commit b647d95713ed118cc14a52bd5ad64cdb01dc22fa
Author: Janis <janis@nirgendwo.xyz>
Date:   Tue Nov 26 20:35:38 2024 +0100

    initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..6fd230a
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "grisly"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "1.0.93"
+bytemuck = "1.20.0"
+clap = "4.5.21"
+env_logger = "0.11.5"
+image = "0.25.5"
+libc = "0.2.165"
+log = "0.4.22"
+rand = "0.8.5"
+thiserror = "2.0.3"
+wayland-client = "0.31.7"
+wayland-protocols = { version = "0.32.5", features = ["client", "unstable"] }
+wayland-protocols-wlr = {version = "0.3.5", features = ["client"]}
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..81c0e97
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,940 @@
+use std::{
+    collections::HashMap,
+    ffi::CString,
+    io::BufWriter,
+    os::fd::{AsFd, AsRawFd, FromRawFd},
+};
+
+use image::{math::Rect, GenericImage, GenericImageView};
+use rand::Rng;
+use wayland_client::{
+    backend::ObjectId,
+    globals::{registry_queue_init, GlobalListContents},
+    protocol::{
+        wl_buffer::WlBuffer,
+        wl_output::{self, Mode, Transform, WlOutput},
+        wl_registry::{self, WlRegistry},
+        wl_shm::{self, WlShm},
+        wl_shm_pool::WlShmPool,
+    },
+    Connection, Dispatch, Proxy, QueueHandle, WEnum,
+};
+
+use wayland_protocols::xdg::xdg_output::zv1::client::{
+    zxdg_output_manager_v1::ZxdgOutputManagerV1, zxdg_output_v1::ZxdgOutputV1,
+};
+use wayland_protocols_wlr::screencopy::v1::client::{
+    zwlr_screencopy_frame_v1::{self, ZwlrScreencopyFrameV1},
+    zwlr_screencopy_manager_v1::ZwlrScreencopyManagerV1,
+};
+
+#[derive(Debug, Clone, Copy)]
+struct BufferInfo {
+    format: wl_shm::Format,
+    width: u32,
+    height: u32,
+    stride: u32,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+enum FrameState {
+    Pre,
+    BufferDone,
+    Copied,
+}
+
+#[derive(Debug)]
+enum FrameData {
+    Pre(Vec<BufferInfo>),
+    Buffer(BufferInfo),
+    Copying {
+        buffer: WlBuffer,
+        info: BufferInfo,
+        offset: usize,
+    },
+    Copied {
+        buffer: WlBuffer,
+        info: BufferInfo,
+        offset: usize,
+    },
+    Done,
+}
+
+impl FrameData {
+    fn select_buffer(&mut self) {
+        if let Self::Pre(infos) = self {
+            *self = Self::Buffer(infos.pop().unwrap());
+        }
+    }
+}
+
+#[derive(Debug)]
+struct Frame {
+    frame: ZwlrScreencopyFrameV1,
+    buffer_infos: Vec<BufferInfo>,
+    inverted_y: bool,
+    data: FrameData,
+}
+
+#[derive(Debug)]
+struct Output {
+    output: WlOutput,
+    xdg_output: ZxdgOutputV1,
+    logical_size: Option<(i32, i32)>,
+    physical_size: Option<(i32, i32)>,
+    logical_position: Option<(i32, i32)>,
+    physical_position: Option<(i32, i32)>,
+    transform: Option<Transform>,
+    scale: Option<i32>,
+    frame: Frame,
+}
+
+impl Output {
+    fn bind<
+        U: Send + Sync + 'static,
+        D: Dispatch<WlOutput, U>
+            + Dispatch<ZxdgOutputV1, ObjectId>
+            + Dispatch<ZwlrScreencopyFrameV1, ObjectId>
+            + 'static,
+    >(
+        registry: &WlRegistry,
+        name: u32,
+        version: u32,
+        qh: &QueueHandle<D>,
+        output_data: U,
+        xdg_manager: &ZxdgOutputManagerV1,
+        screencopy: &ZwlrScreencopyManagerV1,
+    ) -> Self {
+        let output = registry.bind(name, version, &qh, output_data);
+        let xdg_output = xdg_manager.get_xdg_output(&output, &qh, output.id());
+        let frame = screencopy.capture_output(0, &output, &qh, output.id());
+        Output {
+            output,
+            xdg_output,
+            logical_size: None,
+            physical_position: None,
+            transform: None,
+            scale: Some(1),
+            logical_position: None,
+            physical_size: None,
+            frame: Frame {
+                frame,
+                inverted_y: false,
+                buffer_infos: Vec::new(),
+                data: FrameData::Pre(vec![]),
+            },
+        }
+    }
+}
+
+#[derive(Debug)]
+struct App {
+    screencopy_mgr: ZwlrScreencopyManagerV1,
+    xdg_manager: ZxdgOutputManagerV1,
+    outputs: HashMap<ObjectId, Output>,
+    shm: WlShm,
+}
+
+impl Dispatch<ZwlrScreencopyManagerV1, ()> for App {
+    fn event(
+        _state: &mut Self,
+        _proxy: &ZwlrScreencopyManagerV1,
+        _event: <ZwlrScreencopyManagerV1 as Proxy>::Event,
+        _data: &(),
+        _conn: &Connection,
