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The following schematic shows the structure of a live window:
____________________________________________
|______________ Header Line ______________|RD| ^
^ |LS|LF|LM| |RM|RF|RS| | |
| | | | | | | | | | |
Window | | | | Text Area | | | | | Window
Body | | | | | (Window Body) | | | | | Total
Height | | | | | | | | | Height
| | | | |<- Window Body Width ->| | | | | |
v |__|__|__|_______________________|__|__|__| | |
|_______________ Mode Line _______________|__| |
|_____________ Bottom Divider _______________| v
<---------- Window Total Width ------------>
At the center of the window is the text area, or body, where the buffer text is displayed. The text area can be surrounded by a series of optional areas. On the left and right, from innermost to outermost, these are the left and right margins, denoted by LM and RM in the schematic (see Display Margins); the left and right fringes, denoted by LF and RF (see Fringes); the left or right scroll bar, only one of which is present at any time, denoted by LS and RS (see Scroll Bars); and the right divider, denoted by RD (see Window Dividers). At the top of the window is the header line (see Header Lines); at the bottom of the window is the mode line (see Mode Line Format) followed by the bottom divider (see Window Dividers).
Emacs provides miscellaneous functions for finding the height and
width of a window. The return value of many of these functions can be
specified either in units of pixels or in units of lines and columns.
On a graphical display, the latter actually correspond to the height and
width of a “default” character specified by the frame’s default font
as returned by frame-char-height and frame-char-width
(see Size and Position). Thus, if a window is displaying text with
a different font or size, the reported line height and column width for
that window may differ from the actual number of text lines or columns
displayed within it.
The total height of a window is the number of lines comprising the window’s body, the header line, the mode line and the bottom divider (if any). Note that the height of a frame is not the same as the height of its root window (see Windows and Frames), since a frame may also contain an echo area, a menu bar, and a tool bar (see Size and Position).
This function returns the total height, in lines, of the window
window. If window is omitted or nil, it defaults to
the selected window. If window is an internal window, the return
value is the total height occupied by its descendant windows.
If a window’s pixel height is not an integral multiple of its frame’s default character height, the number of lines occupied by the window is rounded internally. This is done in a way such that, if the window is a parent window, the sum of the total heights of all its child windows internally equals the total height of their parent. This means that although two windows have the same pixel height, their internal total heights may differ by one line. This means also, that if this window is vertically combined and has a right sibling, the topmost row of that sibling can be calculated as the sum of this window’s topmost row and total height (see Coordinates and Windows)
If the optional argument round is ceiling, this
function returns the smallest integer larger than window’s pixel
height divided by the character height of its frame; if it is
floor, it returns the largest integer smaller than said value;
with any other round it returns the internal value of
windows’s total height.
The total width of a window is the number of lines comprising the window’s body, its margins, fringes, scroll bars and a right divider (if any).
This function returns the total width, in columns, of the window
window. If window is omitted or nil, it defaults to
the selected window. If window is internal, the return value is
the total width occupied by its descendant windows.
If a window’s pixel width is not an integral multiple of its frame’s
character width, the number of lines occupied by the window is rounded
internally. This is done in a way such that, if the window is a parent
window, the sum of the total widths of all its children internally
equals the total width of their parent. This means that although two
windows have the same pixel width, their internal total widths may
differ by one column. This means also, that if this window is
horizontally combined and has a right sibling, the leftmost column of
that sibling can be calculated as the sum of this window’s leftmost
column and total width (see Coordinates and Windows). The
optional argument round behaves as it does for
window-total-height.
This function returns either the total height in lines or the total
width in columns of the window window. If horizontal is
omitted or nil, this is equivalent to calling
window-total-height for window; otherwise it is equivalent
to calling window-total-width for window. The optional
argument round behaves as it does for window-total-height.
The following two functions can be used to return the total size of a window in units of pixels.
This function returns the total height of window window in pixels. window must be a valid window and defaults to the selected one.
The return value includes mode and header line and a bottom divider, if any. If window is an internal window, its pixel height is the pixel height of the screen areas spanned by its children.
This function returns the width of window window in pixels. window must be a valid window and defaults to the selected one.
The return value includes the fringes and margins of window as well as any vertical dividers or scroll bars belonging to window. If window is an internal window, its pixel width is the width of the screen areas spanned by its children.
The following functions can be used to determine whether a given window has any adjacent windows.
This function returns non-nil if window has no other
window above or below it in its frame, i.e., its total height equals
the total height of the root window on that frame. If window is
omitted or nil, it defaults to the selected window.
