Merge pull request #458 from tomaka/detach-wgl

Detach wgl and win32

6 files changed, 529 insertions, 425 deletions

diff --git a/src/api/mod.rs b/src/api/mod.rs
index fe43616..db5590a 100644
--- a/src/api/mod.rs
+++ b/src/api/mod.rs
@@ -7,5 +7,6 @@ pub mod emscripten;
 pub mod glx;
 pub mod osmesa;
 pub mod wayland;
+pub mod wgl;
 pub mod win32;
 pub mod x11;
diff --git a/src/api/win32/gl.rs b/src/api/wgl/gl.rs
index 1354d95..1354d95 100644
--- a/src/api/win32/gl.rs
+++ b/src/api/wgl/gl.rs
diff --git a/src/api/win32/make_current_guard.rs b/src/api/wgl/make_current_guard.rs
index 8983899..b890c82 100644
--- a/src/api/win32/make_current_guard.rs
+++ b/src/api/wgl/make_current_guard.rs
@@ -6,9 +6,6 @@ use winapi;
 use CreationError;
 
 use super::gl;
-use super::ContextWrapper;
-use super::WindowWrapper;
-
 /// A guard for when you want to make the context current. Destroying the guard restores the
 /// previously-current context.
 pub struct CurrentContextGuard<'a, 'b> {
@@ -19,15 +16,13 @@ pub struct CurrentContextGuard<'a, 'b> {
 }
 
 impl<'a, 'b> CurrentContextGuard<'a, 'b> {
-    pub unsafe fn make_current(window: &'a WindowWrapper, context: &'b ContextWrapper)
+    pub unsafe fn make_current(hdc: winapi::HDC, context: winapi::HGLRC)
                                -> Result<CurrentContextGuard<'a, 'b>, CreationError>
     {
         let previous_hdc = gl::wgl::GetCurrentDC() as winapi::HDC;
         let previous_hglrc = gl::wgl::GetCurrentContext() as winapi::HGLRC;
 
