Implement `Primitive::Cached`

12 files changed, 152 insertions, 106 deletions

diff --git a/core/src/point.rs b/core/src/point.rs
index b9a8149c..b55f5099 100644
--- a/core/src/point.rs
+++ b/core/src/point.rs
@@ -46,3 +46,14 @@ impl std::ops::Add<Vector> for Point {
         }
     }
 }
+
+impl std::ops::Sub<Vector> for Point {
+    type Output = Self;
+
+    fn sub(self, vector: Vector) -> Self {
+        Self {
+            x: self.x - vector.x,
+            y: self.y - vector.y,
+        }
+    }
+}
diff --git a/core/src/vector.rs b/core/src/vector.rs
index 4c1cbfab..a75053a0 100644
--- a/core/src/vector.rs
+++ b/core/src/vector.rs
@@ -32,6 +32,17 @@ where
     }
 }
 
+impl<T> std::ops::Sub for Vector<T>
+where
+    T: std::ops::Sub<Output = T>,
+{
+    type Output = Self;
+
+    fn sub(self, b: Self) -> Self {
+        Self::new(self.x - b.x, self.y - b.y)
+    }
+}
+
 impl<T> Default for Vector<T>
 where
     T: Default,
diff --git a/examples/bezier_tool/src/main.rs b/examples/bezier_tool/src/main.rs
index 023eb0f7..c3fbf276 100644
--- a/examples/bezier_tool/src/main.rs
+++ b/examples/bezier_tool/src/main.rs
@@ -23,7 +23,6 @@ mod bezier {
         basic_shapes, BuffersBuilder, StrokeAttributes, StrokeOptions,
         StrokeTessellator, VertexBuffers,
     };
-    use std::sync::Arc;
 
     pub struct Bezier<'a, Message> {
         state: &'a mut State,
@@ -175,10 +174,10 @@ mod bezier {
 
             let mesh = Primitive::Mesh2D {
                 origin: Point::new(bounds.x, bounds.y),
-                buffers: Arc::new(Mesh2D {
+                buffers: Mesh2D {
                     vertices: buffer.vertices,
                     indices: buffer.indices,
-                }),
+                },
             };
 
             (
diff --git a/examples/geometry/src/main.rs b/examples/geometry/src/main.rs
index 795c6a71..13a687ab 100644
--- a/examples/geometry/src/main.rs
+++ b/examples/geometry/src/main.rs
@@ -87,7 +87,7 @@ mod rainbow {
             (
                 Primitive::Mesh2D {
                     origin: Point::new(b.x, b.y),
-                    buffers: std::sync::Arc::new(Mesh2D {
+                    buffers: Mesh2D {
                         vertices: vec![
                             Vertex2D {
                                 position: posn_center,
@@ -136,7 +136,7 @@ mod rainbow {
                             0, 7, 8, // BL
                             0, 8, 1, // L
                         ],
-                    }),
+                    },
                 },
                 MouseCursor::OutOfBounds,
             )
diff --git a/wgpu/src/primitive.rs b/wgpu/src/primitive.rs
index 823b4b72..46d9e624 100644
--- a/wgpu/src/primitive.rs
+++ b/wgpu/src/primitive.rs
@@ -78,7 +78,18 @@ pub enum Primitive {
         origin: Point,
 
         /// The vertex and index buffers of the mesh
-        buffers: Arc<triangle::Mesh2D>,
+        buffers: triangle::Mesh2D,
+    },
+    /// A cached primitive.
+    ///
+    /// This can be useful if you are implementing a widget where primitive
+    /// generation is expensive.
+    Cached {
+        /// The origin of the coordinate system of the cached primitives
+        origin: Point,
+
+        /// The cached primitive
+        cache: Arc<Primitive>,
     },
 }
 
diff --git a/wgpu/src/renderer.rs b/wgpu/src/renderer.rs
index 1da19b1a..c06af339 100644
--- a/wgpu/src/renderer.rs
+++ b/wgpu/src/renderer.rs
@@ -10,7 +10,6 @@ use iced_native::{
     layout, Background, Color, Layout, MouseCursor, Point, Rectangle, Vector,
     Widget,
 };
-use std::sync::Arc;
 
 mod widget;
 
