x11: Add XCB support to the X11 backend (#52)

examples/libxcb.rs

@@ -0,0 +1,136 @@
+//! Example of using `softbuffer` with `libxcb`.
+
+#[cfg(all(feature = "x11", any(target_os = "linux", target_os = "freebsd")))]
+mod example {
+    use raw_window_handle::{RawDisplayHandle, RawWindowHandle, XcbDisplayHandle, XcbWindowHandle};
+    use softbuffer::GraphicsContext;
+    use x11rb::{
+        connection::Connection,
+        protocol::{
+            xproto::{self, ConnectionExt as _},
+            Event,
+        },
+        xcb_ffi::XCBConnection,
+    };
+
+    pub(crate) fn run() {
+        // Create a new XCB connection
+        let (conn, screen) = XCBConnection::connect(None).expect("Failed to connect to X server");
+
+        // x11rb doesn't use raw-window-handle yet, so just create our own.
+        let mut display_handle = XcbDisplayHandle::empty();
+        display_handle.connection = conn.get_raw_xcb_connection() as *mut _;
+        display_handle.screen = screen as _;
+
+        // Create a new window.
+        let mut width = 640u16;
+        let mut height = 480u16;
+
+        let window = conn.generate_id().unwrap();
+        let screen = &conn.setup().roots[screen];
+        let (root_visual, root_parent) = (screen.root_visual, screen.root);
+        conn.create_window(
+            x11rb::COPY_FROM_PARENT as _,
+            window,
+            root_parent,
+            0,
+            0,
+            width,
+            height,
+            0,
+            xproto::WindowClass::COPY_FROM_PARENT,
+            root_visual,
+            &xproto::CreateWindowAux::new()
+                .background_pixel(screen.white_pixel)
+                .event_mask(xproto::EventMask::EXPOSURE | xproto::EventMask::STRUCTURE_NOTIFY),
+        )
+        .unwrap()
+        .check()
+        .unwrap();
+
+        let mut window_handle = XcbWindowHandle::empty();
+        window_handle.window = window as _;
+        window_handle.visual_id = root_visual as _;
+
+        // Create a new softbuffer context.
+        // SAFETY: The display and window handles outlive the context.
+        let mut context = unsafe {
+            GraphicsContext::from_raw(
+                RawWindowHandle::Xcb(window_handle),
+                RawDisplayHandle::Xcb(display_handle),
+            )
+        }
+        .unwrap();
+
+        // Register an atom for closing the window.
+        let wm_protocols_atom = conn
+            .intern_atom(false, "WM_PROTOCOLS".as_bytes())
+            .unwrap()
+            .reply()
+            .unwrap()
+            .atom;
+        let delete_window_atom = conn
+            .intern_atom(false, "WM_DELETE_WINDOW".as_bytes())
+            .unwrap()
+            .reply()
+            .unwrap()
+            .atom;
+        conn.change_property(
+            xproto::PropMode::REPLACE as _,
+            window,
+            wm_protocols_atom,
+            xproto::AtomEnum::ATOM,
+            32,
+            1,
+            &delete_window_atom.to_ne_bytes(),
+        )
+        .unwrap()
+        .check()
+        .unwrap();
+
+        // Map the window to the screen.
+        conn.map_window(window).unwrap().check().unwrap();
+
+        // Pump events.
+        loop {
+            let event = conn.wait_for_event().unwrap();
+
+            match event {
+                Event::Expose(_) => {
+                    // Draw a width x height red rectangle.
+                    let red = 255 << 16;
+                    let source = std::iter::repeat(red)
+                        .take((width as usize * height as usize) as _)
+                        .collect::<Vec<_>>();
+
+                    // Draw the buffer.
+                    context.set_buffer(&source, width, height);
+                }
+                Event::ConfigureNotify(configure_notify) => {
+                    width = configure_notify.width;
+                    height = configure_notify.height;
+                }
+                Event::ClientMessage(cm) => {
+                    if cm.data.as_data32()[0] == delete_window_atom {
+                        break;
+                    }
+                }
+                _ => {}
+            }
+        }
+
+        // Delete the context and drop the window.
+        drop(context);
+        conn.destroy_window(window).unwrap().check().unwrap();
+    }
+}
+
+#[cfg(all(feature = "x11", any(target_os = "linux", target_os = "freebsd")))]
+fn main() {
+    example::run();
+}
+
+#[cfg(not(all(feature = "x11", any(target_os = "linux", target_os = "freebsd"))))]
+fn main() {
+    eprintln!("This example requires the `x11` feature to be enabled on a supported platform.");
+}