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|
#![cfg(any(target_os = "windows"))]
use ContextError;
use CreationError;
use GlAttributes;
use GlContext;
use GlRequest;
use GlProfile;
use PixelFormat;
use PixelFormatRequirements;
use ReleaseBehavior;
use Robustness;
use Api;
use self::make_current_guard::CurrentContextGuard;
use std::ffi::{CStr, CString, OsStr};
use std::os::raw::{c_void, c_int};
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;
/// A WGL context.
///
/// Note: should be destroyed before its window.
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 {
#[inline]
fn drop(&mut self) {
unsafe {
user32::DestroyWindow(self.0);
}
}
}
/// Wraps around a context so that it is destroyed when necessary.
struct ContextWrapper(winapi::HGLRC);
impl Drop for ContextWrapper {
#[inline]
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.
///
/// # Unsafety
///
/// The `window` must continue to exist as long as the resulting `Context` exists.
pub unsafe fn new(pf_reqs: &PixelFormatRequirements, opengl: &GlAttributes<winapi::HGLRC>,
window: winapi::HWND) -> Result<Context, CreationError>
{
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;
}
// loading the functions that are not guaranteed to be supported
let extra_functions = try!(load_extra_functions(window));
// getting the list of the supported extensions
let extensions = if extra_functions.GetExtensionsStringARB.is_loaded() {
let data = extra_functions.GetExtensionsStringARB(hdc as *const _);
let data = CStr::from_ptr(data).to_bytes().to_vec();
String::from_utf8(data).unwrap()
} else if extra_functions.GetExtensionsStringEXT.is_loaded() {
let data = extra_functions.GetExtensionsStringEXT();
let data = CStr::from_ptr(data).to_bytes().to_vec();
String::from_utf8(data).unwrap()
} else {
format!("")
};
// calling SetPixelFormat
let pixel_format = {
let (id, f) = if extensions.split(' ').find(|&i| i == "WGL_ARB_pixel_format")
.is_some()
{
try!(choose_arb_pixel_format(&extra_functions, &extensions, hdc, pf_reqs)
.map_err(|_| CreationError::NoAvailablePixelFormat))
} else {
try!(choose_native_pixel_format(hdc, pf_reqs)
.map_err(|_| CreationError::NoAvailablePixelFormat))
};
try!(set_pixel_format(hdc, id));
f
};
// creating the OpenGL context
let context = try!(create_context(Some((&extra_functions, pf_reqs, opengl, &extensions)),
window, hdc));
// loading the opengl32 module
let gl_library = try!(load_opengl32_dll());
// handling vsync
if extensions.split(' ').find(|&i| i == "WGL_EXT_swap_control").is_some() {
let _guard = try!(CurrentContextGuard::make_current(hdc, context.0));
if extra_functions.SwapIntervalEXT(if opengl.vsync { 1 } else { 0 }) == 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.
#[inline]
pub fn get_hglrc(&self) -> winapi::HGLRC {
self.context.0
}
}
impl GlContext for Context {
#[inline]
unsafe fn make_current(&self) -> Result<(), ContextError> {
if gl::wgl::MakeCurrent(self.hdc as *const _, self.context.0 as *const _) != 0 {
Ok(())
} else {
Err(ContextError::IoError(io::Error::last_os_error()))
}
}
#[inline]
fn is_current(&self) -> bool {
unsafe { gl::wgl::GetCurrentContext() == self.context.0 as *const c_void }
}
fn get_proc_address(&self, addr: &str) -> *const () {
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 _
}
}
#[inline]
fn swap_buffers(&self) -> Result<(), ContextError> {
// TODO: decide how to handle the error
/*if unsafe { gdi32::SwapBuffers(self.hdc) } != 0 {
Ok(())
} else {
Err(ContextError::IoError(io::Error::last_os_error()))
}*/
unsafe { gdi32::SwapBuffers(self.hdc) };
Ok(())
}
#[inline]
fn get_api(&self) -> Api {
// FIXME: can be opengl es
Api::OpenGl
}
#[inline]
fn get_pixel_format(&self) -> PixelFormat {
self.pixel_format.clone()
}
}
unsafe impl Send for Context {}
unsafe impl Sync for Context {}
/// Creates an OpenGL context.
///
/// If `extra` is `Some`, this function will attempt to use the latest WGL functions to create the
/// context.