@@ -29,9 +28,8 @@ pub struct Renderer {
 
 struct Layer<'a> {
     bounds: Rectangle<u32>,
-    offset: Vector<u32>,
     quads: Vec<Quad>,
-    meshes: Vec<(Point, Arc<triangle::Mesh2D>)>,
+    meshes: Vec<(Point, &'a triangle::Mesh2D)>,
     text: Vec<wgpu_glyph::Section<'a>>,
 
     #[cfg(any(feature = "image", feature = "svg"))]
@@ -39,10 +37,9 @@ struct Layer<'a> {
 }
 
 impl<'a> Layer<'a> {
-    pub fn new(bounds: Rectangle<u32>, offset: Vector<u32>) -> Self {
+    pub fn new(bounds: Rectangle<u32>) -> Self {
         Self {
             bounds,
-            offset,
             quads: Vec::new(),
             text: Vec::new(),
             meshes: Vec::new(),
@@ -103,17 +100,14 @@ impl Renderer {
 
         let mut layers = Vec::new();
 
-        layers.push(Layer::new(
-            Rectangle {
-                x: 0,
-                y: 0,
-                width: u32::from(width),
-                height: u32::from(height),
-            },
-            Vector::new(0, 0),
-        ));
-
-        self.draw_primitive(primitive, &mut layers);
+        layers.push(Layer::new(Rectangle {
+            x: 0,
+            y: 0,
+            width: u32::from(width),
+            height: u32::from(height),
+        }));
+
+        self.draw_primitive(Vector::new(0.0, 0.0), primitive, &mut layers);
         self.draw_overlay(overlay, &mut layers);
 
         for layer in layers {
@@ -137,17 +131,16 @@ impl Renderer {
 
     fn draw_primitive<'a>(
         &mut self,
+        translation: Vector,
         primitive: &'a Primitive,
         layers: &mut Vec<Layer<'a>>,
     ) {
-        let layer = layers.last_mut().unwrap();
-
         match primitive {
             Primitive::None => {}
             Primitive::Group { primitives } => {
                 // TODO: Inspect a bit and regroup (?)
                 for primitive in primitives {
-                    self.draw_primitive(primitive, layers)
+                    self.draw_primitive(translation, primitive, layers)
                 }
             }
             Primitive::Text {
@@ -179,12 +172,11 @@ impl Renderer {
                     }
                 };
 
+                let layer = layers.last_mut().unwrap();
+
                 layer.text.push(wgpu_glyph::Section {
                     text: &content,
-                    screen_position: (
-                        x - layer.offset.x as f32,
-                        y - layer.offset.y as f32,
-                    ),
+                    screen_position: (x + translation.x, y + translation.y),
                     bounds: (bounds.width, bounds.height),
                     scale: wgpu_glyph::Scale { x: *size, y: *size },
                     color: color.into_linear(),
@@ -222,11 +214,13 @@ impl Renderer {
                 border_width,
                 border_color,
             } => {
-                // TODO: Move some of this computations to the GPU (?)
+                let layer = layers.last_mut().unwrap();
+
+                // TODO: Move some of these computations to the GPU (?)
                 layer.quads.push(Quad {
                     position: [
-                        bounds.x - layer.offset.x as f32,
-                        bounds.y - layer.offset.y as f32,
+                        bounds.x + translation.x,
+                        bounds.y + translation.y,
                     ],
                     scale: [bounds.width, bounds.height],
                     color: match background {
@@ -238,38 +232,59 @@ impl Renderer {
                 });
             }
             Primitive::Mesh2D { origin, buffers } => {
-                layer.meshes.push((*origin, buffers.clone()));
+                let layer = layers.last_mut().unwrap();
+
+                layer.meshes.push((*origin + translation, buffers));
             }
             Primitive::Clip {
                 bounds,
                 offset,
                 content,
             } => {
+                let layer = layers.last_mut().unwrap();
+
                 let layer_bounds: Rectangle<f32> = layer.bounds.into();
 
                 let clip = Rectangle {
-                    x: bounds.x - layer.offset.x as f32,
-                    y: bounds.y - layer.offset.y as f32,
+                    x: bounds.x + translation.x,
+                    y: bounds.y + translation.y,
                     ..*bounds
                 };
 