-        let result = gl::wgl::MakeCurrent(window.1 as *const libc::c_void,
-                                          context.0 as *const libc::c_void);
-
+        let result = gl::wgl::MakeCurrent(hdc as *const _, context as *const _);
         if result == 0 {
             return Err(CreationError::OsError(format!("wglMakeCurrent function failed: {}",
                                                       format!("{}", io::Error::last_os_error()))));
diff --git a/src/api/wgl/mod.rs b/src/api/wgl/mod.rs
new file mode 100644
index 0000000..1da20aa
--- /dev/null
+++ b/src/api/wgl/mod.rs
@@ -0,0 +1,507 @@
+#![cfg(any(target_os = "windows"))]
+
+use BuilderAttribs;
+use CreationError;
+use GlContext;
+use GlRequest;
+use GlProfile;
+use PixelFormat;
+use Api;
+
+use self::make_current_guard::CurrentContextGuard;
+
+use libc;
+use std::ffi::{CStr, CString, OsStr};
+use std::os::windows::ffi::OsStrExt;
+use std::{mem, ptr};
+use std::io;
+
+use winapi;
+use kernel32;
+use user32;
+use gdi32;
+
+mod make_current_guard;
+mod gl;
+
+pub struct Context {
+    context: ContextWrapper,
+
+    hdc: winapi::HDC,
+
+    /// Binded to `opengl32.dll`.
+    ///
+    /// `wglGetProcAddress` returns null for GL 1.1 functions because they are
+    ///  already defined by the system. This module contains them.
+    gl_library: winapi::HMODULE,
+
+    /// The pixel format that has been used to create this context.
+    pixel_format: PixelFormat,
+}
+
+/// A simple wrapper that destroys the window when it is destroyed.
+struct WindowWrapper(winapi::HWND, winapi::HDC);
+
+impl Drop for WindowWrapper {
+    fn drop(&mut self) {
+        unsafe {
+            user32::DestroyWindow(self.0);
+        }
+    }
+}
+
+struct ContextWrapper(winapi::HGLRC);
+
+impl Drop for ContextWrapper {
+    fn drop(&mut self) {
+        unsafe {
+            gl::wgl::DeleteContext(self.0 as *const _);
+        }
+    }
+}
+
+impl Context {
+    /// Attempt to build a new WGL context on a window.
+    ///
+    /// The window must **not** have had `SetPixelFormat` called on it.
+    pub fn new(builder: &BuilderAttribs<'static>, window: winapi::HWND,
+               builder_sharelists: Option<winapi::HGLRC>)
+               -> Result<Context, CreationError>
+    {
+        unsafe {
+            let hdc = user32::GetDC(window);
+            if hdc.is_null() {
+                let err = Err(CreationError::OsError(format!("GetDC function failed: {}",
+                                                          format!("{}", io::Error::last_os_error()))));
+                return err;
+            }
+
+            // the first step is to create a dummy window and a dummy context which we will use
+            // to load the pointers to some functions in the OpenGL driver in `extra_functions`
+            let extra_functions = {
+                let (ex_style, style) = (winapi::WS_EX_APPWINDOW, winapi::WS_POPUP |
+                                         winapi::WS_CLIPSIBLINGS | winapi::WS_CLIPCHILDREN);
+
+                // creating a dummy invisible window
+                let dummy_window = {
+                    let rect = {
+                        let mut placement: winapi::WINDOWPLACEMENT = unsafe { mem::zeroed() };
+                        placement.length = mem::size_of::<winapi::WINDOWPLACEMENT>() as winapi::UINT;
+                        if unsafe { user32::GetWindowPlacement(window, &mut placement) } == 0 {
+                            panic!();
+                        }
+                        placement.rcNormalPosition
+                    };
+
+                    let mut class_name = [0u16; 128];
+                    if user32::GetClassNameW(window, class_name.as_mut_ptr(), 128) == 0 {
+                        return Err(CreationError::OsError(format!("GetClassNameW function failed: {}",
+                                                          format!("{}", io::Error::last_os_error()))));
+                    }
+
+                    let handle = user32::CreateWindowExW(ex_style, class_name.as_ptr(),
+                                                         b"dummy window\0".as_ptr() as *const _, style,
+                                                         winapi::CW_USEDEFAULT, winapi::CW_USEDEFAULT,
+                                                         rect.right - rect.left, rect.bottom - rect.top,
+                                                         ptr::null_mut(), ptr::null_mut(),
+                                                         kernel32::GetModuleHandleW(ptr::null()),
+                                                         ptr::null_mut());
+
+                    if handle.is_null() {
+                        return Err(CreationError::OsError(format!("CreateWindowEx function failed: {}",
+                                                          format!("{}", io::Error::last_os_error()))));
+                    }
+
+                    let hdc = user32::GetDC(handle);
+                    if hdc.is_null() {
+                        let err = Err(CreationError::OsError(format!("GetDC function failed: {}",
+                                                           format!("{}", io::Error::last_os_error()))));
+                        return err;
+                    }
+
+                    WindowWrapper(handle, hdc)
+                };
+
+                // getting the pixel format that we will use and setting it
+                {
+                    let formats = enumerate_native_pixel_formats(dummy_window.1);
+                    let id = try!(choose_dummy_pixel_format(formats.into_iter()));
+                    try!(set_pixel_format(dummy_window.1, id));
+                }
+
+                // creating the dummy OpenGL context and making it current
+                let dummy_context = try!(create_context(None, dummy_window.0, dummy_window.1, None));
+                let _current_context = try!(CurrentContextGuard::make_current(dummy_window.1,
+                                                                              dummy_context.0));
+
+                // loading the extra WGL functions
+                gl::wgl_extra::Wgl::load_with(|addr| {
+                    let addr = CString::new(addr.as_bytes()).unwrap();
+                    let addr = addr.as_ptr();
+                    gl::wgl::GetProcAddress(addr) as *const libc::c_void
+                })
+            };
+
+            // calling SetPixelFormat
+            let pixel_format = {
+                let formats = if extra_functions.GetPixelFormatAttribivARB.is_loaded() {
+                    let f = enumerate_arb_pixel_formats(&extra_functions, hdc);
+                    if f.is_empty() {
+                        enumerate_native_pixel_formats(hdc)
+                    } else {
+                        f
+                    }
+                } else {
+                    enumerate_native_pixel_formats(hdc)
