9 files changed, 374 insertions, 0 deletions
diff --git a/wgpu/src/renderer.rs b/wgpu/src/renderer.rs
new file mode 100644
index 00000000..df8887e3
--- /dev/null
+++ b/wgpu/src/renderer.rs
@@ -0,0 +1,167 @@
+use crate::Primitive;
+use iced_native::{renderer::Debugger, Color, Layout, Point, Widget};
+
+use raw_window_handle::HasRawWindowHandle;
+use wgpu::{
+    Adapter, CommandEncoderDescriptor, Device, DeviceDescriptor, Extensions,
+    Instance, Limits, PowerPreference, RequestAdapterOptions, Surface,
+    SwapChain, SwapChainDescriptor, TextureFormat, TextureUsage,
+};
+use wgpu_glyph::{GlyphBrush, GlyphBrushBuilder, Section};
+
+use std::{cell::RefCell, rc::Rc};
+
+mod button;
+mod checkbox;
+mod column;
+mod image;
+mod radio;
+mod row;
+mod slider;
+mod text;
+
+pub struct Renderer {
+    instance: Instance,
+    surface: Surface,
+    adapter: Adapter,
+    device: Device,
+    glyph_brush: Rc<RefCell<GlyphBrush<'static, ()>>>,
+}
+
+pub struct Target {
+    width: u16,
+    height: u16,
+    swap_chain: SwapChain,
+}
+
+impl Renderer {
+    pub fn new<W: HasRawWindowHandle>(window: &W) -> Self {
+        let instance = Instance::new();
+
+        let adapter = instance.request_adapter(&RequestAdapterOptions {
+            power_preference: PowerPreference::LowPower,
+        });
+
+        let mut device = adapter.request_device(&DeviceDescriptor {
+            extensions: Extensions {
+                anisotropic_filtering: false,
+            },
+            limits: Limits { max_bind_groups: 1 },
+        });
+
+        let surface = instance.create_surface(window.raw_window_handle());
+
+        // TODO: Think about font loading strategy
+        // Loading system fonts with fallback may be a good idea
+        let font: &[u8] =
+            include_bytes!("../../examples/tour/resources/Roboto-Regular.ttf");
+
+        let glyph_brush = GlyphBrushBuilder::using_font_bytes(font)
+            .build(&mut device, TextureFormat::Bgra8UnormSrgb);
+
+        Self {
+            instance,
+            surface,
+            adapter,
+            device,
+            glyph_brush: Rc::new(RefCell::new(glyph_brush)),
+        }
+    }
+
+    pub fn target(&self, width: u16, height: u16) -> Target {
+        Target {
+            width,
+            height,
+            swap_chain: self.device.create_swap_chain(
+                &self.surface,
+                &SwapChainDescriptor {
+                    usage: TextureUsage::OUTPUT_ATTACHMENT,
+                    format: TextureFormat::Bgra8UnormSrgb,
+                    width: u32::from(width),
+                    height: u32::from(height),
+                    present_mode: wgpu::PresentMode::Vsync,
+                },
+            ),
+        }
+    }
+
+    pub fn draw(&mut self, target: &mut Target, primitive: &Primitive) {
+        let frame = target.swap_chain.get_next_texture();
+
+        let mut encoder = self
+            .device
+            .create_command_encoder(&CommandEncoderDescriptor { todo: 0 });
+
+        let _ = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            color_attachments: &[wgpu::RenderPassColorAttachmentDescriptor {
+                attachment: &frame.view,
+                resolve_target: None,
+                load_op: wgpu::LoadOp::Clear,
+                store_op: wgpu::StoreOp::Store,
+                clear_color: wgpu::Color {
+                    r: 1.0,
+                    g: 1.0,
+                    b: 1.0,
+                    a: 1.0,
+                },
+            }],
+            depth_stencil_attachment: None,
+        });
+
+        self.draw_primitive(primitive);
+
+        self.glyph_brush
+            .borrow_mut()
+            .draw_queued(
+                &mut self.device,
+                &mut encoder,
+                &frame.view,
+                u32::from(target.width),
+                u32::from(target.height),
+            )
+            .expect("Draw text");
+
+        self.device.get_queue().submit(&[encoder.finish()]);
+    }
+
+    fn draw_primitive(&mut self, primitive: &Primitive) {
+        match primitive {
+            Primitive::None => {}
+            Primitive::Group { primitives } => {
+                // TODO: Inspect a bit and regroup (?)