///
/// Otherwise, only the basic API will be used and the chances of `CreationError::NotSupported`
/// being returned increase.
unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &PixelFormatRequirements,
&GlAttributes<winapi::HGLRC>, &str)>,
_: winapi::HWND, hdc: winapi::HDC)
-> Result<ContextWrapper, CreationError>
{
let share;
if let Some((extra_functions, pf_reqs, opengl, extensions)) = extra {
share = opengl.sharing.unwrap_or(ptr::null_mut());
if extensions.split(' ').find(|&i| i == "WGL_ARB_create_context").is_some() {
let mut attributes = Vec::new();
match opengl.version {
GlRequest::Latest => {},
GlRequest::Specific(Api::OpenGl, (major, minor)) => {
attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as c_int);
attributes.push(major as c_int);
attributes.push(gl::wgl_extra::CONTEXT_MINOR_VERSION_ARB as c_int);
attributes.push(minor as c_int);
},
GlRequest::Specific(Api::OpenGlEs, (major, minor)) => {
if extensions.split(' ').find(|&i| i == "WGL_EXT_create_context_es2_profile")
.is_some()
{
attributes.push(gl::wgl_extra::CONTEXT_PROFILE_MASK_ARB as c_int);
attributes.push(gl::wgl_extra::CONTEXT_ES2_PROFILE_BIT_EXT as c_int);
} else {
return Err(CreationError::OpenGlVersionNotSupported);
}
attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as c_int);
attributes.push(major as c_int);
attributes.push(gl::wgl_extra::CONTEXT_MINOR_VERSION_ARB as c_int);
attributes.push(minor as c_int);
},
GlRequest::Specific(_, _) => return Err(CreationError::OpenGlVersionNotSupported),
GlRequest::GlThenGles { opengl_version: (major, minor), .. } => {
attributes.push(gl::wgl_extra::CONTEXT_MAJOR_VERSION_ARB as c_int);
attributes.push(major as c_int);
attributes.push(gl::wgl_extra::CONTEXT_MINOR_VERSION_ARB as c_int);
attributes.push(minor as c_int);
},
}
if let Some(profile) = opengl.profile {
if extensions.split(' ').find(|&i| i == "WGL_ARB_create_context_profile").is_some()
{
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 c_int);
attributes.push(flag as c_int);
} else {
return Err(CreationError::NotSupported);
}
}
let flags = {
let mut flags = 0;
// robustness
if extensions.split(' ').find(|&i| i == "WGL_ARB_create_context_robustness").is_some() {
match opengl.robustness {
Robustness::RobustNoResetNotification | Robustness::TryRobustNoResetNotification => {
attributes.push(gl::wgl_extra::CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB as c_int);
attributes.push(gl::wgl_extra::NO_RESET_NOTIFICATION_ARB as c_int);
flags = flags | gl::wgl_extra::CONTEXT_ROBUST_ACCESS_BIT_ARB as c_int;
},
Robustness::RobustLoseContextOnReset | Robustness::TryRobustLoseContextOnReset => {
attributes.push(gl::wgl_extra::CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB as c_int);
attributes.push(gl::wgl_extra::LOSE_CONTEXT_ON_RESET_ARB as c_int);
flags = flags | gl::wgl_extra::CONTEXT_ROBUST_ACCESS_BIT_ARB as c_int;
},
Robustness::NotRobust => (),
Robustness::NoError => (),
}
} else {
match opengl.robustness {
Robustness::RobustNoResetNotification | Robustness::RobustLoseContextOnReset => {
return Err(CreationError::RobustnessNotSupported);
},
_ => ()
}
}
if opengl.debug {
flags = flags | gl::wgl_extra::CONTEXT_DEBUG_BIT_ARB as c_int;
}
flags
};
attributes.push(gl::wgl_extra::CONTEXT_FLAGS_ARB as c_int);
attributes.push(flags);
attributes.push(0);
let ctxt = extra_functions.CreateContextAttribsARB(hdc as *const c_void,
share as *const c_void,
attributes.as_ptr());
if ctxt.is_null() {
return Err(CreationError::OsError(format!("wglCreateContextAttribsARB failed: {}",
format!("{}", io::Error::last_os_error()))));
} else {
return Ok(ContextWrapper(ctxt as winapi::HGLRC));
}
}
} else {
share = ptr::null_mut();
}
let ctxt = gl::wgl::CreateContext(hdc as *const c_void);
if ctxt.is_null() {
return Err(CreationError::OsError(format!("wglCreateContext failed: {}",
format!("{}", io::Error::last_os_error()))));
}
if !share.is_null() {
if gl::wgl::ShareLists(share as *const c_void, ctxt) == 0 {
return Err(CreationError::OsError(format!("wglShareLists failed: {}",
format!("{}", io::Error::last_os_error()))));
}
};
Ok(ContextWrapper(ctxt as winapi::HGLRC))
}
/// Chooses a pixel formats without using WGL.
