elisp: Window Internals
E.8.2 Window Internals
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The fields of a window (for a complete list, see the definition of
‘struct window’ in ‘window.h’) include:
‘frame’
The frame that this window is on.
‘mini_p’
Non-‘nil’ if this window is a minibuffer window.
‘parent’
Internally, Emacs arranges windows in a tree; each group of
siblings has a parent window whose area includes all the siblings.
This field points to a window’s parent.
Parent windows do not display buffers, and play little role in
display except to shape their child windows. Emacs Lisp programs
usually have no access to the parent windows; they operate on the
windows at the leaves of the tree, which actually display buffers.
‘hchild’
‘vchild’
These fields contain the window’s leftmost child and its topmost
child respectively. ‘hchild’ is used if the window is subdivided
horizontally by child windows, and ‘vchild’ if it is subdivided
vertically. In a live window, only one of ‘hchild’, ‘vchild’, and
‘buffer’ (q.v.) is non-‘nil’.
‘next’
‘prev’
The next sibling and previous sibling of this window. ‘next’ is
‘nil’ if the window is the right-most or bottom-most in its group;
‘prev’ is ‘nil’ if it is the left-most or top-most in its group.
‘left_col’
The left-hand edge of the window, measured in columns, relative to
the leftmost column in the frame (column 0).
‘top_line’
The top edge of the window, measured in lines, relative to the
topmost line in the frame (line 0).
‘total_cols’
‘total_lines’
The width and height of the window, measured in columns and lines
respectively. The width includes the scroll bar and fringes,
and/or the separator line on the right of the window (if any).
‘buffer’
The buffer that the window is displaying.
‘start’
A marker pointing to the position in the buffer that is the first
character displayed in the window.
‘pointm’
This is the value of point in the current buffer when this window
is selected; when it is not selected, it retains its previous
value.
‘force_start’
If this flag is non-‘nil’, it says that the window has been
scrolled explicitly by the Lisp program. This affects what the
next redisplay does if point is off the screen: instead of
scrolling the window to show the text around point, it moves point
to a location that is on the screen.
‘frozen_window_start_p’
This field is set temporarily to 1 to indicate to redisplay that
‘start’ of this window should not be changed, even if point gets
invisible.
‘start_at_line_beg’
Non-‘nil’ means current value of ‘start’ was the beginning of a
line when it was chosen.
‘use_time’
This is the last time that the window was selected. The function
‘get-lru-window’ uses this field.
‘sequence_number’
A unique number assigned to this window when it was created.
‘last_modified’
The ‘modiff’ field of the window’s buffer, as of the last time a
redisplay completed in this window.
‘last_overlay_modified’
The ‘overlay_modiff’ field of the window’s buffer, as of the last
time a redisplay completed in this window.
‘last_point’
The buffer’s value of point, as of the last time a redisplay
completed in this window.
‘last_had_star’
A non-‘nil’ value means the window’s buffer was modified when the
window was last updated.
‘vertical_scroll_bar’
This window’s vertical scroll bar.
‘left_margin_cols’
‘right_margin_cols’
The widths of the left and right margins in this window. A value
of ‘nil’ means no margin.
‘left_fringe_width’
‘right_fringe_width’
The widths of the left and right fringes in this window. A value
of ‘nil’ or ‘t’ means use the values of the frame.
‘fringes_outside_margins’
A non-‘nil’ value means the fringes outside the display margins;
othersize they are between the margin and the text.
‘window_end_pos’
This is computed as ‘z’ minus the buffer position of the last glyph
in the current matrix of the window. The value is only valid if
‘window_end_valid’ is not ‘nil’.
‘window_end_bytepos’
The byte position corresponding to ‘window_end_pos’.
‘window_end_vpos’
The window-relative vertical position of the line containing
‘window_end_pos’.
‘window_end_valid’
This field is set to a non-‘nil’ value if ‘window_end_pos’ is truly
valid. This is ‘nil’ if nontrivial redisplay is pre-empted, since
in that case the display that ‘window_end_pos’ was computed for did
not get onto the screen.
‘cursor’
A structure describing where the cursor is in this window.
‘last_cursor’
The value of ‘cursor’ as of the last redisplay that finished.
‘phys_cursor’
A structure describing where the cursor of this window physically
is.
‘phys_cursor_type’
‘phys_cursor_height’
‘phys_cursor_width’
The type, height, and width of the cursor that was last displayed
on this window.
‘phys_cursor_on_p’
This field is non-zero if the cursor is physically on.
‘cursor_off_p’
Non-zero means the cursor in this window is logically off. This is
used for blinking the cursor.
‘last_cursor_off_p’
This field contains the value of ‘cursor_off_p’ as of the time of
the last redisplay.
‘must_be_updated_p’
This is set to 1 during redisplay when this window must be updated.
‘hscroll’
This is the number of columns that the display in the window is
scrolled horizontally to the left. Normally, this is 0.
‘vscroll’
Vertical scroll amount, in pixels. Normally, this is 0.
‘dedicated’
Non-‘nil’ if this window is dedicated to its buffer.
‘display_table’
The window’s display table, or ‘nil’ if none is specified for it.
‘update_mode_line’
Non-‘nil’ means this window’s mode line needs to be updated.
‘base_line_number’
The line number of a certain position in the buffer, or ‘nil’.
This is used for displaying the line number of point in the mode
line.
‘base_line_pos’
The position in the buffer for which the line number is known, or
‘nil’ meaning none is known. If it is a buffer, don’t display the
line number as long as the window shows that buffer.
‘column_number_displayed’
The column number currently displayed in this window’s mode line,
or ‘nil’ if column numbers are not being displayed.
‘current_matrix’
‘desired_matrix’
Glyph matrices describing the current and desired display of this
window.
Info Catalog
elisp: Buffer Internals
elisp: Object Internals
elisp: Process Internals