+        _qhandle: &wayland_client::QueueHandle<Self>,
+    ) {
+        // this does nothing
+    }
+}
+
+impl Dispatch<ZwlrScreencopyFrameV1, ObjectId> for App {
+    fn event(
+        state: &mut Self,
+        proxy: &ZwlrScreencopyFrameV1,
+        event: <ZwlrScreencopyFrameV1 as Proxy>::Event,
+        data: &ObjectId,
+        _conn: &Connection,
+        _qhandle: &wayland_client::QueueHandle<Self>,
+    ) {
+        let Some(output) = state.outputs.get_mut(data) else {
+            return;
+        };
+        match event {
+            zwlr_screencopy_frame_v1::Event::Buffer {
+                format,
+                width,
+                height,
+                stride,
+            } => {
+                if let FrameData::Pre(ref mut infos) = output.frame.data {
+                    infos.push(BufferInfo {
+                        format: format.into_result().unwrap(),
+                        width,
+                        height,
+                        stride,
+                    });
+                }
+            }
+            zwlr_screencopy_frame_v1::Event::Flags { flags } => {
+                output.frame.inverted_y = flags
+                    .into_result()
+                    .unwrap()
+                    .contains(zwlr_screencopy_frame_v1::Flags::YInvert);
+            }
+            zwlr_screencopy_frame_v1::Event::Ready { .. } => {
+                if let FrameData::Copying {
+                    buffer,
+                    info,
+                    offset,
+                } = core::mem::replace(&mut output.frame.data, FrameData::Done)
+                {
+                    output.frame.data = FrameData::Copied {
+                        buffer,
+                        info,
+                        offset,
+                    };
+                }
+            }
+            zwlr_screencopy_frame_v1::Event::Failed => {
+                output.frame.data = FrameData::Done;
+                panic!("screencopy failed.")
+            }
+            zwlr_screencopy_frame_v1::Event::BufferDone => {
+                // FIXME: pick best buffer format
+                // proxy.copy(buffer)
+                if let FrameData::Pre(infos) =
+                    core::mem::replace(&mut output.frame.data, FrameData::Done)
+                {
+                    let info = infos
+                        .iter()
+                        .max_by_key(|info| match info.format {
+                            wl_shm::Format::Xrgb8888 => 20,
+                            wl_shm::Format::Argb8888 => 10,
+                            _ => 0,
+                        })
+                        .unwrap()
+                        .clone();
+                    output.frame.data = FrameData::Buffer(info);
+                }
+            }
+            _ => {}
+        }
+    }
+}
+
+impl Dispatch<ZxdgOutputManagerV1, ()> for App {
+    fn event(
+        state: &mut Self,
+        proxy: &ZxdgOutputManagerV1,
+        event: <ZxdgOutputManagerV1 as Proxy>::Event,
+        data: &(),
+        conn: &Connection,
+        qhandle: &wayland_client::QueueHandle<Self>,
+    ) {
+    }
+}
+
+impl Dispatch<ZxdgOutputV1, ObjectId> for App {
+    fn event(
+        state: &mut Self,
+        proxy: &ZxdgOutputV1,
+        event: <ZxdgOutputV1 as Proxy>::Event,
+        data: &ObjectId,
+        conn: &Connection,
+        qhandle: &wayland_client::QueueHandle<Self>,
+    ) {
+        let Some(output) = state.outputs.get_mut(data) else {
+            return;
+        };
+        match event {
+            wayland_protocols::xdg::xdg_output::zv1::client::zxdg_output_v1::Event::LogicalPosition { x, y } => {
+                    output.logical_position = Some((x,y));
+            },
+            wayland_protocols::xdg::xdg_output::zv1::client::zxdg_output_v1::Event::LogicalSize { width, height } => {
+                output.logical_size = Some((width, height));
+            },
+            _ => {},
+        }
+    }
+}
+
+impl Dispatch<wl_output::WlOutput, u32> for App {
+    fn event(
+        state: &mut Self,
+        proxy: &wl_output::WlOutput,
+        event: <wl_output::WlOutput as Proxy>::Event,
+        _data: &u32,
+        _conn: &Connection,
+        _qhandle: &wayland_client::QueueHandle<Self>,
+    ) {
+        let Some(output) = state.outputs.get_mut(&proxy.id()) else {
+            return;
+        };
+        match event {
+            wl_output::Event::Geometry {
+                x, y, transform, ..
