cursor: add scroll emulation for cursor motion

diff --git a/src/input/cursor.c b/src/input/cursor.c
index 5787a8ba66afdc1270c92bdb14bfca38af4a5317..ea4fe36973eaed0e07eb6cf41c804aa1306fab8f 100644 (file)
--- a/src/input/cursor.c
+++ b/src/input/cursor.c
@@ -4,6 +4,7 @@
 #include <linux/input-event-codes.h>
 #include <sys/time.h>
 #include <time.h>
+#include <wlr/backend/libinput.h>
 #include <wlr/types/wlr_cursor_shape_v1.h>
 #include <wlr/types/wlr_primary_selection.h>
 #include <wlr/util/region.h>
@@ -832,6 +833,19 @@ preprocess_cursor_motion(struct seat *seat, struct wlr_pointer *pointer,
        }
 }
 
+static double get_natural_scroll_factor(struct wlr_input_device *wlr_input_device)
+{
+       if (wlr_input_device_is_libinput(wlr_input_device)) {
+               struct libinput_device *libinput_device =
+                       wlr_libinput_get_device_handle(wlr_input_device);
+               if (libinput_device_config_scroll_get_natural_scroll_enabled(libinput_device)) {
+                       return -1.0;
+               }
+       }
+
+       return 1.0;
+}
+
 static void
 handle_motion(struct wl_listener *listener, void *data)
 {
@@ -845,14 +859,42 @@ handle_motion(struct wl_listener *listener, void *data)
        idle_manager_notify_activity(seat->seat);
        cursor_set_visible(seat, /* visible */ true);
 
-       wlr_relative_pointer_manager_v1_send_relative_motion(
-               server->relative_pointer_manager,
-               seat->seat, (uint64_t)event->time_msec * 1000,
-               event->delta_x, event->delta_y, event->unaccel_dx,
-               event->unaccel_dy);
+       if (seat->cursor_scroll_wheel_emulation) {
+               uint32_t orientation;
+               double delta;
+               if (fabs(event->delta_x) > fabs(event->delta_y)) {
+                       orientation = WL_POINTER_AXIS_HORIZONTAL_SCROLL;
+                       delta = event->delta_x;
+               } else {
+                       orientation = WL_POINTER_AXIS_VERTICAL_SCROLL;
+                       delta = event->delta_y;
+               }
 
-       preprocess_cursor_motion(seat, event->pointer,
-               event->time_msec, event->delta_x, event->delta_y);
+               /*
+                * arbitrary factor that should give reasonable speed
+                * with the default configured scroll factor of 1.0
+                */
+               double motion_to_scroll_factor = 0.04;
+               double scroll_factor = motion_to_scroll_factor *
+                       get_natural_scroll_factor(&event->pointer->base);
+
+               /* The delta of a single step for mouse wheel emulation */
+               double pointer_axis_step = 15.0;
+
+               cursor_emulate_axis(seat, &event->pointer->base,
+                       orientation,
+                       pointer_axis_step * scroll_factor * delta, 0,
+                       WL_POINTER_AXIS_SOURCE_CONTINUOUS, event->time_msec);
+       } else {
+               wlr_relative_pointer_manager_v1_send_relative_motion(
+                       server->relative_pointer_manager,
+                       seat->seat, (uint64_t)event->time_msec * 1000,
+                       event->delta_x, event->delta_y, event->unaccel_dx,
+                       event->unaccel_dy);
+
+               preprocess_cursor_motion(seat, event->pointer,
+                       event->time_msec, event->delta_x, event->delta_y);
+       }
 }
 
 static void