Working imgui

src/gui.rs

@@ -1,7 +1,139 @@
-struct ImguiDemo {
-    canvas: framework::ShaderCanvas,
+use pixels::{wgpu, PixelsContext};
+use std::time::Instant;
+
+/// Manages all state required for rendering Dear ImGui over `Pixels`.
+pub(crate) struct Gui {
     imgui: imgui::Context,
     platform: imgui_winit_support::WinitPlatform,
-    renderer: Renderer,
-    last_cursor: Option<MouseCursor>,
+    renderer: imgui_wgpu::Renderer,
+    last_frame: Instant,
+    last_cursor: Option<imgui::MouseCursor>,
+    about_open: bool,
+}
+
+impl Gui {
+    /// Create Dear ImGui.
+    pub(crate) fn new(window: &winit::window::Window, pixels: &pixels::Pixels) -> Self {
+        // Create Dear ImGui context
+        let mut imgui = imgui::Context::create();
+        imgui.set_ini_filename(None);
+
+        // Initialize winit platform support
+        let mut platform = imgui_winit_support::WinitPlatform::init(&mut imgui);
+        platform.attach_window(
+            imgui.io_mut(),
+            window,
+            imgui_winit_support::HiDpiMode::Default,
+        );
+
+        // Configure Dear ImGui fonts
+        let hidpi_factor = window.scale_factor();
+        let font_size = (13.0 * hidpi_factor) as f32;
+        imgui.io_mut().font_global_scale = (1.0 / hidpi_factor) as f32;
+        imgui
+            .fonts()
+            .add_font(&[imgui::FontSource::DefaultFontData {
+                config: Some(imgui::FontConfig {
+                    oversample_h: 1,
+                    pixel_snap_h: true,
+                    size_pixels: font_size,
+                    ..Default::default()
+                }),
+            }]);
+
+        // Create Dear ImGui WGPU renderer
+        let device = pixels.device();
+        let queue = pixels.queue();
+        let config = imgui_wgpu::RendererConfig {
+            texture_format: pixels.render_texture_format(),
+            ..Default::default()
+        };
+        let renderer = imgui_wgpu::Renderer::new(&mut imgui, device, queue, config);
+
+        // Return GUI context
+        Self {
+            imgui,
+            platform,
+            renderer,
+            last_frame: Instant::now(),
+            last_cursor: None,
+            about_open: true,
+        }
+    }
+
+    /// Prepare Dear ImGui.
+    pub(crate) fn prepare(
+        &mut self,
+        window: &winit::window::Window,
+    ) -> Result<(), winit::error::ExternalError> {
+        // Prepare Dear ImGui
+        let now = Instant::now();
+        self.imgui.io_mut().update_delta_time(now - self.last_frame);
+        self.last_frame = now;
+        self.platform.prepare_frame(self.imgui.io_mut(), window)
+    }
+
+    /// Render Dear ImGui.
+    pub(crate) fn render(
+        &mut self,
+        window: &winit::window::Window,
+        encoder: &mut wgpu::CommandEncoder,
+        render_target: &wgpu::TextureView,
+        context: &PixelsContext,
+    ) -> imgui_wgpu::RendererResult<()> {
+        // Start a new Dear ImGui frame and update the cursor
+        let ui = self.imgui.new_frame();
+
+        let mouse_cursor = ui.mouse_cursor();
+        if self.last_cursor != mouse_cursor {
+            self.last_cursor = mouse_cursor;
+            self.platform.prepare_render(ui, window);
+        }
+
+        // Draw windows and GUI elements here
+        let mut about_open = false;
+        ui.main_menu_bar(|| {
+            ui.menu("Help", || {
+                about_open = ui.menu_item("About...");
+            });
+        });
+        if about_open {
+            self.about_open = true;
+        }
+
+        if self.about_open {
+            ui.show_about_window(&mut self.about_open);
+        }
+
+        // Render Dear ImGui with WGPU
+        let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: Some("imgui"),
+            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                view: render_target,
+                resolve_target: None,
+                ops: wgpu::Operations {
+                    load: wgpu::LoadOp::Load,
+                    store: true,
+                },
+            })],
+            depth_stencil_attachment: None,
+        });
+
+        self.renderer.render(
+            self.imgui.render(),
+            &context.queue,
+            &context.device,
+            &mut rpass,
+        )
+    }
+
+    /// Handle any outstanding events.
+    pub(crate) fn handle_event(
+        &mut self,
+        window: &winit::window::Window,
+        event: &winit::event::Event<()>,
+    ) {
+        self.platform
+            .handle_event(self.imgui.io_mut(), window, event);
+    }
 }