Merge pull request #115 from robbert-vdh/feature/merge-raw-gl-context

Merge raw-gl-context into baseview to allow OpenGL contexts to be created during window creation

.github/workflows/rust.yml

@@ -21,7 +21,9 @@ jobs:
       with:
         toolchain: stable
         override: true
-    - name: Build
+    - name: Build with default features
       run: cargo build --examples --workspace --verbose
+    - name: Build again with all features
+      run: cargo build --examples --workspace --all-features --verbose
     - name: Run tests
-      run: cargo test --examples --workspace --verbose
+      run: cargo test --examples --workspace --all-features --verbose

Cargo.toml

@@ -9,13 +9,18 @@ authors = [
     "Billy Messenger <billydm@protonmail.com>",
     "Anton Lazarev <https://antonok.com>",
     "Joakim Frostegård <joakim.frostegard@gmail.com>",
+    "Robbert van der Helm <mail@robbertvanderhelm.nl>",
 ]
 edition = "2018"
 license = "MIT OR Apache-2.0"
 
+[features]
+default = []
+opengl = ["uuid", "x11/glx"]
+
 [dependencies]
 keyboard-types = { version = "0.6.1", default-features = false }
-raw-window-handle = "0.3.3"
+raw-window-handle = "0.4.2"
 
 [target.'cfg(target_os="linux")'.dependencies]
 xcb = { version = "0.9", features = ["thread", "xlib_xcb", "dri2"] }
@@ -25,6 +30,7 @@ nix = "0.22.0"
 
 [target.'cfg(target_os="windows")'.dependencies]
 winapi = { version = "0.3.8", features = ["libloaderapi", "winuser", "windef", "minwindef", "guiddef", "combaseapi", "wingdi", "errhandlingapi"] }
+uuid = { version = "0.8", features = ["v4"], optional = true }
 
 [target.'cfg(target_os="macos")'.dependencies]
 cocoa = "0.24.0"

README.md

@@ -10,13 +10,14 @@ Interested in learning more about the project? Join us on [discord](https://disc
 
 Below is a proposed list of milestones (roughly in-order) and their status. Subject to change at any time.
 
-| Feature                                         | Windows            | Mac OS             | Linux              |
-| ----------------------------------------------- | ------------------ | ------------------ | ------------------ |
-| Spawns a window, no parent                      | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
-| Cross-platform API for window spawning          | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
-| Can find DPI scale factor                       |                    | :heavy_check_mark: | :heavy_check_mark: |
-| Basic event handling (mouse, keyboard)          | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
-| Parent window support                           | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
+| Feature                                               | Windows            | Mac OS             | Linux              |
+| ----------------------------------------------------- | ------------------ | ------------------ | ------------------ |
+| Spawns a window, no parent                            | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
+| Cross-platform API for window spawning                | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
+| Can find DPI scale factor                             |                    | :heavy_check_mark: | :heavy_check_mark: |
+| Basic event handling (mouse, keyboard)                | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
+| Parent window support                                 | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
+| OpenGL context creation (behind the `opengl` feature) | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 
 ## Prerequisites
 

examples/open_window.rs

@@ -36,6 +36,10 @@ fn main() {
         title: "baseview".into(),
         size: baseview::Size::new(512.0, 512.0),
         scale: WindowScalePolicy::SystemScaleFactor,
+
+        // TODO: Add an example that uses the OpenGL context
+        #[cfg(feature = "opengl")]
+        gl_config: None,
     };
 
     let (mut tx, rx) = RingBuffer::new(128);

src/gl/macos.rs

@@ -0,0 +1,146 @@
+use std::ffi::c_void;
+use std::str::FromStr;
+
+use raw_window_handle::{HasRawWindowHandle, RawWindowHandle};
+
+use cocoa::appkit::{
+    NSOpenGLContext, NSOpenGLContextParameter, NSOpenGLPFAAccelerated, NSOpenGLPFAAlphaSize,
+    NSOpenGLPFAColorSize, NSOpenGLPFADepthSize, NSOpenGLPFADoubleBuffer, NSOpenGLPFAMultisample,
+    NSOpenGLPFAOpenGLProfile, NSOpenGLPFASampleBuffers, NSOpenGLPFASamples, NSOpenGLPFAStencilSize,
+    NSOpenGLPixelFormat, NSOpenGLProfileVersion3_2Core, NSOpenGLProfileVersion4_1Core,
+    NSOpenGLProfileVersionLegacy, NSOpenGLView, NSView,
+};
+use cocoa::base::{id, nil, YES};
+
+use core_foundation::base::TCFType;
+use core_foundation::bundle::{CFBundleGetBundleWithIdentifier, CFBundleGetFunctionPointerForName};
+use core_foundation::string::CFString;
+
+use objc::{msg_send, sel, sel_impl};
+
+use super::{GlConfig, GlError, Profile};
+
+pub type CreationFailedError = ();
+pub struct GlContext {
+    view: id,
+    context: id,
+}
+
+impl GlContext {
+    pub unsafe fn create(
+        parent: &impl HasRawWindowHandle, config: GlConfig,
+    ) -> Result<GlContext, GlError> {
+        let handle = if let RawWindowHandle::AppKit(handle) = parent.raw_window_handle() {
+            handle
+        } else {
+            return Err(GlError::InvalidWindowHandle);
+        };
+
+        if handle.ns_view.is_null() {
+            return Err(GlError::InvalidWindowHandle);
+        }
+
+        let parent_view = handle.ns_view as id;
+
+        let version = if config.version < (3, 2) && config.profile == Profile::Compatibility {
+            NSOpenGLProfileVersionLegacy
+        } else if config.version == (3, 2) && config.profile == Profile::Core {
+            NSOpenGLProfileVersion3_2Core
+        } else if config.version > (3, 2) && config.profile == Profile::Core {
+            NSOpenGLProfileVersion4_1Core
+        } else {
+            return Err(GlError::VersionNotSupported);
+        };
+
+        #[rustfmt::skip]
+        let mut attrs = vec![
+            NSOpenGLPFAOpenGLProfile as u32, version as u32,
+            NSOpenGLPFAColorSize as u32, (config.red_bits + config.blue_bits + config.green_bits) as u32,
+            NSOpenGLPFAAlphaSize as u32, config.alpha_bits as u32,
+            NSOpenGLPFADepthSize as u32, config.depth_bits as u32,
+            NSOpenGLPFAStencilSize as u32, config.stencil_bits as u32,
+            NSOpenGLPFAAccelerated as u32,
+        ];
+
+        if config.samples.is_some() {
+            #[rustfmt::skip]
+            attrs.extend_from_slice(&[
+                NSOpenGLPFAMultisample as u32,
+                NSOpenGLPFASampleBuffers as u32, 1,
+                NSOpenGLPFASamples as u32, config.samples.unwrap() as u32,
+            ]);
+        }
+
+        if config.double_buffer {
+            attrs.push(NSOpenGLPFADoubleBuffer as u32);
+        }
+
+        attrs.push(0);
+
+        let pixel_format = NSOpenGLPixelFormat::alloc(nil).initWithAttributes_(&attrs);
+
+        if pixel_format == nil {
+            return Err(GlError::CreationFailed(()));
+        }
+
+        let view =
+            NSOpenGLView::alloc(nil).initWithFrame_pixelFormat_(parent_view.frame(), pixel_format);
+
+        if view == nil {
+            return Err(GlError::CreationFailed(()));
+        }
+
+        view.setWantsBestResolutionOpenGLSurface_(YES);
+
+        let () = msg_send![view, retain];
+        NSOpenGLView::display_(view);
+        parent_view.addSubview_(view);
+
+        let context: id = msg_send![view, openGLContext];
+        let () = msg_send![context, retain];
+
+        context.setValues_forParameter_(
+            &(config.vsync as i32),
+            NSOpenGLContextParameter::NSOpenGLCPSwapInterval,
+        );
+
+        let () = msg_send![pixel_format, release];
+
+        Ok(GlContext { view, context })
+    }
+
+    pub unsafe fn make_current(&self) {
+        self.context.makeCurrentContext();
+    }
+
+    pub unsafe fn make_not_current(&self) {
+        NSOpenGLContext::clearCurrentContext(self.context);
+    }
+
+    pub fn get_proc_address(&self, symbol: &str) -> *const c_void {
+        let symbol_name = CFString::from_str(symbol).unwrap();
+        let framework_name = CFString::from_str("com.apple.opengl").unwrap();
+        let framework =
+            unsafe { CFBundleGetBundleWithIdentifier(framework_name.as_concrete_TypeRef()) };
+        let addr = unsafe {
+            CFBundleGetFunctionPointerForName(framework, symbol_name.as_concrete_TypeRef())
+        };
+        addr as *const c_void
+    }
+
+    pub fn swap_buffers(&self) {
+        unsafe {
+            self.context.flushBuffer();
+            let () = msg_send![self.view, setNeedsDisplay: YES];
+        }
+    }
+}
+
+impl Drop for GlContext {
+    fn drop(&mut self) {
+        unsafe {
+            let () = msg_send![self.context, release];
+            let () = msg_send![self.view, release];
+        }
+    }
+}

