right align misc information

1 files changed, 79 insertions, 1 deletions

diff --git a/bard-elisp/bard-modeline.el b/bard-elisp/bard-modeline.el
index 5e8d0a4..f5dcbb1 100644
--- a/bard-elisp/bard-modeline.el
+++ b/bard-elisp/bard-modeline.el
@@ -53,6 +53,84 @@ or not."
 	     (with-selected-window (minibuffer-window)
 	       (eq window (minibuffer-selected-window)))))))
 
+;;;; Right side alignment
+
+(defun prot-modeline--right-align-rest ()
+  "Return string if everything after `prot-modeline-align-right'."
+  (format-mode-line
+   `(""
+     ,@(cdr (memq 'prot-modeline-align-right mode-line-format)))))
+
+(defun prot-modeline--right-align-width ()
+  "Return pixel width of `prot-modeline--right-align-rest'."
+  (string-pixel-width (prot-modeline--right-align-rest)))
+
+(defun prot-modeline--box-p ()
+  "Return non-nil if the `mode-line' has a box attribute."
+  (when-let ((box (face-attribute 'mode-line :box))
+             ((null (eq (face-attribute 'mode-line :box) 'unspecified))))
+    (or (plist-get box :line-width)
+        t)))
+
+;; NOTE 2023-07-13: I could also do what I am doing in
+;; `fontaine--family-list-variable-pitch' and check if the family is a
+;; member of those, but I don't need that as I always inherit
+;; `variable-pitch' in my themes instead of hardcoding the family.
+(defun prot-modeline--variable-pitch-p ()
+  "Return non-nil if the `mode-line' inherits `variable-pitch'."
+  (when-let* ((mode-line-inherit (face-attribute 'mode-line :inherit))
+              ((string-match-p "variable-pitch" (symbol-name mode-line-inherit)))
+              (family-face (face-attribute mode-line-inherit :inherit))
+              (variable-pitch
+               (if (listp family-face)
+                   (memq 'variable-pitch family-face)
+                 (eq 'variable-pitch family-face))))
+    variable-pitch))
+
+;; I just came up with this experimentally, but I am not sure if it is
+;; the best approach.
+(defun prot-modeline--magic-number ()
+  "Return constant for use in `prot-modeline-align-right'."
+  (let ((height (face-attribute 'mode-line :height nil 'default))
+        (m-width (string-pixel-width (propertize "m" 'face 'mode-line))))
+    (round height (* m-width (* height m-width 0.001)))))
+
+(defvar-local prot-modeline-align-right
+    '(:eval
+      (propertize
+       " "
+       'display
+       (let* ((box (prot-modeline--box-p))
+              (box-natnum-p (natnump box))
+              (variable-pitch-p (prot-modeline--variable-pitch-p))
+              (magic-number (prot-modeline--magic-number)))
+         `(space
+           :align-to
+           (- right
+              right-fringe
+              right-margin
+              ,(ceiling
+                (prot-modeline--right-align-width)
+                (string-pixel-width (propertize "m" 'face 'mode-line)))
+              ,(cond
+                ;; FIXME 2023-07-13: These hardcoded numbers are
+                ;; probably wrong in some case.  I am still testing.
+                ((and box-natnum-p variable-pitch-p)
+                 (+ (* box 2.375) magic-number))
+                (box-natnum-p
+                 (* magic-number (* box 1.15)))
+                ((and variable-pitch-p box)
+                 (* magic-number 0.5))
+                ((and (not variable-pitch-p) box)
+                 (* magic-number 0.25))
+                ((and variable-pitch-p (not box))
+                 0)
+                ;; No box, no variable pitch, but I am keeping it as
+                ;; the fallback for the time being.
+                (t (* magic-number -0.1))))))))
+  "Mode line construct to align following elements to the right.
+Read Info node `(elisp) Pixel Specification'.")
+
 ;;;; Faces
 
 (defface prot-modeline-indicator-button nil
@@ -537,7 +615,7 @@ Specific to the current window's mode line.")
                      prot-modeline-vc-branch
                      prot-modeline-flymake
                      prot-modeline-eglot
-                     ;; prot-modeline-align-right
+                     prot-modeline-align-right
                      prot-modeline-notmuch-indicator
                      prot-modeline-misc-info))
   (put construct 'risky-local-variable t))