+            } => {
+                output.physical_position = Some((x, y));
+                output.transform = Some(transform.into_result().unwrap());
+            }
+            wl_output::Event::Mode {
+                flags,
+                width,
+                height,
+                ..
+            } => {
+                if flags == WEnum::Value(Mode::Current) {
+                    output.physical_size = Some((width, height));
+                }
+            }
+            wl_output::Event::Scale { factor } => {
+                output.scale = Some(factor);
+            }
+            _ => {}
+        }
+    }
+}
+
+impl Dispatch<WlShm, ()> for App {
+    fn event(
+        state: &mut Self,
+        proxy: &WlShm,
+        event: <WlShm as Proxy>::Event,
+        data: &(),
+        conn: &Connection,
+        qhandle: &wayland_client::QueueHandle<Self>,
+    ) {
+    }
+}
+
+impl Dispatch<WlShmPool, ()> for App {
+    fn event(
+        _state: &mut Self,
+        _proxy: &WlShmPool,
+        event: <WlShmPool as Proxy>::Event,
+        _data: &(),
+        _conn: &Connection,
+        _qhandle: &wayland_client::QueueHandle<Self>,
+    ) {
+    }
+}
+
+impl Dispatch<WlBuffer, ()> for App {
+    fn event(
+        _state: &mut Self,
+        _proxy: &WlBuffer,
+        event: <WlBuffer as Proxy>::Event,
+        _data: &(),
+        _conn: &Connection,
+        _qhandle: &wayland_client::QueueHandle<Self>,
+    ) {
+    }
+}
+
+impl Dispatch<wl_registry::WlRegistry, GlobalListContents> for App {
+    fn event(
+        state: &mut Self,
+        registry: &wl_registry::WlRegistry,
+        event: <wl_registry::WlRegistry as Proxy>::Event,
+        globals: &GlobalListContents,
+        _conn: &Connection,
+        qh: &wayland_client::QueueHandle<Self>,
+    ) {
+        match event {
+            wl_registry::Event::Global { name, version, .. } => {
+                let output = Output::bind(
+                    registry,
+                    name,
+                    version,
+                    qh,
+                    name,
+                    &state.xdg_manager,
+                    &state.screencopy_mgr,
+                );
+                state.outputs.insert(output.output.id(), output);
+            }
+            wl_registry::Event::GlobalRemove { name } => globals.with_list(|globals| {
+                if globals
+                    .iter()
+                    .find(|global| global.name == name)
+                    .map(|global| &global.interface == wl_output::WlOutput::interface().name)
+                    == Some(true)
+                {
+                    state
+                        .outputs
+                        .retain(|_, output| output.output.data() != Some(&name));
+                }
+            }),
+            _ => {}
+        }
+    }
+}
+
+struct Shm {
+    fd: std::os::unix::io::OwnedFd,
+    name: CString,
+    size: usize,
+}
+
+impl Shm {
+    fn new(size: usize) -> std::io::Result<Self> {
+        let name = CString::new(format!(
+            "grisly-{}",
+            rand::thread_rng()
+                .sample_iter(&rand::distributions::Alphanumeric)
+                .take(8)
+                .map(char::from)
+                .collect::<String>()
+        ))
+        .unwrap();
+        let fd = match unsafe {
+            libc::shm_open(
+                name.as_ptr(),
+                libc::O_RDWR | libc::O_CREAT | libc::O_EXCL,
+                0600,
+            )
+        } {
+            -1 => Err(std::io::Error::last_os_error()),
+            fd => Ok(unsafe { std::os::unix::io::OwnedFd::from_raw_fd(fd) }),
+        }?;
+
