make live-preview follow min or max point

Author: Danny McClanahan

markdown-mode.el

@@ -5872,17 +5872,29 @@ buffer. Inverse of `markdown-live-preview-buffer'.")
   "Get window point and scroll data for all windows displaying BUF if BUF is
 non-nil."
   (when buf
-    (mapcar (lambda (win) (list win (window-point win) (window-start win)))
-            (get-buffer-window-list buf))))
+    (with-current-buffer buf
+      (mapcar
+       (lambda (win)
+         (let* ((pt (window-point win))
+                (pt-or-sym (cond ((= pt (point-min)) 'min)
+                                 ((= pt (point-max)) 'max)
+                                 (t pt))))
+           (list win pt-or-sym (window-start win))))
+       (get-buffer-window-list buf)))))
 
 (defun markdown-live-preview-window-deserialize (window-posns)
   "Apply window point and scroll data from WINDOW-POSNS, given by
 `markdown-live-preview-window-serialize'."
-  (cl-destructuring-bind (win pt start) window-posns
+  (cl-destructuring-bind (win pt-or-sym start) window-posns
     (when (window-live-p win)
       (set-window-buffer win markdown-live-preview-buffer)
-      (set-window-point win pt)
-      (set-window-start win start))))
+      (set-window-start win start)
+      (let ((actual-pt (cl-case pt-or-sym
+                         (min (point-min))
+                         (max (point-max))
+                         (t pt-or-sym))))
+        (with-current-buffer markdown-live-preview-buffer
+          (set-window-point win actual-pt))))))
 
 (defun markdown-live-preview-export ()
   "Export to XHTML using `markdown-export' and browse the resulting file within

tests/markdown-test.el

@@ -3787,6 +3787,27 @@ Detail: https://github.com/jrblevin/markdown-mode/issues/79"
            (should (file-exists-p file-output)))
        (delete-file file-output)))))
 
+(ert-deftest test-markdown-ext/live-preview-follow-min-max ()
+  (markdown-test-temp-file "inline.text"
+    (markdown-live-preview-mode)
+    (should (buffer-live-p markdown-live-preview-buffer))
+    (should (window-live-p (get-buffer-window markdown-live-preview-buffer)))
+    (with-selected-window (get-buffer-window markdown-live-preview-buffer)
+      (goto-char (point-min)))
+    (goto-char (point-min))
+    (insert "a ")
+    (markdown-live-preview-export)
+    (let (final-pt)
+      (with-selected-window (get-buffer-window markdown-live-preview-buffer)
+        (should (= (window-point) 1))
+        (setq final-pt (point-max))
+        (goto-char (point-max)))
+      (goto-char (point-min))
+      (insert "this is ")
+      (markdown-live-preview-export)
+      (with-selected-window (get-buffer-window markdown-live-preview-buffer)
+        (should (= (window-point) (+ final-pt (length "this is "))))))))
+
 (provide 'markdown-test)
 
 ;;; markdown-test.el ends here