+                };
+
+                let (id, f) = try!(builder.choose_pixel_format(formats.into_iter().map(|(a, b)| (b, a))));
+                try!(set_pixel_format(hdc, id));
+                f
+            };
+
+            // creating the OpenGL context
+            let context = try!(create_context(Some((&extra_functions, builder)), window, hdc,
+                                              builder_sharelists));
+
+            // loading the opengl32 module
+            let gl_library = try!(load_opengl32_dll());
+
+            // handling vsync
+            if builder.vsync {
+                if extra_functions.SwapIntervalEXT.is_loaded() {
+                    let _guard = try!(CurrentContextGuard::make_current(hdc, context.0));
+
+                    if extra_functions.SwapIntervalEXT(1) == 0 {
+                        return Err(CreationError::OsError(format!("wglSwapIntervalEXT failed")));
+                    }
+                }
+            }
+
+            Ok(Context {
+                context: context,
+                hdc: hdc,
+                gl_library: gl_library,
+                pixel_format: pixel_format,
+            })
+        }
+    }
+
+    /// Returns the raw HGLRC.
+    pub fn get_hglrc(&self) -> winapi::HGLRC {
+        self.context.0
+    }
+}
+
+impl GlContext for Context {
+    unsafe fn make_current(&self) {
+        // TODO: check return value
+        gl::wgl::MakeCurrent(self.hdc as *const _, self.context.0 as *const _);
+    }
+
+    fn is_current(&self) -> bool {
+        unsafe { gl::wgl::GetCurrentContext() == self.context.0 as *const libc::c_void }
+    }
+
+    fn get_proc_address(&self, addr: &str) -> *const libc::c_void {
+        let addr = CString::new(addr.as_bytes()).unwrap();
+        let addr = addr.as_ptr();
+
+        unsafe {
+            let p = gl::wgl::GetProcAddress(addr) as *const _;
+            if !p.is_null() { return p; }
+            kernel32::GetProcAddress(self.gl_library, addr) as *const _
+        }
+    }
+
+    fn swap_buffers(&self) {
+        unsafe {
+            gdi32::SwapBuffers(self.hdc);
+        }
+    }
+
+    fn get_api(&self) -> Api {
+        // FIXME: can be opengl es
+        Api::OpenGl
+    }
+
+    fn get_pixel_format(&self) -> PixelFormat {
+        self.pixel_format.clone()
+    }
+}
+
+unsafe impl Send for Context {}
+unsafe impl Sync for Context {}
+
+unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'static>)>,
+                         _: winapi::HWND, hdc: winapi::HDC, share: Option<winapi::HGLRC>)
+                         -> Result<ContextWrapper, CreationError>
+{
+    let share = share.unwrap_or(ptr::null_mut());
+
+    let ctxt = if let Some((extra_functions, builder)) = extra {
+        if extra_functions.CreateContextAttribsARB.is_loaded() {
+            let mut attributes = Vec::new();
+
+            match builder.gl_version {
+                GlRequest::Latest => {},
+                GlRequest::Specific(Api::OpenGl, (major, minor)) => {
+                    attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as libc::c_int);
+                    attributes.push(major as libc::c_int);
+                    attributes.push(gl::wgl_extra::CONTEXT_MINOR_VERSION_ARB as libc::c_int);
+                    attributes.push(minor as libc::c_int);
+                },
+                GlRequest::Specific(Api::OpenGlEs, (major, minor)) => {
+                    if is_extension_supported(extra_functions, hdc,
+                                              "WGL_EXT_create_context_es2_profile")
+                    {
+                        attributes.push(gl::wgl_extra::CONTEXT_PROFILE_MASK_ARB as libc::c_int);
+                        attributes.push(gl::wgl_extra::CONTEXT_ES2_PROFILE_BIT_EXT as libc::c_int);
+                    } else {
+                        return Err(CreationError::NotSupported);
+                    }
+
+                    attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as libc::c_int);
+                    attributes.push(major as libc::c_int);
+                    attributes.push(gl::wgl_extra::CONTEXT_MINOR_VERSION_ARB as libc::c_int);
+                    attributes.push(minor as libc::c_int);
+                },
+                GlRequest::Specific(_, _) => return Err(CreationError::NotSupported),
+                GlRequest::GlThenGles { opengl_version: (major, minor), .. } => {
+                    attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as libc::c_int);
+                    attributes.push(major as libc::c_int);
+                    attributes.push(gl::wgl_extra::CONTEXT_MINOR_VERSION_ARB as libc::c_int);
+                    attributes.push(minor as libc::c_int);
+                },
+            }
+
+            if let Some(profile) = builder.gl_profile {
+                if is_extension_supported(extra_functions, hdc,
+                                          "WGL_ARB_create_context_profile")
+                {
+                    let flag = match profile {
+                        GlProfile::Compatibility =>
+                            gl::wgl_extra::CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB,
+                        GlProfile::Core =>
+                            gl::wgl_extra::CONTEXT_CORE_PROFILE_BIT_ARB,
+                    };
+                    attributes.push(gl::wgl_extra::CONTEXT_PROFILE_MASK_ARB as libc::c_int);
+                    attributes.push(flag as libc::c_int);
+                } else {
+                    return Err(CreationError::NotSupported);
+                }
+            }
+
+            if builder.gl_debug {
+                attributes.push(gl::wgl_extra::CONTEXT_FLAGS_ARB as libc::c_int);
+                attributes.push(gl::wgl_extra::CONTEXT_DEBUG_BIT_ARB as libc::c_int);
+            }
+
+            attributes.push(0);
+
+            Some(extra_functions.CreateContextAttribsARB(hdc as *const libc::c_void,
+                                                         share as *const libc::c_void,
+                                                         attributes.as_ptr()))
+
+        } else {
+            None
+        }
+    } else {
+        None
+    };
+
+    let ctxt = match ctxt {
+        Some(ctxt) => ctxt,
+        None => {
+            let ctxt = gl::wgl::CreateContext(hdc as *const libc::c_void);
+            if !ctxt.is_null() && !share.is_null() {
+                gl::wgl::ShareLists(share as *const libc::c_void, ctxt);
+            };
+            ctxt
+        }
+    };
+
+    if ctxt.is_null() {
+        return Err(CreationError::OsError(format!("OpenGL context creation failed: {}",
+                                                  format!("{}", io::Error::last_os_error()))));
+    }
+
+    Ok(ContextWrapper(ctxt as winapi::HGLRC))
+}
+
+unsafe fn enumerate_native_pixel_formats(hdc: winapi::HDC) -> Vec<(PixelFormat, libc::c_int)> {
