first attempt at reading touchscreen presses from /dev/input/

linux/src/input.rs

@@ -0,0 +1,108 @@
+use std::os::fd::RawFd;
+use std::mem::size_of;
+use std::ffi::CString;
+
+use libc::{ open, close, read, poll, pollfd, input_event, timeval, __u16, __s32, c_void };
+
+//https://stackoverflow.com/questions/15949163/read-from-dev-input#15949311
+//https://www.man7.org/linux/man-pages/man2/poll.2.html
+
+#[allow(non_camel_case_types)]
+#[repr(u16)]
+#[derive(Clone, Copy, PartialEq)]
+pub enum EventType {
+  EV_SYN = 0, //event sep
+  EV_KEY,
+  EV_REL,
+  EV_ABS,
+  //nothing below will probably ever be relevant to ming-wm
+  EV_MSC, //misc
+  EV_SW, //switch/toggle
+  EV_LED,
+  EV_SND,
+  EV_REP,
+  EV_FF,
+  EV_PWR,
+  EV_FF_STATUS,
+  Unknown(__u16),
+}
+
+impl TryFrom<__u16> for EventType {
+  type Error = ();
+
+  fn try_from(value: __u16) -> Result<Self, Self::Error> {
+    //if the list is any longer should probably somehow make this a macro
+    let values = [Self::EV_SYN, Self::EV_KEY, Self::EV_REL, Self::EV_ABS, Self::EV_MSC, Self::EV_SW, Self::EV_LED, Self::EV_SND, Self::EV_REP, Self::EV_FF, Self::EV_PWR, Self::EV_FF_STATUS];
+    let value = value as usize;
+    if value >= values.len() {
+      Err(())
+    } else {
+      Ok(values[value])
+    }
+  }
+}
+
+//we do not care about time. no one cares about time (probably)
+pub struct InputEvent {
+  pub type_: EventType,
+  pub code: __u16, //depends on EventType
+  pub value: __s32,
+}
+
+pub struct Input(RawFd);
+
+impl Input {
+  pub fn new(input_name: &str) -> Result<Self, ()> {
+    let input_name = CString::new(input_name).unwrap();
+    let fd = unsafe { open(input_name.as_ptr(), libc::O_RDONLY | libc::O_NONBLOCK) };
+    if fd == -1 {
+      Err(())
+    } else {
+      Ok(Self(fd))
+    }
+  }
+}
+
+impl Iterator for Input {
+  type Item = InputEvent;
+
+  fn next(&mut self) -> Option<Self::Item> {
+    //wait until there is something available
+    let mut fds = vec![pollfd {
+      fd: self.0,
+      events: libc::POLLIN, //return when "there is data to read"
+      revents: 0,
+    }];
+    let poll_result = unsafe { poll(fds.as_mut_ptr(), 1, -1) }; //neg num means no timeout
+    if poll_result == -1 {
+      return None;
+    }
+    //now read the event
+    let ie_size = size_of::<input_event>();
+    let mut ie = input_event {
+      time: timeval {
+        tv_sec: 0,
+        tv_usec: 0,
+      },
+      type_: 0,
+      code: 0,
+      value: 0,
+    };
+    let read_result = unsafe { read(self.0, &mut ie as *mut _ as *mut c_void, ie_size) };
+    if read_result == -1 {
+      return None;
+    }
+    let type_ = ie.type_.try_into().unwrap_or(EventType::Unknown(ie.type_));
+    Some(Self::Item {
+      type_,
+      code: ie.code,
+      value: ie.value,
+    })
+  }
+}
+
+impl Drop for Input {
+  fn drop(&mut self) {
+    unsafe { close(self.0) };
+  }
+}