                 // Only draw visible content
                 if let Some(clip_bounds) = layer_bounds.intersection(&clip) {
-                    let clip_layer =
-                        Layer::new(clip_bounds.into(), layer.offset + *offset);
-                    let new_layer = Layer::new(layer.bounds, layer.offset);
+                    let clip_layer = Layer::new(clip_bounds.into());
+                    let new_layer = Layer::new(layer.bounds);
 
                     layers.push(clip_layer);
-                    self.draw_primitive(content, layers);
+                    self.draw_primitive(
+                        translation
+                            - Vector::new(offset.x as f32, offset.y as f32),
+                        content,
+                        layers,
+                    );
                     layers.push(new_layer);
                 }
             }
 
+            Primitive::Cached { origin, cache } => {
+                self.draw_primitive(
+                    translation + Vector::new(origin.x, origin.y),
+                    &cache,
+                    layers,
+                );
+            }
+
             #[cfg(feature = "image")]
             Primitive::Image { handle, bounds } => {
+                let layer = layers.last_mut().unwrap();
+
                 layer.images.push(Image {
                     handle: image::Handle::Raster(handle.clone()),
-                    position: [bounds.x, bounds.y],
+                    position: [
+                        bounds.x + translation.x,
+                        bounds.y + translation.y,
+                    ],
                     size: [bounds.width, bounds.height],
                 });
             }
@@ -278,9 +293,14 @@ impl Renderer {
 
             #[cfg(feature = "svg")]
             Primitive::Svg { handle, bounds } => {
+                let layer = layers.last_mut().unwrap();
+
                 layer.images.push(Image {
                     handle: image::Handle::Vector(handle.clone()),
-                    position: [bounds.x, bounds.y],
+                    position: [
+                        bounds.x + translation.x,
+                        bounds.y + translation.y,
+                    ],
                     size: [bounds.width, bounds.height],
                 });
             }
@@ -295,7 +315,7 @@ impl Renderer {
         layers: &mut Vec<Layer<'a>>,
     ) {
         let first = layers.first().unwrap();
-        let mut overlay = Layer::new(first.bounds, Vector::new(0, 0));
+        let mut overlay = Layer::new(first.bounds);
 
         let font_id = self.text_pipeline.overlay_font();
         let scale = wgpu_glyph::Scale { x: 20.0, y: 20.0 };
@@ -337,12 +357,8 @@ impl Renderer {
         let bounds = layer.bounds * scale_factor;
 
         if layer.meshes.len() > 0 {
-            let translated = transformation
-                * Transformation::scale(scale_factor, scale_factor)
-                * Transformation::translate(
-                    -(layer.offset.x as f32),
-                    -(layer.offset.y as f32),
-                );
+            let scaled = transformation
+                * Transformation::scale(scale_factor, scale_factor);
 
             self.triangle_pipeline.draw(
                 device,
@@ -350,7 +366,7 @@ impl Renderer {
                 target,
                 target_width,
                 target_height,
-                translated,
+                scaled,
                 &layer.meshes,
                 bounds,
             );
@@ -371,18 +387,14 @@ impl Renderer {
         #[cfg(any(feature = "image", feature = "svg"))]
         {
             if layer.images.len() > 0 {
-                let translated_and_scaled = transformation
-                    * Transformation::scale(scale_factor, scale_factor)
-                    * Transformation::translate(
-                        -(layer.offset.x as f32),
-                        -(layer.offset.y as f32),
-                    );
+                let scaled = transformation
+                    * Transformation::scale(scale_factor, scale_factor);
 
                 self.image_pipeline.draw(
                     device,
                     encoder,
                     &layer.images,
-                    translated_and_scaled,
+                    scaled,
                     bounds,
                     target,
                     scale_factor,
diff --git a/wgpu/src/triangle.rs b/wgpu/src/triangle.rs
index 85ed4bd5..be61cc15 100644
--- a/wgpu/src/triangle.rs
+++ b/wgpu/src/triangle.rs
@@ -1,7 +1,7 @@
 //! Draw meshes of triangles.
 use crate::{settings, Transformation};
 use iced_native::{Point, Rectangle};
-use std::{mem, sync::Arc};
+use std::mem;
 
 mod msaa;
 
