Use Wayland subsurfaces, dmabuf screencopy

More efficient than shm screencopy, and rendering an iced image into the
window. Done right, should espeically help with multiple GPUs, but more
testing and work is needed there.

Removes mmapping of dmabuf, which errored... I guess not allocated with
right options for that. Relevant only if we want a fallback/test that
involves reading dmabufs.

Using `OnDamage` doesn't seem to work correctly currently. Likely a
compositor issue.

src/view/mod.rs

@@ -14,6 +14,7 @@ use cosmic::{
         Border,
     },
     iced_core::Shadow,
+    iced_sctk::subsurface_widget::Subsurface,
     widget,
 };
 use cosmic_comp_config::workspace::WorkspaceLayout;
@@ -284,7 +285,7 @@ fn toplevel_previews<'a>(
 
 fn capture_image(image: Option<&CaptureImage>) -> cosmic::Element<'_, Msg> {
     if let Some(image) = image {
-        widget::Image::new(image.img.clone()).into()
+        Subsurface::new(image.width, image.height, &image.wl_buffer).into()
     } else {
         widget::Image::new(widget::image::Handle::from_pixels(1, 1, vec![0, 0, 0, 255])).into()
     }

src/wayland/buffer.rs

@@ -8,11 +8,13 @@ use cctk::{
 };
 use cosmic::cctk;
 use cosmic::iced::widget::image;
+use cosmic::iced_sctk::subsurface_widget::{BufferSource, Dmabuf, Plane, Shmbuf, SubsurfaceBuffer};
 use memmap2::Mmap;
 use rustix::{io::Errno, shm::ShmOFlags};
 use std::{
     os::fd::{AsFd, OwnedFd},
     path::{Path, PathBuf},
+    sync::Arc,
     time::{SystemTime, UNIX_EPOCH},
 };
 use wayland_protocols::wp::linux_dmabuf::zv1::client::zwp_linux_buffer_params_v1;
@@ -70,10 +72,9 @@ enum BufferBacking {
 }
 
 pub struct Buffer {
-    backing: BufferBacking,
+    pub backing: Arc<BufferSource>,
     pub buffer: wl_buffer::WlBuffer,
     pub buffer_info: BufferInfo,
-    mmap: Mmap,
     node: Option<PathBuf>,
 }
 
@@ -89,6 +90,12 @@ impl AppData {
             (),
         );
 
+        pool.destroy();
+
+        // XXX
+        let fd = rustix::fs::memfd_create("shm-buffer", rustix::fs::MemfdFlags::CLOEXEC).unwrap();
+        rustix::fs::ftruncate(&fd, buffer_info.stride as u64 * buffer_info.height as u64).unwrap();
+
         let format = wl_shm::Format::try_from(buffer_info.format).unwrap();
         let buffer = pool.create_buffer(
             0,
@@ -100,11 +107,18 @@ impl AppData {
             (),
         );
 
-        let mmap = unsafe { Mmap::map(&fd).unwrap() };
-
         Buffer {
-            backing: BufferBacking::Shm { fd },
+            backing: Arc::new(
-            mmap,
+                Shmbuf {
+                    fd,
+                    offset: 0,
+                    width: buffer_info.width as i32,
+                    height: buffer_info.height as i32,
+                    stride: buffer_info.stride as i32,
+                    format,
+                }
+                .into(),
+            ),
             buffer,
             buffer_info: buffer_info.clone(),
             node: None,
@@ -158,8 +172,8 @@ impl AppData {
             )?
         };
 
-        let fd = bo.fd()?;
+        let mut planes = Vec::new();
-        let stride = bo.stride()?;
+
         let params = self.dmabuf_state.create_params(&self.qh)?;
         let modifier = bo.modifier()?;
         for i in 0..bo.plane_count()? as i32 {
@@ -173,6 +187,12 @@ impl AppData {
                 plane_stride,
                 modifier.into(),
             );
+            planes.push(Plane {
+                fd: plane_fd,
+                plane_idx: i as u32,
+                offset: plane_offset,
+                stride: plane_stride,
+            });
         }
         let buffer = params
             .create_immed(
@@ -184,12 +204,17 @@ impl AppData {
             )
             .0;
 
-        // Is there any cost to mmapping dma memory if it isn't accessed?
-        let mmap = unsafe { Mmap::map(&fd).unwrap() };
-
         Ok(Some(Buffer {
-            backing: BufferBacking::Dmabuf { fd, stride },
+            backing: Arc::new(
-            mmap,
+                Dmabuf {
+                    width: buffer_info.width as i32,
+                    height: buffer_info.height as i32,
+                    planes,
+                    format: buffer_info.format,
+                    modifier: modifier.into(),
+                }
+                .into(),
+            ),
             buffer,
             buffer_info: buffer_info.clone(),
             node: Some(node.clone()),
@@ -200,12 +225,11 @@ impl AppData {
         // XXX Handle other formats?
         let format = wl_shm::Format::Abgr8888.into();
 
-        /*
         if let Some(buffer_info) = buffer_infos
             .iter()
             .find(|x| x.type_ == WEnum::Value(BufferType::Dmabuf) && x.format == format)
         {
-            match self.create_gbm_buffer(buffer_info, true) {
+            match self.create_gbm_buffer(buffer_info, false) {
                 Ok(Some(buffer)) => {
                     return buffer;
                 }
@@ -213,7 +237,6 @@ impl AppData {
                 Err(err) => eprintln!("Failed to create gbm buffer: {}", err),
             }
         }
-        */
 