+    let size_of_pxfmtdescr = mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>() as u32;
+    let num = gdi32::DescribePixelFormat(hdc, 1, size_of_pxfmtdescr, ptr::null_mut());
+
+    let mut result = Vec::new();
+
+    for index in (0 .. num) {
+        let mut output: winapi::PIXELFORMATDESCRIPTOR = mem::zeroed();
+        
+        if gdi32::DescribePixelFormat(hdc, index, size_of_pxfmtdescr, &mut output) == 0 {
+            continue;
+        }
+
+        if (output.dwFlags & winapi::PFD_DRAW_TO_WINDOW) == 0 {
+            continue;
+        }
+
+        if (output.dwFlags & winapi::PFD_SUPPORT_OPENGL) == 0 {
+            continue;
+        }
+
+        if output.iPixelType != winapi::PFD_TYPE_RGBA {
+            continue;
+        }
+
+        result.push((PixelFormat {
+            hardware_accelerated: (output.dwFlags & winapi::PFD_GENERIC_FORMAT) == 0,
+            color_bits: output.cRedBits + output.cGreenBits + output.cBlueBits,
+            alpha_bits: output.cAlphaBits,
+            depth_bits: output.cDepthBits,
+            stencil_bits: output.cStencilBits,
+            stereoscopy: (output.dwFlags & winapi::PFD_STEREO) != 0,
+            double_buffer: (output.dwFlags & winapi::PFD_DOUBLEBUFFER) != 0,
+            multisampling: None,
+            srgb: false,
+        }, index));
+    }
+
+    result
+}
+
+unsafe fn enumerate_arb_pixel_formats(extra: &gl::wgl_extra::Wgl, hdc: winapi::HDC)
+                                      -> Vec<(PixelFormat, libc::c_int)>
+{
+    let get_info = |index: u32, attrib: u32| {
+        let mut value = mem::uninitialized();
+        extra.GetPixelFormatAttribivARB(hdc as *const _, index as libc::c_int,
+                                        0, 1, [attrib as libc::c_int].as_ptr(),
+                                        &mut value);
+        value as u32
+    };
+
+    // getting the number of formats
+    // the `1` is ignored
+    let num = get_info(1, gl::wgl_extra::NUMBER_PIXEL_FORMATS_ARB);
+
+    let mut result = Vec::new();
+
+    for index in (0 .. num) {
+        if get_info(index, gl::wgl_extra::DRAW_TO_WINDOW_ARB) == 0 {
+            continue;
+        }
+        if get_info(index, gl::wgl_extra::SUPPORT_OPENGL_ARB) == 0 {
+            continue;
+        }
+
+        if get_info(index, gl::wgl_extra::ACCELERATION_ARB) == gl::wgl_extra::NO_ACCELERATION_ARB {
+            continue;
+        }
+
+        if get_info(index, gl::wgl_extra::PIXEL_TYPE_ARB) != gl::wgl_extra::TYPE_RGBA_ARB {
+            continue;
+        }
+
+        result.push((PixelFormat {
+            hardware_accelerated: true,
+            color_bits: get_info(index, gl::wgl_extra::RED_BITS_ARB) as u8 + 
+                        get_info(index, gl::wgl_extra::GREEN_BITS_ARB) as u8 +
+                        get_info(index, gl::wgl_extra::BLUE_BITS_ARB) as u8,
+            alpha_bits: get_info(index, gl::wgl_extra::ALPHA_BITS_ARB) as u8,
+            depth_bits: get_info(index, gl::wgl_extra::DEPTH_BITS_ARB) as u8,
+            stencil_bits: get_info(index, gl::wgl_extra::STENCIL_BITS_ARB) as u8,
+            stereoscopy: get_info(index, gl::wgl_extra::STEREO_ARB) != 0,
+            double_buffer: get_info(index, gl::wgl_extra::DOUBLE_BUFFER_ARB) != 0,
+            multisampling: {
+                if is_extension_supported(extra, hdc, "WGL_ARB_multisample") {
+                    match get_info(index, gl::wgl_extra::SAMPLES_ARB) {
+                        0 => None,
+                        a => Some(a as u16),
+                    }
+                } else {
+                    None
+                }
+            },
+            srgb: if is_extension_supported(extra, hdc, "WGL_ARB_framebuffer_sRGB") {
+                get_info(index, gl::wgl_extra::FRAMEBUFFER_SRGB_CAPABLE_ARB) != 0
+            } else if is_extension_supported(extra, hdc, "WGL_EXT_framebuffer_sRGB") {
+                get_info(index, gl::wgl_extra::FRAMEBUFFER_SRGB_CAPABLE_EXT) != 0
+            } else {
+                false
+            },
+        }, index as libc::c_int));
+    }
+
+    result
+}
+
+unsafe fn set_pixel_format(hdc: winapi::HDC, id: libc::c_int) -> Result<(), CreationError> {
+    let mut output: winapi::PIXELFORMATDESCRIPTOR = mem::zeroed();
+
+    if gdi32::DescribePixelFormat(hdc, id, mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>()
+                                  as winapi::UINT, &mut output) == 0
+    {
+        return Err(CreationError::OsError(format!("DescribePixelFormat function failed: {}",
+                                                  format!("{}", io::Error::last_os_error()))));
+    }
+
+    if gdi32::SetPixelFormat(hdc, id, &output) == 0 {
+        return Err(CreationError::OsError(format!("SetPixelFormat function failed: {}",
+                                                  format!("{}", io::Error::last_os_error()))));
+    }
+
+    Ok(())
+}
+
+unsafe fn load_opengl32_dll() -> Result<winapi::HMODULE, CreationError> {
+    let name = OsStr::new("opengl32.dll").encode_wide().chain(Some(0).into_iter())
+                                         .collect::<Vec<_>>();
+
+    let lib = kernel32::LoadLibraryW(name.as_ptr());
+
+    if lib.is_null() {
+        return Err(CreationError::OsError(format!("LoadLibrary function failed: {}",
+                                                  format!("{}", io::Error::last_os_error()))));
+    }
+
+    Ok(lib)
+}
+
+unsafe fn is_extension_supported(extra: &gl::wgl_extra::Wgl, hdc: winapi::HDC,
+                                 extension: &str) -> bool
+{
+    let extensions = if extra.GetExtensionsStringARB.is_loaded() {
+        let data = extra.GetExtensionsStringARB(hdc as *const _);
+        let data = CStr::from_ptr(data).to_bytes().to_vec();
+        String::from_utf8(data).unwrap()
+
+    } else if extra.GetExtensionsStringEXT.is_loaded() {
+        let data = extra.GetExtensionsStringEXT();
+        let data = CStr::from_ptr(data).to_bytes().to_vec();
+        String::from_utf8(data).unwrap()
+
+    } else {
+        return false;
+    };
+
+    extensions.split(" ").find(|&e| e == extension).is_some()
+}
+
+fn choose_dummy_pixel_format<I>(iter: I) -> Result<libc::c_int, CreationError>
+                                where I: Iterator<Item=(PixelFormat, libc::c_int)>
+{
+    let mut backup_id = None;
+
+    for (format, id) in iter {
+        if backup_id.is_none() {
+            backup_id = Some(id);
+        }
+
+        if format.hardware_accelerated {
+            return Ok(id);
+        }
+    }
+
+    backup_id.ok_or(CreationError::NotSupported)
+}
diff --git a/src/api/win32/init.rs b/src/api/win32/init.rs
index e5b0b3a..9223105 100644
--- a/src/api/win32/init.rs
+++ b/src/api/win32/init.rs
@@ -8,37 +8,32 @@ use std::thread;
 use super::callback;
 use super::Window;
 use super::MonitorID;
-use super::ContextWrapper;
 use super::WindowWrapper;
-use super::make_current_guard::CurrentContextGuard;
 
