From e43f8b0efb98eea4b0ad16827ed29230c7e8add3 Mon Sep 17 00:00:00 2001
From: devdesk <tami@tami.org.il>
Date: Mon, 19 Feb 2024 22:31:07 +0200
Subject: [PATCH] correct for rotation and axes for greyscale

---
 examples/live.rs | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/examples/live.rs b/examples/live.rs
index 53ad1d9..8341a4c 100644
--- a/examples/live.rs
+++ b/examples/live.rs
@@ -67,7 +67,8 @@ fn main() -> anyhow::Result<()> {
     let mut out = v4l::Device::with_path(output)?;
     // To find the fourcc code, use v4l2-ctl --list-formats-out /dev/video0
     // (or read the source :)
-    let format = v4l::Format::new(WIDTH as u32, HEIGHT as u32, fourcc);
+    // flip axes
+    let format = v4l::Format::new(HEIGHT as u32, WIDTH as u32, fourcc);
     Output::set_format(&out, &format)?;
 
     // Setup Capture
@@ -105,13 +106,16 @@ fn main() -> anyhow::Result<()> {
                 // swap the bytes, we are using LE, not BE, 16 bit grayscale
                 // possibly limitation of current v4l2loopback or v4l rust wrapper or libv4l2
                 for i in 0..FRAME_LEN / 2 {
+                    let x = i % WIDTH;
+                    let y = (i / WIDTH) % HEIGHT;
                     let mut pixel = u16::from_be_bytes([frame[i * 2], frame[i * 2 + 1]]);
                     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);
+                        let out_i = ((HEIGHT - 1 - y) + (WIDTH - 1 - x) * HEIGHT) * 2;
+                        swapped[out_i..out_i + 2].copy_from_slice(&pixel_swapped);
                     } else {
                         pixel = pixel_to_celcius(pixel);
                         let cutoff = args.red_cutoff.unwrap();
@@ -122,7 +126,8 @@ fn main() -> anyhow::Result<()> {
                         };
                         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 out_i = (y + x * HEIGHT) * 2;
+                        swapped[out_i..out_i + 4].copy_from_slice(&[0, r, g, b]);
                     }
                 }
                 out.write_all(&swapped[..])?;