+        match unsafe { libc::ftruncate(fd.as_raw_fd(), size as i64) } {
+            -1 => Err(std::io::Error::last_os_error()),
+            _ => Ok(()),
+        }?;
+
+        Ok(Self { fd, name, size })
+    }
+
+    fn map<'a>(&'a self) -> std::io::Result<&'a mut [u8]> {
+        match unsafe {
+            libc::mmap(
+                core::ptr::null_mut(),
+                self.size,
+                libc::PROT_READ | libc::PROT_WRITE,
+                libc::MAP_SHARED,
+                self.fd.as_raw_fd(),
+                0,
+            )
+        } {
+            libc::MAP_FAILED => Err(std::io::Error::last_os_error()),
+            ptr => Ok(unsafe { core::slice::from_raw_parts_mut(ptr as *mut _, self.size) }),
+        }
+    }
+}
+
+impl Drop for Shm {
+    fn drop(&mut self) {
+        unsafe {
+            libc::shm_unlink(self.name.as_ptr());
+        }
+    }
+}
+
+//
+// Post-Processing transforms & scalings:
+// wl_output gives an integer scale to apply to buffer contents.
+// - question: does this apply after the xdg_output logical size?
+// - we use a sampled image to copy to a differently sized logical size anyway
+//
+// wl_output gives a transform which is applied to buffer contents.
+//
+
+fn main() {
+    let conn = Connection::connect_to_env().unwrap();
+
+    let (globals, mut queue) = registry_queue_init(&conn).unwrap();
+
+    let qh = queue.handle();
+
+    let screencopy_mgr = globals
+        .bind::<ZwlrScreencopyManagerV1, _, _>(&queue.handle(), 1..=3, ())
+        .unwrap();
+    let xdg_manager = globals
+        .bind::<ZxdgOutputManagerV1, _, _>(&queue.handle(), 3..=3, ())
+        .unwrap();
+
+    let outputs = globals.contents().with_list(|list| {
+        list.iter()
+            .filter(|global| &global.interface == wl_output::WlOutput::interface().name)
+            .map(|global| {
+                let output = Output::bind(
+                    globals.registry(),
+                    global.name,
+                    global.version,
+                    &qh,
+                    global.name,
+                    &xdg_manager,
+                    &screencopy_mgr,
+                );
+
+                (output.output.id(), output)
+            })
+            .collect::<HashMap<_, _>>()
+    });
+
+    let shm = globals.bind(&queue.handle(), 0..=2, ()).unwrap();
+
+    let mut app = App {
+        outputs,
+        xdg_manager,
+        screencopy_mgr,
+        shm,
+    };
+
+    while !app
+        .outputs
+        .iter()
+        .all(|(_, output)| matches!(output.frame.data, FrameData::Buffer(_)))
+    {
+        _ = queue.roundtrip(&mut app).unwrap();
+    }
+
+    let mut total_size = 0;
+    let buffers = app
+        .outputs
+        .iter_mut()
+        .map(|(_, output)| {
+            let FrameData::Buffer(info) =
+                core::mem::replace(&mut output.frame.data, FrameData::Done)
+            else {
+                unreachable!();
+            };
+            let size = info.height * info.stride;
+            let offset = total_size;
+            total_size += size;
+
+            (output, info, offset)
+        })
+        .collect::<Vec<_>>();
+
+    let shm = Shm::new(total_size as usize).unwrap();
+    let buffer = shm.map().unwrap();
+
+    let pool = app
+        .shm
+        .create_pool(shm.fd.as_fd(), total_size as i32, &qh, ());
+
+    for (output, info, offset) in buffers {
+        let buffer = pool.create_buffer(
+            offset as i32,
+            info.width as i32,
+            info.height as i32,
+            info.stride as i32,
+            info.format,
+            &qh,
+            (),
+        );
+
+        output.frame.frame.copy(&buffer);
+
