svn commit: r316735 - head/sys/dev/syscons

[Bruce Evans]

Author: bde
Date: Wed Apr 12 17:06:24 2017
New Revision: 316735
URL: https://svnweb.freebsd.org/changeset/base/316735

Log:
  Fix removing of the mouse image in vga planar mode with 8x8 fonts, and
  reduce hard-coded assumptions on font sizes so that the cursor size
  can be more independent of the font size.  Moving the mouse in the
  buggy mode left trails of garbage.
  
  The mouse cursor currently has size 9x13 in all modes.  This can occupy
  2x3 character cells with 8x8 fonts, but the algorithm was hard-coded
  for only 2x2 character cells.  Rearrange to hard-code only a maximum
  cursor size (now 10x16) and to not hard-code in the logic.  The number
  of cells needed is now over-estimated in some cases.
  
  2x3 character cells should also be used in text mode with 8x8 fonts
  (except with large pixels, the cursor size should be reduced), but
  hard-coding for 2x2 in the implementation makes it not very easy to
  expand, and it practice it shifts out bits to reduce to 2x2.
  
  In graphics modes, expansion is easier and there is no shifting out
  for 9x13 cursors (but 9 is a limit for hard-coding for 2 8-bit VGA
  cells wide).  A previous commit removed the same buggy hard-coding for
  removal at a lower level in planar mode.  Another previous commit fixed
  the much larger code for lower-level removal in direct mode; this is
  independent of the font size so worked for 8x8 fonts.  Text mode always
  depended on the higher-level removal here, and always worked since
  everything was hard-coded consistently for 2x2 character cells.

Modified:
  head/sys/dev/syscons/scmouse.c

Modified: head/sys/dev/syscons/scmouse.c
==============================================================================
--- head/sys/dev/syscons/scmouse.c	Wed Apr 12 16:28:40 2017	(r316734)
+++ head/sys/dev/syscons/scmouse.c	Wed Apr 12 17:06:24 2017	(r316735)
@@ -232,30 +232,33 @@ sc_draw_mouse_image(scr_stat *scp)
 void
 sc_remove_mouse_image(scr_stat *scp)
 {
-    int size;
-    int i;
+    int cols, i, rows;
 
     if (ISGRAPHSC(scp))
 	return;
 
     SC_VIDEO_LOCK(scp->sc);
-    (*scp->rndr->draw_mouse)(scp,
-			     (scp->mouse_oldpos%scp->xsize + scp->xoff)
-			         * scp->font_width,
-			     (scp->mouse_oldpos/scp->xsize + scp->yoff)
-				 * scp->font_size,
+    (*scp->rndr->draw_mouse)(scp, scp->mouse_oldxpos, scp->mouse_oldypos,
 			     FALSE);
-    size = scp->xsize*scp->ysize;
+    /*
+     * To simplify the renderer and ensure undrawing with correct
+     * attributes, mark for update a region containing the cursor
+     * (usually 2x2 character cells joined by almost a full line o
+     * character cells).
+     *
+     * The renderer should only undraw any pixels outside of the text
+     * window (e.g., ones in borders and hardware cursors).
+     */
     i = scp->mouse_oldpos;
     mark_for_update(scp, i);
     mark_for_update(scp, i);
-    if (i + scp->xsize + 1 < size) {
-	mark_for_update(scp, i + scp->xsize + 1);
-    } else if (i + scp->xsize < size) {
-	mark_for_update(scp, i + scp->xsize);
-    } else if (i + 1 < size) {
-	mark_for_update(scp, i + 1);
-    }
+    cols = 1 + howmany(10 - 1, scp->font_width);	/* up to VGA cursor width 9 */
+    cols = imax(cols, 2);	/* in case it is text mode 2x2 char cells */
+    cols = imin(cols, scp->xsize - i % scp->xsize);
+    rows = 1 + howmany(16 - 1, scp->font_size);	/* up to VGA cursor height 16 */
+    rows = imax(rows, 2);	/* don't bother reducing 3 to 2 if text */
+    rows = imin(rows, scp->ysize - i / scp->xsize);
+    mark_for_update(scp, i + (rows - 1) * scp->xsize + cols - 1);
     scp->status &= ~MOUSE_VISIBLE;
     SC_VIDEO_UNLOCK(scp->sc);
 }