@@ -194,7 +194,7 @@ impl Pipeline {
         target_width: u32,
         target_height: u32,
         transformation: Transformation,
-        meshes: &Vec<(Point, Arc<Mesh2D>)>,
+        meshes: &Vec<(Point, &Mesh2D)>,
         bounds: Rectangle<u32>,
     ) {
         // This looks a bit crazy, but we are just counting how many vertices
diff --git a/wgpu/src/widget/canvas.rs b/wgpu/src/widget/canvas.rs
index 9741ee9d..3a9605c9 100644
--- a/wgpu/src/widget/canvas.rs
+++ b/wgpu/src/widget/canvas.rs
@@ -123,7 +123,10 @@ impl<'a, Message> Widget<Message, Renderer> for Canvas<'a> {
                 primitives: self
                     .layers
                     .iter()
-                    .map(|layer| layer.draw(origin, size))
+                    .map(|layer| Primitive::Cached {
+                        origin,
+                        cache: layer.draw(size),
+                    })
                     .collect(),
             },
             MouseCursor::Idle,
diff --git a/wgpu/src/widget/canvas/frame.rs b/wgpu/src/widget/canvas/frame.rs
index 5b82c951..0bf58320 100644
--- a/wgpu/src/widget/canvas/frame.rs
+++ b/wgpu/src/widget/canvas/frame.rs
@@ -1,12 +1,10 @@
-use iced_native::{Point, Size, Vector};
+use iced_native::{Point, Rectangle, Size, Vector};
 
 use crate::{
     canvas::{Fill, Path, Stroke, Text},
     triangle, Primitive,
 };
 
-use std::sync::Arc;
-
 /// The frame of a [`Canvas`].
 ///
 /// [`Canvas`]: struct.Canvas.html
@@ -15,8 +13,8 @@ pub struct Frame {
     width: f32,
     height: f32,
     buffers: lyon::tessellation::VertexBuffers<triangle::Vertex2D, u32>,
+    primitives: Vec<Primitive>,
     transforms: Transforms,
-    texts: Vec<Text>,
 }
 
 #[derive(Debug)]
@@ -43,7 +41,7 @@ impl Frame {
             width,
             height,
             buffers: lyon::tessellation::VertexBuffers::new(),
-            texts: Vec::new(),
+            primitives: Vec::new(),
             transforms: Transforms {
                 previous: Vec::new(),
                 current: Transform {
@@ -165,7 +163,23 @@ impl Frame {
     /// [`Frame`]: struct.Frame.html
     #[inline]
     pub fn fill_text(&mut self, text: Text) {
-        self.texts.push(text);
+        use std::f32;
+
+        // TODO: Use vectorial text instead of primitive
+        self.primitives.push(Primitive::Text {
+            content: text.content,
+            bounds: Rectangle {
+                x: text.position.x,
+                y: text.position.y,
+                width: f32::INFINITY,
+                height: f32::INFINITY,
+            },
+            color: text.color,
+            size: text.size,
+            font: text.font,
+            horizontal_alignment: text.horizontal_alignment,
+            vertical_alignment: text.vertical_alignment,
+        });
     }
 
     /// Stores the current transform of the [`Frame`] and executes the given
@@ -226,35 +240,18 @@ impl Frame {
     /// Produces the primitive representing everything drawn on the [`Frame`].
     ///
     /// [`Frame`]: struct.Frame.html
-    pub fn into_primitive(self, origin: Point) -> Primitive {
-        let mut primitives: Vec<Primitive> = self
-            .texts
-            .into_iter()
-            .map(|mut t| {
-                t.bounds.x += origin.x;
-                t.bounds.y += origin.y;
-
-                Primitive::Text {
-                    content: t.content,
-                    bounds: t.bounds,
-                    color: t.color,
-                    size: t.size,
-                    font: t.font,
-                    horizontal_alignment: t.horizontal_alignment,
-                    vertical_alignment: t.vertical_alignment,
-                }
-            })
-            .collect();
-
-        primitives.push(Primitive::Mesh2D {
-            origin,
-            buffers: Arc::new(triangle::Mesh2D {
+    pub fn into_primitive(mut self) -> Primitive {
+        self.primitives.push(Primitive::Mesh2D {
+            origin: Point::ORIGIN,
+            buffers: triangle::Mesh2D {
                 vertices: self.buffers.vertices,
                 indices: self.buffers.indices,
-            }),
+            },
         });
 