///
/// Gives less precise results than `enumerate_arb_pixel_formats`.
unsafe fn choose_native_pixel_format(hdc: winapi::HDC, reqs: &PixelFormatRequirements)
-> Result<(c_int, PixelFormat), ()>
{
// TODO: hardware acceleration is not handled
// handling non-supported stuff
if reqs.float_color_buffer {
return Err(());
}
match reqs.multisampling {
Some(0) => (),
None => (),
Some(_) => return Err(())
};
if reqs.stereoscopy {
return Err(());
}
if reqs.srgb {
return Err(());
}
if reqs.release_behavior != ReleaseBehavior::Flush {
return Err(());
}
// building the descriptor to pass to ChoosePixelFormat
let descriptor = winapi::PIXELFORMATDESCRIPTOR {
nSize: mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>() as u16,
nVersion: 1,
dwFlags: {
let f1 = match reqs.double_buffer {
None => winapi::PFD_DOUBLEBUFFER, // Should be PFD_DOUBLEBUFFER_DONTCARE after you can choose
Some(true) => winapi::PFD_DOUBLEBUFFER,
Some(false) => 0,
};
let f2 = if reqs.stereoscopy {
winapi::PFD_STEREO
} else {
0
};
winapi::PFD_DRAW_TO_WINDOW | winapi::PFD_SUPPORT_OPENGL | f1 | f2
},
iPixelType: winapi::PFD_TYPE_RGBA,
cColorBits: reqs.color_bits.unwrap_or(0),
cRedBits: 0,
cRedShift: 0,
cGreenBits: 0,
cGreenShift: 0,
cBlueBits: 0,
cBlueShift: 0,
cAlphaBits: reqs.alpha_bits.unwrap_or(0),
cAlphaShift: 0,
cAccumBits: 0,
cAccumRedBits: 0,
cAccumGreenBits: 0,
cAccumBlueBits: 0,
cAccumAlphaBits: 0,
cDepthBits: reqs.depth_bits.unwrap_or(0),
cStencilBits: reqs.stencil_bits.unwrap_or(0),
cAuxBuffers: 0,
iLayerType: winapi::PFD_MAIN_PLANE,
bReserved: 0,
dwLayerMask: 0,
dwVisibleMask: 0,
dwDamageMask: 0,
};
// now querying
let pf_id = gdi32::ChoosePixelFormat(hdc, &descriptor);
if pf_id == 0 {
return Err(());
}
// querying back the capabilities of what windows told us
let mut output: winapi::PIXELFORMATDESCRIPTOR = mem::zeroed();
if gdi32::DescribePixelFormat(hdc, pf_id, mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>() as u32,
&mut output) == 0
{
return Err(());
}
// windows may return us a non-conforming pixel format if none are supported, so we have to
// check this
if (output.dwFlags & winapi::PFD_DRAW_TO_WINDOW) == 0 {
return Err(());
}
if (output.dwFlags & winapi::PFD_SUPPORT_OPENGL) == 0 {
return Err(());
}
if output.iPixelType != winapi::PFD_TYPE_RGBA {
return Err(());
}
let pf_desc = 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,
};
if pf_desc.alpha_bits < reqs.alpha_bits.unwrap_or(0) {
return Err(());
}
if pf_desc.depth_bits < reqs.depth_bits.unwrap_or(0) {
return Err(());
}
if pf_desc.stencil_bits < reqs.stencil_bits.unwrap_or(0) {
return Err(());
}
if pf_desc.color_bits < reqs.color_bits.unwrap_or(0) {
return Err(());
}
if let Some(req) = reqs.hardware_accelerated {
if pf_desc.hardware_accelerated != req {
return Err(());
}
}
if let Some(req) = reqs.double_buffer {
if pf_desc.double_buffer != req {
return Err(());
}
}
Ok((pf_id, pf_desc))
}
/// Enumerates the list of pixel formats by using extra WGL functions.
