Align corner clipping, antialiasing, and fractional material regions

compositor/src/render/decorations.rs

@@ -32,11 +32,22 @@ pub(super) fn rounded_clip_program(state: &mut Ferese, renderer: &mut GlesRender
     let texture = renderer.compile_custom_texture_shader(&corner_shader(ROUNDED_TEXTURE_SHADER), &texture_uniforms);
     let border = renderer.compile_custom_pixel_shader(&corner_shader(ROUNDED_BORDER_SHADER), &border_uniforms);
     let shadow = renderer.compile_custom_pixel_shader(&corner_shader(WINDOW_SHADOW_SHADER), &shadow_uniforms);
-    let compiled = texture.and_then(|texture| border.and_then(|border| shadow.map(|shadow| (texture, border, shadow))));
+    let solid = renderer.compile_custom_pixel_shader(
+        &corner_shader(ROUNDED_SOLID_SHADER),
+        &[
+            UniformName::new("clip_rect", UniformType::_4f),
+            UniformName::new("radius", UniformType::_1f),
+            UniformName::new("color", UniformType::_4f),
+        ],
+    );
+    let compiled = texture.and_then(|texture| {
+        border.and_then(|border| shadow.and_then(|shadow| solid.map(|solid| (texture, border, shadow, solid))))
+    });
     match compiled {
-        Ok((texture, border, shadow)) => {
+        Ok((texture, border, shadow, solid)) => {
             let programs = RoundedClipPrograms {
                 texture,
+                solid,
                 border,
                 shadow,
             };
@@ -343,7 +354,7 @@ pub(super) fn rounded_window_elements(
     alpha: f32,
     clip_changed: bool,
     output: &Output,
-    program: GlesTexProgram,
+    programs: RoundedClipPrograms,
     behavior: ConstrainScaleBehavior,
 ) -> Vec<AnimatedWindowRenderElement> {
     let Some(toplevel) = window.toplevel() else {
@@ -390,7 +401,7 @@ pub(super) fn rounded_window_elements(
         .map(|inner| {
             RoundedSurfaceRenderElement {
                 inner,
-                program: program.clone(),
+                programs: programs.clone(),
                 clip_rect: clip,
                 radius,
                 clip_changed,

compositor/src/render/materials.rs

@@ -20,23 +20,12 @@ pub(super) fn append_material_surface(
         };
     let regions = crate::effects::surface_regions(surface);
     let targets: Vec<_> = match &regions {
-        None => vec![(geometry, radius as f32)],
+        None => vec![(geometry, RoundedRect::from_logical(geometry, scale, radius))],
         Some(regions) => regions
             .iter()
-            .filter_map(|r| {
-                Rectangle::new(
-                    (content_origin.x + r[0], content_origin.y + r[1]).into(),
-                    (r[2], r[3]).into(),
-                )
-                .intersection(geometry)
-                .map(|rect| (rect, r[4] as f32))
-            })
+            .filter_map(|r| material_region_geometry(*r, geometry, content_origin, scale))
             .collect(),
     };
-    let targets: Vec<_> = targets
-        .into_iter()
-        .map(|(rect, radius)| (rect, RoundedRect::from_logical(rect, scale, f64::from(radius))))
-        .collect();
     let materials: Vec<_> = targets
         .iter()
         .enumerate()
@@ -65,7 +54,7 @@ pub(super) fn append_material_surface(
         let mode = output.current_mode()?;
         let program = rounded_clip_program(state, renderer)?;
         Some((
-            program.texture,
+            program,
             framebuffer_clip_rect(corners.rect, mode.size, output.current_transform().invert()),
             corners.radius,
         ))
@@ -84,7 +73,7 @@ pub(super) fn append_material_surface(
         let element = if let Some((program, clip_rect, radius)) = &clip {
             WindowContentRenderElement::Rounded(RoundedSurfaceRenderElement {
                 inner: element,
-                program: program.clone(),
+                programs: program.clone(),
                 clip_rect: *clip_rect,
                 radius: *radius,
                 clip_changed: false,
@@ -102,6 +91,27 @@ pub(super) fn append_material_surface(
     }
 }
 
