Add `integration` example

It showcases how to integrate iced in an existing graphical application.

6 files changed, 436 insertions, 0 deletions

diff --git a/examples/integration/Cargo.toml b/examples/integration/Cargo.toml
new file mode 100644
index 00000000..afc2c791
--- /dev/null
+++ b/examples/integration/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "integration"
+version = "0.1.0"
+authors = ["Héctor Ramón Jiménez <hector0193@gmail.com>"]
+edition = "2018"
+publish = false
+
+[dependencies]
+iced_winit = { path = "../../winit" }
+iced_wgpu = { path = "../../wgpu" }
+env_logger = "0.7"
diff --git a/examples/integration/src/controls.rs b/examples/integration/src/controls.rs
new file mode 100644
index 00000000..0457a058
--- /dev/null
+++ b/examples/integration/src/controls.rs
@@ -0,0 +1,102 @@
+use crate::Scene;
+
+use iced_wgpu::Renderer;
+use iced_winit::{
+    slider, Align, Color, Column, Element, Length, Row, Slider, Text,
+};
+
+pub struct Controls {
+    sliders: [slider::State; 3],
+}
+
+#[derive(Debug)]
+pub enum Message {
+    BackgroundColorChanged(Color),
+}
+
+impl Controls {
+    pub fn new() -> Controls {
+        Controls {
+            sliders: Default::default(),
+        }
+    }
+
+    pub fn update(&self, message: Message, scene: &mut Scene) {
+        match message {
+            Message::BackgroundColorChanged(color) => {
+                scene.background_color = color;
+            }
+        }
+    }
+
+    pub fn view<'a>(
+        &'a mut self,
+        scene: &Scene,
+    ) -> Element<'a, Message, Renderer> {
+        let [r, g, b] = &mut self.sliders;
+        let background_color = scene.background_color;
+
+        let sliders = Row::new()
+            .width(Length::Units(500))
+            .spacing(20)
+            .push(Slider::new(
+                r,
+                0.0..=1.0,
+                scene.background_color.r,
+                move |r| {
+                    Message::BackgroundColorChanged(Color {
+                        r,
+                        ..background_color
+                    })
+                },
+            ))
+            .push(Slider::new(
+                g,
+                0.0..=1.0,
+                scene.background_color.g,
+                move |g| {
+                    Message::BackgroundColorChanged(Color {
+                        g,
+                        ..background_color
+                    })
+                },
+            ))
+            .push(Slider::new(
+                b,
+                0.0..=1.0,
+                scene.background_color.b,
+                move |b| {
+                    Message::BackgroundColorChanged(Color {
+                        b,
+                        ..background_color
+                    })
+                },
+            ));
+
+        Row::new()
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .align_items(Align::End)
+            .push(
+                Column::new()
+                    .width(Length::Fill)
+                    .align_items(Align::End)
+                    .push(
+                        Column::new()
+                            .padding(10)
+                            .spacing(10)
+                            .push(
+                                Text::new("Background color")
+                                    .color(Color::WHITE),
+                            )
+                            .push(sliders)
+                            .push(
+                                Text::new(format!("{:?}", background_color))
+                                    .size(14)
+                                    .color(Color::WHITE),
+                            ),
+                    ),
+            )
+            .into()
+    }
+}
diff --git a/examples/integration/src/main.rs b/examples/integration/src/main.rs
new file mode 100644
index 00000000..ed36f736
--- /dev/null
+++ b/examples/integration/src/main.rs
@@ -0,0 +1,204 @@
+mod controls;
+mod scene;
+
+use controls::Controls;
+use scene::Scene;
+
+use iced_wgpu::{
+    wgpu, window::SwapChain, Primitive, Renderer, Settings, Target,
+};
+use iced_winit::{winit, Cache, Clipboard, MouseCursor, Size, UserInterface};
+
+use winit::{
+    event::{DeviceEvent, Event, ModifiersState, WindowEvent},
+    event_loop::{ControlFlow, EventLoop},
+};
+
+pub fn main() {
+    env_logger::init();
+
+    // Initialize winit
+    let event_loop = EventLoop::new();
+    let window = winit::window::Window::new(&event_loop).unwrap();
+    let mut logical_size =
+        window.inner_size().to_logical(window.scale_factor());
+    let mut modifiers = ModifiersState::default();
+
+    // Initialize WGPU
+    let adapter = wgpu::Adapter::request(&wgpu::RequestAdapterOptions {
+        power_preference: wgpu::PowerPreference::Default,
+        backends: wgpu::BackendBit::PRIMARY,
+    })
+    .expect("Request adapter");
+
+    let (mut device, mut queue) =
+        adapter.request_device(&wgpu::DeviceDescriptor {
+            extensions: wgpu::Extensions {
+                anisotropic_filtering: false,
+            },
+            limits: wgpu::Limits::default(),
+        });
+
+    let surface = wgpu::Surface::create(&window);
+
+    let mut swap_chain = {
+        let size = window.inner_size();
+
+        SwapChain::new(&device, &surface, size.width, size.height)
+    };
+    let mut resized = false;
+
+    // Initialize iced
+    let mut events = Vec::new();
+    let mut cache = Some(Cache::default());
+    let mut renderer = Renderer::new(&mut device, Settings::default());
+    let mut output = (Primitive::None, MouseCursor::OutOfBounds);
+    let clipboard = Clipboard::new(&window);
+
+    // Initialize scene and GUI controls
+    let mut scene = Scene::new(&device);
+    let mut controls = Controls::new();
+
+    // Run event loop
+    event_loop.run(move |event, _, control_flow| {
+        // You should change this if you want to render continuosly
+        *control_flow = ControlFlow::Wait;
+
+        match event {
+            Event::DeviceEvent {
+                event: DeviceEvent::ModifiersChanged(new_modifiers),
+                ..