-use Api;
 use BuilderAttribs;
 use CreationError;
 use CreationError::OsError;
 use CursorState;
-use GlProfile;
-use GlRequest;
-use PixelFormat;
 
-use std::ffi::{CStr, CString, OsStr};
+use std::ffi::OsStr;
 use std::os::windows::ffi::OsStrExt;
 use std::sync::mpsc::channel;
 
-use libc;
-use super::gl;
 use winapi;
 use kernel32;
 use user32;
-use gdi32;
+
+use api::wgl::{self, Context};
 
 /// Work-around the fact that HGLRC doesn't implement Send
-pub struct ContextHack(pub winapi::HGLRC);
+struct ContextHack(winapi::HGLRC);
 unsafe impl Send for ContextHack {}
 
-pub fn new_window(builder: BuilderAttribs<'static>, builder_sharelists: Option<ContextHack>)
+pub fn new_window(builder: BuilderAttribs<'static>, builder_sharelists: Option<winapi::HGLRC>)
                   -> Result<Window, CreationError>
 {
+    let builder_sharelists = builder_sharelists.map(|s| ContextHack(s));
+
     // initializing variables to be sent to the task
 
     let title = OsStr::new(&builder.title).encode_wide().chain(Some(0).into_iter())
@@ -110,57 +105,6 @@ unsafe fn init(title: Vec<u16>, builder: BuilderAttribs<'static>,
     // adjusting the window coordinates using the style
     user32::AdjustWindowRectEx(&mut rect, style, 0, ex_style);
 
-    // the first step is to create a dummy window and a dummy context which we will use
-    // to load the pointers to some functions in the OpenGL driver in `extra_functions`
-    let extra_functions = {
-        // creating a dummy invisible window
-        let dummy_window = {
-            let handle = user32::CreateWindowExW(ex_style, class_name.as_ptr(),
-                title.as_ptr() as winapi::LPCWSTR,
-                style | winapi::WS_CLIPSIBLINGS | winapi::WS_CLIPCHILDREN,
-                winapi::CW_USEDEFAULT, winapi::CW_USEDEFAULT,
-                rect.right - rect.left, rect.bottom - rect.top,
-                ptr::null_mut(), ptr::null_mut(), kernel32::GetModuleHandleW(ptr::null()),
-                ptr::null_mut());
-
-            if handle.is_null() {
-                return Err(OsError(format!("CreateWindowEx function failed: {}",
-                                           format!("{}", io::Error::last_os_error()))));
-            }
-
-            let hdc = user32::GetDC(handle);
-            if hdc.is_null() {
-                let err = Err(OsError(format!("GetDC function failed: {}",
-                                              format!("{}", io::Error::last_os_error()))));
-                return err;
-            }
-
-            WindowWrapper(handle, hdc)
-        };
-
-        // getting the pixel format that we will use and setting it
-        {
-            let formats = enumerate_native_pixel_formats(&dummy_window);
-            let id = try!(choose_dummy_pixel_format(formats.into_iter()));
-            try!(set_pixel_format(&dummy_window, id));
-        }
-
-        // creating the dummy OpenGL context and making it current
-        let dummy_context = try!(create_context(None, &dummy_window, None));
-        let current_context = try!(CurrentContextGuard::make_current(&dummy_window,
-                                                                     &dummy_context));
-
-        // loading the extra WGL functions
-        gl::wgl_extra::Wgl::load_with(|addr| {
-            use libc;
-
-            let addr = CString::new(addr.as_bytes()).unwrap();
-            let addr = addr.as_ptr();
-
-            gl::wgl::GetProcAddress(addr) as *const libc::c_void
-        })
-    };
-
     // creating the real window this time, by using the functions in `extra_functions`
     let real_window = {
         let (width, height) = if builder.monitor.is_some() || builder.dimensions.is_some() {
@@ -203,27 +147,8 @@ unsafe fn init(title: Vec<u16>, builder: BuilderAttribs<'static>,
         WindowWrapper(handle, hdc)
     };
 
-    // calling SetPixelFormat
-    let pixel_format = {
-        let formats = if extra_functions.GetPixelFormatAttribivARB.is_loaded() {
-            let f = enumerate_arb_pixel_formats(&extra_functions, &real_window);
-            if f.is_empty() {
-                enumerate_native_pixel_formats(&real_window)
-            } else {
-                f
-            }
-        } else {
-            enumerate_native_pixel_formats(&real_window)
-        };
-
-        let (id, f) = try!(builder.choose_pixel_format(formats.into_iter().map(|(a, b)| (b, a))));
-        try!(set_pixel_format(&real_window, id));
-        f
-    };
-
-    // creating the OpenGL context
-    let context = try!(create_context(Some((&extra_functions, &builder)), &real_window,
-                                      builder_sharelists));
+    // 
+    let context = try!(wgl::Context::new(&builder, real_window.0, builder_sharelists));
 
     // calling SetForegroundWindow if fullscreen
     if builder.monitor.is_some() {
@@ -248,29 +173,13 @@ unsafe fn init(title: Vec<u16>, builder: BuilderAttribs<'static>,
         rx
     };
 