src/gl/mod.rs

@@ -0,0 +1,109 @@
+use std::ffi::c_void;
+use std::marker::PhantomData;
+
+// On X11 creating the context is a two step process
+#[cfg(not(target_os = "linux"))]
+use raw_window_handle::HasRawWindowHandle;
+
+#[cfg(target_os = "windows")]
+mod win;
+#[cfg(target_os = "windows")]
+use win as platform;
+
+// We need to use this directly within the X11 window creation to negotiate the correct visual
+#[cfg(target_os = "linux")]
+pub(crate) mod x11;
+#[cfg(target_os = "linux")]
+pub(crate) use self::x11 as platform;
+
+#[cfg(target_os = "macos")]
+mod macos;
+#[cfg(target_os = "macos")]
+use macos as platform;
+
+#[derive(Clone, Debug)]
+pub struct GlConfig {
+    pub version: (u8, u8),
+    pub profile: Profile,
+    pub red_bits: u8,
+    pub blue_bits: u8,
+    pub green_bits: u8,
+    pub alpha_bits: u8,
+    pub depth_bits: u8,
+    pub stencil_bits: u8,
+    pub samples: Option<u8>,
+    pub srgb: bool,
+    pub double_buffer: bool,
+    pub vsync: bool,
+}
+
+impl Default for GlConfig {
+    fn default() -> Self {
+        GlConfig {
+            version: (3, 2),
+            profile: Profile::Core,
+            red_bits: 8,
+            blue_bits: 8,
+            green_bits: 8,
+            alpha_bits: 8,
+            depth_bits: 24,
+            stencil_bits: 8,
+            samples: None,
+            srgb: true,
+            double_buffer: true,
+            vsync: false,
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum Profile {
+    Compatibility,
+    Core,
+}
+
+#[derive(Debug)]
+pub enum GlError {
+    InvalidWindowHandle,
+    VersionNotSupported,
+    CreationFailed(platform::CreationFailedError),
+}
+
+pub struct GlContext {
+    context: platform::GlContext,
+    phantom: PhantomData<*mut ()>,
+}
+
+impl GlContext {
+    #[cfg(not(target_os = "linux"))]
+    pub(crate) unsafe fn create(
+        parent: &impl HasRawWindowHandle, config: GlConfig,
+    ) -> Result<GlContext, GlError> {
+        platform::GlContext::create(parent, config)
+            .map(|context| GlContext { context, phantom: PhantomData })
+    }
+
+    /// The X11 version needs to be set up in a different way compared to the Windows and macOS
+    /// versions. So the platform-specific versions should be used to construct the context within
+    /// baseview, and then this object can be passed to the user.
+    #[cfg(target_os = "linux")]
+    pub(crate) fn new(context: platform::GlContext) -> GlContext {
+        GlContext { context, phantom: PhantomData }
+    }
+
+    pub unsafe fn make_current(&self) {
+        self.context.make_current();
+    }
+
+    pub unsafe fn make_not_current(&self) {
+        self.context.make_not_current();
+    }
+
+    pub fn get_proc_address(&self, symbol: &str) -> *const c_void {
+        self.context.get_proc_address(symbol)
+    }
+
+    pub fn swap_buffers(&self) {
+        self.context.swap_buffers();
+    }
+}

src/gl/win.rs

@@ -0,0 +1,306 @@
+use std::ffi::{c_void, CString, OsStr};
+use std::os::windows::ffi::OsStrExt;
+
+use raw_window_handle::{HasRawWindowHandle, RawWindowHandle};
+
+use winapi::shared::minwindef::{HINSTANCE, HMODULE};
+use winapi::shared::ntdef::WCHAR;
+use winapi::shared::windef::{HDC, HGLRC, HWND};
+use winapi::um::libloaderapi::{FreeLibrary, GetProcAddress, LoadLibraryA};
+use winapi::um::wingdi::{
+    wglCreateContext, wglDeleteContext, wglGetProcAddress, wglMakeCurrent, ChoosePixelFormat,
+    DescribePixelFormat, SetPixelFormat, SwapBuffers, PFD_DOUBLEBUFFER, PFD_DRAW_TO_WINDOW,
+    PFD_MAIN_PLANE, PFD_SUPPORT_OPENGL, PFD_TYPE_RGBA, PIXELFORMATDESCRIPTOR,
+};
+use winapi::um::winnt::IMAGE_DOS_HEADER;
+use winapi::um::winuser::{
+    CreateWindowExW, DefWindowProcW, DestroyWindow, GetDC, RegisterClassW, ReleaseDC,
+    UnregisterClassW, CS_OWNDC, CW_USEDEFAULT, WNDCLASSW,
+};
+
+use super::{GlConfig, GlError, Profile};
+
+// See https://www.khronos.org/registry/OpenGL/extensions/ARB/WGL_ARB_create_context.txt
+
+type WglCreateContextAttribsARB = extern "system" fn(HDC, HGLRC, *const i32) -> HGLRC;
+
+const WGL_CONTEXT_MAJOR_VERSION_ARB: i32 = 0x2091;
+const WGL_CONTEXT_MINOR_VERSION_ARB: i32 = 0x2092;
+const WGL_CONTEXT_PROFILE_MASK_ARB: i32 = 0x9126;
+
+const WGL_CONTEXT_CORE_PROFILE_BIT_ARB: i32 = 0x00000001;
+const WGL_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB: i32 = 0x00000002;
+
+// See https://www.khronos.org/registry/OpenGL/extensions/ARB/WGL_ARB_pixel_format.txt
+
+type WglChoosePixelFormatARB =
+    extern "system" fn(HDC, *const i32, *const f32, u32, *mut i32, *mut u32) -> i32;
+
+const WGL_DRAW_TO_WINDOW_ARB: i32 = 0x2001;
+const WGL_ACCELERATION_ARB: i32 = 0x2003;
+const WGL_SUPPORT_OPENGL_ARB: i32 = 0x2010;
+const WGL_DOUBLE_BUFFER_ARB: i32 = 0x2011;
+const WGL_PIXEL_TYPE_ARB: i32 = 0x2013;
+const WGL_RED_BITS_ARB: i32 = 0x2015;
+const WGL_GREEN_BITS_ARB: i32 = 0x2017;
+const WGL_BLUE_BITS_ARB: i32 = 0x2019;
+const WGL_ALPHA_BITS_ARB: i32 = 0x201B;
+const WGL_DEPTH_BITS_ARB: i32 = 0x2022;
+const WGL_STENCIL_BITS_ARB: i32 = 0x2023;
+
+const WGL_FULL_ACCELERATION_ARB: i32 = 0x2027;
+const WGL_TYPE_RGBA_ARB: i32 = 0x202B;
+
+// See https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_multisample.txt
+
+const WGL_SAMPLE_BUFFERS_ARB: i32 = 0x2041;
+const WGL_SAMPLES_ARB: i32 = 0x2042;
+
+// See https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_framebuffer_sRGB.txt
+
+const WGL_FRAMEBUFFER_SRGB_CAPABLE_ARB: i32 = 0x20A9;
+
+// See https://www.khronos.org/registry/OpenGL/extensions/EXT/WGL_EXT_swap_control.txt
+
+type WglSwapIntervalEXT = extern "system" fn(i32) -> i32;
+
+pub type CreationFailedError = ();
+pub struct GlContext {
+    hwnd: HWND,
+    hdc: HDC,
+    hglrc: HGLRC,
+    gl_library: HMODULE,
+}
+
+extern "C" {
+    static __ImageBase: IMAGE_DOS_HEADER;
+}
+
+impl GlContext {
+    pub unsafe fn create(
+        parent: &impl HasRawWindowHandle, config: GlConfig,
+    ) -> Result<GlContext, GlError> {
+        let handle = if let RawWindowHandle::Win32(handle) = parent.raw_window_handle() {
+            handle
+        } else {
+            return Err(GlError::InvalidWindowHandle);
+        };
+
+        if handle.hwnd.is_null() {
+            return Err(GlError::InvalidWindowHandle);
+        }
+
+        // Create temporary window and context to load function pointers
+
+        let class_name_str = format!("raw-gl-context-window-{}", uuid::Uuid::new_v4().to_simple());
+        let mut class_name: Vec<WCHAR> = OsStr::new(&class_name_str).encode_wide().collect();
+        class_name.push(0);
+
+        let hinstance = &__ImageBase as *const IMAGE_DOS_HEADER as HINSTANCE;
+
+        let wnd_class = WNDCLASSW {
+            style: CS_OWNDC,
+            lpfnWndProc: Some(DefWindowProcW),
+            hInstance: hinstance,
+            lpszClassName: class_name.as_ptr(),
+            ..std::mem::zeroed()
+        };
+
+        let class = RegisterClassW(&wnd_class);
+        if class == 0 {
+            return Err(GlError::CreationFailed(()));
+        }
+
+        let hwnd_tmp = CreateWindowExW(
+            0,
+            class as *const WCHAR,
+            [0].as_ptr(),
+            0,
+            CW_USEDEFAULT,
+            CW_USEDEFAULT,
+            CW_USEDEFAULT,
+            CW_USEDEFAULT,
+            std::ptr::null_mut(),
+            std::ptr::null_mut(),
+            hinstance,
+            std::ptr::null_mut(),
+        );
+
+        if hwnd_tmp.is_null() {
+            return Err(GlError::CreationFailed(()));
+        }
+
+        let hdc_tmp = GetDC(hwnd_tmp);
+
+        let pfd_tmp = PIXELFORMATDESCRIPTOR {
+            nSize: std::mem::size_of::<PIXELFORMATDESCRIPTOR>() as u16,
+            nVersion: 1,
+            dwFlags: PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER,
+            iPixelType: PFD_TYPE_RGBA,
+            cColorBits: 32,
+            cAlphaBits: 8,
+            cDepthBits: 24,
+            cStencilBits: 8,
+            iLayerType: PFD_MAIN_PLANE,
+            ..std::mem::zeroed()
+        };
+
+        SetPixelFormat(hdc_tmp, ChoosePixelFormat(hdc_tmp, &pfd_tmp), &pfd_tmp);
+
+        let hglrc_tmp = wglCreateContext(hdc_tmp);
+        if hglrc_tmp.is_null() {
+            ReleaseDC(hwnd_tmp, hdc_tmp);
+            UnregisterClassW(class as *const WCHAR, hinstance);
+            DestroyWindow(hwnd_tmp);
+            return Err(GlError::CreationFailed(()));
+        }
+
+        wglMakeCurrent(hdc_tmp, hglrc_tmp);
+
+        #[allow(non_snake_case)]
+        let wglCreateContextAttribsARB: Option<WglCreateContextAttribsARB> = {
+            let symbol = CString::new("wglCreateContextAttribsARB").unwrap();
+            let addr = wglGetProcAddress(symbol.as_ptr());
+            if !addr.is_null() {
+                Some(std::mem::transmute(addr))
+            } else {
+                None
+            }
+        };
+
+        #[allow(non_snake_case)]
+        let wglChoosePixelFormatARB: Option<WglChoosePixelFormatARB> = {
+            let symbol = CString::new("wglChoosePixelFormatARB").unwrap();
+            let addr = wglGetProcAddress(symbol.as_ptr());
+            if !addr.is_null() {
+                Some(std::mem::transmute(addr))
+            } else {
+                None
+            }
+        };
+
+        #[allow(non_snake_case)]
+        let wglSwapIntervalEXT: Option<WglSwapIntervalEXT> = {
+            let symbol = CString::new("wglSwapIntervalEXT").unwrap();
+            let addr = wglGetProcAddress(symbol.as_ptr());
+            if !addr.is_null() {
+                Some(std::mem::transmute(addr))
+            } else {
+                None
+            }
+        };
+
+        wglMakeCurrent(hdc_tmp, std::ptr::null_mut());
+        ReleaseDC(hwnd_tmp, hdc_tmp);
+        UnregisterClassW(class as *const WCHAR, hinstance);
+        DestroyWindow(hwnd_tmp);
+
+        // Create actual context
+
+        let hwnd = handle.hwnd as HWND;
+
+        let hdc = GetDC(hwnd);
+
+        #[rustfmt::skip]
+        let pixel_format_attribs = [
+            WGL_DRAW_TO_WINDOW_ARB, 1,
+            WGL_ACCELERATION_ARB, WGL_FULL_ACCELERATION_ARB,
+            WGL_SUPPORT_OPENGL_ARB, 1,
+            WGL_DOUBLE_BUFFER_ARB, config.double_buffer as i32,
+            WGL_PIXEL_TYPE_ARB, WGL_TYPE_RGBA_ARB,
+            WGL_RED_BITS_ARB, config.red_bits as i32,
+            WGL_GREEN_BITS_ARB, config.green_bits as i32,
+            WGL_BLUE_BITS_ARB, config.blue_bits as i32,
+            WGL_ALPHA_BITS_ARB, config.alpha_bits as i32,
+            WGL_DEPTH_BITS_ARB, config.depth_bits as i32,
+            WGL_STENCIL_BITS_ARB, config.stencil_bits as i32,
+            WGL_SAMPLE_BUFFERS_ARB, config.samples.is_some() as i32,
+            WGL_SAMPLES_ARB, config.samples.unwrap_or(0) as i32,
+            WGL_FRAMEBUFFER_SRGB_CAPABLE_ARB, config.srgb as i32,
+            0,
+        ];
+
+        let mut pixel_format = 0;
+        let mut num_formats = 0;
+        wglChoosePixelFormatARB.unwrap()(
+            hdc,
+            pixel_format_attribs.as_ptr(),
+            std::ptr::null(),
+            1,
+            &mut pixel_format,
+            &mut num_formats,
+        );
+
+        let mut pfd: PIXELFORMATDESCRIPTOR = std::mem::zeroed();
+        DescribePixelFormat(
+            hdc,
+            pixel_format,
+            std::mem::size_of::<PIXELFORMATDESCRIPTOR>() as u32,
+            &mut pfd,
+        );
+        SetPixelFormat(hdc, pixel_format, &pfd);
+
+        let profile_mask = match config.profile {
+            Profile::Core => WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
+            Profile::Compatibility => WGL_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB,
+        };
+
+        #[rustfmt::skip]
+        let ctx_attribs = [
+            WGL_CONTEXT_MAJOR_VERSION_ARB, config.version.0 as i32,
+            WGL_CONTEXT_MINOR_VERSION_ARB, config.version.1 as i32,
+            WGL_CONTEXT_PROFILE_MASK_ARB, profile_mask,
+            0
+        ];
+
+        let hglrc =
+            wglCreateContextAttribsARB.unwrap()(hdc, std::ptr::null_mut(), ctx_attribs.as_ptr());
+        if hglrc.is_null() {
+            return Err(GlError::CreationFailed(()));
+        }
+
+        let gl_library_name = CString::new("opengl32.dll").unwrap();
+        let gl_library = LoadLibraryA(gl_library_name.as_ptr());
+
+        wglMakeCurrent(hdc, hglrc);
+        wglSwapIntervalEXT.unwrap()(config.vsync as i32);
+        wglMakeCurrent(hdc, std::ptr::null_mut());
+
+        Ok(GlContext { hwnd, hdc, hglrc, gl_library })
+    }
+
+    pub unsafe fn make_current(&self) {
+        wglMakeCurrent(self.hdc, self.hglrc);
+    }
+
+    pub unsafe fn make_not_current(&self) {
+        wglMakeCurrent(self.hdc, std::ptr::null_mut());
+    }
+
+    pub fn get_proc_address(&self, symbol: &str) -> *const c_void {
+        let symbol = CString::new(symbol).unwrap();
+        let addr = unsafe { wglGetProcAddress(symbol.as_ptr()) as *const c_void };
+        if !addr.is_null() {
+            addr
+        } else {
+            unsafe { GetProcAddress(self.gl_library, symbol.as_ptr()) as *const c_void }
+        }
+    }
+
+    pub fn swap_buffers(&self) {
+        unsafe {
+            SwapBuffers(self.hdc);
+        }
+    }
+}
+
+impl Drop for GlContext {
+    fn drop(&mut self) {
+        unsafe {
+            wglMakeCurrent(std::ptr::null_mut(), std::ptr::null_mut());
+            wglDeleteContext(self.hglrc);
+            ReleaseDC(self.hwnd, self.hdc);
+            FreeLibrary(self.gl_library);
+        }
+    }
+}

