Allow disabling tap-and-drag

Similar to #1088, this adds a new
touchpad `drag` configuration option that configures tap-and-drag
behavior.

Currently tap-and-drag is always enabled when the `tap` setting is
enabled, but other compositors allow setting this separately.

niri-config/src/lib.rs

@@ -184,6 +184,8 @@ pub struct Touchpad {
     #[knuffel(child)]
     pub dwtp: bool,
     #[knuffel(child)]
+    pub drag: bool,
+    #[knuffel(child)]
     pub drag_lock: bool,
     #[knuffel(child)]
     pub natural_scroll: bool,
@@ -3612,6 +3614,7 @@ mod tests {
                         tap: true,
                         dwt: true,
                         dwtp: true,
+                        drag: false,
                         drag_lock: false,
                         click_method: Some(ClickMethod::Clickfinger),
                         natural_scroll: false,

resources/default-config.kdl

@@ -25,6 +25,7 @@ input {
         tap
         // dwt
         // dwtp
+        // drag
         // drag-lock
         natural-scroll
         // accel-speed 0.2

src/input/mod.rs

@@ -3253,6 +3253,7 @@ pub fn apply_libinput_settings(config: &niri_config::Input, device: &mut input::
         let _ = device.config_tap_set_enabled(c.tap);
         let _ = device.config_dwt_set_enabled(c.dwt);
         let _ = device.config_dwtp_set_enabled(c.dwtp);
+        let _ = device.config_tap_set_drag_enabled(c.drag);
         let _ = device.config_tap_set_drag_lock_enabled(c.drag_lock);
         let _ = device.config_scroll_set_natural_scroll_enabled(c.natural_scroll);
         let _ = device.config_accel_set_speed(c.accel_speed);

wiki/Configuration:-Input.md

@@ -30,6 +30,7 @@ input {
         tap
         // dwt
         // dwtp
+        // drag
         // drag-lock
         natural-scroll
         // accel-speed 0.2
@@ -182,6 +183,7 @@ Settings specific to `touchpad`s:
 - `tap`: tap-to-click.
 - `dwt`: disable-when-typing.
 - `dwtp`: disable-when-trackpointing.
+- `drag`: tap-to-drag
 - `drag-lock`: if set, lifting the finger off for a short time while dragging will not drop the dragged item. See the [libinput documentation](https://wayland.freedesktop.org/libinput/doc/latest/tapping.html#tap-and-drag).
 - `tap-button-map`: can be `left-right-middle` or `left-middle-right`, controls which button corresponds to a two-finger tap and a three-finger tap.
 - `click-method`: can be `button-areas` or `clickfinger`, changes the [click method](https://wayland.freedesktop.org/libinput/doc/latest/clickpad-softbuttons.html).