master 07d9532: Fix pixel scrolling over lines with different sized glyphs

[Po Lu]

branch: master
commit 07d95325e4bb955c4b660f632c77c4693374282f
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix pixel scrolling over lines with different sized glyphs
    
    * lisp/pixel-scroll.el
    (pixel-scroll-precision-scroll-down-page): Calculate desired
    vscroll with `window-text-pixel-size'.
---
 lisp/pixel-scroll.el | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lisp/pixel-scroll.el b/lisp/pixel-scroll.el
index f21cdae..66aa480 100644
--- a/lisp/pixel-scroll.el
+++ b/lisp/pixel-scroll.el
@@ -436,7 +436,10 @@ the height of the current window."
                                        (window-header-line-height))))
          (object (posn-object desired-pos))
         (desired-start (posn-point desired-pos))
-        (desired-vscroll (cdr (posn-object-x-y desired-pos)))
+         (scroll-area-total-height (cdr (window-text-pixel-size nil
+                                                                (window-start)
+                                                                (1- 
desired-start))))
+        (desired-vscroll (- delta scroll-area-total-height))
          (edges (window-edges nil t))
          (usable-height (- (nth 3 edges)
                            (nth 1 edges)))