src/gl/x11.rs

@@ -0,0 +1,253 @@
+use std::ffi::{c_void, CString};
+use std::os::raw::{c_int, c_ulong};
+
+use raw_window_handle::{HasRawWindowHandle, RawWindowHandle};
+
+use x11::glx;
+use x11::xlib;
+
+use super::{GlConfig, GlError, Profile};
+
+mod errors;
+
+#[derive(Debug)]
+pub enum CreationFailedError {
+    InvalidFBConfig,
+    NoVisual,
+    GetProcAddressFailed,
+    MakeCurrentFailed,
+    ContextCreationFailed,
+    X11Error(errors::XLibError),
+}
+
+impl From<errors::XLibError> for GlError {
+    fn from(e: errors::XLibError) -> Self {
+        GlError::CreationFailed(CreationFailedError::X11Error(e))
+    }
+}
+
+// See https://www.khronos.org/registry/OpenGL/extensions/ARB/GLX_ARB_create_context.txt
+
+type GlXCreateContextAttribsARB = unsafe extern "C" fn(
+    dpy: *mut xlib::Display,
+    fbc: glx::GLXFBConfig,
+    share_context: glx::GLXContext,
+    direct: xlib::Bool,
+    attribs: *const c_int,
+) -> glx::GLXContext;
+
+// See https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_swap_control.txt
+
+type GlXSwapIntervalEXT =
+    unsafe extern "C" fn(dpy: *mut xlib::Display, drawable: glx::GLXDrawable, interval: i32);
+
+// See https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_framebuffer_sRGB.txt
+
+const GLX_FRAMEBUFFER_SRGB_CAPABLE_ARB: i32 = 0x20B2;
+
+fn get_proc_address(symbol: &str) -> *const c_void {
+    let symbol = CString::new(symbol).unwrap();
+    unsafe { glx::glXGetProcAddress(symbol.as_ptr() as *const u8).unwrap() as *const c_void }
+}
+
+pub struct GlContext {
+    window: c_ulong,
+    display: *mut xlib::_XDisplay,
+    context: glx::GLXContext,
+}
+
+/// The frame buffer configuration along with the general OpenGL configuration to somewhat minimize
+/// misuse.
+pub struct FbConfig {
+    gl_config: GlConfig,
+    fb_config: *mut glx::__GLXFBConfigRec,
+}
+
+/// The configuration a window should be created with after calling
+/// [GlContext::get_fb_config_and_visual].
+pub struct WindowConfig {
+    pub depth: u8,
+    pub visual: u32,
+}
+
+impl GlContext {
+    /// Creating an OpenGL context under X11 works slightly different. Different OpenGL
+    /// configurations require different framebuffer configurations, and to be able to use that
+    /// context with a window the window needs to be created with a matching visual. This means that
+    /// you need to decide on the framebuffer config before creating the window, ask the X11 server
+    /// for a matching visual for that framebuffer config, crate the window with that visual, and
+    /// only then create the OpenGL context.
+    ///
+    /// Use [Self::get_fb_config_and_visual] to create both of these things.
+    pub unsafe fn create(
+        parent: &impl HasRawWindowHandle, config: FbConfig,
+    ) -> Result<GlContext, GlError> {
+        let handle = if let RawWindowHandle::Xlib(handle) = parent.raw_window_handle() {
+            handle
+        } else {
+            return Err(GlError::InvalidWindowHandle);
+        };
+
+        if handle.display.is_null() {
+            return Err(GlError::InvalidWindowHandle);
+        }
+
+        let display = handle.display as *mut xlib::_XDisplay;
+
+        errors::XErrorHandler::handle(display, |error_handler| {
+            #[allow(non_snake_case)]
+            let glXCreateContextAttribsARB: GlXCreateContextAttribsARB = {
+                let addr = get_proc_address("glXCreateContextAttribsARB");
+                if addr.is_null() {
+                    return Err(GlError::CreationFailed(CreationFailedError::GetProcAddressFailed));
+                } else {
+                    std::mem::transmute(addr)
+                }
+            };
+
+            #[allow(non_snake_case)]
+            let glXSwapIntervalEXT: GlXSwapIntervalEXT = {
+                let addr = get_proc_address("glXSwapIntervalEXT");
+                if addr.is_null() {
+                    return Err(GlError::CreationFailed(CreationFailedError::GetProcAddressFailed));
+                } else {
+                    std::mem::transmute(addr)
+                }
+            };
+
+            error_handler.check()?;
+
+            let profile_mask = match config.gl_config.profile {
+                Profile::Core => glx::arb::GLX_CONTEXT_CORE_PROFILE_BIT_ARB,
+                Profile::Compatibility => glx::arb::GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB,
+            };
+
+            #[rustfmt::skip]
+                let ctx_attribs = [
+                glx::arb::GLX_CONTEXT_MAJOR_VERSION_ARB, config.gl_config.version.0 as i32,
+                glx::arb::GLX_CONTEXT_MINOR_VERSION_ARB, config.gl_config.version.1 as i32,
+                glx::arb::GLX_CONTEXT_PROFILE_MASK_ARB, profile_mask,
+                0,
+            ];
+
+            let context = glXCreateContextAttribsARB(
+                display,
+                config.fb_config,
+                std::ptr::null_mut(),
+                1,
+                ctx_attribs.as_ptr(),
+            );
+
+            error_handler.check()?;
+
+            if context.is_null() {
+                return Err(GlError::CreationFailed(CreationFailedError::ContextCreationFailed));
+            }
+
+            let res = glx::glXMakeCurrent(display, handle.window, context);
+            error_handler.check()?;
+            if res == 0 {
+                return Err(GlError::CreationFailed(CreationFailedError::MakeCurrentFailed));
+            }
+
+            glXSwapIntervalEXT(display, handle.window, config.gl_config.vsync as i32);
+            error_handler.check()?;
+
+            if glx::glXMakeCurrent(display, 0, std::ptr::null_mut()) == 0 {
+                error_handler.check()?;
+                return Err(GlError::CreationFailed(CreationFailedError::MakeCurrentFailed));
+            }
+
+            Ok(GlContext { window: handle.window, display, context })
+        })
+    }
+
+    /// Find a matching framebuffer config and window visual for the given OpenGL configuration.
+    /// This needs to be passed to [Self::create] along with a handle to a window that was created
+    /// using the visual also returned from this function.
+    pub unsafe fn get_fb_config_and_visual(
+        display: *mut xlib::_XDisplay, config: GlConfig,
+    ) -> Result<(FbConfig, WindowConfig), GlError> {
+        errors::XErrorHandler::handle(display, |error_handler| {
+            let screen = xlib::XDefaultScreen(display);
+
+            #[rustfmt::skip]
+                let fb_attribs = [
+                glx::GLX_X_RENDERABLE, 1,
+                glx::GLX_X_VISUAL_TYPE, glx::GLX_TRUE_COLOR,
+                glx::GLX_DRAWABLE_TYPE, glx::GLX_WINDOW_BIT,
+                glx::GLX_RENDER_TYPE, glx::GLX_RGBA_BIT,
+                glx::GLX_RED_SIZE, config.red_bits as i32,
+                glx::GLX_GREEN_SIZE, config.green_bits as i32,
+                glx::GLX_BLUE_SIZE, config.blue_bits as i32,
+                glx::GLX_ALPHA_SIZE, config.alpha_bits as i32,
+                glx::GLX_DEPTH_SIZE, config.depth_bits as i32,
+                glx::GLX_STENCIL_SIZE, config.stencil_bits as i32,
+                glx::GLX_DOUBLEBUFFER, config.double_buffer as i32,
+                glx::GLX_SAMPLE_BUFFERS, config.samples.is_some() as i32,
+                glx::GLX_SAMPLES, config.samples.unwrap_or(0) as i32,
+                GLX_FRAMEBUFFER_SRGB_CAPABLE_ARB, config.srgb as i32,
+                0,
+            ];
+
+            let mut n_configs = 0;
+            let fb_config =
+                glx::glXChooseFBConfig(display, screen, fb_attribs.as_ptr(), &mut n_configs);
+
+            error_handler.check()?;
+            if n_configs <= 0 || fb_config.is_null() {
+                return Err(GlError::CreationFailed(CreationFailedError::InvalidFBConfig));
+            }
+
+            // Now that we have a matching framebuffer config, we need to know which visual matches
+            // thsi config so the window is compatible with the OpenGL context we're about to create
+            let fb_config = *fb_config;
+            let visual = glx::glXGetVisualFromFBConfig(display, fb_config);
+            if visual.is_null() {
+                return Err(GlError::CreationFailed(CreationFailedError::NoVisual));
+            }
+
+            Ok((
+                FbConfig { fb_config, gl_config: config },
+                WindowConfig { depth: (*visual).depth as u8, visual: (*visual).visualid as u32 },
+            ))
+        })
+    }
+
+    pub unsafe fn make_current(&self) {
+        errors::XErrorHandler::handle(self.display, |error_handler| {
+            let res = glx::glXMakeCurrent(self.display, self.window, self.context);
+            error_handler.check().unwrap();
+            if res == 0 {
+                panic!("make_current failed")
+            }
+        })
+    }
+
+    pub unsafe fn make_not_current(&self) {
+        errors::XErrorHandler::handle(self.display, |error_handler| {
+            let res = glx::glXMakeCurrent(self.display, 0, std::ptr::null_mut());
+            error_handler.check().unwrap();
+            if res == 0 {
+                panic!("make_not_current failed")
+            }
+        })
+    }
+
+    pub fn get_proc_address(&self, symbol: &str) -> *const c_void {
+        get_proc_address(symbol)
+    }
+
+    pub fn swap_buffers(&self) {
+        errors::XErrorHandler::handle(self.display, |error_handler| {
+            unsafe {
+                glx::glXSwapBuffers(self.display, self.window);
+            }
+            error_handler.check().unwrap();
+        })
+    }
+}
+
+impl Drop for GlContext {
+    fn drop(&mut self) {}
+}

