render: force black background color for fullscreen nodes

src/backends/metal/video.rs

@@ -505,6 +505,7 @@ impl MetalConnector {
             Some(rr),
             output.global.preferred_scale.get(),
             render_hw_cursor,
+            output.has_fullscreen(),
         );
         let try_direct_scanout = try_direct_scanout
             && !output.global.have_shm_screencopies()

src/gfx_api.rs

@@ -8,7 +8,7 @@ use {
         scale::Scale,
         state::State,
         theme::Color,
-        tree::Node,
+        tree::{Node, OutputNode},
         utils::numcell::NumCell,
         video::{dmabuf::DmaBuf, gbm::GbmDevice, Modifier},
     },
@@ -211,6 +211,7 @@ impl dyn GfxFramebuffer {
         result: Option<&mut RenderResult>,
         scale: Scale,
         render_hardware_cursor: bool,
+        black_background: bool,
     ) -> GfxRenderPass {
         let mut ops = self.take_render_ops();
         let (width, height) = self.size();
@@ -251,7 +252,10 @@ impl dyn GfxFramebuffer {
                 }
             }
         }
-        let c = state.theme.colors.background.get();
+        let c = match black_background {
+            true => Color::SOLID_BLACK,
+            false => state.theme.colors.background.get(),
+        };
         GfxRenderPass {
             ops,
             clear: Some(c),
@@ -262,6 +266,26 @@ impl dyn GfxFramebuffer {
         self.render(pass.ops, pass.clear.as_ref())
     }
 
+    pub fn render_output(
+        &self,
+        node: &OutputNode,
+        state: &State,
+        cursor_rect: Option<Rect>,
+        result: Option<&mut RenderResult>,
+        scale: Scale,
+        render_hardware_cursor: bool,
+    ) {
+        self.render_node(
+            node,
+            state,
+            cursor_rect,
+            result,
+            scale,
+            render_hardware_cursor,
+            node.has_fullscreen(),
+        )
+    }
+
     pub fn render_node(
         &self,
         node: &dyn Node,
@@ -270,6 +294,7 @@ impl dyn GfxFramebuffer {
         result: Option<&mut RenderResult>,
         scale: Scale,
         render_hardware_cursor: bool,
+        black_background: bool,
     ) {
         let pass = self.create_render_pass(
             node,
@@ -278,6 +303,7 @@ impl dyn GfxFramebuffer {
             result,
             scale,
             render_hardware_cursor,
+            black_background,
         );
         self.perform_render_pass(pass);
     }

src/screenshoter.rs

@@ -75,6 +75,7 @@ pub fn take_screenshot(state: &State) -> Result<Screenshot, ScreenshooterError>
         None,
         Scale::from_int(1),
         true,
+        false,
     );
     let drm = gbm.drm.dup_render()?.fd().clone();
     Ok(Screenshot { drm, bo })

src/state.rs

@@ -743,7 +743,7 @@ impl State {
         rr: &mut RenderResult,
         render_hw_cursor: bool,
     ) {
-        fb.render_node(
+        fb.render_output(
             output,
             self,
             Some(output.global.pos.get()),
@@ -794,7 +794,7 @@ impl State {
                 }
             }
         }
-        let clear = target.format().has_alpha.then_some(&Color::TRANSPARENT);
+        let clear = target.format().has_alpha.then_some(&Color::SOLID_BLACK);
         target.render(ops, clear);
     }
 }

src/theme.rs

@@ -45,6 +45,13 @@ impl Color {
         a: 0.0,
     };
 
+    pub const SOLID_BLACK: Self = Self {
+        r: 0.0,
+        g: 0.0,
+        b: 0.0,
+        a: 1.0,
+    };
+
     pub fn from_gray(g: u8) -> Self {
         Self::from_rgb(g, g, g)
     }

src/tree/output.rs

@@ -477,6 +477,13 @@ impl OutputNode {
     fn pointer_move(self: &Rc<Self>, seat: &Rc<WlSeatGlobal>, x: i32, y: i32) {
         self.pointer_positions.set(seat.id(), (x, y));
     }
+
+    pub fn has_fullscreen(&self) -> bool {
+        self.workspace
+            .get()
+            .map(|w| w.fullscreen.get().is_some())
+            .unwrap_or(false)
+    }
 }
 
 pub struct OutputTitle {