+                for primitive in primitives {
+                    self.draw_primitive(primitive)
+                }
+            }
+            Primitive::Text {
+                content,
+                bounds,
+                size,
+            } => self.glyph_brush.borrow_mut().queue(Section {
+                text: &content,
+                screen_position: (bounds.x, bounds.y),
+                bounds: (bounds.width, bounds.height),
+                scale: wgpu_glyph::Scale { x: *size, y: *size },
+                ..Default::default()
+            }),
+        }
+    }
+}
+
+impl iced_native::Renderer for Renderer {
+    // TODO: Add `MouseCursor` here (?)
+    type Primitive = Primitive;
+}
+
+impl Debugger for Renderer {
+    fn explain<Message>(
+        &mut self,
+        widget: &dyn Widget<Message, Self>,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        _color: Color,
+    ) -> Self::Primitive {
+        // TODO: Include a bordered box to display layout bounds
+        widget.draw(self, layout, cursor_position)
+    }
+}
diff --git a/wgpu/src/renderer/button.rs b/wgpu/src/renderer/button.rs
new file mode 100644
index 00000000..24bc1de6
--- /dev/null
+++ b/wgpu/src/renderer/button.rs
@@ -0,0 +1,18 @@
+use crate::{Primitive, Renderer};
+use iced_native::{button, Button, Layout, Node, Point, Style};
+
+impl button::Renderer for Renderer {
+    fn node<Message>(&self, _button: &Button<Message>) -> Node {
+        Node::new(Style::default())
+    }
+
+    fn draw<Message>(
+        &mut self,
+        _button: &Button<Message>,
+        _layout: Layout<'_>,
+        _cursor_position: Point,
+    ) -> Self::Primitive {
+        // TODO
+        Primitive::None
+    }
+}
diff --git a/wgpu/src/renderer/checkbox.rs b/wgpu/src/renderer/checkbox.rs
new file mode 100644
index 00000000..c94a2157
--- /dev/null
+++ b/wgpu/src/renderer/checkbox.rs
@@ -0,0 +1,18 @@
+use crate::{Primitive, Renderer};
+use iced_native::{checkbox, Checkbox, Layout, Node, Point, Style};
+
+impl checkbox::Renderer for Renderer {
+    fn node<Message>(&mut self, _checkbox: &Checkbox<Message>) -> Node {
+        Node::new(Style::default())
+    }
+
+    fn draw<Message>(
+        &mut self,
+        _checkbox: &Checkbox<Message>,
+        _layout: Layout<'_>,
+        _cursor_position: Point,
+    ) -> Self::Primitive {
+        // TODO
+        Primitive::None
+    }
+}
diff --git a/wgpu/src/renderer/column.rs b/wgpu/src/renderer/column.rs
new file mode 100644
index 00000000..1b9adad6
--- /dev/null
+++ b/wgpu/src/renderer/column.rs
@@ -0,0 +1,22 @@
+use crate::{Primitive, Renderer};
+use iced_native::{column, Column, Layout, Point};
+
+impl column::Renderer for Renderer {
+    fn draw<Message>(
+        &mut self,
+        column: &Column<'_, Message, Self>,
+        layout: Layout<'_>,
+        cursor_position: Point,
+    ) -> Self::Primitive {
+        Primitive::Group {
+            primitives: column
+                .children
+                .iter()
+                .zip(layout.children())
+                .map(|(child, layout)| {
+                    child.draw(self, layout, cursor_position)
+                })
+                .collect(),
+        }
+    }
+}
diff --git a/wgpu/src/renderer/image.rs b/wgpu/src/renderer/image.rs
new file mode 100644
index 00000000..6ff39d30
--- /dev/null
+++ b/wgpu/src/renderer/image.rs
@@ -0,0 +1,16 @@
+use crate::{Primitive, Renderer};
+use iced_native::{image, Image, Layout, Node, Style};
+
+impl image::Renderer<&str> for Renderer {
+    fn node(&mut self, _image: &Image<&str>) -> Node {
+        Node::new(Style::default())
+    }
+
+    fn draw(
+        &mut self,
+        _image: &Image<&str>,
+        _layout: Layout<'_>,
+    ) -> Self::Primitive {
+        Primitive::None
+    }
+}
diff --git a/wgpu/src/renderer/radio.rs b/wgpu/src/renderer/radio.rs
new file mode 100644
index 00000000..ce419ae0
--- /dev/null
+++ b/wgpu/src/renderer/radio.rs
@@ -0,0 +1,17 @@
+use crate::{Primitive, Renderer};
+use iced_native::{radio, Layout, Node, Point, Radio, Style};
+
+impl radio::Renderer for Renderer {
+    fn node<Message>(&mut self, _checkbox: &Radio<Message>) -> Node {
+        Node::new(Style::default())
+    }
+
+    fn draw<Message>(
+        &mut self,
+        _radio: &Radio<Message>,
+        _layout: Layout<'_>,
+        _cursor_position: Point,
+    ) -> Self::Primitive {