src/gl/x11/errors.rs

@@ -0,0 +1,122 @@
+use std::ffi::CStr;
+use std::fmt::{Debug, Formatter};
+use x11::xlib;
+
+use std::cell::RefCell;
+use std::panic::AssertUnwindSafe;
+
+thread_local! {
+    /// Used as part of [`XerrorHandler::handle()`]. When an X11 error occurs during this function,
+    /// the error gets copied to this RefCell after which the program is allowed to resume. The
+    /// error can then be converted to a regular Rust Result value afterwards.
+    static CURRENT_X11_ERROR: RefCell<Option<xlib::XErrorEvent>> = RefCell::new(None);
+}
+
+/// A helper struct for safe X11 error handling
+pub struct XErrorHandler<'a> {
+    display: *mut xlib::Display,
+    error: &'a RefCell<Option<xlib::XErrorEvent>>,
+}
+
+impl<'a> XErrorHandler<'a> {
+    /// Syncs and checks if any previous X11 calls returned an error
+    pub fn check(&mut self) -> Result<(), XLibError> {
+        // Flush all possible previous errors
+        unsafe {
+            xlib::XSync(self.display, 0);
+        }
+        let error = self.error.borrow_mut().take();
+
+        match error {
+            None => Ok(()),
+            Some(inner) => Err(XLibError { inner }),
+        }
+    }
+
+    /// Sets up a temporary X11 error handler for the duration of the given closure, and allows
+    /// that closure to check on the latest X11 error at any time
+    pub fn handle<T, F: FnOnce(&mut XErrorHandler) -> T>(
+        display: *mut xlib::Display, handler: F,
+    ) -> T {
+        unsafe extern "C" fn error_handler(
+            _dpy: *mut xlib::Display, err: *mut xlib::XErrorEvent,
+        ) -> i32 {
+            // SAFETY: the error pointer should be safe to copy
+            let err = *err;
+
+            CURRENT_X11_ERROR.with(|error| {
+                let mut error = error.borrow_mut();
+                match error.as_mut() {
+                    // If multiple errors occur, keep the first one since that's likely going to be the
+                    // cause of the other errors
+                    Some(_) => 1,
+                    None => {
+                        *error = Some(err);
+                        0
+                    }
+                }
+            })
+        }
+
+        // Flush all possible previous errors
+        unsafe {
+            xlib::XSync(display, 0);
+        }
+
+        CURRENT_X11_ERROR.with(|error| {
+            // Make sure to clear any errors from the last call to this function
+            *error.borrow_mut() = None;
+
+            let old_handler = unsafe { xlib::XSetErrorHandler(Some(error_handler)) };
+            let panic_result = std::panic::catch_unwind(AssertUnwindSafe(|| {
+                let mut h = XErrorHandler { display, error };
+                handler(&mut h)
+            }));
+            // Whatever happened, restore old error handler
+            unsafe { xlib::XSetErrorHandler(old_handler) };
+
+            match panic_result {
+                Ok(v) => v,
+                Err(e) => std::panic::resume_unwind(e),
+            }
+        })
+    }
+}
+
+pub struct XLibError {
+    inner: xlib::XErrorEvent,
+}
+
+impl XLibError {
+    pub fn get_display_name(&self, buf: &mut [u8]) -> &CStr {
+        unsafe {
+            xlib::XGetErrorText(
+                self.inner.display,
+                self.inner.error_code.into(),
+                buf.as_mut_ptr().cast(),
+                (buf.len() - 1) as i32,
+            );
+        }
+
+        *buf.last_mut().unwrap() = 0;
+        // SAFETY: whatever XGetErrorText did or not, we guaranteed there is a nul byte at the end of the buffer
+        unsafe { CStr::from_ptr(buf.as_mut_ptr().cast()) }
+    }
+}
+
+impl Debug for XLibError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        let mut buf = [0; 255];
+        let display_name = self.get_display_name(&mut buf).to_string_lossy();
+
+        f.debug_struct("XLibError")
+            .field("error_code", &self.inner.error_code)
+            .field("error_message", &display_name)
+            .field("minor_code", &self.inner.minor_code)
+            .field("request_code", &self.inner.request_code)
+            .field("type", &self.inner.type_)
+            .field("resource_id", &self.inner.resourceid)
+            .field("serial", &self.inner.serial)
+            .finish()
+    }
+}

src/keyboard.rs

@@ -17,6 +17,7 @@
 
 //! Keyboard types.
 
+#[cfg(any(target_os = "linux", target_os = "macos"))]
 use keyboard_types::{Code, Location};
 
 #[cfg(any(target_os = "linux", target_os = "macos"))]

src/lib.rs

@@ -12,6 +12,9 @@ mod window;
 mod window_info;
 mod window_open_options;
 
+#[cfg(feature = "opengl")]
+pub mod gl;
+
 pub use event::*;
 pub use mouse_cursor::MouseCursor;
 pub use window::*;

src/macos/window.rs

@@ -1,5 +1,6 @@
 use std::ffi::c_void;
 use std::marker::PhantomData;
+use std::ptr;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 
@@ -16,7 +17,7 @@ use keyboard_types::KeyboardEvent;
 
 use objc::{msg_send, runtime::Object, sel, sel_impl};
 
-use raw_window_handle::{macos::MacOSHandle, HasRawWindowHandle, RawWindowHandle};
+use raw_window_handle::{AppKitHandle, HasRawWindowHandle, RawWindowHandle};
 
 use crate::{
     Event, EventStatus, WindowEvent, WindowHandler, WindowInfo, WindowOpenOptions,
@@ -26,6 +27,12 @@ use crate::{
 use super::keyboard::KeyboardState;
 use super::view::{create_view, BASEVIEW_STATE_IVAR};
 
+#[cfg(feature = "opengl")]
+use crate::{
+    gl::{GlConfig, GlContext},
+    window::RawWindowHandleWrapper,
+};
+
 pub struct WindowHandle {
     raw_window_handle: Option<RawWindowHandle>,
     close_requested: Arc<AtomicBool>,
@@ -37,7 +44,7 @@ pub struct WindowHandle {
 
 impl WindowHandle {
     pub fn close(&mut self) {
-        if let Some(_) = self.raw_window_handle.take() {
+        if self.raw_window_handle.take().is_some() {
             self.close_requested.store(true, Ordering::Relaxed);
         }
     }
@@ -55,7 +62,7 @@ unsafe impl HasRawWindowHandle for WindowHandle {
             }
         }
 
-        RawWindowHandle::MacOS(MacOSHandle { ..MacOSHandle::empty() })
+        RawWindowHandle::AppKit(AppKitHandle::empty())
     }
 }
 
@@ -102,6 +109,9 @@ pub struct Window {
     /// Our subclassed NSView
     ns_view: id,
     close_requested: bool,
+
+    #[cfg(feature = "opengl")]
+    gl_context: Option<GlContext>,
 }
 
 impl Window {
@@ -114,7 +124,7 @@ impl Window {
     {
         let pool = unsafe { NSAutoreleasePool::new(nil) };
 