-        Primitive::Group { primitives }
+        Primitive::Group {
+            primitives: self.primitives,
+        }
     }
 }
 
diff --git a/wgpu/src/widget/canvas/layer.rs b/wgpu/src/widget/canvas/layer.rs
index 95e2d0ee..a46b7fb1 100644
--- a/wgpu/src/widget/canvas/layer.rs
+++ b/wgpu/src/widget/canvas/layer.rs
@@ -4,21 +4,22 @@ mod cache;
 pub use cache::Cache;
 
 use crate::Primitive;
+use iced_native::Size;
 
-use iced_native::{Point, Size};
+use std::sync::Arc;
 
 /// A layer that can be presented at a [`Canvas`].
 ///
 /// [`Canvas`]: ../struct.Canvas.html
 pub trait Layer: std::fmt::Debug {
-    /// Draws the [`Layer`] in the given bounds and produces [`Mesh2D`] as a
-    /// result.
+    /// Draws the [`Layer`] in the given bounds and produces a [`Primitive`] as
+    /// a result.
     ///
-    /// The [`Layer`] may choose to store the produced [`Mesh2D`] locally and
+    /// The [`Layer`] may choose to store the produced [`Primitive`] locally and
     /// only recompute it when the bounds change, its contents change, or is
     /// otherwise explicitly cleared by other means.
     ///
     /// [`Layer`]: trait.Layer.html
-    /// [`Mesh2D`]: ../../../triangle/struct.Mesh2D.html
-    fn draw(&self, origin: Point, bounds: Size) -> Primitive;
+    /// [`Primitive`]: ../../../enum.Primitive.html
+    fn draw(&self, bounds: Size) -> Arc<Primitive>;
 }
diff --git a/wgpu/src/widget/canvas/layer/cache.rs b/wgpu/src/widget/canvas/layer/cache.rs
index f05028da..6b69f01e 100644
--- a/wgpu/src/widget/canvas/layer/cache.rs
+++ b/wgpu/src/widget/canvas/layer/cache.rs
@@ -3,8 +3,8 @@ use crate::{
     Primitive,
 };
 
-use iced_native::{Point, Size};
-use std::{cell::RefCell, marker::PhantomData};
+use iced_native::Size;
+use std::{cell::RefCell, marker::PhantomData, sync::Arc};
 
 /// A simple cache that stores generated geometry to avoid recomputation.
 ///
@@ -22,7 +22,10 @@ pub struct Cache<T: Drawable> {
 #[derive(Debug)]
 enum State {
     Empty,
-    Filled { bounds: Size, primitive: Primitive },
+    Filled {
+        bounds: Size,
+        primitive: Arc<Primitive>,
+    },
 }
 
 impl<T> Cache<T>
@@ -70,7 +73,7 @@ impl<'a, T> Layer for Bind<'a, T>
 where
     T: Drawable + std::fmt::Debug,
 {
-    fn draw(&self, origin: Point, current_bounds: Size) -> Primitive {
+    fn draw(&self, current_bounds: Size) -> Arc<Primitive> {
         use std::ops::Deref;
 
         if let State::Filled { bounds, primitive } =
@@ -84,7 +87,7 @@ where
         let mut frame = Frame::new(current_bounds.width, current_bounds.height);
         self.input.draw(&mut frame);
 
-        let primitive = frame.into_primitive(origin);
+        let primitive = Arc::new(frame.into_primitive());
 
         *self.cache.state.borrow_mut() = State::Filled {
             bounds: current_bounds,
diff --git a/wgpu/src/widget/canvas/text.rs b/wgpu/src/widget/canvas/text.rs
index 241f8503..1f9bdc19 100644
--- a/wgpu/src/widget/canvas/text.rs
+++ b/wgpu/src/widget/canvas/text.rs
@@ -1,14 +1,12 @@
-use iced_native::{
-    Color, Font, HorizontalAlignment, Rectangle, VerticalAlignment,
-};
+use iced_native::{Color, Font, HorizontalAlignment, Point, VerticalAlignment};
 
 /// A bunch of text that can be drawn to a canvas
 #[derive(Debug, Clone)]
 pub struct Text {
     /// The contents of the text
     pub content: String,
-    /// The bounds of the text
-    pub bounds: Rectangle,
+    /// The position where to begin drawing the text (top-left corner coordinates)
+    pub position: Point,
     /// The color of the text
     pub color: Color,
     /// The size of the text