windows 0.32.0

Rust for Windows
Documentation 
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use super::*;
use bindings::*;

/// Provides low-level access to a COM interface.
///
/// This trait is automatically used by the generated bindings and should not be
/// used directly.
/// # Safety
pub unsafe trait Interface: Sized {
    #[doc(hidden)]
    type Vtable;

    /// A unique identifier representing this interface.
    const IID: GUID;

    #[doc(hidden)]
    unsafe fn vtable(&self) -> &Self::Vtable {
        self.assume_vtable::<Self>()
    }

    #[doc(hidden)]
    unsafe fn assume_vtable<T: Interface>(&self) -> &T::Vtable {
        let this: RawPtr = core::mem::transmute_copy(self);
        &(*(*(this as *mut *mut _) as *mut _))
    }

    #[doc(hidden)]
    unsafe fn query(&self, iid: &GUID, interface: *mut RawPtr) -> HRESULT {
        (self.assume_vtable::<IUnknown>().QueryInterface)(core::mem::transmute_copy(self), iid, interface)
    }

    /// Attempts to cast the current interface to another interface using `QueryInterface`.
    /// The name `cast` is preferred to `query` because there is a WinRT method named query but not one
    /// named cast.
    fn cast<T: Interface>(&self) -> Result<T> {
        unsafe {
            let mut result = None;

            (self.assume_vtable::<IUnknown>().QueryInterface)(core::mem::transmute_copy(self), &T::IID, &mut result as *mut _ as _).and_some(result)
        }
    }

    /// Attempts to create a [`Weak`] reference to this object.
    fn downgrade(&self) -> Result<Weak<Self>> {
        self.cast::<IWeakReferenceSource>().and_then(|source| Weak::downgrade(&source))
    }
}