perf(blur): only damage when about to re-render

README.md

@@ -90,8 +90,9 @@ layer-rule {
 
 - True blur currently only works for horizontal monitor configurations. When using any sort of 90 or 270 degree
   transformations, only x-ray blur will be available.
-- True blur is rather performance intensive as of right now, since it renders itself on every frame. It is recommended
-  to only enable it for surfaces that don't take up a lot of screen time (e.g. notifications, dialogs).
+- True blur is rather performance intensive as of right now, since it re-renders itself on a fixed timer as opposed to
+  reacting to screen damage. It is recommended to only enable it for surfaces that don't take up a lot of screen time
+  (e.g. notifications, dialogs).
 - Blur is currently only possible to be enabled through the config. Implementing both
   [KDE blur](https://wayland.app/protocols/kde-blur) and
   [background effect](https://wayland.app/protocols/ext-background-effect-v1) is planned though.

src/render_helpers/blur/element.rs

@@ -204,7 +204,9 @@ impl Blur {
                 texture.size().w != fx_buffers.output_size().w
                     || texture.size().h != fx_buffers.output_size().h
             }
-            _ => true,
+            BlurVariant::True { rerender_at, .. } => {
+                rerender_at.borrow().is_none_or(|r| r < Instant::now())
+            }
         };
 
         let variant_needs_reconfigure = match &inner.variant {
@@ -223,8 +225,6 @@ impl Blur {
             && !variant_needs_reconfigure
         {
             if variant_needs_rerender {
-                // If we are true blur, or if our output size changed, we need to always be
-                // damaged. True blur has a separate internal timer to regulate frame rate.
                 inner.damage_all();
             }