         // Fallback to shm buffer
         // Assume format is already known to be valid
@@ -226,33 +249,6 @@ impl AppData {
 }
 
 impl Buffer {
-    // Buffer must be released by server for safety
-    // XXX is this at all a performance issue?
-    #[allow(clippy::wrong_self_convention)]
-    pub unsafe fn to_image(&mut self) -> image::Handle {
-        let pixels = match &self.backing {
-            BufferBacking::Shm { .. } => self.mmap.to_vec(),
-            // NOTE: Only will work with linear modifier
-            BufferBacking::Dmabuf { fd, stride } => {
-                if self.buffer_info.stride == self.buffer_info.width * 4 {
-                    self.mmap.to_vec()
-                } else {
-                    let width = self.buffer_info.width as usize;
-                    let height = self.buffer_info.height as usize;
-                    let stride = *stride as usize;
-                    let output_stride = width * 4;
-                    let mut pixels = vec![0; height * output_stride];
-                    for y in 0..height {
-                        pixels[y * output_stride..y * output_stride + output_stride]
-                            .copy_from_slice(&self.mmap[y * stride..y * stride + output_stride]);
-                    }
-                    pixels
-                }
-            }
-        };
-        image::Handle::from_pixels(self.buffer_info.width, self.buffer_info.height, pixels)
-    }
-
     pub fn node(&self) -> Option<&Path> {
         self.node.as_deref()
     }

src/wayland/mod.rs

@@ -20,7 +20,7 @@ use cctk::{
     toplevel_management::ToplevelManagerState,
     wayland_client::{
         globals::registry_queue_init,
-        protocol::{wl_output, wl_seat},
+        protocol::{wl_buffer, wl_output, wl_seat},
         Connection, QueueHandle,
     },
     workspace::WorkspaceState,
@@ -30,6 +30,7 @@ use cosmic::iced::{
     self,
     futures::{executor::block_on, FutureExt, SinkExt},
 };
+use cosmic::iced_sctk::subsurface_widget::SubsurfaceBuffer;
 use futures_channel::mpsc;
 use std::{
     cell::RefCell,
@@ -83,7 +84,9 @@ pub enum Event {
 
 #[derive(Clone, Debug)]
 pub struct CaptureImage {
-    pub img: iced::widget::image::Handle,
+    pub width: u32,
+    pub height: u32,
+    pub wl_buffer: SubsurfaceBuffer,
 }
 
 pub fn subscription(conn: Connection) -> iced::Subscription<Event> {

src/wayland/screencopy.rs

@@ -9,6 +9,7 @@ use cosmic::cctk::{
     },
     wayland_client::{Connection, QueueHandle, WEnum},
 };
+use cosmic::iced_sctk::subsurface_widget::{SubsurfaceBuffer, SubsurfaceBufferRelease};
 use std::{
     array,
     sync::{Arc, Weak},
@@ -21,6 +22,9 @@ pub struct ScreencopySession {
     buffers: Option<[Buffer; 2]>,
     session: zcosmic_screencopy_session_v1::ZcosmicScreencopySessionV1,
     first_frame: bool,
+    // Future signaled when buffer is signaled.
+    // if triple buffer is used, will need more than one.
+    release: Option<SubsurfaceBufferRelease>,
 }
 
 impl ScreencopySession {
@@ -54,6 +58,7 @@ impl ScreencopySession {
             buffers: None,
             session,
             first_frame: true,
+            release: None,
         }
     }
 
@@ -70,8 +75,9 @@ impl ScreencopySession {
                 .commit(zcosmic_screencopy_session_v1::Options::empty());
             self.first_frame = false;
         } else {
+            // TODO Not updating properly if `Options::OnDamage` is used
             self.session
-                .commit(zcosmic_screencopy_session_v1::Options::OnDamage);
+                .commit(zcosmic_screencopy_session_v1::Options::empty());
         }
         conn.flush().unwrap();
     }
@@ -149,11 +155,34 @@ impl ScreencopyHandler for AppData {
         session.buffers.as_mut().unwrap().rotate_left(1);
 
         // Capture again on damage
-        session.attach_buffer_and_commit(&capture, conn);
+        let capture_clone = capture.clone();
+        let conn = conn.clone();
+        let release = session.release.take();
+        self.scheduler
+            .schedule(async move {
+                if let Some(release) = release {
+                    // Wait for buffer to be released by server
+                    release.await;
+                }
+                let mut session = capture_clone.session.lock().unwrap();
+                let Some(session) = session.as_mut() else {
+                    return;
+                };
+                session.attach_buffer_and_commit(&capture_clone, &conn);
+            })
+            .unwrap();
 
         let front = session.buffers.as_mut().unwrap().first_mut().unwrap();
-        let img = unsafe { front.to_image() };
+        let (buffer, release) = SubsurfaceBuffer::new(front.backing.clone());
-        let image = CaptureImage { img };
+        session.release = Some(release);
+        // let img = unsafe { front.to_image() };
+        // let image = CaptureImage { img };
+        let buffer_info = &front.buffer_info;
+        let image = CaptureImage {
+            wl_buffer: buffer,
+            width: buffer_info.width,
+            height: buffer_info.height,
+        };
         match &capture.source {
             CaptureSource::Toplevel(toplevel) => {
                 self.send_event(Event::ToplevelCapture(toplevel.clone(), image))