eldoc-overlay-mode.el

   1 ;;; eldoc-overlay-mode.el --- Display eldoc with contextual documentation overlay.
   2
   3 ;; Author: stardiviner <numbchild@gmail.com>
   4 ;; Keywords: eldoc overlay
   5 ;; URL: https://github.com/stardiviner/eldoc-overlay-mode
   6 ;; Created: 14th Jan 2017
   7 ;; Version: 0.0.1
   8 ;; Package-Requires: ((emacs "25.1"))
   9
  10 ;;; Commentary:
  11
  12
  13
  14 ;;; Code:
  15 ;;; ----------------------------------------------------------------------------
  16
  17 (defvar eldoc-overlay--overlay nil)
  18
  19 (defface eldoc-overlay-face
  20   '((t (:inherit italic)))
  21   "Face for eldoc-overlay-mode."
  22   :group 'eldoc)
  23
  24 (defun eldoc-overlay--clear-overlay ()
  25   "Clear eldoc-overlay overlays."
  26   (when (overlayp eldoc-overlay--overlay)
  27     (delete-overlay eldoc-overlay--overlay))
  28   (remove-hook 'post-command-hook 'eldoc-overlay--clear-overlay))
  29
  30 (defun eldoc-overlay--string-display-next-line (string)
  31   "Overwrite contents of next line with STRING until next command."
  32   (let* ((indent-spaces (make-string (- (current-indentation) 2) ?\s))
  33          (str (concat (propertize "➜ " 'face 'font-lock-doc-face)
  34                       (copy-sequence string) ; original eldoc string with format
  35                       "\n"))
  36          start-pos end-pos)
  37     (unwind-protect
  38         (save-excursion
  39           (eldoc-overlay--clear-overlay)
  40           (forward-line)
  41           (setq start-pos (point))
  42           (end-of-line)
  43           (setq end-pos (point))
  44           (setq eldoc-overlay--overlay (make-overlay start-pos end-pos (current-buffer)))
  45           ;; Change the face
  46           ;; (overlay-put eldoc-overlay--overlay 'face 'eldoc-overlay-face)
  47           ;; Hide full line
  48           ;; (overlay-put eldoc-overlay--overlay 'display "")
  49           ;; (overlay-put eldoc-overlay--overlay 'display :height 120)
  50           ;; pre-pend indentation spaces
  51           ;; (overlay-put eldoc-overlay--overlay 'line-prefix indent-spaces)
  52           ;; auto delete overlay with property 'evaporate
  53           (overlay-put eldoc-overlay--overlay 'evaporate t)
  54           ;; Display message
  55           (overlay-put eldoc-overlay--overlay 'before-string str))
  56       (add-hook 'post-command-hook 'eldoc-overlay--clear-overlay))))
  57
  58 (defun eldoc-overlay-display-message-momentary (format-string &rest args)
  59   "Display eldoc message FORMAT-STRING near point with extra ARGS."
  60   (when format-string
  61     (eldoc-overlay--string-display-next-line
  62      (apply 'format format-string args))))
  63
  64 (defvar eldoc-overlay-mode-map
  65   (let ((map (make-sparse-keymap)))
  66     map))
  67
  68 ;;;###autoload
  69 (define-minor-mode eldoc-overlay-mode
  70   "Minor mode for displaying eldoc with contextual documentation overlay."
  71   :init-value t
  72   :lighter " ElDoc overlay"
  73   :keymap eldoc-overlay-mode-map
  74   :global t
  75   (if eldoc-overlay-mode
  76       (setq eldoc-message-function #'eldoc-overlay-display-message-momentary)
  77     (setq eldoc-message-function #'eldoc-minibuffer-message)
  78     )
  79   )
  80
  81 ;;; ----------------------------------------------------------------------------
  82
  83 (provide 'eldoc-overlay-mode)
  84
  85 ;;; eldoc-overlay-mode.el ends here