From a5de77f321fae0cdd928d3b806e6291c3036f6bc Mon Sep 17 00:00:00 2001
From: siikamiika <miika9764@gmail.com>
Date: Wed, 14 Nov 2018 01:55:09 +0200
Subject: [PATCH] optimize mouse events, refactoring

---
 src/input_thread.rs | 98 +++++++++++++++++++++++++++++++--------------
 src/main.rs         |  1 +
 2 files changed, 70 insertions(+), 29 deletions(-)

diff --git a/src/input_thread.rs b/src/input_thread.rs
index ccc6430..eb02099 100644
--- a/src/input_thread.rs
+++ b/src/input_thread.rs
@@ -2,6 +2,7 @@ use std::thread;
 use std::time::Duration;
 
 use evdev_rs::util::event_code_to_int;
+use evdev_rs::enums::EventType::EV_REL;
 
 use crossbeam::crossbeam_channel::{unbounded, Select, Receiver, Sender};
 
@@ -27,42 +28,81 @@ pub fn create_evdev_thread(device_path: &str) -> (String, Receiver<ThreadInputEv
         // sleep for testing purposes
         thread::sleep(Duration::from_secs(1));
 
+        // cache mouse movement before consuming all events
+        let mut mouse_move = vec![0, 0];
         loop {
-            // check for stop requests
-            let mut sel = Select::new();
-            // create stop channel receive operation
-            let oper1 = sel.recv(&recv_stop_channel);
-            // try to select from stop channel
-            let oper = sel.try_select();
-            match oper {
-                // no stop requests
-                Err(_) => (),
-                // stop request received, break out of the loop
-                Ok(oper) => match oper.index() {
-                    i if i == oper1 => {
-                        assert_eq!(oper.recv(&recv_stop_channel), Ok(true));
-                        break;
-                    },
-                    // shouldn't happen
-                    _ => (),
-                },
+            if stop_requested(&recv_stop_channel) {
+                continue;
             }
 
-            // read next input event
-            let event = dev.device.next_event(evdev_rs::NORMAL | evdev_rs::BLOCKING);
-            match event {
-                // send input event to event channel
-                Ok(e) => send_event_channel.send(
-                    ThreadInputEvent {
-                        typ: e.1.event_type as u32,
-                        code: event_code_to_int(&e.1.event_code).1,
-                        value: e.1.value,
+            loop {
+                // block before starting while loop again
+                let mut first = true;
+                let mut event = dev.device.next_event(evdev_rs::NORMAL | evdev_rs::BLOCKING);
+                // pending events not required for first round
+                while first || dev.device.has_event_pending() {
+                    first = false;
+                    match event {
+                        // send input event to event channel
+                        Ok(e) => {
+                            let e = ThreadInputEvent {
+                                typ: e.1.event_type as u32,
+                                code: event_code_to_int(&e.1.event_code).1,
+                                value: e.1.value,
+                            };
+                            if e.typ == 2 && e.code <= 1 {
+                                mouse_move[e.code as usize] += e.value;
+                            } else {
+                                send_event_channel.send(e).unwrap();
+                            }
+                        },
+                        Err(_) => (),
                     }
-                ).unwrap(),
-                Err(_) => (),
+                    // read next input event
+                    event = dev.device.next_event(evdev_rs::NORMAL | evdev_rs::BLOCKING);
+                }
+                // combined mouse event
+                send_combined_mouse_move(&mut mouse_move, &send_event_channel);
+                // save cpu by sleeping after consuming all events
+                thread::sleep(Duration::from_millis(5));
             }
         }
     });
 
     (return_device_path, recv_event_channel, send_stop_channel)
 }
+
+fn stop_requested(chan: &Receiver<bool>) -> bool {
+    // check for stop requests
+    let mut sel = Select::new();
+    // create stop channel receive operation
+    let oper1 = sel.recv(&chan);
+    // try to select from stop channel
+    let oper = sel.try_select();
+    match oper {
+        // no stop requests
+        Err(_) => false,
+        // stop request received, break out of the loop
+        Ok(oper) => match oper.index() {
+            i if i == oper1 => {
+                oper.recv(&chan).unwrap()
+            },
+            // shouldn't happen
+            _ => false,
+        },
+    }
+}
+
+fn send_combined_mouse_move(mouse_move: &mut Vec<i32>, chan: &Sender<ThreadInputEvent>) {
+    // REL_X..=REL_Y
+    for code in 0..=1 {
+        if mouse_move[code] != 0 {
+            chan.send(ThreadInputEvent {
+                typ: EV_REL as u32,
+                code: code as u32,
+                value: mouse_move[code],
+            }).unwrap();
+            mouse_move[code] = 0;
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 151cb4d..ffd3667 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,6 +2,7 @@ extern crate uinput;
 extern crate evdev_rs;
 extern crate crossbeam;
 
+use std::thread;
 use std::env::args;
 use std::time::Duration;
 use std::collections::HashMap;