code @Verbatim {
@Tbl
    paint { lightgrey }
}
And finally, there is a @Code "paint" option in the
setup file (Section {@NumberOf tbl_setu}), which if set will paint every
table in the document.  When a more general setting of an option is
contradicted by a more specific setting (e.g. when @Code "@Tbl" has
@Code "paint { lightgrey }" but some cell or row has
{@Code "paint { none }"}), the more specific setting applies.  For a
precise description, see Section {@NumberOf tbl_summ}.
@End @Section