-        let handle = if let RawWindowHandle::MacOS(handle) = parent.raw_window_handle() {
+        let handle = if let RawWindowHandle::AppKit(handle) = parent.raw_window_handle() {
             handle
         } else {
             panic!("Not a macOS window");
@@ -122,7 +132,17 @@ impl Window {
 
         let ns_view = unsafe { create_view(&options) };
 
-        let window = Window { ns_app: None, ns_window: None, ns_view, close_requested: false };
+        let window = Window {
+            ns_app: None,
+            ns_window: None,
+            ns_view,
+            close_requested: false,
+
+            #[cfg(feature = "opengl")]
+            gl_context: options
+                .gl_config
+                .map(|gl_config| Self::create_gl_context(None, ns_view, gl_config)),
+        };
 
         let window_handle = Self::init(true, window, build);
 
@@ -146,7 +166,17 @@ impl Window {
 
         let ns_view = unsafe { create_view(&options) };
 
-        let window = Window { ns_app: None, ns_window: None, ns_view, close_requested: false };
+        let window = Window {
+            ns_app: None,
+            ns_window: None,
+            ns_view,
+            close_requested: false,
+
+            #[cfg(feature = "opengl")]
+            gl_context: options
+                .gl_config
+                .map(|gl_config| Self::create_gl_context(None, ns_view, gl_config)),
+        };
 
         let window_handle = Self::init(true, window, build);
 
@@ -217,6 +247,11 @@ impl Window {
             ns_window: Some(ns_window),
             ns_view,
             close_requested: false,
+
+            #[cfg(feature = "opengl")]
+            gl_context: options
+                .gl_config
+                .map(|gl_config| Self::create_gl_context(Some(ns_window), ns_view, gl_config)),
         };
 
         let _ = Self::init(false, window, build);
@@ -266,6 +301,21 @@ impl Window {
     pub fn close(&mut self) {
         self.close_requested = true;
     }
+
+    #[cfg(feature = "opengl")]
+    pub fn gl_context(&self) -> Option<&GlContext> {
+        self.gl_context.as_ref()
+    }
+
+    #[cfg(feature = "opengl")]
+    fn create_gl_context(ns_window: Option<id>, ns_view: id, config: GlConfig) -> GlContext {
+        let mut handle = AppKitHandle::empty();
+        handle.ns_window = ns_window.unwrap_or(ptr::null_mut()) as *mut c_void;
+        handle.ns_view = ns_view as *mut c_void;
+        let handle = RawWindowHandleWrapper { handle: RawWindowHandle::AppKit(handle) };
+
+        unsafe { GlContext::create(&handle, config).expect("Could not create OpenGL context") }
+    }
 }
 
 pub(super) struct WindowState {
@@ -373,7 +423,7 @@ impl WindowState {
         // Clear ivar before triggering WindowEvent::WillClose. Otherwise, if the
         // handler of the event causes another call to release, this function could be
         // called again, leading to a double free.
-        ns_view_obj.set_ivar(BASEVIEW_STATE_IVAR, ::std::ptr::null() as *const c_void);
+        ns_view_obj.set_ivar(BASEVIEW_STATE_IVAR, ptr::null() as *const c_void);
 
         window_state.trigger_event(Event::Window(WindowEvent::WillClose));
 
@@ -386,12 +436,12 @@ impl WindowState {
 
 unsafe impl HasRawWindowHandle for Window {
     fn raw_window_handle(&self) -> RawWindowHandle {
-        let ns_window = self.ns_window.unwrap_or(::std::ptr::null_mut()) as *mut c_void;
+        let ns_window = self.ns_window.unwrap_or(ptr::null_mut()) as *mut c_void;
 
-        RawWindowHandle::MacOS(MacOSHandle {
-            ns_window,
-            ns_view: self.ns_view as *mut c_void,
-            ..MacOSHandle::empty()
-        })
+        let mut handle = AppKitHandle::empty();
+        handle.ns_window = ns_window;
+        handle.ns_view = self.ns_view as *mut c_void;
+
+        RawWindowHandle::AppKit(handle)
     }
 }

src/win/keyboard.rs

@@ -19,7 +19,6 @@
 
 use std::cmp::Ordering;
 use std::collections::{HashMap, HashSet};
-use std::convert::TryInto;
 use std::mem;
 use std::ops::RangeInclusive;
 
@@ -29,15 +28,15 @@ use winapi::shared::minwindef::{HKL, INT, LPARAM, UINT, WPARAM};
 use winapi::shared::ntdef::SHORT;
 use winapi::shared::windef::HWND;
 use winapi::um::winuser::{
-    GetKeyState, GetKeyboardLayout, MapVirtualKeyExW, PeekMessageW, ToUnicodeEx, VkKeyScanW,
-    MAPVK_VK_TO_CHAR, MAPVK_VSC_TO_VK_EX, PM_NOREMOVE, VK_ACCEPT, VK_ADD, VK_APPS, VK_ATTN,
-    VK_BACK, VK_BROWSER_BACK, VK_BROWSER_FAVORITES, VK_BROWSER_FORWARD, VK_BROWSER_HOME,
-    VK_BROWSER_REFRESH, VK_BROWSER_SEARCH, VK_BROWSER_STOP, VK_CANCEL, VK_CAPITAL, VK_CLEAR,
-    VK_CONTROL, VK_CONVERT, VK_CRSEL, VK_DECIMAL, VK_DELETE, VK_DIVIDE, VK_DOWN, VK_END, VK_EREOF,
-    VK_ESCAPE, VK_EXECUTE, VK_EXSEL, VK_F1, VK_F10, VK_F11, VK_F12, VK_F2, VK_F3, VK_F4, VK_F5,
-    VK_F6, VK_F7, VK_F8, VK_F9, VK_FINAL, VK_HELP, VK_HOME, VK_INSERT, VK_JUNJA, VK_KANA, VK_KANJI,
-    VK_LAUNCH_APP1, VK_LAUNCH_APP2, VK_LAUNCH_MAIL, VK_LAUNCH_MEDIA_SELECT, VK_LCONTROL, VK_LEFT,
-    VK_LMENU, VK_LSHIFT, VK_LWIN, VK_MEDIA_NEXT_TRACK, VK_MEDIA_PLAY_PAUSE, VK_MEDIA_PREV_TRACK,
+    GetKeyState, GetKeyboardLayout, MapVirtualKeyExW, PeekMessageW, ToUnicodeEx, MAPVK_VK_TO_CHAR,
+    MAPVK_VSC_TO_VK_EX, PM_NOREMOVE, VK_ACCEPT, VK_ADD, VK_APPS, VK_ATTN, VK_BACK, VK_BROWSER_BACK,
+    VK_BROWSER_FAVORITES, VK_BROWSER_FORWARD, VK_BROWSER_HOME, VK_BROWSER_REFRESH,
+    VK_BROWSER_SEARCH, VK_BROWSER_STOP, VK_CANCEL, VK_CAPITAL, VK_CLEAR, VK_CONTROL, VK_CONVERT,
+    VK_CRSEL, VK_DECIMAL, VK_DELETE, VK_DIVIDE, VK_DOWN, VK_END, VK_EREOF, VK_ESCAPE, VK_EXECUTE,
+    VK_EXSEL, VK_F1, VK_F10, VK_F11, VK_F12, VK_F2, VK_F3, VK_F4, VK_F5, VK_F6, VK_F7, VK_F8,
+    VK_F9, VK_FINAL, VK_HELP, VK_HOME, VK_INSERT, VK_JUNJA, VK_KANA, VK_KANJI, VK_LAUNCH_APP1,
+    VK_LAUNCH_APP2, VK_LAUNCH_MAIL, VK_LAUNCH_MEDIA_SELECT, VK_LCONTROL, VK_LEFT, VK_LMENU,
+    VK_LSHIFT, VK_LWIN, VK_MEDIA_NEXT_TRACK, VK_MEDIA_PLAY_PAUSE, VK_MEDIA_PREV_TRACK,
     VK_MEDIA_STOP, VK_MENU, VK_MODECHANGE, VK_MULTIPLY, VK_NEXT, VK_NONCONVERT, VK_NUMLOCK,
     VK_NUMPAD0, VK_NUMPAD1, VK_NUMPAD2, VK_NUMPAD3, VK_NUMPAD4, VK_NUMPAD5, VK_NUMPAD6, VK_NUMPAD7,
     VK_NUMPAD8, VK_NUMPAD9, VK_OEM_ATTN, VK_OEM_CLEAR, VK_PAUSE, VK_PLAY, VK_PRINT, VK_PRIOR,
@@ -344,110 +343,6 @@ fn vk_to_key(vk: VkCode) -> Option<Key> {
     })
 }
 
