Fix fractional-scale capture sizing and release idle capture caches

compositor/src/backends/direct/capture.rs

@@ -3,12 +3,51 @@ use smithay::backend::renderer::element::RenderElement;
 use smithay::backend::renderer::gles::{GlesError, GlesRenderer, GlesTarget, GlesTexture};
 use smithay::backend::renderer::{Bind, Offscreen, Texture};
 use smithay::output::Output;
+use smithay::reexports::calloop::timer::{TimeoutAction, Timer};
 use std::fmt::Display;
+use std::time::{Duration, Instant};
 
 use crate::Ferese;
 use crate::render::{capture_output_elements, redraw_output};
 use crate::state::FrameScene;
 
+const CACHE_IDLE: Duration = Duration::from_secs(2);
+
+pub(crate) fn touch_cache(state: &mut Ferese) {
+    if state.capture_last_used.replace(Instant::now()).is_some() {
+        return;
+    }
+    if let Err(error) = state
+        .loop_handle
+        .insert_source(Timer::from_duration(CACHE_IDLE), |_, _, state| {
+            let Some(last_used) = state.capture_last_used else {
+                return TimeoutAction::Drop;
+            };
+            let idle = last_used.elapsed();
+            if idle < CACHE_IDLE {
+                return TimeoutAction::ToDuration(CACHE_IDLE - idle);
+            }
+            // A stream can pause or fail without another repaint. Release its
+            // offscreen targets and filtered-scene caches from the event loop.
+            state.capture_last_used = None;
+            state.capture_render = Default::default();
+            state.nested_capture_texture = None;
+            if let Some(backend) = state.direct_backend.as_mut() {
+                for device in backend.devices.values_mut() {
+                    for output in device.outputs.values_mut() {
+                        output.capture_texture = None;
+                        output.mirror_capture_texture = None;
+                    }
+                }
+            }
+            TimeoutAction::Drop
+        })
+    {
+        state.capture_last_used = None;
+        tracing::warn!(%error, "could not schedule capture cache cleanup");
+    }
+}
+
 pub(crate) fn capture_output(
     state: &mut Ferese,
     renderer: &mut GlesRenderer,

compositor/src/handlers/screencopy.rs

@@ -447,6 +447,15 @@ pub(crate) fn capture_region_for_geometry(
     transform: smithay::utils::Transform,
     requested: Option<Rectangle<i32, Logical>>,
 ) -> Option<Rectangle<i32, Buffer>> {
+    let buffer_bounds = Rectangle::from_size(Size::<i32, Buffer>::from((mode_size.w, mode_size.h)));
+    if mode_size.w <= 0 || mode_size.h <= 0 {
+        return None;
+    }
+    // Full-output captures must match the framebuffer exactly. Rounding the
+    // logical size and scaling it back can add a pixel at fractional scales.
+    if requested.is_none() {
+        return Some(buffer_bounds);
+    }
     let logical_size = output_logical_size(mode_size, scale, transform);
     let output_region = Rectangle::from_size(logical_size);
     let logical_region = requested.unwrap_or(output_region).intersection(output_region)?;
@@ -455,12 +464,11 @@ pub(crate) fn capture_region_for_geometry(
         return None;
     }
 
-    Some(
     logical_region
         .to_f64()
         .to_buffer(scale, transform, &logical_size.to_f64())
-            .to_i32_round(),
-    )
+        .to_i32_round()
+        .intersection(buffer_bounds)
 }
 
 pub(super) fn valid_shm_buffer(buffer: &WlBuffer, expected: Size<i32, Buffer>) -> bool {

compositor/src/render/scene.rs

@@ -44,6 +44,7 @@ pub(crate) fn capture_output_elements(
 ) -> Vec<AnimatedWindowRenderElement> {
     // Blur textures and resize handoff snapshots must never be shared with
     // display rendering. Only the capture scene can populate these caches.
+    crate::backends::direct::capture::touch_cache(state);
     std::mem::swap(&mut state.render, &mut state.capture_render);
     let elements = scene_elements(state, renderer, output, include_cursor, frame, true);
     std::mem::swap(&mut state.render, &mut state.capture_render);

compositor/src/state.rs

@@ -440,6 +440,8 @@ pub struct Ferese {
     pub(crate) windows: WindowRegistry<Window>,
     pub(crate) render: crate::render::RenderResources,
     pub(crate) capture_render: crate::render::RenderResources,
+    pub(crate) capture_last_used: Option<Instant>,
+    pub(crate) nested_capture_texture: Option<smithay::backend::renderer::gles::GlesTexture>,
     pub(crate) capture_epoch: u64,
     capture_protected_windows: HashSet<WindowId>,
     capture_protected_cursor: Option<WlSurface>,
@@ -742,6 +744,8 @@ impl Ferese {
             windows: WindowRegistry::default(),
             render: Default::default(),
             capture_render: Default::default(),
+            capture_last_used: None,
+            nested_capture_texture: None,
             capture_epoch: 0,
             capture_protected_windows: HashSet::new(),
             capture_protected_cursor: None,

compositor/src/winit.rs

@@ -94,7 +94,6 @@ pub fn init(event_loop: &mut EventLoop<Ferese>, state: &mut Ferese) -> Result<()
             }
         })?;
 
-    let mut capture_texture = None;
     event_loop
         .handle()
         .insert_source(event_source, move |event, _, state| {
@@ -157,6 +156,7 @@ pub fn init(event_loop: &mut EventLoop<Ferese>, state: &mut Ferese) -> Result<()
                                         || state.has_pending_screencopy(&output, true)
                                     {
                                         let scene = state.sample_frame(&output, Duration::ZERO);
+                                        let mut capture_texture = state.nested_capture_texture.take();
                                         crate::backends::direct::capture::capture_output(
                                             state,
                                             renderer,
@@ -164,6 +164,7 @@ pub fn init(event_loop: &mut EventLoop<Ferese>, state: &mut Ferese) -> Result<()
                                             &output,
                                             &scene,
                                         );
+                                        state.nested_capture_texture = capture_texture;
                                         changed = true;
                                     }