Add a new example for OpenGL setup using femtovg (#176)

Cargo.toml

@@ -40,3 +40,6 @@ uuid = { version = "0.8", features = ["v4"] }
 [dev-dependencies]
 rtrb = "0.2"
 softbuffer = "0.3.4"
+
+[workspace]
+members = ["examples/render_femtovg"]

examples/render_femtovg/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "render_femtovg"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+baseview = { path = "../..", features = ["opengl"] }
+femtovg = "0.9.0"

examples/render_femtovg/src/main.rs

@@ -0,0 +1,115 @@
+use baseview::gl::GlConfig;
+use baseview::{
+    Event, EventStatus, MouseEvent, PhyPoint, Size, Window, WindowEvent, WindowHandler, WindowInfo,
+    WindowOpenOptions, WindowScalePolicy,
+};
+use femtovg::renderer::OpenGl;
+use femtovg::{Canvas, Color};
+
+struct FemtovgExample {
+    canvas: Canvas<OpenGl>,
+    current_size: WindowInfo,
+    current_mouse_position: PhyPoint,
+    damaged: bool,
+}
+
+impl FemtovgExample {
+    fn new(window: &mut Window) -> Self {
+        let context = window.gl_context().unwrap();
+        unsafe { context.make_current() };
+
+        let renderer =
+            unsafe { OpenGl::new_from_function(|s| context.get_proc_address(s)) }.unwrap();
+
+        let mut canvas = Canvas::new(renderer).unwrap();
+        // TODO: get actual window width
+        canvas.set_size(512, 512, 1.0);
+
+        unsafe { context.make_not_current() };
+        Self {
+            canvas,
+            current_size: WindowInfo::from_logical_size(Size { width: 512.0, height: 512.0 }, 1.0),
+            current_mouse_position: PhyPoint { x: 256, y: 256 },
+            damaged: true,
+        }
+    }
+}
+
+impl WindowHandler for FemtovgExample {
+    fn on_frame(&mut self, window: &mut Window) {
+        if !self.damaged {
+            return;
+        }
+
+        let context = window.gl_context().unwrap();
+        unsafe { context.make_current() };
+
+        let screen_height = self.canvas.height();
+        let screen_width = self.canvas.width();
+
+        // Clear
+        self.canvas.clear_rect(0, 0, screen_width, screen_height, Color::rgb(0xAA, 0xAA, 0xAA));
+
+        // Make big blue rectangle
+        self.canvas.clear_rect(
+            (screen_width as f32 * 0.1).floor() as u32,
+            (screen_height as f32 * 0.1).floor() as u32,
+            (screen_width as f32 * 0.8).floor() as u32,
+            (screen_height as f32 * 0.8).floor() as u32,
+            Color::rgbf(0., 0.3, 0.9),
+        );
+
+        // Make smol orange rectangle
+        self.canvas.clear_rect(
+            (self.current_mouse_position.x - 15).clamp(0, screen_width as i32 - 30) as u32,
+            (self.current_mouse_position.y - 15).clamp(0, screen_height as i32 - 30) as u32,
+            30,
+            30,
+            Color::rgbf(0.9, 0.3, 0.),
+        );
+
+        // Tell renderer to execute all drawing commands
+        self.canvas.flush();
+        context.swap_buffers();
+        unsafe { context.make_not_current() };
+        self.damaged = false;
+    }
+
+    fn on_event(&mut self, _window: &mut Window, event: Event) -> EventStatus {
+        match event {
+            Event::Window(WindowEvent::Resized(size)) => {
+                let phy_size = size.physical_size();
+                self.current_size = size;
+                self.canvas.set_size(phy_size.width, phy_size.height, size.scale() as f32);
+                self.damaged = true;
+            }
+            Event::Mouse(MouseEvent::CursorMoved { position, .. }) => {
+                self.current_mouse_position = position.to_physical(&self.current_size);
+                self.damaged = true;
+            }
+            _ => {}
+        };
+        log_event(&event);
+        EventStatus::Captured
+    }
+}
+
+fn main() {
+    let window_open_options = WindowOpenOptions {
+        title: "Femtovg on Baseview".into(),
+        size: Size::new(512.0, 512.0),
+        scale: WindowScalePolicy::SystemScaleFactor,
+
+        gl_config: Some(GlConfig { alpha_bits: 8, ..GlConfig::default() }),
+    };
+
+    Window::open_blocking(window_open_options, FemtovgExample::new);
+}
+
+fn log_event(event: &Event) {
+    match event {
+        Event::Mouse(e) => println!("Mouse event: {:?}", e),
+        Event::Keyboard(e) => println!("Keyboard event: {:?}", e),
+        Event::Window(e) => println!("Window event: {:?}", e),
+    }
+}