This function returns non-nil if window has no other
window to the left or right in its frame, i.e., its total width equals
that of the root window on that frame. If window is omitted or
nil, it defaults to the selected window.
The body height of a window is the height of its text area, which does not include a mode or header line or a bottom divider.
This function returns the height, in lines, of the body of window
window. If window is omitted or nil, it defaults to
the selected window; otherwise it must be a live window.
If the optional argument pixelwise is non-nil, this
function returns the body height of window counted in pixels.
If pixelwise is nil, the return value is rounded down to
the nearest integer, if necessary. This means that if a line at the
bottom of the text area is only partially visible, that line is not
counted. It also means that the height of a window’s body can never
exceed its total height as returned by window-total-height.
The body width of a window is the width of its text area, which does not include the scroll bar, fringes, margins or a right divider.
This function returns the width, in columns, of the body of window
window. If window is omitted or nil, it defaults to
the selected window; otherwise it must be a live window.
If the optional argument pixelwise is non-nil, this
function returns the body width of window in units of pixels.
If pixelwise is nil, the return value is rounded down to
the nearest integer, if necessary. This means that if a column on the
right of the text area is only partially visible, that column is not
counted. It also means that the width of a window’s body can never
exceed its total width as returned by window-total-width.
This function returns the body height or body width of window. If
horizontal is omitted or nil, it is equivalent to calling
window-body-height for window; otherwise it is equivalent
to calling window-body-width. In either case, the optional
argument pixelwise is passed to the function called.
For compatibility with previous versions of Emacs,
window-height is an alias for window-total-height, and
window-width is an alias for window-body-width. These
aliases are considered obsolete and will be removed in the future.
The pixel heights of a window’s mode and header line can be retrieved with the functions given below. Their return value is usually accurate unless the window has not been displayed before: In that case, the return value is based on an estimate of the font used for the window’s frame.
This function returns the height in pixels of window’s mode line. window must be a live window and defaults to the selected one. If window has no mode line, the return value is zero.
This function returns the height in pixels of window’s header line. window must be a live window and defaults to the selected one. If window has no header line, the return value is zero.
Functions for retrieving the height and/or width of window dividers (see Window Dividers), fringes (see Fringes), scroll bars (see Scroll Bars), and display margins (see Display Margins) are described in the corresponding sections.
Commands that change the size of windows (see Resizing Windows),
or split them (see Splitting Windows), obey the variables
window-min-height and window-min-width, which specify the
smallest allowable window height and width. They also obey the variable
window-size-fixed, with which a window can be fixed in
size:
This option specifies the minimum total height, in lines, of any window. Its value has to accommodate at least one text line as well as a mode and header line and a bottom divider, if present.
This option specifies the minimum total width, in columns, of any window. Its value has to accommodate two text columns as well as margins, fringes, a scroll bar and a right divider, if present.
If this buffer-local variable is non-nil, the size of any
window displaying the buffer cannot normally be changed. Deleting a
window or changing the frame’s size may still change its size, if
there is no choice.
If the value is height, then only the window’s height is fixed;
if the value is width, then only the window’s width is fixed.
Any other non-nil value fixes both the width and the height.
If this variable is nil, this does not necessarily mean that any
window showing the buffer can be resized in the desired direction. To
determine that, use the function window-resizable.
See Resizing Windows.
The following function tells how small a specific window can get taking
into account the sizes of its areas and the values of
window-min-height, window-min-width and
window-size-fixed.
This function returns the minimum size of window. window
must be a valid window and defaults to the selected one. The optional
argument horizontal non-nil means to return the minimum
number of columns of window; otherwise return the minimum number
of window’s lines.
The return value makes sure that all components of window remain
fully visible if window’s size were actually set to it. With
horizontal nil it includes the mode and header line and the
bottom divider. With horizontal non-nil it includes the
fringes, a scroll bar, and a right divider, if present. It does not,
however, include the space reserved for the margins.
The optional argument ignore, if non-nil, means ignore
restrictions imposed by fixed size windows, window-min-height or
window-min-width settings. If ignore equals safe,
live windows may get as small as window-safe-min-height lines and
window-safe-min-width columns. If ignore is a window,
ignore restrictions for that window only. Any other non-nil
value means ignore all of the above restrictions for all windows.
The optional argument pixelwise non-nil means to return the
minimum size of window counted in pixels.
Next: Resizing Windows, Previous: Windows and Frames, Up: Windows [Contents][Index]