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-rw-r--r--src/api/wgl/make_current_guard.rs47
1 files changed, 47 insertions, 0 deletions
diff --git a/src/api/wgl/make_current_guard.rs b/src/api/wgl/make_current_guard.rs
new file mode 100644
index 0000000..b890c82
--- /dev/null
+++ b/src/api/wgl/make_current_guard.rs
@@ -0,0 +1,47 @@
+use std::marker::PhantomData;
+use std::io;
+
+use libc;
+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 libc::c_void,
+ self.previous_hglrc as *const libc::c_void);
+ }
+ }
+}