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(elisp)Size and Position

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Frame Size And Position
-----------------------

   You can read or change the size and position of a frame using the
frame parameters `left', `top', `height', and `width'.  Whatever
geometry parameters you don't specify are chosen by the window manager
in its usual fashion.

   Here are some special features for working with sizes and positions.
(For the precise meaning of "selected frame" used by these functions,
see Note: Input Focus.)

 - Function: set-frame-position frame left top
     This function sets the position of the top left corner of FRAME to
     LEFT and TOP.  These arguments are measured in pixels, and
     normally count from the top left corner of the screen.

     Negative parameter values position the bottom edge of the window
     up from the bottom edge of the screen, or the right window edge to
     the left of the right edge of the screen.  It would probably be
     better if the values were always counted from the left and top, so
     that negative arguments would position the frame partly off the
     top or left edge of the screen, but it seems inadvisable to change
     that now.

 - Function: frame-height &optional frame
 - Function: frame-width &optional frame
     These functions return the height and width of FRAME, measured in
     lines and columns.  If you don't supply FRAME, they use the
     selected frame.

 - Function: screen-height
 - Function: screen-width
     These functions are old aliases for `frame-height' and
     `frame-width'.  When you are using a non-window terminal, the size
     of the frame is normally the same as the size of the terminal
     screen.

 - Function: frame-pixel-height &optional frame
 - Function: frame-pixel-width &optional frame
     These functions return the height and width of FRAME, measured in
     pixels.  If you don't supply FRAME, they use the selected frame.

 - Function: frame-char-height &optional frame
 - Function: frame-char-width &optional frame
     These functions return the height and width of a character in
     FRAME, measured in pixels.  The values depend on the choice of
     font.  If you don't supply FRAME, these functions use the selected
     frame.

 - Function: set-frame-size frame cols rows
     This function sets the size of FRAME, measured in characters; COLS
     and ROWS specify the new width and height.

     To set the size based on values measured in pixels, use
     `frame-char-height' and `frame-char-width' to convert them to
     units of characters.

 - Function: set-frame-height frame lines &optional pretend
     This function resizes FRAME to a height of LINES lines.  The sizes
     of existing windows in FRAME are altered proportionally to fit.

     If PRETEND is non-`nil', then Emacs displays LINES lines of output
     in FRAME, but does not change its value for the actual height of
     the frame.  This is only useful for a terminal frame.  Using a
     smaller height than the terminal actually implements may be useful
     to reproduce behavior observed on a smaller screen, or if the
     terminal malfunctions when using its whole screen.  Setting the
     frame height "for real" does not always work, because knowing the
     correct actual size may be necessary for correct cursor
     positioning on a terminal frame.

 - Function: set-frame-width frame width &optional pretend
     This function sets the width of FRAME, measured in characters.
     The argument PRETEND has the same meaning as in `set-frame-height'.

   The older functions `set-screen-height' and `set-screen-width' were
used to specify the height and width of the screen, in Emacs versions
that did not support multiple frames.  They are semi-obsolete, but
still work; they apply to the selected frame.

 - Function: x-parse-geometry geom
     The function `x-parse-geometry' converts a standard X window
     geometry string to an alist that you can use as part of the
     argument to `make-frame'.

     The alist describes which parameters were specified in GEOM, and
     gives the values specified for them.  Each element looks like
     `(PARAMETER . VALUE)'.  The possible PARAMETER values are `left',
     `top', `width', and `height'.

     For the size parameters, the value must be an integer.  The
     position parameter names `left' and `top' are not totally accurate,
     because some values indicate the position of the right or bottom
     edges instead.  These are the VALUE possibilities for the position
     parameters:

    an integer
          A positive integer relates the left edge or top edge of the
          window to the left or top edge of the screen.  A negative
          integer relates the right or bottom edge of the window to the
          right or bottom edge of the screen.

    `(+ POSITION)'
          This specifies the position of the left or top edge of the
          window relative to the left or top edge of the screen.  The
          integer POSITION may be positive or negative; a negative
          value specifies a position outside the screen.

    `(- POSITION)'
          This specifies the position of the right or bottom edge of
          the window relative to the right or bottom edge of the
          screen.  The integer POSITION may be positive or negative; a
          negative value specifies a position outside the screen.

     Here is an example:

          (x-parse-geometry "35x70+0-0")
               => ((height . 70) (width . 35)
                   (top - 0) (left . 0))