1 files changed, 68 insertions, 0 deletions
diff --git a/crates/wayland/src/protocols/buffer.rs b/crates/wayland/src/protocols/buffer.rs
new file mode 100644
index 0000000..7730de6
--- /dev/null
+++ b/crates/wayland/src/protocols/buffer.rs
@@ -0,0 +1,68 @@
+//! `wl_shm`/`wl_buffer`/`zwp_linux_dmabuf_v1`: the three buffer-transport
+//! protocols, grouped together since none has more than a handful of lines
+//! on its own.
+
+use smithay::backend::allocator::dmabuf::Dmabuf;
+use smithay::backend::renderer::ImportDma;
+use smithay::reexports::wayland_server::protocol::wl_buffer::WlBuffer;
+use smithay::wayland::buffer::BufferHandler;
+use smithay::wayland::dmabuf::{DmabufGlobal, DmabufHandler, DmabufState, ImportNotifier};
+use smithay::wayland::shm::{ShmHandler, ShmState};
+
+use crate::state::CompState;
+
+impl ShmHandler for CompState {
+    fn shm_state(&self) -> &ShmState {
+        &self.shm_state
+    }
+}
+
+impl BufferHandler for CompState {
+    fn buffer_destroyed(&mut self, _buffer: &WlBuffer) {}
+}
+
+impl DmabufHandler for CompState {
+    fn dmabuf_state(&mut self) -> &mut DmabufState {
+        &mut self.dmabuf_state
+    }
+
+    /// Validates a client's dmabuf by actually importing it wherever a
+    /// renderer is reachable from here, so a genuinely bad buffer (wrong
+    /// modifier, format the renderer doesn't support) gets the protocol
+    /// error instead of silently rendering garbage later.
+    ///
+    /// That's only the udev backend: its `PixmanRenderer` lives inside
+    /// `self.udev` (`UdevState`), a field of this same struct.
+    /// `PixmanRenderer` supports dmabuf import despite being a pure
+    /// software renderer - `dmabuf_formats()` only advertises the Linear
+    /// modifier, which it imports by mmap'ing the buffer and reading it
+    /// directly as pixels, no GPU involved. This is what actually answers
+    /// `docs/PANEL_SUPPORT_TODO.md`'s P0.3: GTK4 allocates via its own
+    /// EGL/gbm path against the real DRM render node (untouched by this
+    /// compositor either way) and hands the result here as a Linear-
+    /// modifier dmabuf, which pixman can read straight off.
+    ///
+    /// The winit (nested/dev) backend's `GlesRenderer` lives on
+    /// `WaylandPlatform`, a sibling of `CompState`, not reachable from a
+    /// method on `CompState` itself. Accepted there without eager
+    /// validation - the buffer still gets imported the same way every
+    /// other buffer type already is, lazily, the first time it is actually
+    /// rendered via `render_elements_from_surface_tree`. Real hardware,
+    /// where P0.3 actually bites, always goes through the udev path.
+    fn dmabuf_imported(&mut self, _global: &DmabufGlobal, dmabuf: Dmabuf, notifier: ImportNotifier) {
+        match self.udev.as_mut() {
+            Some(udev) => match udev.renderer.import_dmabuf(&dmabuf, None) {
+                Ok(_) => {
+                    let _ = notifier.successful::<CompState>();
+                }
+                Err(e) => {
+                    log::warn!("udev: rejecting dmabuf import: {e}");
+                    notifier.failed();
+                }
+            },
+            None => {
+                let _ = notifier.successful::<CompState>();
+            }
+        }
+    }
+}