Add Mouse{Left,Right,Middle,Back,Forward} binds

I don't know the history behind `BTN_BACK == BTN_SIDE` and `BTN_FORWARD == BTN_EXTRA`,
but everyone seems to be doing it so if it's "wrong" it's better for compatability.
It's my fault it's like that on winit too :P

Fixes YaLTeR#761.

niri-config/src/lib.rs

@@ -1092,6 +1092,11 @@ pub struct Key {
 #[derive(Debug, PartialEq, Eq, Clone, Copy, Hash)]
 pub enum Trigger {
     Keysym(Keysym),
+    MouseLeft,
+    MouseRight,
+    MouseMiddle,
+    MouseBack,
+    MouseForward,
     WheelScrollDown,
     WheelScrollUp,
     WheelScrollLeft,
@@ -2822,7 +2827,17 @@ impl FromStr for Key {
             }
         }
 
-        let trigger = if key.eq_ignore_ascii_case("WheelScrollDown") {
+        let trigger = if key.eq_ignore_ascii_case("MouseLeft") {
+            Trigger::MouseLeft
+        } else if key.eq_ignore_ascii_case("MouseRight") {
+            Trigger::MouseRight
+        } else if key.eq_ignore_ascii_case("MouseMiddle") {
+            Trigger::MouseMiddle
+        } else if key.eq_ignore_ascii_case("MouseBack") {
+            Trigger::MouseBack
+        } else if key.eq_ignore_ascii_case("MouseForward") {
+            Trigger::MouseForward
+        } else if key.eq_ignore_ascii_case("WheelScrollDown") {
             Trigger::WheelScrollDown
         } else if key.eq_ignore_ascii_case("WheelScrollUp") {
             Trigger::WheelScrollUp

src/input/mod.rs

@@ -1543,6 +1543,15 @@ impl State {
     }
 
     fn on_pointer_button<I: InputBackend>(&mut self, event: I::PointerButtonEvent) {
+        // These values are coming from <linux/input-event-codes.h>.
+        const BTN_LEFT: u32 = 0x110;
+        const BTN_RIGHT: u32 = 0x111;
+        const BTN_MIDDLE: u32 = 0x112;
+        const BTN_SIDE: u32 = 0x113;
+        const BTN_EXTRA: u32 = 0x114;
+        const BTN_FORWARD: u32 = 0x115;
+        const BTN_BACK: u32 = 0x116;
+
         let pointer = self.niri.seat.get_pointer().unwrap();
 
         let serial = SERIAL_COUNTER.next_serial();
@@ -1552,6 +1561,31 @@ impl State {
         let button_state = event.state();
 
         if ButtonState::Pressed == button_state {
+            let mods = self.niri.seat.get_keyboard().unwrap().modifier_state();
+            let modifiers = modifiers_from_state(mods);
+
+            if self.niri.mods_with_mouse_binds.contains(&modifiers) {
+                let comp_mod = self.backend.mod_key();
+
+                if let Some(bind) = match button {
+                    BTN_LEFT => Some(Trigger::MouseLeft),
+                    BTN_RIGHT => Some(Trigger::MouseRight),
+                    BTN_MIDDLE => Some(Trigger::MouseMiddle),
+                    // Chromium treats these as equivalent: https://chromium.googlesource.com/chromium/src/+/refs/heads/main/ui/ozone/platform/wayland/host/wayland_pointer.cc
+                    BTN_BACK | BTN_SIDE => Some(Trigger::MouseBack),
+                    BTN_FORWARD | BTN_EXTRA => Some(Trigger::MouseForward),
+                    _ => None,
+                }
+                .and_then(|trigger| {
+                    let config = self.niri.config.borrow();
+                    let bindings = &config.binds;
+                    find_configured_bind(bindings, comp_mod, trigger, mods)
+                }) {
+                    self.handle_bind(bind.clone());
+                    return;
+                };
+            }
+
             // We received an event for the regular pointer, so show it now.
             self.niri.pointer_hidden = false;
             self.niri.tablet_cursor_location = None;
@@ -1561,7 +1595,6 @@ impl State {
 
