Public encoding API

shader/fine.wgsl

@@ -138,7 +138,7 @@ fn fill_path(tile: Tile, xy: vec2<f32>) -> array<f32, PIXELS_PER_THREAD> {
     }
     // nonzero winding rule
     for (var i = 0u; i < PIXELS_PER_THREAD; i += 1u) {
-        area[i] = abs(area[i]);
+        area[i] = min(abs(area[i]), 1.0);
     }
     return area;
 }

src/encoding.rs

@@ -0,0 +1,36 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Also licensed under MIT license, at your choice.
+
+//! Raw scene encoding.
+
+mod draw;
+mod encoding;
+mod math;
+mod monoid;
+mod packed;
+mod path;
+
+pub mod resource;
+
+pub use draw::{
+    DrawBeginClip, DrawColor, DrawImage, DrawLinearGradient, DrawMonoid, DrawRadialGradient,
+    DrawTag,
+};
+pub use encoding::Encoding;
+pub use math::Transform;
+pub use monoid::Monoid;
+pub use packed::{Config, Layout, PackedEncoding};
+pub use path::{PathBbox, PathEncoder, PathMonoid, PathSegment, PathSegmentType, PathTag};

src/encoding/draw.rs

@@ -0,0 +1,164 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Also licensed under MIT license, at your choice.
+
+use bytemuck::{Pod, Zeroable};
+use peniko::{BlendMode, Color};
+
+use super::Monoid;
+
+/// Draw tag representation.
+#[derive(Copy, Clone, PartialEq, Eq, Pod, Zeroable)]
+#[repr(C)]
+pub struct DrawTag(pub u32);
+
+impl DrawTag {
+    /// No operation.
+    pub const NOP: Self = Self(0);
+
+    /// Color fill.
+    pub const COLOR: Self = Self(0x44);
+
+    /// Linear gradient fill.
+    pub const LINEAR_GRADIENT: Self = Self(0x114);
+
+    /// Radial gradient fill.
+    pub const RADIAL_GRADIENT: Self = Self(0x2dc);
+
+    /// Image fill.
+    pub const IMAGE: Self = Self(0x48);
+
+    /// Begin layer/clip.
+    pub const BEGIN_CLIP: Self = Self(0x9);
+
+    /// End layer/clip.
+    pub const END_CLIP: Self = Self(0x21);
+}
+
+impl DrawTag {
+    /// Returns the size of the info buffer used by this tag.
+    pub fn info_size(self) -> u32 {
+        (self.0 >> 6) & 0xf
+    }
+}
+
+/// Draw data for a solid color.
+#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
+#[repr(C)]
+pub struct DrawColor {
+    /// Packed RGBA color.
+    pub rgba: u32,
+}
+
+impl DrawColor {
+    /// Creates new solid color draw data.
+    pub fn new(color: Color) -> Self {
+        Self {
+            rgba: color.to_premul_u32(),
+        }
+    }
+}
+
+/// Draw data for a linear gradient.
+#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
+#[repr(C)]
+pub struct DrawLinearGradient {
+    /// Ramp index.
+    pub index: u32,
+    /// Start point.
+    pub p0: [f32; 2],
+    /// End point.
+    pub p1: [f32; 2],
+}
+
+/// Draw data for a radial gradient.
+#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
+#[repr(C)]
+pub struct DrawRadialGradient {
+    /// Ramp index.
+    pub index: u32,
+    /// Start point.
+    pub p0: [f32; 2],
+    /// End point.
+    pub p1: [f32; 2],
+    /// Start radius.
+    pub r0: f32,
+    /// End radius.
+    pub r1: f32,
+}
+
+/// Draw data for an image.
+#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
+#[repr(C)]
+pub struct DrawImage {
+    /// Image index.
+    pub index: u32,
+    /// Packed image offset.
+    pub offset: u32,
+}
+
+/// Draw data for a clip or layer.
+#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
+#[repr(C)]
+pub struct DrawBeginClip {
+    /// Blend mode.
+    pub blend_mode: u32,
+    /// Group alpha.
+    pub alpha: f32,
+}
+
+impl DrawBeginClip {
+    /// Creates new clip draw data.
+    pub fn new(blend_mode: BlendMode, alpha: f32) -> Self {
+        Self {
+            blend_mode: (blend_mode.mix as u32) << 8 | blend_mode.compose as u32,
+            alpha,
+        }
+    }
+}
+
+/// Monoid for the draw tag stream.
+#[derive(Copy, Clone, PartialEq, Eq, Pod, Zeroable, Default)]
+#[repr(C)]
+pub struct DrawMonoid {
+    // The number of paths preceding this draw object.
+    pub path_ix: u32,
+    // The number of clip operations preceding this draw object.
+    pub clip_ix: u32,
+    // The offset of the encoded draw object in the scene (u32s).
+    pub scene_offset: u32,
+    // The offset of the associated info.
+    pub info_offset: u32,
+}
+
+impl Monoid<DrawTag> for DrawMonoid {
+    fn new(tag: DrawTag) -> Self {
+        Self {
+            path_ix: (tag != DrawTag::NOP) as u32,
+            clip_ix: tag.0 & 1,
+            scene_offset: (tag.0 >> 2) & 0x7,
+            info_offset: (tag.0 >> 6) & 0xf,
+        }
+    }
+
+    fn combine(&self, other: &Self) -> Self {
+        Self {
+            path_ix: self.path_ix + other.path_ix,
+            clip_ix: self.clip_ix + other.clip_ix,
+            scene_offset: self.scene_offset + other.scene_offset,
+            info_offset: self.info_offset + other.info_offset,
+        }
+    }
+}