From 2ba4528c1df99b9172733d9b8ff7538714cc8728 Mon Sep 17 00:00:00 2001
From: devdesk <tami@tami.org.il>
Date: Mon, 19 Feb 2024 22:26:25 +0200
Subject: [PATCH] rgb for cutoff temperature

---
 examples/live.rs | 50 ++++++++++++++++++++++++++++++++----------------
 1 file changed, 33 insertions(+), 17 deletions(-)

diff --git a/examples/live.rs b/examples/live.rs
index afb2ad1..53ad1d9 100644
--- a/examples/live.rs
+++ b/examples/live.rs
@@ -50,12 +50,19 @@ fn main() -> anyhow::Result<()> {
 
     const WIDTH: usize = 288;
     const HEIGHT: usize = 384;
-    let fourcc_repr = [
-        b'Y', // | 0b10000000
-        b'1', b'6',
-        b' ', // Note: not using b' ' | 0x80, (V4L2_PIX_FMT_Y16_BE)
-              // because VID_S_FMT ioctl returns EINVAL, so just swap the bytes here
-    ];
+    let greyscale = !args.temperature || args.red_cutoff.is_none();
+    let fourcc_repr = if greyscale {
+        [
+            b'Y', // | 0b10000000
+            b'1', b'6',
+            b' ', // Note: not using b' ' | 0x80, (V4L2_PIX_FMT_Y16_BE)
+                  // because VID_S_FMT ioctl returns EINVAL, so just swap the bytes here
+        ]
+    } else {
+        // RGB32 is 4 bytes R, G, B, A
+        [b'R', b'G', b'B', b'4']
+    };
+    let bytes_per_pixel = if greyscale { 2 } else { 4 };
     let fourcc = v4l::format::FourCC { repr: fourcc_repr };
     let mut out = v4l::Device::with_path(output)?;
     // To find the fourcc code, use v4l2-ctl --list-formats-out /dev/video0
@@ -72,9 +79,13 @@ fn main() -> anyhow::Result<()> {
 
     // get a packet and print its bytes
     const PACKET_LEN: usize = 6972;
+    // input is grayscale 16 bits per pixel
     const FRAME_LEN: usize = WIDTH * HEIGHT * 2;
     let mut frame = [0u8; FRAME_LEN];
     let mut len = 0;
+    let output_frame_len = WIDTH * HEIGHT * bytes_per_pixel;
+    let mut swapped_vec = vec![0u8; output_frame_len];
+    let swapped = &mut swapped_vec;
     while let Ok(p) = cap.next_packet() {
         let data = p.data;
         if data.len() != PACKET_LEN {
@@ -93,21 +104,26 @@ fn main() -> anyhow::Result<()> {
             if len == FRAME_LEN {
                 // swap the bytes, we are using LE, not BE, 16 bit grayscale
                 // possibly limitation of current v4l2loopback or v4l rust wrapper or libv4l2
-                let mut swapped = [0u8; FRAME_LEN];
                 for i in 0..FRAME_LEN / 2 {
                     let mut pixel = u16::from_be_bytes([frame[i * 2], frame[i * 2 + 1]]);
-                    if args.temperature {
-                        pixel = pixel_to_celcius(pixel);
-                        if let Some(cutoff) = args.red_cutoff {
-                            pixel = if pixel > (256.0 * cutoff) as u16 {
-                                50000
-                            } else {
-                                0
-                            }
+                    if greyscale {
+                        if args.temperature {
+                            pixel = pixel_to_celcius(pixel);
                         }
+                        let pixel_swapped = pixel.to_le_bytes();
+                        swapped[i * 2..i * 2 + 2].copy_from_slice(&pixel_swapped);
+                    } else {
+                        pixel = pixel_to_celcius(pixel);
+                        let cutoff = args.red_cutoff.unwrap();
+                        let r = if pixel > (256.0 * cutoff) as u16 {
+                            255
+                        } else {
+                            0
+                        };
+                        let g = frame[i * 2];
+                        let b = frame[i * 2 + 1];
+                        swapped[i * 4..i * 4 + 4].copy_from_slice(&[0, r, g, b]);
                     }
-                    let pixel_swapped = pixel.to_le_bytes();
-                    swapped[i * 2..i * 2 + 2].copy_from_slice(&pixel_swapped);
                 }
                 out.write_all(&swapped[..])?;
             }