Subject: bug#52685: 29.0.50; Horizontal scrolling doesn't work when compiled with pgtk

From: Andrey Listopadov <[email-masked]>
Date: Wed, 22 Dec 2021 11:14:51 +0300

On Wed, Dec 22, 2021 at 9:11 AM Po Lu <[email-masked]> wrote:
>
> Andrey Listopadov <[email-masked]> writes:
>
> > On Wed, Dec 22, 2021 at 4:09 AM Po Lu <[email-masked]> wrote:
> >>
> >> Po Lu <[email-masked]> writes:
> >>
> >> > Andrey Listopadov <[email-masked]> writes:
> >> >
> >> >> When `pixel-scroll-precision-mode' is disabled everything works fine.
> >> >> When compiled without `--with-pgtk' but with `--with-xinput2'
> >> >> `pixel-scroll-precision-mode' works as expected.
> >> >
> >> > Thanks, I will look into this now.
> >>
> >> Please try the following patch to see if it resolves your problem.
> >> Thanks.
> >>
> >> diff --git a/src/pgtkterm.c b/src/pgtkterm.c
> >> index bd61c65edd..bea2650584 100644
> >> --- a/src/pgtkterm.c
> >> +++ b/src/pgtkterm.c
> >> @@ -6133,78 +6133,64 @@ scroll_event (GtkWidget * widget, GdkEvent * event, gpointer * user_data)
> >>      }
> >>    else if (gdk_event_get_scroll_deltas (event, &delta_x, &delta_y))
> >>      {
> >> -      dpyinfo->scroll.acc_x += delta_x;
> >> -      dpyinfo->scroll.acc_y += delta_y;
> >> -      if (dpyinfo->scroll.acc_y >= dpyinfo->scroll.y_per_line
> >> -         || !mwheel_coalesce_scroll_events)
> >> +      if (!mwheel_coalesce_scroll_events)
> >>         {
> >> -         int nlines = dpyinfo->scroll.acc_y / dpyinfo->scroll.y_per_line;
> >> -         inev.ie.kind = WHEEL_EVENT;
> >> -         inev.ie.modifiers |= down_modifier;
> >> -         inev.ie.arg = list3 (make_fixnum (nlines),
> >> -                              make_float (-dpyinfo->scroll.acc_x * 100),
> >> -                              make_float (-dpyinfo->scroll.acc_y * 100));
> >> -         if (!mwheel_coalesce_scroll_events)
> >> -           {
> >> -             dpyinfo->scroll.acc_y = 0;
> >> -             dpyinfo->scroll.acc_x = 0;
> >> -           }
> >> -         else
> >> +         inev.ie.kind = ((fabs (delta_x) > fabs (delta_y))
> >> +                         ? HORIZ_WHEEL_EVENT
> >> +                         : WHEEL_EVENT);
> >> +         inev.ie.modifiers = (inev.ie.kind == HORIZ_WHEEL_EVENT
> >> +                              ? (delta_x >= 0 ? down_modifier : up_modifier)
> >> +                              : (delta_y >= 0 ? down_modifier : up_modifier));
> >> +         inev.ie.arg = list3 (Qnil, make_float (delta_x),
> >> +                              make_float (delta_y));
> >> +       }
> >> +      else
> >> +       {
> >> +         dpyinfo->scroll.acc_x += delta_x;
> >> +         dpyinfo->scroll.acc_y += delta_y;
> >> +         if (dpyinfo->scroll.acc_y >= dpyinfo->scroll.y_per_line)
> >>             {
> >> +             int nlines = dpyinfo->scroll.acc_y / dpyinfo->scroll.y_per_line;
> >> +             inev.ie.kind = WHEEL_EVENT;
> >> +             inev.ie.modifiers |= down_modifier;
> >> +             inev.ie.arg = list3 (make_fixnum (nlines),
> >> +                                  make_float (-dpyinfo->scroll.acc_x * 100),
> >> +                                  make_float (-dpyinfo->scroll.acc_y * 100));
> >>               dpyinfo->scroll.acc_y -= dpyinfo->scroll.y_per_line * nlines;
> >>             }
> >> -       }
> >> -      else if (dpyinfo->scroll.acc_y <= -dpyinfo->scroll.y_per_line
> >> -              || !mwheel_coalesce_scroll_events)
> >> -       {
> >> -         int nlines = -dpyinfo->scroll.acc_y / dpyinfo->scroll.y_per_line;
> >> -         inev.ie.kind = WHEEL_EVENT;
> >> -         inev.ie.modifiers |= up_modifier;
> >> -         inev.ie.arg = list3 (make_fixnum (nlines),
> >> -                              make_float (-dpyinfo->scroll.acc_x * 100),
> >> -                              make_float (-dpyinfo->scroll.acc_y * 100));
> >> -
> >> -         if (!mwheel_coalesce_scroll_events)
> >> +         else if (dpyinfo->scroll.acc_y <= -dpyinfo->scroll.y_per_line)
> >>             {
> >> -             dpyinfo->scroll.acc_y = 0;
> >> -             dpyinfo->scroll.acc_x = 0;
> >> +             int nlines = -dpyinfo->scroll.acc_y / dpyinfo->scroll.y_per_line;
> >> +             inev.ie.kind = WHEEL_EVENT;
> >> +             inev.ie.modifiers |= up_modifier;
> >> +             inev.ie.arg = list3 (make_fixnum (nlines),
> >> +                                  make_float (-dpyinfo->scroll.acc_x * 100),
