Ignore all multi-touch compositor events

This patch increases the strictness for multi-touch events for
compositor input.

Previously when multiple touch slots were active, the first touch slot
was consumed and all others were ignored, which lead to issues with
triggering double-taps too easily.

To ensure double-taps are only activated without any other touch slots
being present in between, we now ignore **both** touch sequences when
more than one touch slot is active at the same time, rather than just
the secondary ones.

catacomb_ipc/src/lib.rs

@@ -465,7 +465,7 @@ pub fn send_message(message: &IpcMessage) -> Result<Option<IpcMessage>, Box<dyn
 
     // Write message to socket.
     let json = serde_json::to_string(&message)?;
-    stream.write_all(json[..].as_bytes())?;
+    stream.write_all(json.as_bytes())?;
     stream.flush()?;
 
     // Shutdown write, to allow reading.

src/input.rs

@@ -94,8 +94,8 @@ impl TouchState {
 
     /// Start a new touch session.
     fn start(&mut self, canvas: &Canvas, slot: TouchSlot, position: Point<f64, Logical>) {
-        // Allow only a single touch at a time.
-        if self.slot.is_some() {
+        // Invalidate both sequences if more than one slot is active.
+        if self.slot.take().is_some() {
             self.last_tap = None;
             return;
         }
@@ -448,8 +448,7 @@ impl Catacomb {
                             let canvas = self.windows.canvas();
                             self.touch_state.start(canvas, event.slot, event.position);
                         },
-                        TouchEventType::Up if self.touch_state.slot == Some(event.slot) => {
-                            self.touch_state.slot = None;
+                        TouchEventType::Up if self.touch_state.slot.take() == Some(event.slot) => {
                             match self.touch_state.action(self.windows.canvas()) {
                                 Some(TouchAction::Tap) => {
                                     self.touch_state.last_tap =

src/ipc_server.rs

@@ -176,7 +176,7 @@ fn send_reply_fallible(
     message: &IpcMessage,
 ) -> Result<(), Box<dyn Error>> {
     let json = serde_json::to_string(&message)?;
-    stream.write_all(json[..].as_bytes())?;
+    stream.write_all(json.as_bytes())?;
     stream.flush()?;
     Ok(())
 }

src/udev.rs

@@ -502,7 +502,7 @@ impl Udev {
             None,
             allocator,
             gbm.clone(),
-            SUPPORTED_COLOR_FORMATS.into_iter().copied(),
+            SUPPORTED_COLOR_FORMATS.iter().copied(),
             formats,
             Size::default(),
             None,