-/// Convert a key to a virtual key code.
-///
-/// The virtual key code is needed in various winapi interfaces, including
-/// accelerators. This provides the virtual key code in the current keyboard
-/// map.
-///
-/// The virtual key code can have modifiers in the higher order byte when the
-/// argument is a `Character` variant. See:
-/// https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-vkkeyscanw
-pub(crate) fn key_to_vk(key: &Key) -> Option<i32> {
-    Some(match key {
-        Key::Character(s) => {
-            if let Some(code_point) = s.chars().next() {
-                if let Ok(wchar) = (code_point as u32).try_into() {
-                    unsafe { VkKeyScanW(wchar) as i32 }
-                } else {
-                    return None;
-                }
-            } else {
-                return None;
-            }
-        }
-        Key::Cancel => VK_CANCEL,
-        Key::Backspace => VK_BACK,
-        Key::Tab => VK_TAB,
-        Key::Clear => VK_CLEAR,
-        Key::Enter => VK_RETURN,
-        Key::Shift => VK_SHIFT,
-        Key::Control => VK_CONTROL,
-        Key::Alt => VK_MENU,
-        Key::Pause => VK_PAUSE,
-        Key::CapsLock => VK_CAPITAL,
-        // TODO: disambiguate kana and hangul? same vk
-        Key::KanaMode => VK_KANA,
-        Key::JunjaMode => VK_JUNJA,
-        Key::FinalMode => VK_FINAL,
-        Key::KanjiMode => VK_KANJI,
-        Key::Escape => VK_ESCAPE,
-        Key::NonConvert => VK_NONCONVERT,
-        Key::Accept => VK_ACCEPT,
-        Key::PageUp => VK_PRIOR,
-        Key::PageDown => VK_NEXT,
-        Key::End => VK_END,
-        Key::Home => VK_HOME,
-        Key::ArrowLeft => VK_LEFT,
-        Key::ArrowUp => VK_UP,
-        Key::ArrowRight => VK_RIGHT,
-        Key::ArrowDown => VK_DOWN,
-        Key::Select => VK_SELECT,
-        Key::Print => VK_PRINT,
-        Key::Execute => VK_EXECUTE,
-        Key::PrintScreen => VK_SNAPSHOT,
-        Key::Insert => VK_INSERT,
-        Key::Delete => VK_DELETE,
-        Key::Help => VK_HELP,
-        Key::Meta => VK_LWIN,
-        Key::ContextMenu => VK_APPS,
-        Key::Standby => VK_SLEEP,
-        Key::F1 => VK_F1,
-        Key::F2 => VK_F2,
-        Key::F3 => VK_F3,
-        Key::F4 => VK_F4,
-        Key::F5 => VK_F5,
-        Key::F6 => VK_F6,
-        Key::F7 => VK_F7,
-        Key::F8 => VK_F8,
-        Key::F9 => VK_F9,
-        Key::F10 => VK_F10,
-        Key::F11 => VK_F11,
-        Key::F12 => VK_F12,
-        Key::NumLock => VK_NUMLOCK,
-        Key::ScrollLock => VK_SCROLL,
-        Key::BrowserBack => VK_BROWSER_BACK,
-        Key::BrowserForward => VK_BROWSER_FORWARD,
-        Key::BrowserRefresh => VK_BROWSER_REFRESH,
-        Key::BrowserStop => VK_BROWSER_STOP,
-        Key::BrowserSearch => VK_BROWSER_SEARCH,
-        Key::BrowserFavorites => VK_BROWSER_FAVORITES,
-        Key::BrowserHome => VK_BROWSER_HOME,
-        Key::AudioVolumeMute => VK_VOLUME_MUTE,
-        Key::AudioVolumeDown => VK_VOLUME_DOWN,
-        Key::AudioVolumeUp => VK_VOLUME_UP,
-        Key::MediaTrackNext => VK_MEDIA_NEXT_TRACK,
-        Key::MediaTrackPrevious => VK_MEDIA_PREV_TRACK,
-        Key::MediaStop => VK_MEDIA_STOP,
-        Key::MediaPlayPause => VK_MEDIA_PLAY_PAUSE,
-        Key::LaunchMail => VK_LAUNCH_MAIL,
-        Key::LaunchMediaPlayer => VK_LAUNCH_MEDIA_SELECT,
-        Key::LaunchApplication1 => VK_LAUNCH_APP1,
-        Key::LaunchApplication2 => VK_LAUNCH_APP2,
-        Key::Alphanumeric => VK_OEM_ATTN,
-        Key::Convert => VK_CONVERT,
-        Key::ModeChange => VK_MODECHANGE,
-        Key::Process => VK_PROCESSKEY,
-        Key::Attn => VK_ATTN,
-        Key::CrSel => VK_CRSEL,
-        Key::ExSel => VK_EXSEL,
-        Key::EraseEof => VK_EREOF,
-        Key::Play => VK_PLAY,
-        Key::ZoomToggle => VK_ZOOM,
-        _ => return None,
-    })
-}
-
 fn code_unit_to_key(code_unit: u32) -> Key {
     match code_unit {
         0x8 | 0x7F => Key::Backspace,
@@ -692,6 +587,7 @@ impl KeyboardState {
                 key_state[VK_LCONTROL as usize] = if has_altgr { 0x80 } else { 0 };
                 key_state[VK_MENU as usize] = if has_altgr { 0x80 } else { 0 };
                 key_state[VK_RMENU as usize] = if has_altgr { 0x80 } else { 0 };
+                #[allow(clippy::iter_overeager_cloned)]
                 for vk in PRINTABLE_VKS.iter().cloned().flatten() {
                     let ret = ToUnicodeEx(
                         vk as UINT,

src/win/window.rs

@@ -16,14 +16,14 @@ use winapi::um::winuser::{
 };
 
 use std::cell::RefCell;
-use std::ffi::OsStr;
+use std::ffi::{c_void, OsStr};
 use std::marker::PhantomData;
 use std::os::windows::ffi::OsStrExt;
 use std::ptr::null_mut;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 
-use raw_window_handle::{windows::WindowsHandle, HasRawWindowHandle, RawWindowHandle};
+use raw_window_handle::{HasRawWindowHandle, RawWindowHandle, Win32Handle};
 
 const BV_WINDOW_MUST_CLOSE: UINT = WM_USER + 1;
 
@@ -34,6 +34,9 @@ use crate::{
 
 use super::keyboard::KeyboardState;
 
+#[cfg(feature = "opengl")]
+use crate::{gl::GlContext, window::RawWindowHandleWrapper};
+
 unsafe fn generate_guid() -> String {
     let mut guid: GUID = std::mem::zeroed();
     CoCreateGuid(&mut guid);
@@ -80,12 +83,12 @@ impl WindowHandle {
 unsafe impl HasRawWindowHandle for WindowHandle {
     fn raw_window_handle(&self) -> RawWindowHandle {
         if let Some(hwnd) = self.hwnd {
-            RawWindowHandle::Windows(WindowsHandle {
-                hwnd: hwnd as *mut std::ffi::c_void,
-                ..WindowsHandle::empty()
-            })
+            let mut handle = Win32Handle::empty();
+            handle.hwnd = hwnd as *mut c_void;
+
+            RawWindowHandle::Win32(handle)
         } else {
-            RawWindowHandle::Windows(WindowsHandle { ..WindowsHandle::empty() })
+            RawWindowHandle::Win32(Win32Handle::empty())
         }
     }
 }
@@ -124,18 +127,17 @@ unsafe extern "system" fn wnd_proc(
 
     let window_state_ptr = GetWindowLongPtrW(hwnd, GWLP_USERDATA) as *mut RefCell<WindowState>;
     if !window_state_ptr.is_null() {
-        let mut window = Window { hwnd };
-        let mut window = crate::Window::new(&mut window);
-
         match msg {
             WM_MOUSEMOVE => {
+                let mut window_state = (*window_state_ptr).borrow_mut();
+                let mut window = window_state.create_window(hwnd);
+                let mut window = crate::Window::new(&mut window);
+
                 let x = (lparam & 0xFFFF) as i16 as i32;
                 let y = ((lparam >> 16) & 0xFFFF) as i16 as i32;
 
                 let physical_pos = PhyPoint { x, y };
 
-                let mut window_state = (&*window_state_ptr).borrow_mut();
-
                 let logical_pos = physical_pos.to_logical(&window_state.window_info);
 
                 window_state.handler.on_event(
@@ -145,12 +147,14 @@ unsafe extern "system" fn wnd_proc(
                 return 0;
             }
             WM_MOUSEWHEEL => {
+                let mut window_state = (*window_state_ptr).borrow_mut();
+                let mut window = window_state.create_window(hwnd);
+                let mut window = crate::Window::new(&mut window);
+
                 let value = (wparam >> 16) as i16;
                 let value = value as i32;
                 let value = value as f32 / WHEEL_DELTA as f32;
 
-                let mut window_state = (&*window_state_ptr).borrow_mut();
-
                 window_state.handler.on_event(
                     &mut window,
                     Event::Mouse(MouseEvent::WheelScrolled(ScrollDelta::Lines {
@@ -162,7 +166,11 @@ unsafe extern "system" fn wnd_proc(
             }
             WM_LBUTTONDOWN | WM_LBUTTONUP | WM_MBUTTONDOWN | WM_MBUTTONUP | WM_RBUTTONDOWN
             | WM_RBUTTONUP | WM_XBUTTONDOWN | WM_XBUTTONUP => {
-                let mut mouse_button_counter = (&*window_state_ptr).borrow().mouse_button_counter;
+                let mut window_state = (*window_state_ptr).borrow_mut();
+                let mut window = window_state.create_window(hwnd);
+                let mut window = crate::Window::new(&mut window);
+
+                let mut mouse_button_counter = window_state.mouse_button_counter;
 
                 let button = match msg {
                     WM_LBUTTONDOWN | WM_LBUTTONUP => Some(MouseButton::Left),
@@ -198,44 +206,48 @@ unsafe extern "system" fn wnd_proc(
                         }
                     };
 
-                    (&*window_state_ptr).borrow_mut().mouse_button_counter = mouse_button_counter;
+                    window_state.mouse_button_counter = mouse_button_counter;
 
-                    (&*window_state_ptr)
-                        .borrow_mut()
-                        .handler
-                        .on_event(&mut window, Event::Mouse(event));
+                    window_state.handler.on_event(&mut window, Event::Mouse(event));
                 }
             }
             WM_TIMER => {
-                match wparam {
-                    WIN_FRAME_TIMER => {
-                        (&*window_state_ptr).borrow_mut().handler.on_frame(&mut window);
-                    }
-                    _ => (),
+                let mut window_state = (*window_state_ptr).borrow_mut();
+                let mut window = window_state.create_window(hwnd);
+                let mut window = crate::Window::new(&mut window);
+
+                if wparam == WIN_FRAME_TIMER {
+                    window_state.handler.on_frame(&mut window);
                 }
                 return 0;
             }
             WM_CLOSE => {
-                (&*window_state_ptr)
-                    .borrow_mut()
-                    .handler
-                    .on_event(&mut window, Event::Window(WindowEvent::WillClose));
+                // Make sure to release the borrow before the DefWindowProc call
+                {
+                    let mut window_state = (*window_state_ptr).borrow_mut();
+                    let mut window = window_state.create_window(hwnd);
+                    let mut window = crate::Window::new(&mut window);
+
+                    window_state
+                        .handler
+                        .on_event(&mut window, Event::Window(WindowEvent::WillClose));
+                }
+
                 // DestroyWindow(hwnd);
                 // return 0;
                 return DefWindowProcW(hwnd, msg, wparam, lparam);
             }
             WM_CHAR | WM_SYSCHAR | WM_KEYDOWN | WM_SYSKEYDOWN | WM_KEYUP | WM_SYSKEYUP
             | WM_INPUTLANGCHANGE => {
-                let opt_event = (&*window_state_ptr)
-                    .borrow_mut()
-                    .keyboard_state
-                    .process_message(hwnd, msg, wparam, lparam);
+                let mut window_state = (*window_state_ptr).borrow_mut();
+                let mut window = window_state.create_window(hwnd);
+                let mut window = crate::Window::new(&mut window);
+
+                let opt_event =
+                    window_state.keyboard_state.process_message(hwnd, msg, wparam, lparam);
 
                 if let Some(event) = opt_event {
-                    (&*window_state_ptr)
-                        .borrow_mut()
-                        .handler
-                        .on_event(&mut window, Event::Keyboard(event));
+                    window_state.handler.on_event(&mut window, Event::Keyboard(event));
                 }
 
                 if msg != WM_SYSKEYDOWN {
@@ -243,11 +255,13 @@ unsafe extern "system" fn wnd_proc(
                 }
             }
             WM_SIZE => {
+                let mut window_state = (*window_state_ptr).borrow_mut();
+                let mut window = window_state.create_window(hwnd);
+                let mut window = crate::Window::new(&mut window);
+
                 let width = (lparam & 0xFFFF) as u16 as u32;
                 let height = ((lparam >> 16) & 0xFFFF) as u16 as u32;
 
