Re: About x_draw_xwidget_glyph_string

[joakim@verona.se]

YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp> writes:

> I have a question and a comment about x_draw_xwidget_glyph_string in
> src/xwidget.c.
>
> 1. Question about xwidget initialization.
>
>    559	x_draw_xwidget_glyph_string (struct glyph_string *s)
>    560	{
>    561	  /* This method is called by the redisplay engine and places the
>    562	     xwidget on screen.  Moving and clipping is done here.  Also view
>    563	     initialization.  */
>    564	  struct xwidget *xww = s->xwidget;
>    565	  struct xwidget_view *xv = xwidget_view_lookup (xww, s->w);
> (snip)
>    574	  /* Do initialization here in the display loop because there is no
>    575	     other time to know things like window placement etc.  */
>    576	  xv = xwidget_init_view (xww, s, x, y);
>
> Line 576 indicates a new xwidget view is created in every
> x_draw_xwidget_glyph_string call.  But this makes xwidget-view-list
> longer and longer, and looks like a waste of memory, if not a leak.
> Also, if it is an intended behavior, then it looks strange to look up
> a view at Line 565.
>
> 2. Comment on clipping.
>
>    578	  /* Calculate clipping, which is used for all manner of onscreen
>    579	     xwidget views.  Each widget border can get clipped by other emacs
>    580	     objects so there are four clipping variables.  */
>    581	  clip_right =
>    582	    min (xww->width,
>    583	         WINDOW_RIGHT_EDGE_X (s->w) - x -
>    584	         WINDOW_RIGHT_SCROLL_BAR_AREA_WIDTH (s->w) -
>    585	         WINDOW_RIGHT_FRINGE_WIDTH (s->w));
>    586	  clip_left =
>    587	    max (0,
>    588	         WINDOW_LEFT_EDGE_X (s->w) - x +
>    589	         WINDOW_LEFT_SCROLL_BAR_AREA_WIDTH (s->w) +
>    590	         WINDOW_LEFT_FRINGE_WIDTH (s->w));
>    591	
>    592	  clip_bottom =
>    593	    min (xww->height,
>    594	         WINDOW_BOTTOM_EDGE_Y (s->w) - WINDOW_MODE_LINE_HEIGHT (s->w) - y);
>    595	  clip_top = max (0, WINDOW_TOP_EDGE_Y (s->w) - y);
>
> I think the calculation of clipping should use the function window_box
> rather than manual calculation with various window macros.  Otherwise,
> xwidget views will cover horizontal scroll bars, for example.
>
> 				     YAMAMOTO Mitsuharu
> 				mituharu@math.s.chiba-u.ac.jp
>

I won't have time to have a look at this until a couple of days, but
your suggestions sound promising. If you have a patch I can test I would
be grateful.

-- 
Joakim Verona