+            } => {
+                modifiers = new_modifiers;
+            }
+            Event::WindowEvent { event, .. } => {
+                match event {
+                    WindowEvent::Resized(new_size) => {
+                        logical_size =
+                            new_size.to_logical(window.scale_factor());
+                        resized = true;
+                    }
+                    WindowEvent::CloseRequested => {
+                        *control_flow = ControlFlow::Exit;
+                    }
+                    _ => {}
+                }
+
+                // Map window event to iced event
+                if let Some(event) = iced_winit::conversion::window_event(
+                    event,
+                    window.scale_factor(),
+                    modifiers,
+                ) {
+                    events.push(event);
+                }
+            }
+            Event::MainEventsCleared => {
+                // If no relevant events happened, we can simply skip this
+                if events.is_empty() {
+                    return;
+                }
+
+                // We need to:
+                // 1. Process events of our user interface.
+                // 2. Update state as a result of any interaction.
+                // 3. Generate a new output for our renderer.
+
+                // First, we build our user interface.
+                let mut user_interface = UserInterface::build(
+                    controls.view(&scene),
+                    Size::new(logical_size.width, logical_size.height),
+                    cache.take().unwrap(),
+                    &mut renderer,
+                );
+
+                // Then, we process the events, obtaining messages in return.
+                let messages = user_interface.update(
+                    events.drain(..),
+                    clipboard.as_ref().map(|c| c as _),
+                    &renderer,
+                );
+
+                let user_interface = if messages.is_empty() {
+                    // If there are no messages, no interactions we care about have
+                    // happened. We can simply leave our user interface as it is.
+                    user_interface
+                } else {
+                    // If there are messages, we need to update our state
+                    // accordingly and rebuild our user interface.
+                    // We can only do this if we drop our user interface first
+                    // by turning it into its cache.
+                    cache = Some(user_interface.into_cache());
+
+                    // In this example, `Controls` is the only part that cares
+                    // about messages, so updating our state is pretty
+                    // straightforward.
+                    for message in messages {
+                        controls.update(message, &mut scene);
+                    }
+
+                    // Once the state has been changed, we rebuild our updated
+                    // user interface.
+                    UserInterface::build(
+                        controls.view(&scene),
+                        Size::new(logical_size.width, logical_size.height),
+                        cache.take().unwrap(),
+                        &mut renderer,
+                    )
+                };
+
+                // Finally, we just need to draw a new output for our renderer,
+                output = user_interface.draw(&mut renderer);
+
+                // update our cache,
+                cache = Some(user_interface.into_cache());
+
+                // and request a redraw
+                window.request_redraw();
+            }
+            Event::RedrawRequested(_) => {
+                if resized {
+                    let size = window.inner_size();
+
+                    swap_chain = SwapChain::new(
+                        &device,
+                        &surface,
+                        size.width,
+                        size.height,
+                    );
+                }
+
+                let (frame, viewport) = swap_chain.next_frame();
+
+                let mut encoder = device.create_command_encoder(
+                    &wgpu::CommandEncoderDescriptor { todo: 0 },
+                );
+
+                // We draw the scene first
+                scene.draw(&mut encoder, &frame.view);
+
+                // And then iced on top
+                let mouse_cursor = renderer.draw(
+                    &mut device,
+                    &mut encoder,
+                    Target {
+                        texture: &frame.view,
+                        viewport,
+                    },
+                    &output,
+                    window.scale_factor(),
+                    &["Some debug information!"],
+                );
+
+                // Then we submit the work