///
/// Gives more precise results than `enumerate_native_pixel_formats`.
unsafe fn choose_arb_pixel_format(extra: &gl::wgl_extra::Wgl, extensions: &str,
hdc: winapi::HDC, reqs: &PixelFormatRequirements)
-> Result<(c_int, PixelFormat), ()>
{
let descriptor = {
let mut out: Vec<c_int> = Vec::with_capacity(37);
out.push(gl::wgl_extra::DRAW_TO_WINDOW_ARB as c_int);
out.push(1);
out.push(gl::wgl_extra::SUPPORT_OPENGL_ARB as c_int);
out.push(1);
out.push(gl::wgl_extra::PIXEL_TYPE_ARB as c_int);
if reqs.float_color_buffer {
if extensions.split(' ').find(|&i| i == "WGL_ARB_pixel_format_float").is_some() {
out.push(gl::wgl_extra::TYPE_RGBA_FLOAT_ARB as c_int);
} else {
return Err(());
}
} else {
out.push(gl::wgl_extra::TYPE_RGBA_ARB as c_int);
}
if let Some(hardware_accelerated) = reqs.hardware_accelerated {
out.push(gl::wgl_extra::ACCELERATION_ARB as c_int);
out.push(if hardware_accelerated {
gl::wgl_extra::FULL_ACCELERATION_ARB as c_int
} else {
gl::wgl_extra::NO_ACCELERATION_ARB as c_int
});
}
if let Some(color) = reqs.color_bits {
out.push(gl::wgl_extra::COLOR_BITS_ARB as c_int);
out.push(color as c_int);
}
if let Some(alpha) = reqs.alpha_bits {
out.push(gl::wgl_extra::ALPHA_BITS_ARB as c_int);
out.push(alpha as c_int);
}
if let Some(depth) = reqs.depth_bits {
out.push(gl::wgl_extra::DEPTH_BITS_ARB as c_int);
out.push(depth as c_int);
}
if let Some(stencil) = reqs.stencil_bits {
out.push(gl::wgl_extra::STENCIL_BITS_ARB as c_int);
out.push(stencil as c_int);
}
// Prefer double buffering if unspecified (probably shouldn't once you can choose)
let double_buffer = reqs.double_buffer.unwrap_or(true);
out.push(gl::wgl_extra::DOUBLE_BUFFER_ARB as c_int);
out.push(if double_buffer { 1 } else { 0 });
if let Some(multisampling) = reqs.multisampling {
if extensions.split(' ').find(|&i| i == "WGL_ARB_multisample").is_some() {
out.push(gl::wgl_extra::SAMPLE_BUFFERS_ARB as c_int);
out.push(if multisampling == 0 { 0 } else { 1 });
out.push(gl::wgl_extra::SAMPLES_ARB as c_int);
out.push(multisampling as c_int);
} else {
return Err(());
}
}
out.push(gl::wgl_extra::STEREO_ARB as c_int);
out.push(if reqs.stereoscopy { 1 } else { 0 });
if reqs.srgb {
if extensions.split(' ').find(|&i| i == "WGL_ARB_framebuffer_sRGB").is_some() {
out.push(gl::wgl_extra::FRAMEBUFFER_SRGB_CAPABLE_ARB as c_int);
out.push(1);
} else if extensions.split(' ').find(|&i| i == "WGL_EXT_framebuffer_sRGB").is_some() {
out.push(gl::wgl_extra::FRAMEBUFFER_SRGB_CAPABLE_EXT as c_int);
out.push(1);
} else {
return Err(());
}
}
match reqs.release_behavior {
ReleaseBehavior::Flush => (),
ReleaseBehavior::None => {
if extensions.split(' ').find(|&i| i == "WGL_ARB_context_flush_control").is_some() {
out.push(gl::wgl_extra::CONTEXT_RELEASE_BEHAVIOR_ARB as c_int);
out.push(gl::wgl_extra::CONTEXT_RELEASE_BEHAVIOR_NONE_ARB as c_int);
}
},
}
out.push(0);
out
};
let mut format_id = mem::uninitialized();
let mut num_formats = mem::uninitialized();
if extra.ChoosePixelFormatARB(hdc as *const _, descriptor.as_ptr(), ptr::null(), 1,
&mut format_id, &mut num_formats) == 0
{
return Err(());
}
if num_formats == 0 {
return Err(());
}
let get_info = |attrib: u32| {
let mut value = mem::uninitialized();
extra.GetPixelFormatAttribivARB(hdc as *const _, format_id as c_int,
0, 1, [attrib as c_int].as_ptr(),
&mut value);
value as u32
};
let pf_desc = PixelFormat {
hardware_accelerated: get_info(gl::wgl_extra::ACCELERATION_ARB) !=
gl::wgl_extra::NO_ACCELERATION_ARB,
color_bits: get_info(gl::wgl_extra::RED_BITS_ARB) as u8 +
get_info(gl::wgl_extra::GREEN_BITS_ARB) as u8 +
get_info(gl::wgl_extra::BLUE_BITS_ARB) as u8,
alpha_bits: get_info(gl::wgl_extra::ALPHA_BITS_ARB) as u8,
depth_bits: get_info(gl::wgl_extra::DEPTH_BITS_ARB) as u8,
