Move damage tracking logic to `compositor` in `iced_tiny_skia`

2 files changed, 42 insertions, 92 deletions

diff --git a/tiny_skia/src/backend.rs b/tiny_skia/src/backend.rs
index 16a7f9b8..9c69e1d2 100644
--- a/tiny_skia/src/backend.rs
+++ b/tiny_skia/src/backend.rs
@@ -16,10 +16,6 @@ pub struct Backend {
 
     #[cfg(feature = "svg")]
     vector_pipeline: crate::vector::Pipeline,
-
-    last_primitives: Vec<Primitive>,
-    last_background_color: Color,
-    last_size: Size<u32>,
 }
 
 impl Backend {
@@ -34,10 +30,6 @@ impl Backend {
 
             #[cfg(feature = "svg")]
             vector_pipeline: crate::vector::Pipeline::new(),
-
-            last_primitives: Vec::new(),
-            last_background_color: Color::BLACK,
-            last_size: Size::new(0, 0),
         }
     }
 
@@ -47,31 +39,13 @@ impl Backend {
         clip_mask: &mut tiny_skia::Mask,
         primitives: &[Primitive],
         viewport: &Viewport,
+        damage: &[Rectangle],
         background_color: Color,
         overlay: &[T],
-    ) -> bool {
+    ) {
         let physical_size = viewport.physical_size();
-
-        let damage = if self.last_background_color == background_color
-            && self.last_size == physical_size
-        {
-            Primitive::damage_list(&self.last_primitives, primitives)
-        } else {
-            vec![Rectangle::with_size(viewport.logical_size())]
-        };
-
-        if damage.is_empty() {
-            return false;
-        }
-
-        self.last_primitives = primitives.to_vec();
-        self.last_background_color = background_color;
-        self.last_size = physical_size;
-
         let scale_factor = viewport.scale_factor() as f32;
 
-        let damage = group_damage(damage, scale_factor, physical_size);
-
         if !overlay.is_empty() {
             let path = tiny_skia::PathBuilder::from_rect(
                 tiny_skia::Rect::from_xywh(
@@ -99,7 +73,7 @@ impl Backend {
             );
         }
 
-        for region in damage {
+        for &region in damage {
             let path = tiny_skia::PathBuilder::from_rect(
                 tiny_skia::Rect::from_xywh(
                     region.x,
@@ -164,8 +138,6 @@ impl Backend {
 
         #[cfg(feature = "svg")]
         self.vector_pipeline.trim_cache();
-
-        true
     }
 
     fn draw_primitive(
@@ -629,52 +601,6 @@ fn adjust_clip_mask(clip_mask: &mut tiny_skia::Mask, bounds: Rectangle) {
     );
 }
 
-fn group_damage(
-    mut damage: Vec<Rectangle>,
-    scale_factor: f32,
-    bounds: Size<u32>,
-) -> Vec<Rectangle> {
-    use std::cmp::Ordering;
-
-    const AREA_THRESHOLD: f32 = 20_000.0;
-
-    let bounds = Rectangle {
-        x: 0.0,
-        y: 0.0,
-        width: bounds.width as f32,
-        height: bounds.height as f32,
-    };
-
-    damage.sort_by(|a, b| {
-        a.x.partial_cmp(&b.x)
-            .unwrap_or(Ordering::Equal)
-            .then_with(|| a.y.partial_cmp(&b.y).unwrap_or(Ordering::Equal))
-    });
-
-    let mut output = Vec::new();
-    let mut scaled = damage
-        .into_iter()
-        .filter_map(|region| (region * scale_factor).intersection(&bounds))
-        .filter(|region| region.width >= 1.0 && region.height >= 1.0);
-
-    if let Some(mut current) = scaled.next() {
-        for region in scaled {
-            let union = current.union(&region);
-
-            if union.area() - current.area() - region.area() <= AREA_THRESHOLD {
-                current = union;
-            } else {
-                output.push(current);
-                current = region;
-            }
-        }
-
-        output.push(current);
-    }
-
-    output
-}
-
 impl iced_graphics::Backend for Backend {
     fn trim_measurements(&mut self) {
         self.text_pipeline.trim_measurement_cache();
diff --git a/tiny_skia/src/window/compositor.rs b/tiny_skia/src/window/compositor.rs
index 7523e06f..d3dffb18 100644
--- a/tiny_skia/src/window/compositor.rs
+++ b/tiny_skia/src/window/compositor.rs
@@ -1,5 +1,6 @@
-use crate::core::Color;
+use crate::core::{Color, Rectangle};
 use crate::graphics::compositor::{self, Information, SurfaceError};
+use crate::graphics::damage;
 use crate::graphics::{Error, Primitive, Viewport};
 use crate::{Backend, Renderer, Settings};
 
@@ -14,6 +15,8 @@ pub struct Surface {
     window: softbuffer::GraphicsContext,
     buffer: Vec<u32>,
     clip_mask: tiny_skia::Mask,
+    last_primitives: Vec<Primitive>,
+    last_background_color: Color,
 }
 
 impl<Theme> crate::graphics::Compositor for Compositor<Theme> {
@@ -45,6 +48,8 @@ impl<Theme> crate::graphics::Compositor for Compositor<Theme> {
             buffer: vec![0; width as usize * height as usize],
             clip_mask: tiny_skia::Mask::new(width, height)
                 .expect("Create clip mask"),
+            last_primitives: Vec::new(),
+            last_background_color: Color::BLACK,
         }
     }
 
@@ -57,6 +62,8 @@ impl<Theme> crate::graphics::Compositor for Compositor<Theme> {
         surface.buffer.resize((width * height) as usize, 0);
         surface.clip_mask =
             tiny_skia::Mask::new(width, height).expect("Create clip mask");
+
+        surface.last_primitives.clear();
     }
 
     fn fetch_information(&self) -> Information {
@@ -105,28 +112,45 @@ pub fn present<T: AsRef<str>>(
     overlay: &[T],
 ) -> Result<(), compositor::SurfaceError> {
     let physical_size = viewport.physical_size();
+    let scale_factor = viewport.scale_factor() as f32;
+
+    let mut pixels = &mut tiny_skia::PixmapMut::from_bytes(
+        bytemuck::cast_slice_mut(&mut surface.buffer),
+        physical_size.width,
+        physical_size.height,
+    )
+    .expect("Create pixel map");
+
+    let damage = if surface.last_background_color == background_color {
+        damage::list(&surface.last_primitives, primitives)
+    } else {
+        vec![Rectangle::with_size(viewport.logical_size())]
+    };
+
+    if damage.is_empty() {
+        return Ok(());
+    }
+
+    surface.last_primitives = primitives.to_vec();
+    surface.last_background_color = background_color;
+
+    let damage = damage::group(damage, scale_factor, physical_size);
 
-    let drawn = backend.draw(
-        &mut tiny_skia::PixmapMut::from_bytes(
-            bytemuck::cast_slice_mut(&mut surface.buffer),
-            physical_size.width,
-            physical_size.height,
-        )
-        .expect("Create pixel map"),
+    backend.draw(
+        &mut pixels,
         &mut surface.clip_mask,
         primitives,
         viewport,
+        &damage,
         background_color,
         overlay,
     );
 
-    if drawn {
-        surface.window.set_buffer(
-            &surface.buffer,
-            physical_size.width as u16,
-            physical_size.height as u16,
-        );
-    }
+    surface.window.set_buffer(
+        &surface.buffer,
+        physical_size.width as u16,
+        physical_size.height as u16,
+    );
 
     Ok(())
 }