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Since not all characters have the same width, these functions let you check the width of a character. See Primitive Indent, and Screen Lines, for related functions.
This function returns the width in columns of the character
char, if it were displayed in the current buffer (i.e., taking
into account the buffer’s display table, if any; see Display Tables). The width of a tab character is usually tab-width
(see Usual Display).
This function returns the width in columns of the string string, if it were displayed in the current buffer and the selected window.
This function returns the part of string that fits within width columns, as a new string.
If string does not reach width, then the result ends where string ends. If one multi-column character in string extends across the column width, that character is not included in the result. Thus, the result can fall short of width but cannot go beyond it.
The optional argument start-column specifies the starting column.
If this is non-nil
, then the first start-column columns of
the string are omitted from the value. If one multi-column character in
string extends across the column start-column, that
character is not included.
The optional argument padding, if non-nil
, is a padding
character added at the beginning and end of the result string, to extend
it to exactly width columns. The padding character is used at the
end of the result if it falls short of width. It is also used at
the beginning of the result if one multi-column character in
string extends across the column start-column.
If ellipsis is non-nil
, it should be a string which will
replace the end of string (including any padding) if it extends
beyond width, unless the display width of string is equal
to or less than the display width of ellipsis. If
ellipsis is non-nil
and not a string, it stands for
the value of the variable truncate-string-ellipsis
.
(truncate-string-to-width "\tab\t" 12 4) ⇒ "ab" (truncate-string-to-width "\tab\t" 12 4 ?\s) ⇒ " ab "
The following function returns the size in pixels of text as if it were
displayed in a given window. This function is used by
fit-window-to-buffer
and fit-frame-to-buffer
(see Resizing Windows) to make a window exactly as large as the text
it contains.
This function returns the size of the text of window’s buffer in pixels. window must be a live window and defaults to the selected one. The return value is a cons of the maximum pixel-width of any text line and the maximum pixel-height of all text lines.
The optional argument from, if non-nil
, specifies the first
text position to consider and defaults to the minimum accessible
position of the buffer. If from is t
, it uses the minimum
accessible position that is not a newline character. The optional
argument to, if non-nil
, specifies the last text position
to consider and defaults to the maximum accessible position of the
buffer. If to is t
, it uses the maximum accessible
position that is not a newline character.
The optional argument x-limit, if non-nil
, specifies the
maximum pixel-width that can be returned. x-limit nil
or
omitted, means to use the pixel-width of window’s body
(see Window Sizes); this is useful when the caller does not intend
to change the width of window. Otherwise, the caller should
specify here the maximum width window’s body may assume. Text
whose x-coordinate is beyond x-limit is ignored. Since
calculating the width of long lines can take some time, it’s always a
good idea to make this argument as small as needed; in particular, if
the buffer might contain long lines that will be truncated anyway.
The optional argument y-limit, if non-nil
, specifies the
maximum pixel-height that can be returned. Text lines whose
y-coordinate is beyond y-limit are ignored. Since calculating the
pixel-height of a large buffer can take some time, it makes sense to
specify this argument; in particular, if the caller does not know the
size of the buffer.
The optional argument mode-and-header-line nil
or omitted
means to not include the height of the mode- or header-line of
window in the return value. If it is either the symbol
mode-line
or header-line
, include only the height of that
line, if present, in the return value. If it is t
, include the
height of both, if present, in the return value.
window-text-pixel-size
treats the text displayed in a window as a
whole and does not care about the size of individual lines. The
following function does.
This function calculates the pixel dimensions of each line displayed in the specified window. It does so by walking window’s current glyph matrix—a matrix storing the glyph (see Glyphs) of each buffer character currently displayed in window. If successful, it returns a list of cons pairs representing the x- and y-coordinates of the lower right corner of the last character of each line. Coordinates are measured in pixels from an origin (0, 0) at the top-left corner of window. window must be a live window and defaults to the selected one.
If the optional argument first is an integer, it denotes the index
(starting with 0) of the first line of window’s glyph matrix to be
returned. Note that if window has a header line, the line with
index 0 is that header line. If first is nil
, the first line to
be considered is determined by the value of the optional argument
body: If body is non-nil
, this means to start with
the first line of window’s body, skipping any header line, if
present. Otherwise, this function will start with the first line of
window’s glyph matrix, possibly the header line.
If the optional argument last is an integer, it denotes the index
of the last line of window’s glyph matrix that shall be returned.
If last is nil
, the last line to be considered is determined by
the value of body: If body is non-nil
, this means to
use the last line of window’s body, omitting window’s mode
line, if present. Otherwise, this means to use the last line of
window which may be the mode line.
The optional argument inverse, if nil
, means that the
y-pixel value returned for any line specifies the distance in pixels
from the left edge (body edge if body is non-nil
) of
window to the right edge of the last glyph of that line.
inverse non-nil
means that the y-pixel value returned for
any line specifies the distance in pixels from the right edge of the
last glyph of that line to the right edge (body edge if body is
non-nil
) of window. This is useful for determining the
amount of slack space at the end of each line.
The optional argument left, if non-nil
means to return the
x- and y-coordinates of the lower left corner of the leftmost character
on each line. This is the value that should be used for windows that
mostly display text from right to left.
If left is non-nil
and inverse is nil
, this
means that the y-pixel value returned for any line specifies the
distance in pixels from the left edge of the last (leftmost) glyph of
that line to the right edge (body edge if body is non-nil
)
of window. If left and inverse are both
non-nil
, the y-pixel value returned for any line specifies the
distance in pixels from the left edge (body edge if body is
non-nil
) of window to the left edge of the last (leftmost)
glyph of that line.
This function returns nil
if the current glyph matrix of
window is not up-to-date which usually happens when Emacs is busy,
for example, when processing a command. The value should be retrievable
though when this function is run from an idle timer with a delay of zero
seconds.
This function returns the height in pixels of the line at point in the selected window. The value includes the line spacing of the line (see Line Height).
When a buffer is displayed with line numbers (see Display Custom in The GNU Emacs Manual), it is sometimes useful to know the width taken for displaying the line numbers. The following function is for Lisp programs which need this information for layout calculations.
This function returns the width used for displaying the line numbers
in the selected window. If the optional argument pixelwise is
the symbol columns
, the return value is a float number of the
frame’s canonical columns; if pixelwise is t
or any other
non-nil
value, the value is an integer and is measured in
pixels. If pixelwise is omitted or nil
, the value is the
integer number of columns of the font defined for the
line-number
face, and doesn’t include the 2 columns used to pad
the numbers on display. If line numbers are not displayed in the
selected window, the value is zero regardless of the value of
pixelwise. Use with-selected-window
(see Selecting Windows) if you need this information about another window.
Next: Line Height, Previous: Overlays, Up: Display [Contents][Index]