-    // loading the opengl32 module
-    let gl_library = try!(load_opengl32_dll());
-
-    // handling vsync
-    if builder.vsync {
-        if extra_functions.SwapIntervalEXT.is_loaded() {
-            let _guard = try!(CurrentContextGuard::make_current(&real_window, &context));
-
-            if extra_functions.SwapIntervalEXT(1) == 0 {
-                return Err(OsError(format!("wglSwapIntervalEXT failed")));
-            }
-        }
-    }
-
     // building the struct
     Ok(Window {
         window: real_window,
         context: context,
-        gl_library: gl_library,
         events_receiver: events_receiver,
         is_closed: AtomicBool::new(false),
         cursor_state: cursor_state,
-        pixel_format: pixel_format,
     })
 }
 
@@ -332,276 +241,3 @@ unsafe fn switch_to_fullscreen(rect: &mut winapi::RECT, monitor: &MonitorID)
 
     Ok(())
 }
-
-unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'static>)>,
-                         hdc: &WindowWrapper, share: Option<winapi::HGLRC>)
-                         -> Result<ContextWrapper, CreationError>
-{
-    let share = share.unwrap_or(ptr::null_mut());
-
-    let ctxt = if let Some((extra_functions, builder)) = extra {
-        if extra_functions.CreateContextAttribsARB.is_loaded() {
-            let mut attributes = Vec::new();
-
-            match builder.gl_version {
-                GlRequest::Latest => {},
-                GlRequest::Specific(Api::OpenGl, (major, minor)) => {
-                    attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as libc::c_int);
-                    attributes.push(major as libc::c_int);
-                    attributes.push(gl::wgl_extra::CONTEXT_MINOR_VERSION_ARB as libc::c_int);
-                    attributes.push(minor as libc::c_int);
-                },
-                GlRequest::Specific(Api::OpenGlEs, (major, minor)) => {
-                    if is_extension_supported(extra_functions, hdc,
-                                              "WGL_EXT_create_context_es2_profile")
-                    {
-                        attributes.push(gl::wgl_extra::CONTEXT_PROFILE_MASK_ARB as libc::c_int);
-                        attributes.push(gl::wgl_extra::CONTEXT_ES2_PROFILE_BIT_EXT as libc::c_int);
-                    } else {
-                        return Err(CreationError::NotSupported);
-                    }
-
-                    attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as libc::c_int);
-                    attributes.push(major as libc::c_int);
-                    attributes.push(gl::wgl_extra::CONTEXT_MINOR_VERSION_ARB as libc::c_int);
-                    attributes.push(minor as libc::c_int);
-                },
-                GlRequest::Specific(_, _) => return Err(CreationError::NotSupported),
-                GlRequest::GlThenGles { opengl_version: (major, minor), .. } => {
-                    attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as libc::c_int);
-                    attributes.push(major as libc::c_int);
-                    attributes.push(gl::wgl_extra::CONTEXT_MINOR_VERSION_ARB as libc::c_int);
-                    attributes.push(minor as libc::c_int);
-                },
-            }
-
-            if let Some(profile) = builder.gl_profile {
-                if is_extension_supported(extra_functions, hdc,
-                                          "WGL_ARB_create_context_profile")
-                {
-                    let flag = match profile {
-                        GlProfile::Compatibility =>
-                            gl::wgl_extra::CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB,
-                        GlProfile::Core =>
-                            gl::wgl_extra::CONTEXT_CORE_PROFILE_BIT_ARB,
-                    };
-                    attributes.push(gl::wgl_extra::CONTEXT_PROFILE_MASK_ARB as libc::c_int);
-                    attributes.push(flag as libc::c_int);
-                } else {
-                    return Err(CreationError::NotSupported);
-                }
-            }
-
-            if builder.gl_debug {
-                attributes.push(gl::wgl_extra::CONTEXT_FLAGS_ARB as libc::c_int);
-                attributes.push(gl::wgl_extra::CONTEXT_DEBUG_BIT_ARB as libc::c_int);
-            }
-
-            attributes.push(0);
-
-            Some(extra_functions.CreateContextAttribsARB(hdc.1 as *const libc::c_void,
-                                                         share as *const libc::c_void,
-                                                         attributes.as_ptr()))
-
-        } else {
-            None
-        }
-    } else {
-        None
-    };
-
-    let ctxt = match ctxt {
-        Some(ctxt) => ctxt,
-        None => {
-            let ctxt = gl::wgl::CreateContext(hdc.1 as *const libc::c_void);
-            if !ctxt.is_null() && !share.is_null() {
-                gl::wgl::ShareLists(share as *const libc::c_void, ctxt);
-            };
-            ctxt
-        }
-    };
-
-    if ctxt.is_null() {
-        return Err(OsError(format!("OpenGL context creation failed: {}",
-                           format!("{}", io::Error::last_os_error()))));
-    }
-
-    Ok(ContextWrapper(ctxt as winapi::HGLRC))
-}
-
-unsafe fn enumerate_native_pixel_formats(hdc: &WindowWrapper) -> Vec<(PixelFormat, libc::c_int)> {
-    let size_of_pxfmtdescr = mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>() as u32;
-    let num = gdi32::DescribePixelFormat(hdc.1, 1, size_of_pxfmtdescr, ptr::null_mut());
-
-    let mut result = Vec::new();
-
-    for index in (0 .. num) {
-        let mut output: winapi::PIXELFORMATDESCRIPTOR = mem::zeroed();
-        
-        if gdi32::DescribePixelFormat(hdc.1, index, size_of_pxfmtdescr, &mut output) == 0 {
-            continue;
-        }
-
-        if (output.dwFlags & winapi::PFD_DRAW_TO_WINDOW) == 0 {
-            continue;
-        }
-
-        if (output.dwFlags & winapi::PFD_SUPPORT_OPENGL) == 0 {
-            continue;
-        }
-
-        if output.iPixelType != winapi::PFD_TYPE_RGBA {
-            continue;
-        }
-
-        result.push((PixelFormat {
-            hardware_accelerated: (output.dwFlags & winapi::PFD_GENERIC_FORMAT) == 0,
