add text-sizes example (#114)

* add text-sizes example

* rename window title in text-sizes example

examples/text-sizes.rs

@@ -0,0 +1,303 @@
+use glyphon::{
+    Attrs, Buffer, Cache, Color, ColorMode, Family, FontSystem, Metrics, Resolution, Shaping,
+    SwashCache, TextArea, TextAtlas, TextBounds, TextRenderer, Viewport, Weight,
+};
+use std::sync::Arc;
+use wgpu::{
+    CommandEncoderDescriptor, CompositeAlphaMode, DeviceDescriptor, Instance, InstanceDescriptor,
+    LoadOp, MultisampleState, Operations, PresentMode, RenderPassColorAttachment,
+    RenderPassDescriptor, RequestAdapterOptions, SurfaceConfiguration, TextureFormat,
+    TextureUsages, TextureViewDescriptor,
+};
+use winit::{
+    dpi::{LogicalSize, PhysicalSize},
+    event::WindowEvent,
+    event_loop::EventLoop,
+    window::Window,
+};
+
+const TEXT: &str = "The quick brown fox jumped over the lazy doggo. 🐕";
+const WEIGHT: Weight = Weight::NORMAL;
+const SIZES: [f32; 16] = [
+    8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 18.0, 20.0, 22.0, 24.0, 28.0, 32.0, 48.0,
+];
+const LINE_HEIGHT: f32 = 1.15;
+const BG_COLOR: wgpu::Color = wgpu::Color::WHITE;
+const FONT_COLOR: Color = Color::rgb(0, 0, 0);
+//const BG_COLOR: wgpu::Color = wgpu::Color::BLACK;
+//const FONT_COLOR: Color = Color::rgb(255, 255, 255);
+const USE_WEB_COLORS: bool = true;
+
+fn main() {
+    let event_loop = EventLoop::new().unwrap();
+    event_loop
+        .run_app(&mut Application { window_state: None })
+        .unwrap();
+}
+
+struct WindowState {
+    device: wgpu::Device,
+    queue: wgpu::Queue,
+    surface: wgpu::Surface<'static>,
+    surface_config: SurfaceConfiguration,
+    physical_size: PhysicalSize<i32>,
+    scale_factor: f32,
+
+    font_system: FontSystem,
+    swash_cache: SwashCache,
+    viewport: glyphon::Viewport,
+    atlas: glyphon::TextAtlas,
+    text_renderer: glyphon::TextRenderer,
+    buffers: Vec<glyphon::Buffer>,
+
+    // Make sure that the winit window is last in the struct so that
+    // it is dropped after the wgpu surface is dropped, otherwise the
+    // program may crash when closed. This is probably a bug in wgpu.
+    window: Arc<Window>,
+}
+
+impl WindowState {
+    async fn new(window: Arc<Window>) -> Self {
+        let physical_size = window.inner_size();
+        let scale_factor = window.scale_factor() as f32;
+
+        // Set up surface
+        let instance = Instance::new(InstanceDescriptor::default());
+        let adapter = instance
+            .request_adapter(&RequestAdapterOptions::default())
+            .await
+            .unwrap();
+        let (device, queue) = adapter
+            .request_device(&DeviceDescriptor::default(), None)
+            .await
+            .unwrap();
+
+        let (color_mode, swapchain_format) = if USE_WEB_COLORS {
+            (ColorMode::Web, TextureFormat::Bgra8Unorm)
+        } else {
+            (ColorMode::Accurate, TextureFormat::Bgra8UnormSrgb)
+        };
+
+        let surface = instance
+            .create_surface(window.clone())
+            .expect("Create surface");
+        let surface_config = SurfaceConfiguration {
+            usage: TextureUsages::RENDER_ATTACHMENT,
+            format: swapchain_format,
+            width: physical_size.width,
+            height: physical_size.height,
+            present_mode: PresentMode::Fifo,
+            alpha_mode: CompositeAlphaMode::Opaque,
+            view_formats: vec![],
+            desired_maximum_frame_latency: 2,
+        };
+        surface.configure(&device, &surface_config);
+
+        let logical_width = physical_size.width as f32 / scale_factor;
+
+        // Set up text renderer
+        let mut font_system = FontSystem::new();
+        let swash_cache = SwashCache::new();
+        let cache = Cache::new(&device);
+        let viewport = Viewport::new(&device, &cache);
+        let mut atlas =
+            TextAtlas::with_color_mode(&device, &queue, &cache, swapchain_format, color_mode);
+        let text_renderer =
+            TextRenderer::new(&mut atlas, &device, MultisampleState::default(), None);
+
+        let attrs = Attrs::new().family(Family::SansSerif).weight(WEIGHT);
+        let shaping = Shaping::Advanced;
+
+        let buffers: Vec<glyphon::Buffer> = SIZES
+            .iter()
+            .copied()
+            .map(|s| {
+                let mut text_buffer =
+                    Buffer::new(&mut font_system, Metrics::relative(s, LINE_HEIGHT));
+
+                text_buffer.set_size(&mut font_system, Some(logical_width - 20.0), None);
+
+                text_buffer.set_text(
+                    &mut font_system,
+                    &format!("size {s}: {TEXT}"),
+                    attrs,
+                    shaping,
+                );
+
+                text_buffer.shape_until_scroll(&mut font_system, false);
+
+                text_buffer
+            })
+            .collect();
+
+        Self {
+            device,
+            queue,
+            surface,
+            surface_config,
+            physical_size: physical_size.cast(),
+            scale_factor: scale_factor as f32,
+            font_system,
+            swash_cache,
+            viewport,
+            atlas,
+            text_renderer,
+            buffers,
+            window,
+        }
+    }
+}
+
+struct Application {
+    window_state: Option<WindowState>,
+}
+