+/// Preserve the surface-local fractional edges until the shared physical snap.
+fn material_region_geometry(
+    region: [f64; 5],
+    geometry: Rectangle<i32, Logical>,
+    origin: Point<i32, Logical>,
+    scale: f64,
+) -> Option<(Rectangle<i32, Logical>, RoundedRect)> {
+    let rect = Rectangle::<f64, Logical>::new(
+        (f64::from(origin.x) + region[0], f64::from(origin.y) + region[1]).into(),
+        (region[2], region[3]).into(),
+    )
+    .intersection(geometry.to_f64())?;
+    let corners = RoundedRect::new(
+        ferese_layout::Rect::new(rect.loc.x, rect.loc.y, rect.size.w, rect.size.h),
+        (0, 0).into(),
+        scale,
+        region[4],
+    );
+    Some((rect.to_i32_up(), corners))
+}
+
 pub(super) struct MaterialSurface {
     pub geometry: Rectangle<i32, Logical>,
     pub corners: RoundedRect,
@@ -424,3 +434,22 @@ pub(super) fn blur_damage(
         DamageSet::from_slice(&[Rectangle::from_size((size.w, size.h).into())])
     }
 }
+
+#[cfg(test)]
+mod region_geometry_tests {
+    use super::*;
+
+    #[test]
+    fn fractional_regions_snap_once_in_output_pixels() {
+        let bounds = Rectangle::from_size((200, 100).into());
+        let (_, corners) = material_region_geometry([0.4, 0.4, 100.4, 40.4, 14.0], bounds, (0, 0).into(), 1.5).unwrap();
+        assert_eq!(corners.rect, Rectangle::new((1, 1).into(), (150, 60).into()));
+        assert_eq!(corners.radius, 21.0);
+        // The old logical rounding would put this at physical (0, 0).
+        let (_, clipped) =
+            material_region_geometry([-0.4, -0.4, 100.4, 40.4, 100.0], bounds, (0, 0).into(), 1.5).unwrap();
+        assert_eq!(clipped.rect, Rectangle::from_size((150, 60).into()));
+        assert_eq!(clipped.radius, 30.0);
+        assert!(material_region_geometry([300.0, 0.0, 10.0, 10.0, 2.0], bounds, (0, 0).into(), 1.5).is_none());
+    }
+}

compositor/src/render/mod.rs

@@ -96,6 +96,8 @@ render_elements! {
 
 const ROUNDED_TEXTURE_SHADER: &str = include_str!("shaders/rounded_texture_shader.frag");
 
+const ROUNDED_SOLID_SHADER: &str = include_str!("shaders/rounded_solid_shader.frag");
+
 const ROUNDED_BORDER_SHADER: &str = include_str!("shaders/rounded_border_shader.frag");
 
 const WINDOW_SHADOW_SHADER: &str = include_str!("shaders/window_shadow_shader.frag");
@@ -280,6 +282,7 @@ impl RenderElement<GlesRenderer> for BlurRenderElement {
 
 #[derive(Clone, Debug)]
 pub(crate) struct RoundedClipPrograms {
+    solid: GlesPixelProgram,
     texture: GlesTexProgram,
     border: GlesPixelProgram,
     shadow: GlesPixelProgram,
@@ -390,7 +393,7 @@ pub(crate) struct WindowShadowBuffers {
 #[derive(Debug)]
 struct RoundedSurfaceRenderElement {
     inner: WaylandSurfaceRenderElement<GlesRenderer>,
-    program: GlesTexProgram,
+    programs: RoundedClipPrograms,
     clip_rect: [f32; 4],
     radius: f32,
     clip_changed: bool,
@@ -459,13 +462,25 @@ impl RenderElement<GlesRenderer> for RoundedSurfaceRenderElement {
                 opaque_regions,
                 self.transform(),
                 self.alpha(),
-                Some(&self.program),
+                Some(&self.programs.texture),
                 &[
                     Uniform::new("clip_rect", self.clip_rect),
                     Uniform::new("radius", self.radius),
                 ],
             ),
-            WaylandSurfaceTexture::SolidColor(_) => self.inner.draw(frame, src, dst, damage, opaque_regions),
+            WaylandSurfaceTexture::SolidColor(color) => frame.render_pixel_shader_to(
+                &self.programs.solid,
+                src,
+                dst,
+                (dst.size.w, dst.size.h).into(),
+                Some(damage),
+                self.alpha(),
+                &[
+                    Uniform::new("clip_rect", self.clip_rect),
+                    Uniform::new("radius", self.radius),
+                    Uniform::new("color", color.components()),
+                ],
+            ),
         }
     }
 
@@ -514,6 +529,65 @@ mod tests {
         scaled_visual_rect, shadow_bounds,
     };
 
