Re: About x_draw_xwidget_glyph_string

[Eli Zaretskii <eliz@gnu.org>]

> Date: Mon, 25 Jan 2016 11:07:16 +0900
> From: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>
> 
> 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.

I agree.

Thanks.