+impl winit::application::ApplicationHandler for Application {
+    fn resumed(&mut self, event_loop: &winit::event_loop::ActiveEventLoop) {
+        if self.window_state.is_some() {
+            return;
+        }
+
+        // Set up window
+        let (width, height) = (800, 600);
+        let window_attributes = Window::default_attributes()
+            .with_inner_size(LogicalSize::new(width as f64, height as f64))
+            .with_title("glyphon text sizes test");
+        let window = Arc::new(event_loop.create_window(window_attributes).unwrap());
+
+        self.window_state = Some(pollster::block_on(WindowState::new(window)));
+    }
+
+    fn window_event(
+        &mut self,
+        event_loop: &winit::event_loop::ActiveEventLoop,
+        _window_id: winit::window::WindowId,
+        event: WindowEvent,
+    ) {
+        let Some(state) = &mut self.window_state else {
+            return;
+        };
+
+        let WindowState {
+            window,
+            device,
+            queue,
+            surface,
+            surface_config,
+            font_system,
+            swash_cache,
+            viewport,
+            atlas,
+            text_renderer,
+            buffers,
+            scale_factor,
+            physical_size,
+            ..
+        } = state;
+
+        match event {
+            WindowEvent::Resized(size) => {
+                surface_config.width = size.width;
+                surface_config.height = size.height;
+                surface.configure(&device, &surface_config);
+                window.request_redraw();
+
+                *scale_factor = window.scale_factor() as f32;
+                *physical_size = size.cast();
+
+                let logical_width = size.width as f32 / *scale_factor;
+
+                for b in buffers.iter_mut() {
+                    b.set_size(font_system, Some(logical_width - 20.0), None);
+                    b.shape_until_scroll(font_system, false);
+                }
+            }
+            WindowEvent::RedrawRequested => {
+                viewport.update(
+                    &queue,
+                    Resolution {
+                        width: surface_config.width,
+                        height: surface_config.height,
+                    },
+                );
+
+                let scale_factor = *scale_factor;
+
+                let left = 10.0 * scale_factor;
+                let mut top = 10.0 * scale_factor;
+
+                let bounds_left = left.floor() as i32;
+                let bounds_right = physical_size.width - 10;
+
+                let text_areas: Vec<TextArea> = buffers
+                    .iter()
+                    .map(|b| {
+                        let a = TextArea {
+                            buffer: b,
+                            left,
+                            top,
+                            scale: scale_factor,
+                            bounds: TextBounds {
+                                left: bounds_left,
+                                top: top.floor() as i32,
+                                right: bounds_right,
+                                bottom: top.floor() as i32 + physical_size.height,
+                            },
+                            default_color: FONT_COLOR,
+                        };
+
+                        let total_lines = b
+                            .layout_runs()
+                            .fold(0usize, |total_lines, _| total_lines + 1);
+
+                        top += (total_lines as f32 * b.metrics().line_height + 5.0) * scale_factor;
+
+                        a
+                    })
+                    .collect();
+
+                text_renderer
+                    .prepare(
+                        device,
+                        queue,
+                        font_system,
+                        atlas,
+                        viewport,
+                        text_areas,
+                        swash_cache,
+                    )
+                    .unwrap();
+
+                let frame = surface.get_current_texture().unwrap();
+                let view = frame.texture.create_view(&TextureViewDescriptor::default());
+                let mut encoder =
+                    device.create_command_encoder(&CommandEncoderDescriptor { label: None });
+                {
+                    let mut pass = encoder.begin_render_pass(&RenderPassDescriptor {
+                        label: None,
+                        color_attachments: &[Some(RenderPassColorAttachment {
+                            view: &view,
+                            resolve_target: None,
+                            ops: Operations {
+                                load: LoadOp::Clear(BG_COLOR),
+                                store: wgpu::StoreOp::Store,
+                            },
+                        })],
+                        depth_stencil_attachment: None,
+                        timestamp_writes: None,
+                        occlusion_query_set: None,
+                    });
+
+                    text_renderer.render(&atlas, &viewport, &mut pass).unwrap();
+                }
+
+                queue.submit(Some(encoder.finish()));
+                frame.present();
+
+                atlas.trim();
+            }
+            WindowEvent::CloseRequested => event_loop.exit(),
+            _ => {}
+        }
+    }
+}