Function: frame-pixel-width
frame-pixel-width is a function alias for frame-native-width, defined
in frame.c.
Signature
(frame-pixel-width &optional FRAME)
Documentation
Return FRAME's native width in pixels.
For a terminal frame, the result really gives the width in characters. If FRAME is omitted or nil, the selected frame is used.
If you're interested only in the width of the text portion of the
frame, see frame-text-width instead.