Added mc-hide-unmatched-lines mode

This minor mode when enabled hides all lines where no cursors (and
also hum/lines-to-expand below and above) To make use of this mode
press "C-'" while multiple-cursor-mode is active. You can still
edit lines while you are in mc-hide-unmatched-lines mode. To leave
this mode press "<return>" or "C-g"

mc-hide-unmatched-lines-mode.el

@@ -0,0 +1,119 @@
+;;; mc-hide-unmatched-lines.el
+
+;; Copyright (C) 2014 Aleksey Fedotov
+
+;; Author: Aleksey Fedotov <lexa@cfotr.com>
+;; Keywords: editing cursors
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This minor mode when enabled hides all lines where no cursors (and
+;; also hum/lines-to-expand below and above) To make use of this mode
+;; press "C-'" while multiple-cursor-mode is active. You can still
+;; edit lines while you are in mc-hide-unmatched-lines mode. To leave
+;; this mode press "<return>" or "C-g"
+;;
+
+;;; Code:
+
+
+(require 'multiple-cursors-core)
+
+(defvar hum/hide-unmatched-lines-mode-map (make-sparse-keymap)
+  "Keymap for hide unmatched lines is mainly for rebinding C-g")
+
+(define-key hum/hide-unmatched-lines-mode-map (kbd "C-g") 'hum/keyboard-quit)
+(define-key hum/hide-unmatched-lines-mode-map (kbd "<return>") 'hum/keyboard-quit)
+
+(defun hum/keyboard-quit ()
+  "Leave hide-unmatched-lines mode"
+  (interactive)
+  (mc-hide-unmatched-lines-mode 0))
+
+;; used only in in multiple-cursors-mode-disabled-hook
+(defun hum/disable-hum-mode ()
+  (mc-hide-unmatched-lines-mode 0)
+)
+
+(define-minor-mode mc-hide-unmatched-lines-mode
+  "Minor mode when enabled hides all lines where no cursos (and
+also hum/lines-to-expand below and above) To make use of this
+mode press \"C-'\" while multiple-cursor-mode is active. You can
+still edit lines while you are in mc-hide-unmatched-lines
+mode. To leave this mode press <return> or \"C-g\"" 
+  nil " hu"
+  hum/hide-unmatched-lines-mode-map
+  (if mc-hide-unmatched-lines-mode
+      ;;just in case if mc mode will be disabled while hide-unmatched-lines is active
+      (progn
+        (hum/hide-unmatched-lines)
+        (add-hook 'multiple-cursors-mode-disabled-hook 'hum/disable-hum-mode t t))
+    (progn
+      (hum/unhide-unmatched-lines)
+      (remove-hook 'multiple-cursors-mode-disabled-hook 'hum/disable-hum-mode))
+    )
+)
+
+(defconst hum/invisible-overlay-name 'hum/invisible-overlay-name)
+
+(defcustom hum/lines-to-expand 2
+  "How many lines below and above cursor to show"
+  :type '(integer)
+  :group 'multiple-cursors)
+
+(defcustom hum/placeholder "..."
+  "Placeholder which will be placed insted of hiden text"
+  :type '(string)
+  :group 'multiple-cursors
+)
+
+(defun hum/add-invisible-overlay (begin end)
+  (let ((overlay (make-overlay begin
+                               end
+                               (current-buffer)
+                               t
+                               nil
+                               )))
+    (overlay-put overlay hum/invisible-overlay-name t)
+    (overlay-put overlay 'invisible t)
+    (overlay-put overlay 'intangible t)
+    (overlay-put overlay 'evaporate t)
+    (overlay-put overlay 'after-string hum/placeholder)
+    )
+  )
+
+
+(defun hum/hide-unmatched-lines ()
+  (let ((begin (point-min)))
+    (mc/for-each-cursor-ordered
+     (save-excursion
+       (goto-char (mc/cursor-beg cursor))
+       (if (< begin (line-beginning-position (- hum/lines-to-expand)))
+           (hum/add-invisible-overlay begin (line-end-position (- hum/lines-to-expand)))
+         )
+       (setq begin (line-beginning-position (+ 2 hum/lines-to-expand)))
+       )
+     )
+    (hum/add-invisible-overlay begin (point-max))
+    )
+  )
+
+(defun hum/unhide-unmatched-lines ()
+  (remove-overlays nil nil hum/invisible-overlay-name t)
+  )
+
+(provide 'mc-hide-unmatched-lines-mode)
+(define-key mc/keymap (kbd "C-'") 'mc-hide-unmatched-lines-mode)

multiple-cursors-core.el

@@ -596,6 +596,9 @@ for running commands with multiple cursors.")
                                      mc/skip-to-next-like-this
                                      mc/skip-to-previous-like-this
                                      rrm/switch-to-multiple-cursors
+                                     mc-hide-unmatched-lines-mode
+                                     hum/keyboard-quit
+                                     hum/unhide-invisible-overlays
                                      save-buffer
                                      ido-exit-minibuffer
                                      exit-minibuffer

multiple-cursors.el

@@ -185,6 +185,7 @@
 (require 'mc-mark-pop)
 (require 'rectangular-region-mode)
 (require 'mc-separate-operations)
+(require 'mc-hide-unmatched-lines-mode)
 
 (provide 'multiple-cursors)