From 6ecbf0d55695335f52d6fcf2b6a22ed45f5e4d99 Mon Sep 17 00:00:00 2001
From: dyknon <dyknon@r5f.jp>
Date: Mon, 24 Feb 2025 18:58:32 +0900
Subject: Remote camera capability.

---
 src/v4l2abst.rs | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 src/v4l2abst.rs

(limited to 'src/v4l2abst.rs')

diff --git a/src/v4l2abst.rs b/src/v4l2abst.rs
new file mode 100644
index 0000000..baefea0
--- /dev/null
+++ b/src/v4l2abst.rs
@@ -0,0 +1,103 @@
+use anyhow::{anyhow, Result};
+use crate::v4l2;
+use chrono::{DateTime, Local};
+use std::io::{Read, Write};
+use std::mem::size_of;
+
+pub struct Frame<'a>{
+    pub format: v4l2::ImageFormat,
+    pub width: usize,
+    pub height: usize,
+    pub stride: usize,
+    pub buf: &'a [u8],
+    pub timestamp: DateTime<Local>,
+}
+impl<'a> Frame<'a>{
+    pub fn serialize(&self, dst: &mut impl Write) -> Result<()>{
+        dst.write_all(&u32::to_be_bytes(self.format.into()))?;
+        dst.write_all(&self.timestamp.timestamp_subsec_nanos().to_be_bytes())?;
+        dst.write_all(&self.timestamp.timestamp().to_be_bytes())?;
+        dst.write_all(&self.width.to_be_bytes())?;
+        dst.write_all(&self.height.to_be_bytes())?;
+        dst.write_all(&self.stride.to_be_bytes())?;
+        dst.write_all(&self.buf.len().to_be_bytes())?;
+        dst.write_all(self.buf)?;
+        Ok(())
+    }
+    pub fn deserialize<'b>(src: &'b mut impl Read, buf: &'a mut Vec<u8>)
+    -> Result<Self>{
+        struct Rh<'c>(&'c mut dyn Read);
+        impl<'c> Rh<'c>{
+            fn u32(&mut self) -> Result<u32>{
+                let mut tmp: [u8; 4] = Default::default();
+                self.0.read_exact(&mut tmp)?;
+                Ok(u32::from_be_bytes(tmp))
+            }
+            fn i64(&mut self) -> Result<i64>{
+                let mut tmp: [u8; 8] = Default::default();
+                self.0.read_exact(&mut tmp)?;
+                Ok(i64::from_be_bytes(tmp))
+            }
+            fn usize(&mut self) -> Result<usize>{
+                let mut tmp: [u8; size_of::<usize>()] = Default::default();
+                self.0.read_exact(&mut tmp)?;
+                Ok(usize::from_be_bytes(tmp))
+            }
+        }
+        let mut src = Rh(src);
+        let format = src.u32()?.into();
+        let (ns, s) = (src.u32()?, src.i64()?);
+        let timestamp = DateTime::from_timestamp(s, ns)
+            .ok_or(anyhow!("Invalid DateTime"))?.into();
+        let width = src.usize()?;
+        let height = src.usize()?;
+        let stride = src.usize()?;
+        let len = src.usize()?;
+        buf.resize(len, 0);
+        src.0.read_exact(buf)?;
+        Ok(Frame{ format, width, height, stride, buf, timestamp })
+    }
+}
+
+pub trait CaptStream{
+    fn next<R>(&mut self, cb: impl FnOnce(Frame) -> R) -> Result<R>;
+}
+
+impl CaptStream for v4l2::CaptStream{
+    fn next<R>(&mut self, cb: impl FnOnce(Frame) -> R) -> Result<R>{
+        let (width, height) = (self.width(), self.height());
+        let stride = self.bytesperline();
+        let format = self.pixelformat();
+        let mut cb = Some(cb);
+        loop{
+            if let Some(ret) = v4l2::CaptStream::next(self, |buf, attr|{
+                if attr.flags.error{
+                    return None;
+                }
+                let timestamp = attr.get_datetime().unwrap();
+                Some(cb.take().unwrap()(Frame{
+                    format, width, height, stride, buf, timestamp
+                }))
+            })?{
+                return Ok(ret);
+            }
+        }
+    }
+}
+
+pub struct RemoteCam<I: Read + Write>(I);
+impl<I: Read + Write> RemoteCam<I>{
+    pub fn new(inner: I) -> Self{
+        Self(inner)
+    }
+}
+impl<I: Read + Write> CaptStream for RemoteCam<I>{
+    fn next<R>(&mut self, cb: impl FnOnce(Frame) -> R) -> Result<R>{
+        let ack: [u8; 1] = [0x2e];
+        let mut buf = Vec::new();
+        let frame = Frame::deserialize(&mut self.0, &mut buf)?;
+        self.0.write_all(&ack)?;
+        self.0.flush()?;
+        Ok(cb(frame))
+    }
+}
-- 
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