-            color_bits: output.cRedBits + output.cGreenBits + output.cBlueBits,
-            alpha_bits: output.cAlphaBits,
-            depth_bits: output.cDepthBits,
-            stencil_bits: output.cStencilBits,
-            stereoscopy: (output.dwFlags & winapi::PFD_STEREO) != 0,
-            double_buffer: (output.dwFlags & winapi::PFD_DOUBLEBUFFER) != 0,
-            multisampling: None,
-            srgb: false,
-        }, index));
-    }
-
-    result
-}
-
-unsafe fn enumerate_arb_pixel_formats(extra: &gl::wgl_extra::Wgl, hdc: &WindowWrapper)
-                                      -> Vec<(PixelFormat, libc::c_int)>
-{
-    let get_info = |index: u32, attrib: u32| {
-        let mut value = mem::uninitialized();
-        extra.GetPixelFormatAttribivARB(hdc.1 as *const libc::c_void, index as libc::c_int,
-                                        0, 1, [attrib as libc::c_int].as_ptr(),
-                                        &mut value);
-        value as u32
-    };
-
-    // getting the number of formats
-    // the `1` is ignored
-    let num = get_info(1, gl::wgl_extra::NUMBER_PIXEL_FORMATS_ARB);
-
-    let mut result = Vec::new();
-
-    for index in (0 .. num) {
-        if get_info(index, gl::wgl_extra::DRAW_TO_WINDOW_ARB) == 0 {
-            continue;
-        }
-        if get_info(index, gl::wgl_extra::SUPPORT_OPENGL_ARB) == 0 {
-            continue;
-        }
-
-        if get_info(index, gl::wgl_extra::ACCELERATION_ARB) == gl::wgl_extra::NO_ACCELERATION_ARB {
-            continue;
-        }
-
-        if get_info(index, gl::wgl_extra::PIXEL_TYPE_ARB) != gl::wgl_extra::TYPE_RGBA_ARB {
-            continue;
-        }
-
-        result.push((PixelFormat {
-            hardware_accelerated: true,
-            color_bits: get_info(index, gl::wgl_extra::RED_BITS_ARB) as u8 + 
-                        get_info(index, gl::wgl_extra::GREEN_BITS_ARB) as u8 +
-                        get_info(index, gl::wgl_extra::BLUE_BITS_ARB) as u8,
-            alpha_bits: get_info(index, gl::wgl_extra::ALPHA_BITS_ARB) as u8,
-            depth_bits: get_info(index, gl::wgl_extra::DEPTH_BITS_ARB) as u8,
-            stencil_bits: get_info(index, gl::wgl_extra::STENCIL_BITS_ARB) as u8,
-            stereoscopy: get_info(index, gl::wgl_extra::STEREO_ARB) != 0,
-            double_buffer: get_info(index, gl::wgl_extra::DOUBLE_BUFFER_ARB) != 0,
-            multisampling: {
-                if is_extension_supported(extra, hdc, "WGL_ARB_multisample") {
-                    match get_info(index, gl::wgl_extra::SAMPLES_ARB) {
-                        0 => None,
-                        a => Some(a as u16),
-                    }
-                } else {
-                    None
-                }
-            },
-            srgb: if is_extension_supported(extra, hdc, "WGL_ARB_framebuffer_sRGB") {
-                get_info(index, gl::wgl_extra::FRAMEBUFFER_SRGB_CAPABLE_ARB) != 0
-            } else if is_extension_supported(extra, hdc, "WGL_EXT_framebuffer_sRGB") {
-                get_info(index, gl::wgl_extra::FRAMEBUFFER_SRGB_CAPABLE_EXT) != 0
-            } else {
-                false
-            },
-        }, index as libc::c_int));
-    }
-
-    result
-}
-
-unsafe fn set_pixel_format(hdc: &WindowWrapper, id: libc::c_int) -> Result<(), CreationError> {
-    let mut output: winapi::PIXELFORMATDESCRIPTOR = mem::zeroed();
-
-    if gdi32::DescribePixelFormat(hdc.1, id, mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>()
-                                  as winapi::UINT, &mut output) == 0
-    {
-        return Err(OsError(format!("DescribePixelFormat function failed: {}",
-                                   format!("{}", io::Error::last_os_error()))));
-    }
-
-    if gdi32::SetPixelFormat(hdc.1, id, &output) == 0 {
-        return Err(OsError(format!("SetPixelFormat function failed: {}",
-                                   format!("{}", io::Error::last_os_error()))));
-    }
-
-    Ok(())
-}
-
-unsafe fn load_opengl32_dll() -> Result<winapi::HMODULE, CreationError> {
-    let name = OsStr::new("opengl32.dll").encode_wide().chain(Some(0).into_iter())
-                                         .collect::<Vec<_>>();
-
-    let lib = kernel32::LoadLibraryW(name.as_ptr());
-
-    if lib.is_null() {
-        return Err(OsError(format!("LoadLibrary function failed: {}",
-                                    format!("{}", io::Error::last_os_error()))));
-    }
-
-    Ok(lib)
-}
-
-unsafe fn is_extension_supported(extra: &gl::wgl_extra::Wgl, hdc: &WindowWrapper,
-                                 extension: &str) -> bool
-{
-    let extensions = if extra.GetExtensionsStringARB.is_loaded() {
-        let data = extra.GetExtensionsStringARB(hdc.1 as *const _);
-        let data = CStr::from_ptr(data).to_bytes().to_vec();
-        String::from_utf8(data).unwrap()
-
-    } else if extra.GetExtensionsStringEXT.is_loaded() {
-        let data = extra.GetExtensionsStringEXT();
-        let data = CStr::from_ptr(data).to_bytes().to_vec();
-        String::from_utf8(data).unwrap()
-
-    } else {
-        return false;
-    };
-
-    extensions.split(" ").find(|&e| e == extension).is_some()
-}
-
-fn choose_dummy_pixel_format<I>(iter: I) -> Result<libc::c_int, CreationError>
-                                where I: Iterator<Item=(PixelFormat, libc::c_int)>
-{
-    let mut backup_id = None;
-
-    for (format, id) in iter {
-        if backup_id.is_none() {
-            backup_id = Some(id);
-        }
-
-        if format.hardware_accelerated {
-            return Ok(id);
-        }
-    }
-
-    backup_id.ok_or(CreationError::NotSupported)
-}
diff --git a/src/api/win32/mod.rs b/src/api/win32/mod.rs
index d0caea7..ff42408 100644
--- a/src/api/win32/mod.rs
+++ b/src/api/win32/mod.rs
@@ -3,7 +3,6 @@
 use std::sync::atomic::AtomicBool;
 use std::mem;
 use std::ptr;
-use std::ffi::CString;
 use std::ffi::OsStr;
 use std::os::windows::ffi::OsStrExt;
 use std::sync::{
@@ -25,13 +24,12 @@ pub use self::monitor::{MonitorID, get_available_monitors, get_primary_monitor};
 use winapi;
 use user32;
 use kernel32;
-use gdi32;
+
+use api::wgl;
 