+        Primitive::None
+    }
+}
diff --git a/wgpu/src/renderer/row.rs b/wgpu/src/renderer/row.rs
new file mode 100644
index 00000000..be9e4ede
--- /dev/null
+++ b/wgpu/src/renderer/row.rs
@@ -0,0 +1,22 @@
+use crate::{Primitive, Renderer};
+use iced_native::{row, Layout, Point, Row};
+
+impl row::Renderer for Renderer {
+    fn draw<Message>(
+        &mut self,
+        row: &Row<'_, Message, Self>,
+        layout: Layout<'_>,
+        cursor_position: Point,
+    ) -> Self::Primitive {
+        Primitive::Group {
+            primitives: row
+                .children
+                .iter()
+                .zip(layout.children())
+                .map(|(child, layout)| {
+                    child.draw(self, layout, cursor_position)
+                })
+                .collect(),
+        }
+    }
+}
diff --git a/wgpu/src/renderer/slider.rs b/wgpu/src/renderer/slider.rs
new file mode 100644
index 00000000..2e76022d
--- /dev/null
+++ b/wgpu/src/renderer/slider.rs
@@ -0,0 +1,17 @@
+use crate::{Primitive, Renderer};
+use iced_native::{slider, Layout, Node, Point, Slider, Style};
+
+impl slider::Renderer for Renderer {
+    fn node<Message>(&self, _slider: &Slider<Message>) -> Node {
+        Node::new(Style::default())
+    }
+
+    fn draw<Message>(
+        &mut self,
+        _slider: &Slider<Message>,
+        _layout: Layout<'_>,
+        _cursor_position: Point,
+    ) -> Self::Primitive {
+        Primitive::None
+    }
+}
diff --git a/wgpu/src/renderer/text.rs b/wgpu/src/renderer/text.rs
new file mode 100644
index 00000000..4434cc22
--- /dev/null
+++ b/wgpu/src/renderer/text.rs
@@ -0,0 +1,77 @@
+use crate::{Primitive, Renderer};
+use iced_native::{text, Layout, Node, Style, Text};
+
+use wgpu_glyph::{GlyphCruncher, Section};
+
+use std::cell::RefCell;
+use std::f32;
+
+impl text::Renderer for Renderer {
+    fn node(&self, text: &Text) -> Node {
+        let glyph_brush = self.glyph_brush.clone();
+        let content = text.content.clone();
+
+        // TODO: Investigate why stretch tries to measure this MANY times
+        // with every ancestor's bounds.
+        // Bug? Using the library wrong? I should probably open an issue on
+        // the stretch repository.
+        // I noticed that the first measure is the one that matters in
+        // practice. Here, we use a RefCell to store the cached measurement.
+        let measure = RefCell::new(None);
+        let size = text.size.map(f32::from).unwrap_or(20.0);
+
+        let style = Style::default().width(text.width);
+
+        iced_native::Node::with_measure(style, move |bounds| {
+            let mut measure = measure.borrow_mut();
+
+            if measure.is_none() {
+                let bounds = (
+                    match bounds.width {
+                        iced_native::Number::Undefined => f32::INFINITY,
+                        iced_native::Number::Defined(w) => w,
+                    },
+                    match bounds.height {
+                        iced_native::Number::Undefined => f32::INFINITY,
+                        iced_native::Number::Defined(h) => h,
+                    },
+                );
+
+                let text = Section {
+                    text: &content,
+                    scale: wgpu_glyph::Scale { x: size, y: size },
+                    bounds,
+                    ..Default::default()
+                };
+
+                let (width, height) = if let Some(bounds) =
+                    glyph_brush.borrow_mut().glyph_bounds(&text)
+                {
+                    (bounds.width(), bounds.height())
+                } else {
+                    (0.0, 0.0)
+                };
+
+                let size = iced_native::Size { width, height };
+
+                // If the text has no width boundary we avoid caching as the
+                // layout engine may just be measuring text in a row.
+                if bounds.0 == f32::INFINITY {
+                    return size;
+                } else {
+                    *measure = Some(size);
+                }
+            }
+
+            measure.unwrap()
+        })
+    }
+
+    fn draw(&mut self, text: &Text, layout: Layout<'_>) -> Self::Primitive {
+        Primitive::Text {
+            content: text.content.clone(),
+            size: f32::from(text.size.unwrap_or(20)),
+            bounds: layout.bounds(),
+        }
+    }
+}