+                queue.submit(&[encoder.finish()]);
+
+                // And update the mouse cursor
+                window.set_cursor_icon(iced_winit::conversion::mouse_cursor(
+                    mouse_cursor,
+                ));
+            }
+            _ => {}
+        }
+    })
+}
diff --git a/examples/integration/src/scene.rs b/examples/integration/src/scene.rs
new file mode 100644
index 00000000..efb1921b
--- /dev/null
+++ b/examples/integration/src/scene.rs
@@ -0,0 +1,119 @@
+use iced_wgpu::wgpu;
+use iced_winit::Color;
+
+pub struct Scene {
+    pub background_color: Color,
+    pipeline: wgpu::RenderPipeline,
+    bind_group: wgpu::BindGroup,
+}
+
+impl Scene {
+    pub fn new(device: &wgpu::Device) -> Scene {
+        let (pipeline, bind_group) = build_pipeline(device);
+
+        Scene {
+            background_color: Color::BLACK,
+            pipeline,
+            bind_group,
+        }
+    }
+
+    pub fn draw(
+        &self,
+        encoder: &mut wgpu::CommandEncoder,
+        target: &wgpu::TextureView,
+    ) {
+        let mut rpass =
+            encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+                color_attachments: &[
+                    wgpu::RenderPassColorAttachmentDescriptor {
+                        attachment: target,
+                        resolve_target: None,
+                        load_op: wgpu::LoadOp::Clear,
+                        store_op: wgpu::StoreOp::Store,
+                        clear_color: {
+                            let [r, g, b, a] =
+                                self.background_color.into_linear();
+
+                            wgpu::Color {
+                                r: r as f64,
+                                g: g as f64,
+                                b: b as f64,
+                                a: a as f64,
+                            }
+                        },
+                    },
+                ],
+                depth_stencil_attachment: None,
+            });
+
+        rpass.set_pipeline(&self.pipeline);
+        rpass.set_bind_group(0, &self.bind_group, &[]);
+        rpass.draw(0..3, 0..1);
+    }
+}
+
+fn build_pipeline(
+    device: &wgpu::Device,
+) -> (wgpu::RenderPipeline, wgpu::BindGroup) {
+    let vs = include_bytes!("shader/vert.spv");
+    let fs = include_bytes!("shader/frag.spv");
+
+    let vs_module = device.create_shader_module(
+        &wgpu::read_spirv(std::io::Cursor::new(&vs[..])).unwrap(),
+    );
+
+    let fs_module = device.create_shader_module(
+        &wgpu::read_spirv(std::io::Cursor::new(&fs[..])).unwrap(),
+    );
+
+    let bind_group_layout =
+        device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            bindings: &[],
+        });
+
+    let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+        layout: &bind_group_layout,
+        bindings: &[],
+    });
+
+    let pipeline_layout =
+        device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+            bind_group_layouts: &[&bind_group_layout],
+        });
+
+    let pipeline =
+        device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+            layout: &pipeline_layout,
+            vertex_stage: wgpu::ProgrammableStageDescriptor {
+                module: &vs_module,
+                entry_point: "main",
+            },
+            fragment_stage: Some(wgpu::ProgrammableStageDescriptor {
+                module: &fs_module,
+                entry_point: "main",
+            }),
+            rasterization_state: Some(wgpu::RasterizationStateDescriptor {
+                front_face: wgpu::FrontFace::Ccw,
+                cull_mode: wgpu::CullMode::None,
+                depth_bias: 0,
+                depth_bias_slope_scale: 0.0,
+                depth_bias_clamp: 0.0,
+            }),
+            primitive_topology: wgpu::PrimitiveTopology::TriangleList,
+            color_states: &[wgpu::ColorStateDescriptor {
+                format: wgpu::TextureFormat::Bgra8UnormSrgb,
+                color_blend: wgpu::BlendDescriptor::REPLACE,
+                alpha_blend: wgpu::BlendDescriptor::REPLACE,
+                write_mask: wgpu::ColorWrite::ALL,
+            }],
+            depth_stencil_state: None,
+            index_format: wgpu::IndexFormat::Uint16,
+            vertex_buffers: &[],
+            sample_count: 1,
+            sample_mask: !0,
+            alpha_to_coverage_enabled: false,
+        });
+
+    (pipeline, bind_group)
+}
diff --git a/examples/integration/src/shader/frag.spv b/examples/integration/src/shader/frag.spv
new file mode 100644
index 00000000..9d6807c9
--- /dev/null
+++ b/examples/integration/src/shader/frag.spv
diff --git a/examples/integration/src/shader/vert.spv b/examples/integration/src/shader/vert.spv
new file mode 100644
index 00000000..0cabc9c0
--- /dev/null
+++ b/examples/integration/src/shader/vert.spv