get touch control example working through /dev/input/event0

touch/Cargo.toml

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+[package]
+name = "touch"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+evdev = "0.13.2"

touch/README.md

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+# touch
+
+Simple touch input reader for Linux evdev devices.
+
+By default it reads `/dev/input/event0` and prints touch-related events in an
+`evtest`-style format:
+
+```sh
+sudo cargo run
+```
+
+To read another input device, pass the device path:
+
+```sh
+sudo cargo run -- /dev/input/event1
+```

touch/src/main.rs

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+use evdev::{
+    AbsoluteAxisCode, Device, EventSummary, EventType, InputEvent, KeyCode, SynchronizationCode,
+};
+use std::env;
+use std::error::Error;
+use std::path::Path;
+use std::time::UNIX_EPOCH;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let path = env::args()
+        .nth(1)
+        .unwrap_or_else(|| "/dev/input/event0".to_string());
+    let mut device = Device::open(Path::new(&path))?;
+    let id = device.input_id();
+
+    println!(
+        "Input device name: {:?}",
+        device.name().unwrap_or("unknown input device")
+    );
+    println!(
+        "Input device ID: bus 0x{:x} vendor 0x{:x} product 0x{:x} version 0x{:x}",
+        id.bus_type().0,
+        id.vendor(),
+        id.product(),
+        id.version()
+    );
+    println!("Reading touch events from {path}. Press Ctrl-C to stop.\n");
+
+    loop {
+        for event in device.fetch_events()? {
+            if is_touch_event(&event) {
+                print_event(event);
+            }
+        }
+    }
+}
+
+fn is_touch_event(event: &InputEvent) -> bool {
+    match event.destructure() {
+        EventSummary::AbsoluteAxis(_, axis, _) => matches!(
+            axis,
+            AbsoluteAxisCode::ABS_X
+                | AbsoluteAxisCode::ABS_Y
+                | AbsoluteAxisCode::ABS_PRESSURE
+                | AbsoluteAxisCode::ABS_MT_SLOT
+                | AbsoluteAxisCode::ABS_MT_TOUCH_MAJOR
+                | AbsoluteAxisCode::ABS_MT_TOUCH_MINOR
+                | AbsoluteAxisCode::ABS_MT_POSITION_X
+                | AbsoluteAxisCode::ABS_MT_POSITION_Y
+                | AbsoluteAxisCode::ABS_MT_TRACKING_ID
+                | AbsoluteAxisCode::ABS_MT_PRESSURE
+        ),
+        EventSummary::Key(_, key, _) => matches!(
+            key,
+            KeyCode::BTN_TOUCH
+                | KeyCode::BTN_TOOL_FINGER
+                | KeyCode::BTN_TOOL_DOUBLETAP
+                | KeyCode::BTN_TOOL_TRIPLETAP
+                | KeyCode::BTN_TOOL_QUADTAP
+                | KeyCode::BTN_TOOL_QUINTTAP
+        ),
+        EventSummary::Synchronization(_, code, _) => {
+            matches!(
+                code,
+                SynchronizationCode::SYN_REPORT | SynchronizationCode::SYN_MT_REPORT
+            )
+        }
+        _ => false,
+    }
+}
+
+fn print_event(event: InputEvent) {
+    let timestamp = event
+        .timestamp()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default();
+    let event_type = event.event_type();
+    let (type_name, code_name) = event_names(event);
+
+    println!(
+        "Event: time {}.{:06}, type {} ({}), code {} ({}), value {}",
+        timestamp.as_secs(),
+        timestamp.subsec_micros(),
+        event_type.0,
+        type_name,
+        event.code(),
+        code_name,
+        event.value()
+    );
+}
+
+fn event_names(event: InputEvent) -> (&'static str, String) {
+    match event.destructure() {
+        EventSummary::Synchronization(_, code, _) => ("EV_SYN", format!("{code:?}")),
+        EventSummary::Key(_, code, _) => ("EV_KEY", format!("{code:?}")),
+        EventSummary::AbsoluteAxis(_, code, _) => ("EV_ABS", format!("{code:?}")),
+        _ => (
+            event_type_name(event.event_type()),
+            format!("0x{:x}", event.code()),
+        ),
+    }
+}
+
+fn event_type_name(event_type: EventType) -> &'static str {
+    match event_type {
+        EventType::SYNCHRONIZATION => "EV_SYN",
+        EventType::KEY => "EV_KEY",
+        EventType::RELATIVE => "EV_REL",
+        EventType::ABSOLUTE => "EV_ABS",
+        EventType::MISC => "EV_MSC",
+        EventType::SWITCH => "EV_SW",
+        EventType::LED => "EV_LED",
+        EventType::SOUND => "EV_SND",
+        EventType::REPEAT => "EV_REP",
+        EventType::FORCEFEEDBACK => "EV_FF",
+        EventType::POWER => "EV_PWR",
+        EventType::FORCEFEEDBACKSTATUS => "EV_FF_STATUS",
+        EventType::UINPUT => "EV_UINPUT",
+        _ => "EV_UNKNOWN",
+    }
+}