+        output.frame.data = FrameData::Copying {
+            buffer,
+            info,
+            offset: offset as usize,
+        };
+    }
+
+    while !app
+        .outputs
+        .iter()
+        .all(|(_, output)| matches!(output.frame.data, FrameData::Copied { .. }))
+    {
+        _ = queue.roundtrip(&mut app).unwrap();
+    }
+
+    fn rect_union(lhs: Rect, rhs: Rect) -> Rect {
+        struct AABB {
+            ax: u32,
+            ay: u32,
+            bx: u32,
+            by: u32,
+        }
+        let lhs = AABB {
+            ax: lhs.x,
+            ay: lhs.y,
+            bx: lhs.x + lhs.width,
+            by: lhs.y + lhs.height,
+        };
+        let rhs = AABB {
+            ax: rhs.x,
+            ay: rhs.y,
+            bx: rhs.x + rhs.width,
+            by: rhs.y + rhs.height,
+        };
+        let union = AABB {
+            ax: lhs.ax.min(rhs.ax),
+            ay: lhs.ay.min(rhs.ay),
+            bx: lhs.bx.max(rhs.bx),
+            by: lhs.by.max(rhs.by),
+        };
+
+        Rect {
+            x: union.ax,
+            y: union.ay,
+            width: union.bx - union.ax,
+            height: union.by - union.ay,
+        }
+    }
+
+    let mut image_rect = Rect {
+        x: 0,
+        y: 0,
+        width: 0,
+        height: 0,
+    };
+    let buffers = app
+        .outputs
+        .values_mut()
+        .map(|output| {
+            let FrameData::Copied { info, offset, .. } =
+                core::mem::replace(&mut output.frame.data, FrameData::Done)
+            else {
+                unreachable!();
+            };
+
+            let (px, py) = output.physical_position.unwrap_or((0, 0));
+            let (lx, ly) = output.logical_position.unwrap_or((0, 0));
+            // image destination
+            let (x, y) = (lx - px, ly - py);
+
+            let (width, height) = output
+                .logical_size
+                .unwrap_or((info.width as i32, info.height as i32));
+
+            let rect = image::math::Rect {
+                x: x as u32,
+                y: y as u32,
+                width: width as u32,
+                height: height as u32,
+            };
+
+            println!("buffer: {:?}", info);
+            println!(" - invert-y: {}", output.frame.inverted_y);
+            println!("destination rect: {:?}", rect);
+            println!(" - transform: {:?}", output.transform);
+
+            image_rect = rect_union(image_rect, rect);
+
+            (info, offset, rect, output.frame.inverted_y)
+        })
+        .collect::<Vec<_>>();
+
+    let mut image = image::RgbImage::new(image_rect.width, image_rect.height);
+
+    let now = std::time::Instant::now();
+    for (info, offset, rect, inverted_y) in buffers {
+        let size = info.stride * info.height;
+        let view = BufferView {
+            info,
+            inverted_y,
+            bytes: &buffer[offset..][..size as usize],
+        };
+
+        if rect.width != info.width || rect.height != info.height {
+            let sampled = SampledView {
+                view: &view,
+                dimensions: (rect.width, rect.height),
+            };
+            image.copy_from(&sampled, rect.x, rect.y).unwrap();
+        } else {
+            image.copy_from(&view, rect.x, rect.y).unwrap();
+        }
+    }
+    println!("copying: {}s", now.elapsed().as_secs_f64());
+
+    let file = std::fs::File::create("out.png").unwrap();
+    let writer = BufWriter::new(file);
+    let now = std::time::Instant::now();
+    image
+        .write_with_encoder(image::codecs::png::PngEncoder::new_with_quality(
+            writer,
+            image::codecs::png::CompressionType::Default,