-                let mut window_state = (&*window_state_ptr).borrow_mut();
-
                 window_state.window_info = WindowInfo::from_physical_size(
                     PhySize { width, height },
                     window_state.window_info.scale(),
@@ -260,10 +274,10 @@ unsafe extern "system" fn wnd_proc(
                     .on_event(&mut window, Event::Window(WindowEvent::Resized(window_info)));
             }
             WM_DPICHANGED => {
+                let mut window_state = (*window_state_ptr).borrow_mut();
+
                 // To avoid weirdness with the realtime borrow checker.
                 let new_rect = {
-                    let mut window_state = (&*window_state_ptr).borrow_mut();
-
                     if let WindowScalePolicy::SystemScaleFactor = window_state.scale_policy {
                         let dpi = (wparam & 0xFFFF) as u16 as u32;
                         let scale_factor = dpi as f64 / 96.0;
@@ -319,7 +333,7 @@ unsafe extern "system" fn wnd_proc(
         }
     }
 
-    return DefWindowProcW(hwnd, msg, wparam, lparam);
+    DefWindowProcW(hwnd, msg, wparam, lparam)
 }
 
 unsafe fn register_wnd_class() -> ATOM {
@@ -357,10 +371,28 @@ struct WindowState {
     handler: Box<dyn WindowHandler>,
     scale_policy: WindowScalePolicy,
     dw_style: u32,
+
+    #[cfg(feature = "opengl")]
+    gl_context: Arc<Option<GlContext>>,
+}
+
+impl WindowState {
+    #[cfg(not(feature = "opengl"))]
+    fn create_window(&self, hwnd: HWND) -> Window {
+        Window { hwnd }
+    }
+
+    #[cfg(feature = "opengl")]
+    fn create_window(&self, hwnd: HWND) -> Window {
+        Window { hwnd, gl_context: self.gl_context.clone() }
+    }
 }
 
 pub struct Window {
     hwnd: HWND,
+
+    #[cfg(feature = "opengl")]
+    gl_context: Arc<Option<GlContext>>,
 }
 
 impl Window {
@@ -372,7 +404,7 @@ impl Window {
         B: Send + 'static,
     {
         let parent = match parent.raw_window_handle() {
-            RawWindowHandle::Windows(h) => h.hwnd as HWND,
+            RawWindowHandle::Win32(h) => h.hwnd as HWND,
             h => panic!("unsupported parent handle {:?}", h),
         };
 
@@ -410,8 +442,8 @@ impl Window {
                     break;
                 }
 
-                TranslateMessage(&mut msg);
-                DispatchMessageW(&mut msg);
+                TranslateMessage(&msg);
+                DispatchMessageW(&msg);
             }
         }
     }
@@ -478,7 +510,22 @@ impl Window {
             );
             // todo: manage error ^
 
+            #[cfg(feature = "opengl")]
+            let gl_context: Arc<Option<GlContext>> = Arc::new(options.gl_config.map(|gl_config| {
+                let mut handle = Win32Handle::empty();
+                handle.hwnd = hwnd as *mut c_void;
+                let handle = RawWindowHandleWrapper { handle: RawWindowHandle::Win32(handle) };
+
+                GlContext::create(&handle, gl_config).expect("Could not create OpenGL context")
+            }));
+
+            #[cfg(not(feature = "opengl"))]
             let handler = Box::new(build(&mut crate::Window::new(&mut Window { hwnd })));
+            #[cfg(feature = "opengl")]
+            let handler = Box::new(build(&mut crate::Window::new(&mut Window {
+                hwnd,
+                gl_context: gl_context.clone(),
+            })));
 
             let (parent_handle, window_handle) = ParentHandle::new(hwnd);
             let parent_handle = if parented { Some(parent_handle) } else { None };
@@ -492,6 +539,9 @@ impl Window {
                 handler,
                 scale_policy: options.scale,
                 dw_style: flags,
+
+                #[cfg(feature = "opengl")]
+                gl_context,
             }));
 
             // Only works on Windows 10 unfortunately.
@@ -556,13 +606,18 @@ impl Window {
             PostMessageW(self.hwnd, BV_WINDOW_MUST_CLOSE, 0, 0);
         }
     }
+
+    #[cfg(feature = "opengl")]
+    pub fn gl_context(&self) -> Option<&GlContext> {
+        self.gl_context.as_ref().as_ref()
+    }
 }
 
 unsafe impl HasRawWindowHandle for Window {
     fn raw_window_handle(&self) -> RawWindowHandle {
-        RawWindowHandle::Windows(WindowsHandle {
-            hwnd: self.hwnd as *mut std::ffi::c_void,
-            ..WindowsHandle::empty()
-        })
+        let mut handle = Win32Handle::empty();
+        handle.hwnd = self.hwnd as *mut c_void;
+
+        RawWindowHandle::Win32(handle)
     }
 }

src/window.rs

@@ -18,6 +18,12 @@ pub struct WindowHandle {
     phantom: PhantomData<*mut ()>,
 }
 
+/// Quick wrapper to satisfy [HasRawWindowHandle], because of course a raw window handle wouldn't
+/// have a raw window handle, that would be silly.
+pub(crate) struct RawWindowHandleWrapper {
+    pub handle: RawWindowHandle,
+}
+
 impl WindowHandle {
     fn new(window_handle: platform::WindowHandle) -> Self {
         Self { window_handle, phantom: PhantomData::default() }
@@ -91,6 +97,13 @@ impl<'a> Window<'a> {
     pub fn close(&mut self) {
         self.window.close();
     }
+
+    /// If provided, then an OpenGL context will be created for this window. You'll be able to
+    /// access this context through [crate::Window::gl_context].
+    #[cfg(feature = "opengl")]
+    pub fn gl_context(&self) -> Option<&crate::gl::GlContext> {
+        self.window.gl_context()
+    }
 }
 
 unsafe impl<'a> HasRawWindowHandle for Window<'a> {
@@ -98,3 +111,9 @@ unsafe impl<'a> HasRawWindowHandle for Window<'a> {
         self.window.raw_window_handle()
     }
 }
+
+unsafe impl HasRawWindowHandle for RawWindowHandleWrapper {
+    fn raw_window_handle(&self) -> RawWindowHandle {
+        self.handle
+    }
+}

src/window_open_options.rs

@@ -21,4 +21,9 @@ pub struct WindowOpenOptions {
 
     /// The dpi scaling policy
     pub scale: WindowScalePolicy,
+
+    /// If provided, then an OpenGL context will be created for this window. You'll be able to
+    /// access this context through [crate::Window::gl_context].
+    #[cfg(feature = "opengl")]
+    pub gl_config: Option<crate::gl::GlConfig>,
 }

src/x11/cursor.rs

@@ -101,5 +101,5 @@ pub(super) fn get_xcursor(display: *mut x11::xlib::Display, cursor: MouseCursor)
         MouseCursor::RowResize => loadn(&[b"split_v\0", b"v_double_arrow\0"]),
     };
 
-    cursor.or(load(b"left_ptr\0")).unwrap_or(0)
+    cursor.or_else(|| load(b"left_ptr\0")).unwrap_or(0)
 }

src/x11/window.rs

@@ -6,7 +6,9 @@ use std::sync::Arc;
 use std::thread;
 use std::time::*;
 
-use raw_window_handle::{unix::XlibHandle, HasRawWindowHandle, RawWindowHandle};
+use raw_window_handle::{HasRawWindowHandle, RawWindowHandle, XlibHandle};
+use xcb::ffi::xcb_screen_t;
+use xcb::StructPtr;
 
 use super::XcbConnection;
 use crate::{
@@ -16,6 +18,12 @@ use crate::{
 
 use super::keyboard::{convert_key_press_event, convert_key_release_event};
 
+#[cfg(feature = "opengl")]
+use crate::{
+    gl::{platform, GlContext},
+    window::RawWindowHandleWrapper,
+};
+
 pub struct WindowHandle {
     raw_window_handle: Option<RawWindowHandle>,
     close_requested: Arc<AtomicBool>,
@@ -27,7 +35,7 @@ pub struct WindowHandle {
 
 impl WindowHandle {
     pub fn close(&mut self) {
-        if let Some(_) = self.raw_window_handle.take() {
+        if self.raw_window_handle.take().is_some() {
             // FIXME: This will need to be changed from just setting an atomic to somehow
             // synchronizing with the window being closed (using a synchronous channel, or
             // by joining on the event loop thread).
@@ -49,7 +57,7 @@ unsafe impl HasRawWindowHandle for WindowHandle {
             }
         }
 
-        RawWindowHandle::Xlib(XlibHandle { ..raw_window_handle::unix::XlibHandle::empty() })
+        RawWindowHandle::Xlib(XlibHandle::empty())
     }
 }
 
@@ -88,6 +96,7 @@ pub struct Window {
     xcb_connection: XcbConnection,
     window_id: u32,
     window_info: WindowInfo,
+    // FIXME: There's all this mouse cursor logic but it's never actually used, is this correct?
     mouse_cursor: MouseCursor,
 
     frame_interval: Duration,
@@ -96,6 +105,9 @@ pub struct Window {
 
     new_physical_size: Option<PhySize>,
     parent_handle: Option<ParentHandle>,
+
+    #[cfg(feature = "opengl")]
+    gl_context: Option<GlContext>,
 }
 
 // Hack to allow sending a RawWindowHandle between threads. Do not make public
@@ -124,7 +136,7 @@ impl Window {
 
         let (parent_handle, mut window_handle) = ParentHandle::new();
 
-        let thread = thread::spawn(move || {
+        thread::spawn(move || {
             Self::window_thread(Some(parent_id), options, build, tx.clone(), Some(parent_handle));
         });
 
@@ -144,7 +156,7 @@ impl Window {
 
         let (parent_handle, mut window_handle) = ParentHandle::new();
 
-        let thread = thread::spawn(move || {
+        thread::spawn(move || {
             Self::window_thread(None, options, build, tx.clone(), Some(parent_handle));
         });
 