+    #[test]
+    #[ignore = "requires an EGL rendering device"]
+    fn solid_corner_mask_preserves_premultiplied_color() {
+        use smithay::backend::allocator::Fourcc;
+        use smithay::backend::egl::{EGLContext, EGLDevice, EGLDisplay};
+        use smithay::backend::renderer::gles::{GlesRenderer, GlesTexture, Uniform, UniformName, UniformType};
+        use smithay::backend::renderer::{Bind, Color32F, ExportMem, Frame, Offscreen, Renderer};
+        let device = EGLDevice::enumerate().unwrap().last().expect("an EGL device");
+        let display = unsafe { EGLDisplay::new(device).unwrap() };
+        let context = EGLContext::new(&display).unwrap();
+        let mut renderer = unsafe { GlesRenderer::new(context).unwrap() };
+        let program = renderer
+            .compile_custom_pixel_shader(
+                &super::corner_shader(super::ROUNDED_SOLID_SHADER),
+                &[
+                    UniformName::new("clip_rect", UniformType::_4f),
+                    UniformName::new("radius", UniformType::_1f),
+                    UniformName::new("color", UniformType::_4f),
+                ],
+            )
+            .unwrap();
+        let size = (32, 32).into();
+        let mut texture: GlesTexture = renderer.create_buffer(Fourcc::Abgr8888, size).unwrap();
+        let rect = Rectangle::<i32, Physical>::from_size((32, 32).into());
+        for (radius, corner_alpha, inset) in [(12.0f32, 0u8, 0.0f32), (0.0, 64, 0.0), (0.0, 48, 0.25)] {
+            let mut target = renderer.bind(&mut texture).unwrap();
+            {
+                let mut frame = renderer
+                    .render(&mut target, (32, 32).into(), Transform::Normal)
+                    .unwrap();
+                frame.clear(Color32F::TRANSPARENT, &[rect]).unwrap();
+                frame
+                    .render_pixel_shader_to(
+                        &program,
+                        Rectangle::from_size(size.to_f64()),
+                        rect,
+                        size,
+                        Some(&[rect]),
+                        0.5,
+                        &[
+                            Uniform::new("clip_rect", [inset, inset, 32.0 - 2.0 * inset, 32.0 - 2.0 * inset]),
+                            Uniform::new("radius", radius),
+                            Uniform::new("color", [0.5f32, 0.0, 0.0, 0.5]),
+                        ],
+                    )
+                    .unwrap();
+                let _ = frame.finish().unwrap();
+            }
+            let mapping = renderer
+                .copy_framebuffer(&target, Rectangle::from_size(size), Fourcc::Abgr8888)
+                .unwrap();
+            let pixels = renderer.map_texture(&mapping).unwrap();
+            let center = (16 * 32 + 16) * 4;
+            assert!(pixels[center].abs_diff(64) <= 1);
+            assert!(pixels[center + 3].abs_diff(64) <= 1);
+            assert!(pixels[3].abs_diff(corner_alpha) <= 1);
+        }
+    }
+
     #[test]
     #[ignore = "requires an EGL rendering device"]
     fn shared_corner_shaders_compile() {
@@ -529,6 +603,7 @@ mod tests {
                 .unwrap();
         }
         for source in [
+            super::ROUNDED_SOLID_SHADER,
             super::ROUNDED_BORDER_SHADER,
             super::WINDOW_SHADOW_SHADER,
             super::MATERIAL_SHADER,

compositor/src/render/overview.rs

@@ -228,7 +228,7 @@ pub(super) fn overview_strip_elements(
                         alpha,
                         true,
                         output,
-                        programs.texture.clone(),
+                        programs.clone(),
                         ConstrainScaleBehavior::Stretch,
                     ));
                 }

compositor/src/render/scene.rs

@@ -265,7 +265,7 @@ pub(crate) fn output_elements(
                     .get(&id)
                     .is_some_and(|geometry| geometry.presentation_changed),
                 output,
-                programs.texture.clone(),
+                programs.clone(),
                 behavior,
             ));
             let source = window.geometry().size;

compositor/src/render/shaders/corners.glsl

@@ -6,5 +6,6 @@ float rounded_rect_distance(vec2 point, vec4 rect, float radius) {
 }
 
 float edge_coverage(float distance) {
-    return 1.0 - smoothstep(-0.5, 0.5, distance);
+    // Match Iced/WGPU quad edges: a one-physical-pixel linear ramp.
+    return clamp(0.5 - distance, 0.0, 1.0);
 }

compositor/src/render/shaders/rounded_solid_shader.frag

@@ -0,0 +1,13 @@
+precision highp float;
+uniform float alpha;
+uniform vec4 clip_rect;
+uniform float radius;
+uniform vec4 color;
+
+//_CORNERS_
+
+void main() {
+    float distance = rounded_rect_distance(gl_FragCoord.xy, clip_rect, radius);
+    // Single-pixel buffer colors are already premultiplied.
+    gl_FragColor = color * alpha * edge_coverage(distance);
+}