feat: support for setting tablet calibration matrix; this allows for rotating tablet inputs (#1122)

* feat: support for setting tablet calibration matrix

* Change default matrix

niri-config/src/lib.rs

@@ -337,6 +337,8 @@ impl From<TapButtonMap> for input::TapButtonMap {
 pub struct Tablet {
     #[knuffel(child)]
     pub off: bool,
+    #[knuffel(child, unwrap(arguments))]
+    pub calibration_matrix: Option<Vec<f32>>,
     #[knuffel(child, unwrap(argument))]
     pub map_to_output: Option<String>,
     #[knuffel(child)]
@@ -3560,6 +3562,8 @@ mod tests {
 
                 tablet {
                     map-to-output "eDP-1"
+                    calibration-matrix 1.0 2.0 3.0 \
+                                       4.0 5.0 6.0
                 }
 
                 touch {
@@ -3804,6 +3808,8 @@ mod tests {
                     },
                     tablet: Tablet {
                         off: false,
+                        calibration_matrix: Some(vec![1., 2., 3.,
+                                                      4., 5., 6.]),
                         map_to_output: Some("eDP-1".to_owned()),
                         left_handed: false,
                     },

src/input/mod.rs

@@ -3451,6 +3451,20 @@ pub fn apply_libinput_settings(config: &niri_config::Input, device: &mut input::
         } else {
             input::SendEventsMode::ENABLED
         });
+
+        #[rustfmt::skip]
+        const IDENTITY_MATRIX: [f32; 6] = [
+            1., 0., 0.,
+            0., 1., 0.,
+        ];
+
+        let _ = device.config_calibration_set_matrix(
+            c.calibration_matrix
+                .as_deref()
+                .and_then(|m| m.try_into().ok())
+                .or(device.config_calibration_default_matrix())
+                .unwrap_or(IDENTITY_MATRIX),
+        );
         let _ = device.config_left_handed_set(c.left_handed);
     }
 }