@@ -163,12 +175,14 @@ impl Window {
         let (tx, rx) = mpsc::sync_channel::<WindowOpenResult>(1);
 
         let thread = thread::spawn(move || {
-            Self::window_thread(None, options, build, tx.clone(), None);
+            Self::window_thread(None, options, build, tx, None);
         });
 
         let _ = rx.recv().unwrap().unwrap();
 
-        thread.join();
+        thread.join().unwrap_or_else(|err| {
+            eprintln!("Window thread panicked: {:#?}", err);
+        });
     }
 
     fn window_thread<H, B>(
@@ -205,10 +219,49 @@ impl Window {
 
         let window_info = WindowInfo::from_logical_size(options.size, scaling);
 
+        // Now it starts becoming fun. If we're creating an OpenGL context, then we need to create
+        // the window with a visual that matches the framebuffer used for the OpenGL context. So the
+        // idea is that we first retrieve a framebuffer config that matches our wanted OpenGL
+        // configuration, find the visual that matches that framebuffer config, create the window
+        // with that visual, and then finally create an OpenGL context for the window. If we don't
+        // use OpenGL, then we'll just take a random visual with a 32-bit depth.
+        let create_default_config = || {
+            Self::find_visual_for_depth(&screen, 32)
+                .map(|visual| (32, visual))
+                .unwrap_or((xcb::COPY_FROM_PARENT as u8, xcb::COPY_FROM_PARENT as u32))
+        };
+        #[cfg(feature = "opengl")]
+        let (fb_config, (depth, visual)) = match options.gl_config {
+            Some(gl_config) => unsafe {
+                platform::GlContext::get_fb_config_and_visual(
+                    xcb_connection.conn.get_raw_dpy(),
+                    gl_config,
+                )
+                .map(|(fb_config, window_config)| {
+                    (Some(fb_config), (window_config.depth, window_config.visual))
+                })
+                .expect("Could not fetch framebuffer config")
+            },
+            None => (None, create_default_config()),
+        };
+        #[cfg(not(feature = "opengl"))]
+        let (depth, visual) = create_default_config();
+
+        // For this 32-bith depth to work, you also need to define a color map and set a border
+        // pixel: https://cgit.freedesktop.org/xorg/xserver/tree/dix/window.c#n818
+        let colormap = xcb_connection.conn.generate_id();
+        xcb::create_colormap(
+            &xcb_connection.conn,
+            xcb::COLORMAP_ALLOC_NONE as u8,
+            colormap,
+            screen.root(),
+            visual,
+        );
+
         let window_id = xcb_connection.conn.generate_id();
         xcb::create_window_checked(
             &xcb_connection.conn,
-            xcb::COPY_FROM_PARENT as u8,
+            depth,
             window_id,
             parent_id,
             0,                                         // x coordinate of the new window
@@ -217,18 +270,26 @@ impl Window {
             window_info.physical_size().height as u16, // window height
             0,                                         // window border
             xcb::WINDOW_CLASS_INPUT_OUTPUT as u16,
-            if parent.is_some() { xcb::COPY_FROM_PARENT as u32 } else { screen.root_visual() },
-            &[(
-                xcb::CW_EVENT_MASK,
-                xcb::EVENT_MASK_EXPOSURE
-                    | xcb::EVENT_MASK_POINTER_MOTION
-                    | xcb::EVENT_MASK_BUTTON_PRESS
-                    | xcb::EVENT_MASK_BUTTON_RELEASE
-                    | xcb::EVENT_MASK_KEY_PRESS
-                    | xcb::EVENT_MASK_KEY_RELEASE
-                    | xcb::EVENT_MASK_STRUCTURE_NOTIFY,
-            )],
-        ).request_check().unwrap();
+            visual,
+            &[
+                (
+                    xcb::CW_EVENT_MASK,
+                    xcb::EVENT_MASK_EXPOSURE
+                        | xcb::EVENT_MASK_POINTER_MOTION
+                        | xcb::EVENT_MASK_BUTTON_PRESS
+                        | xcb::EVENT_MASK_BUTTON_RELEASE
+                        | xcb::EVENT_MASK_KEY_PRESS
+                        | xcb::EVENT_MASK_KEY_RELEASE
+                        | xcb::EVENT_MASK_STRUCTURE_NOTIFY,
+                ),
+                // As mentioend above, these two values are needed to be able to create a window
+                // with a dpeth of 32-bits when the parent window has a different depth
+                (xcb::CW_COLORMAP, colormap),
+                (xcb::CW_BORDER_PIXEL, 0),
+            ],
+        )
+        .request_check()
+        .unwrap();
 
         xcb::map_window(&xcb_connection.conn, window_id);
 
@@ -244,19 +305,35 @@ impl Window {
             title.as_bytes(),
         );
 
-        xcb_connection.atoms.wm_protocols.zip(xcb_connection.atoms.wm_delete_window).map(
-            |(wm_protocols, wm_delete_window)| {
-                xcb_util::icccm::set_wm_protocols(
-                    &xcb_connection.conn,
-                    window_id,
-                    wm_protocols,
-                    &[wm_delete_window],
-                );
-            },
-        );
+        if let Some((wm_protocols, wm_delete_window)) =
+            xcb_connection.atoms.wm_protocols.zip(xcb_connection.atoms.wm_delete_window)
+        {
+            xcb_util::icccm::set_wm_protocols(
+                &xcb_connection.conn,
+                window_id,
+                wm_protocols,
+                &[wm_delete_window],
+            );
+        }
 
         xcb_connection.conn.flush();
 
+        // TODO: These APIs could use a couple tweaks now that everything is internal and there is
+        //       no error handling anymore at this point. Everything is more or less unchanged
+        //       compared to when raw-gl-context was a separate crate.
+        #[cfg(feature = "opengl")]
+        let gl_context = fb_config.map(|fb_config| {
+            let mut handle = XlibHandle::empty();
+            handle.window = window_id as c_ulong;
+            handle.display = xcb_connection.conn.get_raw_dpy() as *mut c_void;
+            let handle = RawWindowHandleWrapper { handle: RawWindowHandle::Xlib(handle) };
+
+            // Because of the visual negotation we had to take some extra steps to create this context
+            let context = unsafe { platform::GlContext::create(&handle, fb_config) }
+                .expect("Could not create OpenGL context");
+            GlContext::new(context)
+        });
+
         let mut window = Self {
             xcb_connection,
             window_id,
@@ -269,6 +346,9 @@ impl Window {
 
             new_physical_size: None,
             parent_handle,
+
+            #[cfg(feature = "opengl")]
+            gl_context,
         };
 
         let mut handler = build(&mut crate::Window::new(&mut window));
@@ -309,6 +389,27 @@ impl Window {
         self.close_requested = true;
     }
 
+    #[cfg(feature = "opengl")]
+    pub fn gl_context(&self) -> Option<&crate::gl::GlContext> {
+        self.gl_context.as_ref()
+    }
+
+    fn find_visual_for_depth(screen: &StructPtr<xcb_screen_t>, depth: u8) -> Option<u32> {
+        for candidate_depth in screen.allowed_depths() {
+            if candidate_depth.depth() != depth {
+                continue;
+            }
+
+            for candidate_visual in candidate_depth.visuals() {
+                if candidate_visual.class() == xcb::VISUAL_CLASS_TRUE_COLOR as u8 {
+                    return Some(candidate_visual.visual_id());
+                }
+            }
+        }
+
+        None
+    }
+
     #[inline]
     fn drain_xcb_events(&mut self, handler: &mut dyn WindowHandler) {
         // the X server has a tendency to send spurious/extraneous configure notify events when a
@@ -538,7 +639,7 @@ impl Window {
 
                 handler.on_event(
                     &mut crate::Window::new(self),
-                    Event::Keyboard(convert_key_press_event(&event)),
+                    Event::Keyboard(convert_key_press_event(event)),
                 );
             }
 
@@ -547,7 +648,7 @@ impl Window {
 
                 handler.on_event(
                     &mut crate::Window::new(self),
-                    Event::Keyboard(convert_key_release_event(&event)),
+                    Event::Keyboard(convert_key_release_event(event)),
                 );
             }
 
@@ -558,11 +659,11 @@ impl Window {
 
 unsafe impl HasRawWindowHandle for Window {
     fn raw_window_handle(&self) -> RawWindowHandle {
-        RawWindowHandle::Xlib(XlibHandle {
-            window: self.window_id as c_ulong,
-            display: self.xcb_connection.conn.get_raw_dpy() as *mut c_void,
-            ..raw_window_handle::unix::XlibHandle::empty()
-        })
+        let mut handle = XlibHandle::empty();
+        handle.window = self.window_id as c_ulong;
+        handle.display = self.xcb_connection.conn.get_raw_dpy() as *mut c_void;
+
+        RawWindowHandle::Xlib(handle)
     }
 }
 

src/x11/xcb_connection.rs

@@ -11,7 +11,6 @@ use super::cursor;
 pub(crate) struct Atoms {
     pub wm_protocols: Option<u32>,
     pub wm_delete_window: Option<u32>,
-    pub wm_normal_hints: Option<u32>,
 }
 
 pub struct XcbConnection {
@@ -20,6 +19,7 @@ pub struct XcbConnection {
 
     pub(crate) atoms: Atoms,
 
+    // FIXME: Same here, there's a ton of unused cursor machinery in here
     pub(super) cursor_cache: HashMap<MouseCursor, u32>,
 }
 
@@ -46,14 +46,13 @@ impl XcbConnection {
 
         conn.set_event_queue_owner(xcb::base::EventQueueOwner::Xcb);
 
-        let (wm_protocols, wm_delete_window, wm_normal_hints) =
-            intern_atoms!(&conn, WM_PROTOCOLS, WM_DELETE_WINDOW, WM_NORMAL_HINTS);
+        let (wm_protocols, wm_delete_window) = intern_atoms!(&conn, WM_PROTOCOLS, WM_DELETE_WINDOW);
 
         Ok(Self {
             conn,
             xlib_display,
 
-            atoms: Atoms { wm_protocols, wm_delete_window, wm_normal_hints },
+            atoms: Atoms { wm_protocols, wm_delete_window },
 
             cursor_cache: HashMap::new(),
         })
@@ -136,7 +135,7 @@ impl XcbConnection {
 
     #[inline]
     pub fn get_scaling(&self) -> Option<f64> {
-        self.get_scaling_xft().or(self.get_scaling_screen_dimensions())
+        self.get_scaling_xft().or_else(|| self.get_scaling_screen_dimensions())
     }
 
     #[inline]