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use std::marker::PhantomData;
use std::os::raw::c_void;
use std::io;
use winapi;
use CreationError;
use super::gl;
/// A guard for when you want to make the context current. Destroying the guard restores the
/// previously-current context.
pub struct CurrentContextGuard<'a, 'b> {
previous_hdc: winapi::HDC,
previous_hglrc: winapi::HGLRC,
marker1: PhantomData<&'a ()>,
marker2: PhantomData<&'b ()>,
}
impl<'a, 'b> CurrentContextGuard<'a, 'b> {
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(hdc as *const _, context as *const _);
if result == 0 {
return Err(CreationError::OsError(format!("wglMakeCurrent function failed: {}",
format!("{}", io::Error::last_os_error()))));
}
Ok(CurrentContextGuard {
previous_hdc: previous_hdc,
previous_hglrc: previous_hglrc,
marker1: PhantomData,
marker2: PhantomData,
})
}
}
impl<'a, 'b> Drop for CurrentContextGuard<'a, 'b> {
fn drop(&mut self) {
unsafe {
gl::wgl::MakeCurrent(self.previous_hdc as *const c_void,
self.previous_hglrc as *const c_void);
}
}
}
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