+            image::codecs::png::FilterType::Adaptive,
+        ))
+        .unwrap();
+    println!("encoding: {}s", now.elapsed().as_secs_f64());
+}
+
+struct SampledView<'a, V: GenericImageView> {
+    view: &'a V,
+    dimensions: (u32, u32),
+}
+
+impl<'a, V: GenericImageView> GenericImageView for SampledView<'a, V> {
+    type Pixel = V::Pixel;
+
+    fn dimensions(&self) -> (u32, u32) {
+        self.dimensions
+    }
+
+    fn get_pixel(&self, x: u32, y: u32) -> Self::Pixel {
+        let u = x as f32 / self.dimensions.0 as f32;
+        let v = y as f32 / self.dimensions.1 as f32;
+
+        image::imageops::sample_bilinear(self.view, u, v).unwrap()
+    }
+}
+
+struct BufferView<'a> {
+    info: BufferInfo,
+    inverted_y: bool,
+    bytes: &'a [u8],
+}
+
+impl BufferView<'_> {
+    fn pixel_offset(&self, x: u32, y: u32) -> usize {
+        let y = if self.inverted_y {
+            self.info.height - y
+        } else {
+            y
+        };
+
+        self.info.stride as usize * y as usize + (x as usize * self.pixel_stride() as usize)
+    }
+
+    fn pixel_stride(&self) -> u32 {
+        (match self.info.format {
+            wl_shm::Format::Argb8888 => 32,
+            wl_shm::Format::Xrgb8888 => 32,
+            wl_shm::Format::C8 => 8,
+            wl_shm::Format::Rgb332 => 8,
+            wl_shm::Format::Bgr233 => 8,
+            wl_shm::Format::Xrgb4444 => 16,
+            wl_shm::Format::Xbgr4444 => 16,
+            wl_shm::Format::Rgbx4444 => 16,
+            wl_shm::Format::Bgrx4444 => 16,
+            wl_shm::Format::Argb4444 => 16,
+            wl_shm::Format::Abgr4444 => 16,
+            wl_shm::Format::Rgba4444 => 16,
+            wl_shm::Format::Bgra4444 => 16,
+            wl_shm::Format::Xrgb1555 => 16,
+            wl_shm::Format::Xbgr1555 => 16,
+            wl_shm::Format::Rgbx5551 => 16,
+            wl_shm::Format::Bgrx5551 => 16,
+            wl_shm::Format::Argb1555 => 16,
+            wl_shm::Format::Abgr1555 => 16,
+            wl_shm::Format::Rgba5551 => 16,
+            wl_shm::Format::Bgra5551 => 16,
+            wl_shm::Format::Rgb565 => 16,
+            wl_shm::Format::Bgr565 => 16,
+            wl_shm::Format::Rgb888 => 24,
+            wl_shm::Format::Bgr888 => 24,
+            wl_shm::Format::Xbgr8888 => 32,
+            wl_shm::Format::Rgbx8888 => 32,
+            wl_shm::Format::Bgrx8888 => 32,
+            wl_shm::Format::Abgr8888 => 32,
+            wl_shm::Format::Rgba8888 => 32,
+            wl_shm::Format::Bgra8888 => 32,
+            wl_shm::Format::Xrgb2101010 => 32,
+            wl_shm::Format::Xbgr2101010 => 32,
+            wl_shm::Format::Rgbx1010102 => 32,
+            wl_shm::Format::Bgrx1010102 => 32,
+            wl_shm::Format::Argb2101010 => 32,
+            wl_shm::Format::Abgr2101010 => 32,
+            wl_shm::Format::Rgba1010102 => 32,
+            wl_shm::Format::Bgra1010102 => 32,
+            wl_shm::Format::R8 => 8,
+            wl_shm::Format::R16 => 16,
+            wl_shm::Format::Rg88 => 16,
+            wl_shm::Format::Gr88 => 16,
+            wl_shm::Format::Rg1616 => 32,
+            wl_shm::Format::Gr1616 => 32,
+            wl_shm::Format::Xrgb16161616f => 64,
+            wl_shm::Format::Xbgr16161616f => 64,
+            wl_shm::Format::Argb16161616f => 64,
+            wl_shm::Format::Abgr16161616f => 64,
+            wl_shm::Format::Xrgb8888A8 => 40,
+            wl_shm::Format::Xbgr8888A8 => 40,
+            wl_shm::Format::Rgbx8888A8 => 40,
+            wl_shm::Format::Bgrx8888A8 => 40,
+            wl_shm::Format::Rgb888A8 => 32,
+            wl_shm::Format::Bgr888A8 => 32,
+            wl_shm::Format::Rgb565A8 => 24,
+            wl_shm::Format::Bgr565A8 => 24,
