2 files changed, 63 insertions, 0 deletions
diff --git a/src/ui/mod.rs b/src/ui/mod.rs
index a63c6f03..b546bda5 100644
--- a/src/ui/mod.rs
+++ b/src/ui/mod.rs
@@ -1,4 +1,5 @@
 pub mod config_error_notification;
 pub mod exit_confirm_dialog;
 pub mod hotkey_overlay;
+pub mod screen_transition;
 pub mod screenshot_ui;
diff --git a/src/ui/screen_transition.rs b/src/ui/screen_transition.rs
new file mode 100644
index 00000000..0bc10c39
--- /dev/null
+++ b/src/ui/screen_transition.rs
@@ -0,0 +1,62 @@
+use std::time::Duration;
+
+use smithay::backend::renderer::element::texture::{TextureBuffer, TextureRenderElement};
+use smithay::backend::renderer::element::Kind;
+use smithay::backend::renderer::gles::GlesTexture;
+
+use crate::render_helpers::primary_gpu_texture::PrimaryGpuTextureRenderElement;
+use crate::render_helpers::RenderTarget;
+
+pub const DELAY: Duration = Duration::from_millis(250);
+pub const DURATION: Duration = Duration::from_millis(500);
+
+#[derive(Debug)]
+pub struct ScreenTransition {
+    /// Texture to crossfade from for each render target.
+    from_texture: [TextureBuffer<GlesTexture>; 3],
+    /// Monotonic time when to start the crossfade.
+    start_at: Duration,
+    /// Current crossfade alpha.
+    alpha: f32,
+}
+
+impl ScreenTransition {
+    pub fn new(from_texture: [TextureBuffer<GlesTexture>; 3], start_at: Duration) -> Self {
+        Self {
+            from_texture,
+            start_at,
+            alpha: 1.,
+        }
+    }
+
+    pub fn advance_animations(&mut self, current_time: Duration) {
+        if self.start_at + DURATION <= current_time {
+            self.alpha = 0.;
+        } else if self.start_at <= current_time {
+            self.alpha = 1. - (current_time - self.start_at).as_secs_f32() / DURATION.as_secs_f32();
+        } else {
+            self.alpha = 1.;
+        }
+    }
+
+    pub fn is_done(&self) -> bool {
+        self.alpha == 0.
+    }
+
+    pub fn render(&self, target: RenderTarget) -> PrimaryGpuTextureRenderElement {
+        let idx = match target {
+            RenderTarget::Output => 0,
+            RenderTarget::Screencast => 1,
+            RenderTarget::ScreenCapture => 2,
+        };
+
+        PrimaryGpuTextureRenderElement(TextureRenderElement::from_texture_buffer(
+            (0., 0.),
+            &self.from_texture[idx],
+            Some(self.alpha),
+            None,
+            None,
+            Kind::Unspecified,
+        ))
+    }
+}