Implement `raster` pipeline in `iced_tiny_skia`

1 files changed, 107 insertions, 0 deletions

diff --git a/tiny_skia/src/raster.rs b/tiny_skia/src/raster.rs
new file mode 100644
index 00000000..e57f0e50
--- /dev/null
+++ b/tiny_skia/src/raster.rs
@@ -0,0 +1,107 @@
+use crate::core::image as raster;
+use crate::core::{Rectangle, Size};
+use crate::graphics;
+
+use rustc_hash::{FxHashMap, FxHashSet};
+use std::cell::RefCell;
+use std::collections::hash_map;
+
+pub struct Pipeline {
+    cache: RefCell<Cache>,
+}
+
+impl Pipeline {
+    pub fn new() -> Self {
+        Self {
+            cache: RefCell::new(Cache::default()),
+        }
+    }
+
+    pub fn dimensions(&self, handle: &raster::Handle) -> Size<u32> {
+        if let Some(image) = self.cache.borrow_mut().allocate(handle) {
+            Size::new(image.width(), image.height())
+        } else {
+            Size::new(0, 0)
+        }
+    }
+
+    pub fn draw(
+        &mut self,
+        handle: &raster::Handle,
+        bounds: Rectangle,
+        pixels: &mut tiny_skia::PixmapMut<'_>,
+        transform: tiny_skia::Transform,
+        clip_mask: Option<&tiny_skia::ClipMask>,
+    ) {
+        if let Some(image) = self.cache.borrow_mut().allocate(handle) {
+            let width_scale = bounds.width / image.width() as f32;
+            let height_scale = bounds.height / image.height() as f32;
+
+            let transform = transform.pre_scale(width_scale, height_scale);
+
+            pixels.draw_pixmap(
+                (bounds.x / width_scale) as i32,
+                (bounds.y / height_scale) as i32,
+                image,
+                &tiny_skia::PixmapPaint {
+                    quality: tiny_skia::FilterQuality::Bilinear,
+                    ..Default::default()
+                },
+                transform,
+                clip_mask,
+            );
+        }
+    }
+}
+
+#[derive(Default)]
+struct Cache {
+    entries: FxHashMap<u64, Option<Entry>>,
+    hits: FxHashSet<u64>,
+}
+
+impl Cache {
+    pub fn allocate(
+        &mut self,
+        handle: &raster::Handle,
+    ) -> Option<tiny_skia::PixmapRef<'_>> {
+        let id = handle.id();
+
+        if let hash_map::Entry::Vacant(entry) = self.entries.entry(id) {
+            let image = graphics::image::load(handle).ok()?.into_rgba8();
+
+            let mut buffer =
+                vec![0u32; image.width() as usize * image.height() as usize];
+
+            for (i, pixel) in image.pixels().enumerate() {
+                let [r, g, b, a] = pixel.0;
+
+                buffer[i] = tiny_skia::ColorU8::from_rgba(b, g, r, a)
+                    .premultiply()
+                    .get();
+            }
+
+            entry.insert(Some(Entry {
+                width: image.width(),
+                height: image.height(),
+                pixels: buffer,
+            }));
+        }
+
+        self.hits.insert(id);
+        self.entries.get(&id).unwrap().as_ref().map(|entry| {
+            tiny_skia::PixmapRef::from_bytes(
+                bytemuck::cast_slice(&entry.pixels),
+                entry.width,
+                entry.height,
+            )
+            .expect("Build pixmap from image bytes")
+        })
+    }
+}
+
+struct Entry {
+    width: u32,
+    height: u32,
+    pixels: Vec<u32>,
+}