+            wl_shm::Format::Axbxgxrx106106106106 => 64,
+            wl_shm::Format::Xrgb16161616 => 64,
+            wl_shm::Format::Xbgr16161616 => 64,
+            wl_shm::Format::Argb16161616 => 64,
+            wl_shm::Format::Abgr16161616 => 64,
+            _ => 1,
+        }) / 8
+    }
+
+    fn sample_r(&self, x: u32, y: u32) -> u8 {
+        let offset = self.pixel_offset(x, y);
+        let (shift, width) = match self.info.format {
+            // (shift, width)
+            wl_shm::Format::Argb8888 => (8 * 3, u8::BITS),
+            wl_shm::Format::Xrgb8888 => (8 * 3, u8::BITS),
+            wl_shm::Format::Xbgr8888 => (8 * 0, u8::BITS),
+            wl_shm::Format::Abgr8888 => (8 * 0, u8::BITS),
+            wl_shm::Format::Bgr888 => (8 * 2, u8::BITS),
+            wl_shm::Format::Rgb888 => (0, u8::BITS),
+            wl_shm::Format::Bgra8888 => (8 * 2, u8::BITS),
+            wl_shm::Format::Bgrx8888 => (8 * 2, u8::BITS),
+            wl_shm::Format::Rgba4444 => (0, u8::BITS / 2),
+            wl_shm::Format::Rgbx4444 => (0, u8::BITS / 2),
+            wl_shm::Format::Bgra4444 => (8, u8::BITS / 2),
+            wl_shm::Format::Bgrx4444 => (8, u8::BITS / 2),
+            wl_shm::Format::Argb4444 => (4, u8::BITS / 2),
+            wl_shm::Format::Xrgb4444 => (4, u8::BITS / 2),
+            wl_shm::Format::Rgba5551 => (0, 5),
+            wl_shm::Format::Rgbx5551 => (0, 5),
+            wl_shm::Format::Xrgb2101010 => (2, 10),
+            wl_shm::Format::Argb2101010 => (2, 10),
+            wl_shm::Format::Xrgb16161616 => (16, 16),
+            wl_shm::Format::Argb16161616 => (16, 16),
+            wl_shm::Format::Rgb332 => (0, 3),
+            wl_shm::Format::Bgr233 => (5, 3),
+            _ => unimplemented!(),
+        };
+
+        let offset = offset + (shift / 8) as usize;
+        let shift = shift % 8;
+
+        let acc = (self.bytes[offset] >> shift) & !(!1u8 << (width - 1).min(7));
+        let bits = (1..(width / 8)).fold(acc as u64, |acc, i| {
+            // byte chunks:
+            let mask = !(!1u8 << (width - 1 - i * 8).min(8));
+
+            let bits = self.bytes[offset + i as usize] & mask;
+            (acc << 8) & bits as u64
+        });
+
+        let bits = if width > 8 {
+            bits >> (width - 8)
+        } else if width < 8 {
+            bits << (8 - width)
+        } else {
+            bits
+        };
+
+        bits as u8
+    }
+    fn sample_g(&self, x: u32, y: u32) -> u8 {
+        let offset = self.pixel_offset(x, y);
+        let (shift, width) = match self.info.format {
+            // (shift, width)
+            wl_shm::Format::Argb8888 => (8 * 1, u8::BITS),
+            wl_shm::Format::Xrgb8888 => (8 * 1, u8::BITS),
+            wl_shm::Format::Xbgr8888 => (8 * 1, u8::BITS),
+            wl_shm::Format::Abgr8888 => (8 * 1, u8::BITS),
+            wl_shm::Format::Bgr888 => (8 * 1, u8::BITS),
+            wl_shm::Format::Rgb888 => (8, u8::BITS),
+            wl_shm::Format::Bgra8888 => (8 * 1, u8::BITS),
+            wl_shm::Format::Bgrx8888 => (8 * 1, u8::BITS),
+            wl_shm::Format::Rgba4444 => (4, u8::BITS / 2),
+            wl_shm::Format::Rgbx4444 => (4, u8::BITS / 2),
+            wl_shm::Format::Bgra4444 => (4, u8::BITS / 2),
+            wl_shm::Format::Bgrx4444 => (4, u8::BITS / 2),
+            wl_shm::Format::Argb4444 => (8, u8::BITS / 2),
+            wl_shm::Format::Xrgb4444 => (8, u8::BITS / 2),
+            wl_shm::Format::Rgba5551 => (5, 5),
+            wl_shm::Format::Rgbx5551 => (5, 5),
+            wl_shm::Format::Xrgb2101010 => (12, 10),
+            wl_shm::Format::Argb2101010 => (12, 10),
