Fix bug #17281 with infloop in line-pixel-height.

 src/xdisp.c (Fline_pixel_height): Don't assume that the current
 buffer and the selected window's buffer are one and the same.

2 files changed, 16 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index d0aa2e59e01..122b093f2a0 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,9 @@
 2014-04-17  Eli Zaretskii  <eliz@gnu.org>
 
+        * xdisp.c (Fline_pixel_height): Don't assume that the current
+        buffer and the selected window's buffer are one and the same.
+        (Bug#17281)
+
         * insdel.c (invalidate_buffer_caches): Invalidate the bidi
         paragraph-start cache before the newline cache.  (Bug#17269)
 
diff --git a/src/xdisp.c b/src/xdisp.c
index eb3a6df1fc5..ad5f6a6bf83 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -1262,12 +1262,23 @@ Value is the height in pixels of the line at point.  */)
   struct it it;
   struct text_pos pt;
   struct window *w = XWINDOW (selected_window);
+  struct buffer *old_buffer = NULL;
+  Lisp_Object result;
 
+  if (XBUFFER (w->contents) != current_buffer)
+    {
+      old_buffer = current_buffer;
+      set_buffer_internal_1 (XBUFFER (w->contents));
+    }
   SET_TEXT_POS (pt, PT, PT_BYTE);
   start_display (&it, w, pt);
   it.vpos = it.current_y = 0;
   last_height = 0;
-  return make_number (line_bottom_y (&it));
+  result = make_number (line_bottom_y (&it));
+  if (old_buffer)
+    set_buffer_internal_1 (old_buffer);
+
+  return result;
 }
 
 /* Return the default pixel height of text lines in window W.  The