screencopy: Accumulate buffer damage

src/backend/wayland/buffer.rs

@@ -1,5 +1,5 @@
 use cctk::{
-    screencopy::Formats,
+    screencopy::{Formats, Rect},
     wayland_client::{
         Connection, Dispatch, QueueHandle,
         protocol::{wl_buffer, wl_shm, wl_shm_pool},
@@ -20,6 +20,7 @@ use crate::utils;
 pub struct Buffer {
     pub backing: Arc<BufferSource>,
     pub buffer: wl_buffer::WlBuffer,
+    pub buffer_damage: Vec<Rect>,
     pub size: (u32, u32),
     #[cfg(feature = "no-subsurfaces")]
     pub mmap: memmap2::Mmap,
@@ -52,6 +53,13 @@ impl AppData {
         #[cfg(feature = "no-subsurfaces")]
         let mmap = unsafe { memmap2::Mmap::map(&fd).unwrap() };
 
+        let full_damage = vec![Rect {
+            x: 0,
+            y: 0,
+            width: width as i32,
+            height: height as i32,
+        }];
+
         Buffer {
             backing: Arc::new(
                 Shmbuf {
@@ -65,6 +73,7 @@ impl AppData {
                 .into(),
             ),
             buffer,
+            buffer_damage: full_damage,
             #[cfg(feature = "no-subsurfaces")]
             mmap,
             size: (width, height),
@@ -148,6 +157,13 @@ impl AppData {
             )
             .0;
 
+        let full_damage = vec![Rect {
+            x: 0,
+            y: 0,
+            width: width as i32,
+            height: height as i32,
+        }];
+
         Ok(Some(Buffer {
             backing: Arc::new(
                 Dmabuf {
@@ -160,6 +176,7 @@ impl AppData {
                 .into(),
             ),
             buffer,
+            buffer_damage: full_damage,
             size: (width, height),
         }))
     }

src/backend/wayland/screencopy.rs

@@ -19,10 +19,13 @@ use std::{
 
 use super::{AppData, Buffer, Capture, CaptureImage, Event};
 
+// Number of buffers to swap between
+const BUFFER_COUNT: usize = 2;
+
 pub struct ScreencopySession {
     formats: Option<Formats>,
     // swapchain buffers
-    buffers: Option<[Buffer; 2]>,
+    buffers: Option<[Buffer; BUFFER_COUNT]>,
     session: CaptureSession,
     // Future signaled when buffer is signaled.
     // if triple buffer is used, will need more than one.
@@ -66,18 +69,9 @@ impl ScreencopySession {
         // TODO
         // let node = back.node().and_then(|x| x.to_str().map(|x| x.to_string()));
 
-        // TODO: accumulate damage
-        let (width, height) = back.size;
-        let full_damage = &[Rect {
-            x: 0,
-            y: 0,
-            width: width as i32,
-            height: height as i32,
-        }];
-
         self.session.capture(
             &back.buffer,
-            full_damage,
+            &back.buffer_damage,
             qh,
             FrameData {
                 frame_data: Default::default(),
@@ -182,7 +176,13 @@ impl ScreencopyHandler for AppData {
             session.attach_buffer_and_commit(&capture_clone, &conn, &qh);
         });
 
-        let front = session.buffers.as_mut().unwrap().first_mut().unwrap();
+        // Clear `buffer_damage` for front buffer; accumulate for other buffers.
+        session.buffers.as_mut().unwrap()[0].buffer_damage.clear();
+        for buffer in &mut session.buffers.as_mut().unwrap()[1..] {
+            buffer.buffer_damage.extend_from_slice(&frame.damage);
+        }
+
+        let front = &session.buffers.as_ref().unwrap()[0];
         let (buffer, release) = SubsurfaceBuffer::new(front.backing.clone());
         session.release = Some(release);
         let image = CaptureImage {