fix: prevent edge darkening on GPU-blurred wallpaper (v0.5.3)

GskBlurNode samples pixels outside texture bounds as transparent,
causing visible darkening at wallpaper edges. Fix renders the texture
with 3x-sigma padding before blur, then clips back to original size.
Symmetric fix with moonset v0.7.1.

Cargo.lock

@@ -569,7 +569,7 @@ dependencies = [
 
 [[package]]
 name = "moongreet"
-version = "0.5.2"
+version = "0.5.3"
 dependencies = [
  "gdk-pixbuf",
  "gdk4",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "moongreet"
-version = "0.5.2"
+version = "0.5.3"
 edition = "2024"
 description = "A greetd greeter for Wayland with GTK4 and Layer Shell"
 license = "MIT"

src/greeter.rs

@@ -119,6 +119,10 @@ pub fn load_background_texture(bg_path: &Path) -> Option<gdk::Texture> {
 // -- GPU blur via GskBlurNode -------------------------------------------------
 
 /// Render a blurred texture using the GPU via GskBlurNode.
+///
+/// To avoid edge darkening (blur samples transparent pixels outside bounds),
+/// the texture is rendered with padding equal to 3x the blur sigma. The blur
+/// is applied to the padded area, then cropped back to the original size.
 fn render_blurred_texture(
     widget: &impl IsA<gtk::Widget>,
     texture: &gdk::Texture,
@@ -126,15 +130,24 @@ fn render_blurred_texture(
 ) -> Option<gdk::Texture> {
     let native = widget.native()?;
     let renderer = native.renderer()?;
+
+    let w = texture.width() as f32;
+    let h = texture.height() as f32;
+    // Padding must cover the blur kernel radius (typically ~3x sigma)
+    let pad = (sigma * 3.0).ceil();
+
     let snapshot = gtk::Snapshot::new();
-    let bounds = graphene_rs::Rect::new(
-        0.0, 0.0, texture.width() as f32, texture.height() as f32,
-    );
+    // Clip output to original texture size
+    snapshot.push_clip(&graphene_rs::Rect::new(pad, pad, w, h));
     snapshot.push_blur(sigma as f64);
-    snapshot.append_texture(texture, &bounds);
-    snapshot.pop();
+    // Render texture with padding on all sides (edges repeat via oversized bounds)
+    snapshot.append_texture(texture, &graphene_rs::Rect::new(0.0, 0.0, w + 2.0 * pad, h + 2.0 * pad));
+    snapshot.pop(); // blur
+    snapshot.pop(); // clip
+
     let node = snapshot.to_node()?;
-    Some(renderer.render_texture(&node, None))
+    let viewport = graphene_rs::Rect::new(pad, pad, w, h);
+    Some(renderer.render_texture(&node, Some(&viewport)))
 }
 
 /// Create a wallpaper-only window for secondary monitors.