bug#17115: 24.3.50; possible bug in drawing images with box on W32

[YAMAMOTO Mitsuharu]

>>>>> On Thu, 27 Mar 2014 11:42:09 +0900, YAMAMOTO Mitsuharu 
>>>>> <mituharu@math.s.chiba-u.ac.jp> said:

> Recently I found a bug (which is different from Bug#17114) in drawing
> images with box on the Mac port, and I suspect it also happens on W32
> because their code are similar (though I can't test it).  Could
> someone try if it is reproducible on W32 and if so, please try the
> patch at the end?

> Steps to reproduce:

>   1. $ emacs -Q -D &
>   2. (insert-image (create-image "splash.png")
>             (propertize " " 'face '(:box (:line-width 5)))) C-j
>   3. C-p C-p

> Result:

>   The left half of the character `t' just after the image gets erased.

Probably "splash.png" in Step 2 should have been "splash.xpm" on W32
so that s->img->mask != NULL holds.

And I managed to reproduce the similar problem also on X11 by
replacing Step 2 with:

  2'. (insert-image (create-image "splash.png" nil nil :margin 10)
              (propertize " " 'face '(:box (:line-width 5)))) C-j

Below is a patch for X11.

                                     YAMAMOTO Mitsuharu
                                mituharu@math.s.chiba-u.ac.jp

=== modified file 'src/xterm.c'
*** src/xterm.c 2014-03-21 19:04:57 +0000
--- src/xterm.c 2014-03-27 04:34:57 +0000
***************
*** 2402,2416 ****
        {
          int x = s->x;
          int y = s->y;
  
          if (s->first_glyph->left_box_line_p
              && s->slice.x == 0)
!           x += box_line_hwidth;
  
          if (s->slice.y == 0)
            y += box_line_vwidth;
  
!         x_draw_glyph_string_bg_rect (s, x, y, s->background_width, height);
        }
  
        s->background_filled_p = 1;
--- 2402,2420 ----
        {
          int x = s->x;
          int y = s->y;
+         int width = s->background_width;
  
          if (s->first_glyph->left_box_line_p
              && s->slice.x == 0)
!           {
!             x += box_line_hwidth;
!             width -= box_line_hwidth;
!           }
  
          if (s->slice.y == 0)
            y += box_line_vwidth;
  
!         x_draw_glyph_string_bg_rect (s, x, y, width, height);
        }
  
        s->background_filled_p = 1;