stencil_bits: get_info(gl::wgl_extra::STENCIL_BITS_ARB) as u8,
stereoscopy: get_info(gl::wgl_extra::STEREO_ARB) != 0,
double_buffer: get_info(gl::wgl_extra::DOUBLE_BUFFER_ARB) != 0,
multisampling: {
if extensions.split(' ').find(|&i| i == "WGL_ARB_multisample").is_some() {
match get_info(gl::wgl_extra::SAMPLES_ARB) {
0 => None,
a => Some(a as u16),
}
} else {
None
}
},
srgb: if extensions.split(' ').find(|&i| i == "WGL_ARB_framebuffer_sRGB").is_some() {
get_info(gl::wgl_extra::FRAMEBUFFER_SRGB_CAPABLE_ARB) != 0
} else if extensions.split(' ').find(|&i| i == "WGL_EXT_framebuffer_sRGB").is_some() {
get_info(gl::wgl_extra::FRAMEBUFFER_SRGB_CAPABLE_EXT) != 0
} else {
false
},
};
Ok((format_id, pf_desc))
}
/// Calls `SetPixelFormat` on a window.
unsafe fn set_pixel_format(hdc: winapi::HDC, id: 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(())
}
/// Loads the `opengl32.dll` library.
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)
}
/// Loads the WGL functions that are not guaranteed to be supported.
///
/// The `window` must be passed because the driver can vary depending on the window's
/// characteristics.
unsafe fn load_extra_functions(window: winapi::HWND) -> Result<gl::wgl_extra::Wgl, CreationError> {
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 = {
// getting the rect of the real window
let rect = {
let mut placement: winapi::WINDOWPLACEMENT = mem::zeroed();
placement.length = mem::size_of::<winapi::WINDOWPLACEMENT>() as winapi::UINT;
if user32::GetWindowPlacement(window, &mut placement) == 0 {
panic!();
}
placement.rcNormalPosition
};
// getting the class name of the real window
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()))));
}
// this dummy window should match the real one enough to get the same OpenGL driver
let win = 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 win.is_null() {
return Err(CreationError::OsError(format!("CreateWindowEx function failed: {}",
format!("{}", io::Error::last_os_error()))));
}
let hdc = user32::GetDC(win);
if hdc.is_null() {
let err = Err(CreationError::OsError(format!("GetDC function failed: {}",
format!("{}", io::Error::last_os_error()))));
return err;
}
WindowWrapper(win, hdc)
};
// getting the pixel format that we will use and setting it
{
let id = try!(choose_dummy_pixel_format(dummy_window.1));
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));
let _current_context = try!(CurrentContextGuard::make_current(dummy_window.1,
dummy_context.0));
// loading the extra WGL functions
Ok(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 c_void
}))
}
/// This function chooses a pixel format that is likely to be provided by
/// the main video driver of the system.
fn choose_dummy_pixel_format(hdc: winapi::HDC) -> Result<c_int, CreationError> {
// building the descriptor to pass to ChoosePixelFormat
let descriptor = winapi::PIXELFORMATDESCRIPTOR {
nSize: mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>() as u16,
nVersion: 1,
dwFlags: winapi::PFD_DRAW_TO_WINDOW | winapi::PFD_SUPPORT_OPENGL | winapi::PFD_DOUBLEBUFFER,
iPixelType: winapi::PFD_TYPE_RGBA,
cColorBits: 24,
cRedBits: 0,
cRedShift: 0,
cGreenBits: 0,
cGreenShift: 0,
cBlueBits: 0,
cBlueShift: 0,
cAlphaBits: 8,
cAlphaShift: 0,
cAccumBits: 0,
cAccumRedBits: 0,
cAccumGreenBits: 0,
cAccumBlueBits: 0,
cAccumAlphaBits: 0,
cDepthBits: 24,
cStencilBits: 8,
cAuxBuffers: 0,
iLayerType: winapi::PFD_MAIN_PLANE,
bReserved: 0,
dwLayerMask: 0,
dwVisibleMask: 0,
dwDamageMask: 0,
};
// now querying
let pf_id = unsafe { gdi32::ChoosePixelFormat(hdc, &descriptor) };
if pf_id == 0 {
return Err(CreationError::OsError("No available pixel format".to_owned()));
}
Ok(pf_id)
}
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