> >> +                                  make_float (-dpyinfo->scroll.acc_y * 100));
> >> +
> >> +             dpyinfo->scroll.acc_y -= -dpyinfo->scroll.y_per_line * nlines;
> >>             }
> >> -         else
> >> -           dpyinfo->scroll.acc_y -= -dpyinfo->scroll.y_per_line * nlines;
> >> -       }
> >> -      else if (dpyinfo->scroll.acc_x >= dpyinfo->scroll.x_per_char
> >> -              || !mwheel_coalesce_scroll_events)
> >> -       {
> >> -         int nchars = dpyinfo->scroll.acc_x / dpyinfo->scroll.x_per_char;
> >> -         inev.ie.kind = HORIZ_WHEEL_EVENT;
> >> -         inev.ie.modifiers |= up_modifier;
> >> -         inev.ie.arg = list3 (make_fixnum (nchars),
> >> -                              make_float (-dpyinfo->scroll.acc_x * 100),
> >> -                              make_float (-dpyinfo->scroll.acc_y * 100));
> >> -
> >> -         if (mwheel_coalesce_scroll_events)
> >> -           dpyinfo->scroll.acc_x -= dpyinfo->scroll.x_per_char * nchars;
> >> -         else
> >> +         else if (dpyinfo->scroll.acc_x >= dpyinfo->scroll.x_per_char
> >> +                  || !mwheel_coalesce_scroll_events)
> >>             {
> >> -             dpyinfo->scroll.acc_x = 0;
> >> -             dpyinfo->scroll.acc_y = 0;
> >> +             int nchars = dpyinfo->scroll.acc_x / dpyinfo->scroll.x_per_char;
> >> +             inev.ie.kind = HORIZ_WHEEL_EVENT;
> >> +             inev.ie.modifiers |= up_modifier;
> >> +             inev.ie.arg = list3 (make_fixnum (nchars),
> >> +                                  make_float (-dpyinfo->scroll.acc_x * 100),
> >> +                                  make_float (-dpyinfo->scroll.acc_y * 100));
> >> +
> >> +             dpyinfo->scroll.acc_x -= dpyinfo->scroll.x_per_char * nchars;
> >>             }
> >> -       }
> >> -      else if (dpyinfo->scroll.acc_x <= -dpyinfo->scroll.x_per_char)
> >> -       {
> >> -         int nchars = -dpyinfo->scroll.acc_x / dpyinfo->scroll.x_per_char;
> >> -         inev.ie.kind = HORIZ_WHEEL_EVENT;
> >> -         inev.ie.modifiers |= down_modifier;
> >> -         inev.ie.arg = list3 (make_fixnum (nchars),
> >> -                              make_float (-dpyinfo->scroll.acc_x * 100),
> >> -                              make_float (-dpyinfo->scroll.acc_y * 100));
> >> -
> >> -         if (mwheel_coalesce_scroll_events)
> >> -           dpyinfo->scroll.acc_x -= -dpyinfo->scroll.x_per_char * nchars;
> >> -         else
> >> +         else if (dpyinfo->scroll.acc_x <= -dpyinfo->scroll.x_per_char)
> >>             {
> >> -             dpyinfo->scroll.acc_x = 0;
> >> -             dpyinfo->scroll.acc_y = 0;
> >> +             int nchars = -dpyinfo->scroll.acc_x / dpyinfo->scroll.x_per_char;
> >> +             inev.ie.kind = HORIZ_WHEEL_EVENT;
> >> +             inev.ie.modifiers |= down_modifier;
> >> +             inev.ie.arg = list3 (make_fixnum (nchars),
> >> +                                  make_float (-dpyinfo->scroll.acc_x * 100),
> >> +                                  make_float (-dpyinfo->scroll.acc_y * 100));
> >> +
> >> +             dpyinfo->scroll.acc_x -= -dpyinfo->scroll.x_per_char * nchars;
> >>             }
> >>         }
> >>      }
>
> > The patch doesn't apply.
>
> That's odd.  Could you try updating your checkout, or failing that,
> applying it manually?
>
> Thanks.
>

Sorry, seems the mail got corrupted the first time I tried.

I've applied the patch, and now horizontal scrolling works correctly.
However, pressing Ctrl while scrolling doesn't register as `C-' event.
With `pixel-scroll-precision-mode` off, if I press C-h k and scroll in
any direction with the Ctrl key held down I get this:

There were several key-sequences:
  C-<wheel-up> at that spot runs the command mouse-wheel-text-scale
  C-<wheel-down> at that spot runs the command mouse-wheel-text-scale

(Since C-<wheel-left> and C-<wheel-right> aren't mapped to anything
they're not in the list)

With `pixel-scroll-precision-mode` on I get:

There were several key-sequences:
  <wheel-up> at that spot runs the command pixel-scroll-precision
  <wheel-down> at that spot runs the command pixel-scroll-precision
  <wheel-right> at that spot runs the command mwheel-scroll
  <wheel-left> at that spot runs the command mwheel-scroll
  <touch-end> runs the command pixel-scroll-start-momentum

So the scrolling works, but the Ctrl key is ignored now.  The same
happens with other modifier keys.

-- 
Andrey Listopadov