                 // Check if we need to start an interactive move.
                 if event.button() == Some(MouseButton::Left) && !pointer.is_grabbed() {
-                    let mods = self.niri.seat.get_keyboard().unwrap().modifier_state();
                     let mod_down = match self.backend.mod_key() {
                         CompositorMod::Super => mods.logo,
                         CompositorMod::Alt => mods.alt,
@@ -1593,7 +1626,6 @@ impl State {
                 }
                 // Check if we need to start an interactive resize.
                 else if event.button() == Some(MouseButton::Right) && !pointer.is_grabbed() {
-                    let mods = self.niri.seat.get_keyboard().unwrap().modifier_state();
                     let mod_down = match self.backend.mod_key() {
                         CompositorMod::Super => mods.logo,
                         CompositorMod::Alt => mods.alt,
@@ -1670,7 +1702,6 @@ impl State {
             }
 
             if event.button() == Some(MouseButton::Middle) && !pointer.is_grabbed() {
-                let mods = self.niri.seat.get_keyboard().unwrap().modifier_state();
                 let mod_down = match self.backend.mod_key() {
                     CompositorMod::Super => mods.logo,
                     CompositorMod::Alt => mods.alt,
@@ -2993,6 +3024,20 @@ pub fn mods_with_binds(
     rv
 }
 
+pub fn mods_with_mouse_binds(comp_mod: CompositorMod, binds: &Binds) -> HashSet<Modifiers> {
+    mods_with_binds(
+        comp_mod,
+        binds,
+        &[
+            Trigger::MouseLeft,
+            Trigger::MouseRight,
+            Trigger::MouseMiddle,
+            Trigger::MouseBack,
+            Trigger::MouseForward,
+        ],
+    )
+}
+
 pub fn mods_with_wheel_binds(comp_mod: CompositorMod, binds: &Binds) -> HashSet<Modifiers> {
     mods_with_binds(
         comp_mod,

src/niri.rs

@@ -114,7 +114,8 @@ use crate::frame_clock::FrameClock;
 use crate::handlers::{configure_lock_surface, XDG_ACTIVATION_TOKEN_TIMEOUT};
 use crate::input::scroll_tracker::ScrollTracker;
 use crate::input::{
-    apply_libinput_settings, mods_with_finger_scroll_binds, mods_with_wheel_binds, TabletData,
+    apply_libinput_settings, mods_with_finger_scroll_binds, mods_with_mouse_binds,
+    mods_with_wheel_binds, TabletData,
 };
 use crate::ipc::server::IpcServer;
 use crate::layer::mapped::LayerSurfaceRenderElement;
@@ -302,6 +303,7 @@ pub struct Niri {
     pub gesture_swipe_3f_cumulative: Option<(f64, f64)>,
     pub vertical_wheel_tracker: ScrollTracker,
     pub horizontal_wheel_tracker: ScrollTracker,
+    pub mods_with_mouse_binds: HashSet<Modifiers>,
     pub mods_with_wheel_binds: HashSet<Modifiers>,
     pub vertical_finger_scroll_tracker: ScrollTracker,
     pub horizontal_finger_scroll_tracker: ScrollTracker,
@@ -1813,6 +1815,7 @@ impl Niri {
         let cursor_manager =
             CursorManager::new(&config_.cursor.xcursor_theme, config_.cursor.xcursor_size);
 
+        let mods_with_mouse_binds = mods_with_mouse_binds(backend.mod_key(), &config_.binds);
         let mods_with_wheel_binds = mods_with_wheel_binds(backend.mod_key(), &config_.binds);
         let mods_with_finger_scroll_binds =
             mods_with_finger_scroll_binds(backend.mod_key(), &config_.binds);
@@ -1989,6 +1992,7 @@ impl Niri {
             gesture_swipe_3f_cumulative: None,
             vertical_wheel_tracker: ScrollTracker::new(120),
             horizontal_wheel_tracker: ScrollTracker::new(120),
+            mods_with_mouse_binds,
             mods_with_wheel_binds,
 
             // 10 is copied from Clutter: DISCRETE_SCROLL_STEP.

src/ui/hotkey_overlay.rs

@@ -415,6 +415,11 @@ fn key_name(comp_mod: CompositorMod, key: &Key) -> String {
 
     let pretty = match key.trigger {
         Trigger::Keysym(keysym) => prettify_keysym_name(&keysym_get_name(keysym)),
+        Trigger::MouseLeft => String::from("Mouse Left"),
+        Trigger::MouseRight => String::from("Mouse Right"),
+        Trigger::MouseMiddle => String::from("Mouse Middle"),
+        Trigger::MouseBack => String::from("Mouse Back"),
+        Trigger::MouseForward => String::from("Mouse Forward"),
         Trigger::WheelScrollDown => String::from("Wheel Scroll Down"),
         Trigger::WheelScrollUp => String::from("Wheel Scroll Up"),
         Trigger::WheelScrollLeft => String::from("Wheel Scroll Left"),