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(Line Height): Fix errors in description of

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default line height and line-height properyty.
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Richard M. Stallman 2006-05-31 00:24:26 +00:00
parent d792d4449a
commit 6ac209a3f7
2 changed files with 35 additions and 33 deletions
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@ -1,5 +1,8 @@
2006-05-30 Richard Stallman <rms@gnu.org>
* display.texi (Line Height): Fix errors in description of
default line height and line-height properyty.
* nonascii.texi (Default Coding Systems): Further clarification.
2006-05-29 Luc Teirlinck <teirllm@auburn.edu>

65
lispref/display.texi
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@ -1582,41 +1582,41 @@ equal to or less than the display width of @var{ellipsis}. If
@cindex line height
The total height of each display line consists of the height of the
contents of the line, and additional vertical line spacing below the
display row.
contents of the line, plus optional additional vertical line spacing
above or below the display line.
The height of the line contents is normally determined from the
maximum height of any character or image on that display line,
including the final newline if there is one. (A line that is
continued doesn't include a final newline.) In the most common case,
the line height equals the height of the default frame font.
The height of the line contents is the maximum height of any
character or image on that display line, including the final newline
if there is one. (A display line that is continued doesn't include a
final newline.) That is the default line height, if you do nothing to
specify a greater height. (In the most common case, this equals the
height of the default frame font.)
There are several ways to explicitly control or change the line
height, either by specifying an absolute height for the display line,
or by adding additional vertical space below one or all lines.
There are several ways to explicitly specify a larger line height,
either by specifying an absolute height for the display line, or by
specifying vertical space. However, no matter what you specify, the
actual line height can never be less than the default.
@kindex line-height @r{(text property)}
A newline can have a @code{line-height} text or overlay property
that controls the total height of the display line ending in that
newline.
If the property value is a list @code{(@var{height} @var{total})},
then @var{height} is used as the actual property value for the
@code{line-height}, and @var{total} specifies the total displayed
height of the line, so the line spacing added below the line equals
the @var{total} height minus the actual line height. In this case,
the other ways to specify the line spacing are ignored.
If the property value is @code{t}, the newline character has no
effect on the displayed height of the line---the visible contents
alone determine the height. This is useful for tiling small images
(or image slices) without adding blank areas between the images.
If the property value is @code{t}, the displayed height of the
line is exactly what its contents demand; no line-spacing is added.
This case is useful for tiling small images or image slices without
adding blank areas between the images.
If the property value is a list of the form @code{(@var{height}
@var{total})}, that adds extra space @emph{below} the display line.
First Emacs uses @var{height} as a height spec to control extra space
@emph{above} the line; then it adds enough space @emph{below} the line
to bring the total line height up to @var{total}. In this case, the
other ways to specify the line spacing are ignored.
If the property value is not @code{t}, it is a height spec. A height
spec stands for a numeric height value; this height spec specifies the
actual line height, @var{line-height}. There are several ways to
write a height spec; here's how each of them translates into a numeric
height:
Any other kind of property value is a height spec, which translates
into a number---the specified line height. There are several ways to
write a height spec; here's how each of them translates into a number:
@table @code
@item @var{integer}
@ -1634,11 +1634,10 @@ If the height spec is a cons of the format shown, the numeric height
is @var{ratio} times the height of the contents of the line.
@end table
Thus, any valid non-@code{t} property value specifies a height in pixels,
@var{line-height}, one way or another. If the line contents' height
is less than @var{line-height}, Emacs adds extra vertical space above
the line to achieve the total height @var{line-height}. Otherwise,
@var{line-height} has no effect.
Thus, any valid height spec determines the height in pixels, one way
or another. If the line contents' height is less than that, Emacs
adds extra vertical space above the line to achieve the specified
total height.
If you don't specify the @code{line-height} property, the line's
height consists of the contents' height plus the line spacing.
@ -1663,9 +1662,9 @@ height. This overrides line spacings specified for the frame.
@kindex line-spacing @r{(text property)}
Finally, a newline can have a @code{line-spacing} text or overlay
property that controls the height of the display line ending with that
newline. The property value overrides the default frame line spacing
and the buffer local @code{line-spacing} variable.
property that overrides the default frame line spacing and the buffer
local @code{line-spacing} variable, for the display line ending in
that newline.
One way or another, these mechanisms specify a Lisp value for the
spacing of each line. The value is a height spec, and it translates