Expose pixel-wise wheel events to Lisp

* doc/lispref/commands.texi (Misc Events): Document changes to
wheel events.

* src/keyboard.c (make_lispy_event): Handle wheel events with
pixel delta data.
* src/termhooks.h (WHEEL_EVENT): Document changes to
WHEEL_EVENT args.
* src/xfns.c (syms_of_xfns): Declare new symbols.
* src/xterm.c (handle_one_xevent): Give wheel events pixel delta
data.
(x_coalesce_scroll_events): New user option.

diff --git a/doc/lispref/commands.texi b/doc/lispref/commands.texi
index cc9c41623dc7da58a98552c60485d48ee1d6c577..5fd7b55a60b4e67a03e13a1a7e0d12e2f62d3be0 100644 (file)
--- a/doc/lispref/commands.texi
+++ b/doc/lispref/commands.texi
@@ -1994,7 +1994,18 @@ frame has already been made visible, Emacs has no work to do.
 These kinds of event are generated by moving a mouse wheel.  The
 @var{position} element is a mouse position list (@pxref{Click
 Events}), specifying the position of the mouse cursor when the event
-occurred.
+occurred.  The event may have additional arguments after
+@var{position}.  The third argument after @var{position}, if present,
+is a pair of the form @w{@code{(@var{x} . @var{y})}}, where @var{x}
+and @var{y} are the number of pixels to scroll by in each axis.
+
+@cindex pixel-resolution wheel events
+You can use @var{x} and @var{y} to determine how much the mouse wheel
+has actually moved at pixel resolution.
+
+For example, the pixelwise deltas could be used to scroll the display
+at pixel resolution, exactly according to the user's turning the mouse
+wheel.
 
 @vindex mouse-wheel-up-event
 @vindex mouse-wheel-down-event

diff --git a/src/keyboard.c b/src/keyboard.c
index c3bc8307d7f80fb40ca0114e8f5bbc4a773ff78f..0c48790ce8d6621723cbc631183d01a74b387062 100644 (file)
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -5980,7 +5980,11 @@ make_lispy_event (struct input_event *event)
                                      ASIZE (wheel_syms));
        }
 
-        if (NUMBERP (event->arg))
+       if (CONSP (event->arg))
+         return list5 (head, position, make_fixnum (double_click_count),
+                       XCAR (event->arg), Fcons (XCAR (XCDR (event->arg)),
+                                                 XCAR (XCDR (XCDR (event->arg)))));
+        else if (NUMBERP (event->arg))
           return list4 (head, position, make_fixnum (double_click_count),
                         event->arg);
        else if (event->modifiers & (double_modifier | triple_modifier))

diff --git a/src/termhooks.h b/src/termhooks.h
index e7539bbce2fdd4b0634b7295885f88678939ff75..b274be9e3cd4aadf124dbf85e3539360876f12a0 100644 (file)
--- a/src/termhooks.h
+++ b/src/termhooks.h
@@ -119,7 +119,10 @@ enum event_kind
                                   .timestamp gives a timestamp (in
                                   milliseconds) for the event.
                                    .arg may contain the number of
-                                   lines to scroll.  */
+                                   lines to scroll, or a list of
+                                  the form (NUMBER-OF-LINES . (X Y)) where
+                                  X and Y are the number of pixels
+                                  on each axis to scroll by.  */
   HORIZ_WHEEL_EVENT,            /* A wheel event generated by a second
                                    horizontal wheel that is present on some
                                    mice. See WHEEL_EVENT.  */

diff --git a/src/xfns.c b/src/xfns.c
index b33b40b330b4c4a09f0931c923e88c966f390a53..0ea43d1330609c75757faeef8bb6ff666f5a2226 100644 (file)
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -8085,6 +8085,7 @@ eliminated in future versions of Emacs.  */);
 
 #ifdef HAVE_XINPUT2
   DEFSYM (Qxinput2, "xinput2");
+
   Fprovide (Qxinput2, Qnil);
 #endif
 

diff --git a/src/xterm.c b/src/xterm.c
index 63754a2cb61e0613dd82c7b278b38d194b9a3ba6..ed3921f2869eadb30ea4bc7c546ee54a96fbb483 100644 (file)
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -556,6 +556,7 @@ xi_reset_scroll_valuators_for_device_id (struct x_display_info *dpyinfo, int id)
     {
       valuator = &device->valuators[i];
       valuator->invalid_p = true;
+      valuator->emacs_value = 0.0;
     }
 
   return;
@@ -9921,8 +9922,6 @@ handle_one_xevent (struct x_display_info *dpyinfo,
 #endif
            goto XI_OTHER;
          case XI_Motion:
-           /* First test if there is some kind of scroll event
-              here! */
            states = &xev->valuators;
            values = states->values;
 
@@ -9932,10 +9931,8 @@ handle_one_xevent (struct x_display_info *dpyinfo,
              {
                if (XIMaskIsSet (states->mask, i))
                  {
-                   block_input ();
-
                    struct xi_scroll_valuator_t *val;
-                   double delta;
+                   double delta, scroll_unit;
 
                    delta = x_get_scroll_valuator_delta (dpyinfo, xev->deviceid,
                                                         i, *values, &val);
@@ -9943,6 +9940,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                    if (delta != DBL_MAX)
                      {
                        f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+                       scroll_unit = pow (FRAME_PIXEL_HEIGHT (f), 2.0 / 3.0);
                        found_valuator = true;
 
                        if (signbit (delta) != signbit (val->emacs_value))
@@ -9950,15 +9948,16 @@ handle_one_xevent (struct x_display_info *dpyinfo,
 
                        val->emacs_value += delta;
 
+                       if (x_coalesce_scroll_events
+                           && (fabs (val->emacs_value) < 1))
+                         continue;
+
                        if (!f)
                          {
                            f = x_any_window_to_frame (dpyinfo, xev->event);
 
                            if (!f)
-                             {
-                               unblock_input ();
-                               goto XI_OTHER;
-                             }
+                             goto XI_OTHER;
                          }
 
                        bool s = signbit (val->emacs_value);
@@ -9975,13 +9974,26 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                        inev.ie.modifiers
                          |= x_x_to_emacs_modifiers (dpyinfo,
                                                     xev->mods.effective);
-                       inev.ie.arg = Qnil;
+
+                       if (val->horizontal)
+                         {
+                           inev.ie.arg
+                             = list3 (Qnil,
+                                      make_float (val->emacs_value
+                                                  * scroll_unit),
+                                      make_float (0));
+                         }
+                        else
+                         {
+                           inev.ie.arg = list3 (Qnil, make_float (0),
+                                                make_float (val->emacs_value
+                                                            * scroll_unit));
+                         }
 
                        kbd_buffer_store_event_hold (&inev.ie, hold_quit);
 
                        val->emacs_value = 0;
                      }
-                   unblock_input ();
                    values++;
                  }
 
@@ -15048,4 +15060,11 @@ gtk_window_move to set or store frame positions and disables some time
 consuming frame position adjustments.  In newer versions of GTK, Emacs
 always uses gtk_window_move and ignores the value of this variable.  */);
   x_gtk_use_window_move = true;
+
+  DEFVAR_BOOL ("x-coalesce-scroll-events", x_coalesce_scroll_events,
+              doc: /* Non-nil means send a wheel event only for scrolling at least one screen line.
+Otherwise, a wheel event will be sent every time the mouse wheel is
+moved.  This option is only effective when Emacs is built with XInput
+2.  */);
+  x_coalesce_scroll_events = true;
 }