+            wl_shm::Format::Xrgb16161616 => (32, 16),
+            wl_shm::Format::Argb16161616 => (32, 16),
+            wl_shm::Format::Rgb332 => (3, 3),
+            wl_shm::Format::Bgr233 => (2, 3),
+            _ => unimplemented!(),
+        };
+
+        let offset = offset + (shift / 8) as usize;
+        let shift = shift % 8;
+
+        let acc = (self.bytes[offset] >> shift) & !(!1u8 << (width - 1).min(7));
+        let bits = (1..(width / 8)).fold(acc as u64, |acc, i| {
+            // byte chunks:
+            let mask = !(!1u8 << (width - 1 - i * 8).min(8));
+
+            let bits = self.bytes[offset + i as usize] & mask;
+            (acc << 8) & bits as u64
+        });
+
+        let bits = if width > 8 {
+            bits >> (width - 8)
+        } else if width < 8 {
+            bits << (8 - width)
+        } else {
+            bits
+        };
+
+        bits as u8
+    }
+    fn sample_b(&self, x: u32, y: u32) -> u8 {
+        let offset = self.pixel_offset(x, y);
+        let (shift, width) = match self.info.format {
+            // (shift, width)
+            wl_shm::Format::Argb8888 => (8 * 0, u8::BITS),
+            wl_shm::Format::Xrgb8888 => (8 * 0, u8::BITS),
+            wl_shm::Format::Xbgr8888 => (8 * 2, u8::BITS),
+            wl_shm::Format::Abgr8888 => (8 * 2, u8::BITS),
+            wl_shm::Format::Bgr888 => (8 * 0, u8::BITS),
+            wl_shm::Format::Rgb888 => (8 * 2, u8::BITS),
+            wl_shm::Format::Bgra8888 => (8 * 0, u8::BITS),
+            wl_shm::Format::Bgrx8888 => (8 * 0, u8::BITS),
+            wl_shm::Format::Rgba4444 => (8, u8::BITS / 2),
+            wl_shm::Format::Rgbx4444 => (8, u8::BITS / 2),
+            wl_shm::Format::Bgra4444 => (0, u8::BITS / 2),
+            wl_shm::Format::Bgrx4444 => (0, u8::BITS / 2),
+            wl_shm::Format::Argb4444 => (12, u8::BITS / 2),
+            wl_shm::Format::Xrgb4444 => (12, u8::BITS / 2),
+            wl_shm::Format::Rgba5551 => (10, 5),
+            wl_shm::Format::Rgbx5551 => (10, 5),
+            wl_shm::Format::Xrgb2101010 => (22, 10),
+            wl_shm::Format::Argb2101010 => (22, 10),
+            wl_shm::Format::Xrgb16161616 => (48, 16),
+            wl_shm::Format::Argb16161616 => (48, 16),
+            wl_shm::Format::Rgb332 => (6, 2),
+            wl_shm::Format::Bgr233 => (0, 2),
+            _ => unimplemented!(),
+        };
+
+        let offset = offset + (shift / 8) as usize;
+        let shift = shift % 8;
+
+        let acc = (self.bytes[offset] >> shift) & !(!1u8 << (width - 1).min(7));
+        let bits = (1..(width / 8)).fold(acc as u64, |acc, i| {
+            // byte chunks:
+            let mask = !(!1u8 << (width - 1 - i * 8).min(8));
+
+            let bits = self.bytes[offset + i as usize] & mask;
+            (acc << 8) & bits as u64
+        });
+
+        let bits = if width > 8 {
+            bits >> (width - 8)
+        } else if width < 8 {
+            bits << (8 - width)
+        } else {
+            bits
+        };
+
+        bits as u8
+    }
+}
+
+impl GenericImageView for BufferView<'_> {
+    type Pixel = image::Rgb<u8>;
+
+    fn dimensions(&self) -> (u32, u32) {
+        (self.info.width, self.info.height)
+    }
+
+    fn get_pixel(&self, x: u32, y: u32) -> Self::Pixel {
+        match self.info.format {
+            wl_shm::Format::Xbgr8888 => Self::Pixel::from(
+                <[u8; 3] as TryFrom<&[u8]>>::try_from(&self.bytes[self.pixel_offset(x, y)..][..3])
+                    .unwrap(),
+            ),
+            _ => Self::Pixel::from([
+                self.sample_r(x, y),
+                self.sample_g(x, y),
+                self.sample_b(x, y),
+            ]),
+        }
+    }
+}