 mod callback;
 mod event;
-mod gl;
 mod init;
-mod make_current_guard;
 mod monitor;
 
 /// The Win32 implementation of the main `Window` object.
@@ -40,13 +38,7 @@ pub struct Window {
     window: WindowWrapper,
 
     /// OpenGL context.
-    context: ContextWrapper,
-
-    /// Binded to `opengl32.dll`.
-    ///
-    /// `wglGetProcAddress` returns null for GL 1.1 functions because they are
-    ///  already defined by the system. This module contains them.
-    gl_library: winapi::HMODULE,
+    context: wgl::Context,
 
     /// Receiver for the events dispatched by the window callback.
     events_receiver: Receiver<Event>,
@@ -56,27 +48,11 @@ pub struct Window {
 
     /// The current cursor state.
     cursor_state: Arc<Mutex<CursorState>>,
-
-    /// The pixel format that has been used to create this window.
-    pixel_format: PixelFormat,
 }
 
 unsafe impl Send for Window {}
 unsafe impl Sync for Window {}
 
-/// A simple wrapper that destroys the context when it is destroyed.
-// FIXME: remove `pub` (https://github.com/rust-lang/rust/issues/23585)
-#[doc(hidden)]
-pub struct ContextWrapper(pub winapi::HGLRC);
-
-impl Drop for ContextWrapper {
-    fn drop(&mut self) {
-        unsafe {
-            gl::wgl::DeleteContext(self.0 as *const libc::c_void);
-        }
-    }
-}
-
 /// A simple wrapper that destroys the window when it is destroyed.
 // FIXME: remove `pub` (https://github.com/rust-lang/rust/issues/23585)
 #[doc(hidden)]
@@ -103,7 +79,7 @@ impl Window {
     /// See the docs in the crate root file.
     pub fn new(builder: BuilderAttribs) -> Result<Window, CreationError> {
         let (builder, sharing) = builder.extract_non_static();
-        let sharing = sharing.map(|w| init::ContextHack(w.context.0));
+        let sharing = sharing.map(|w| w.context.get_hglrc());
         init::new_window(builder, sharing)
     }
 
@@ -326,38 +302,27 @@ impl Window {
 
 impl GlContext for Window {
     unsafe fn make_current(&self) {
-        // TODO: check return value
-        gl::wgl::MakeCurrent(self.window.1 as *const libc::c_void,
-                             self.context.0 as *const libc::c_void);
+        self.context.make_current()
     }
 
     fn is_current(&self) -> bool {
-        unsafe { gl::wgl::GetCurrentContext() == self.context.0 as *const libc::c_void }
+        self.context.is_current()
     }
 
     fn get_proc_address(&self, addr: &str) -> *const libc::c_void {
-        let addr = CString::new(addr.as_bytes()).unwrap();
-        let addr = addr.as_ptr();
-
-        unsafe {
-            let p = gl::wgl::GetProcAddress(addr) as *const _;
-            if !p.is_null() { return p; }
-            kernel32::GetProcAddress(self.gl_library, addr) as *const _
-        }
+        self.context.get_proc_address(addr)
     }
 
     fn swap_buffers(&self) {
-        unsafe {
-            gdi32::SwapBuffers(self.window.1);
-        }
+        self.context.swap_buffers()
     }
 
     fn get_api(&self) -> Api {
-        Api::OpenGl
+        self.context.get_api()
     }
 
     fn get_pixel_format(&self) -> PixelFormat {
-        self.pixel_format.clone()
+        self.context.get_pixel_format()
     }
 }