Add new functions for computing default font dimensions

 lisp/window.el (window-font-width, window-font-height)
 (window-max-chars-per-line): New functions.
 lisp/simple.el (default-font-height): Doc fix.
 (default-font-width): New function.

 etc/NEWS: Mention `default-font-width', `window-font-height',
 `window-font-width', and `window-max-chars-per-line'.

2 files changed, 23 insertions, 0 deletions

diff --git a/etc/ChangeLog b/etc/ChangeLog
index cd5c54037c8..c94e12296ed 100644
--- a/etc/ChangeLog
+++ b/etc/ChangeLog
@@ -1,3 +1,8 @@
+2015-03-21  Titus von der Malsburg  <malsburg@posteo.de>
+
+        * NEWS: Mention `default-font-width', `window-font-height',
+        `window-font-width', and `window-max-chars-per-line'.
+
 2015-03-03  Kelvin White  <kwhite@gnu.org>
 
         * NEWS.24: Add section to include ERC changes.
diff --git a/etc/NEWS b/etc/NEWS
index cabd0087d92..7cdb24b402e 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -173,6 +173,24 @@ possible inaccuracies in the end position.
 In particular, it now returns the average width of the font's
 characters, which can be used for geometry-related calculations.
 
+** A new function `default-font-width' returns the average width of a
+character in the current buffer's default font.  If the default face
+is remapped (see `face-remapping-alist'), the value for the remapped
+face is returned.  This function complements the existing function
+`default-font-height'.
+
+** New functions `window-font-height' and `window-font-width' return
+the height and average width of characters in a specified face and
+window.  If FACE is remapped (see `face-remapping-alist'), the
+function returns the information for the remapped face.
+
+** A new function `window-max-chars-per-line' returns the maximal
+number of characters that can be displayed on one line.  If a face
+and/or window are provided, these values are used for the
+calculation.  This function is different from `window-body-width' in
+that it accounts for (i) continuation glyphs, (ii) the size of the
+font, and (iii) the specified window.
+
 
 * Editing Changes in Emacs 25.1