Trait IExternalObjectsHandleWrapRenderInterfaceContextFeature

Source

pub trait IExternalObjectsHandleWrapRenderInterfaceContextFeature {
    // Required methods
    fn wrap_image_handle_on_any_thread(
        &self,
        handle: &Rc<dyn IPlatformHandle>,
        properties: PlatformGraphicsExternalImageProperties,
    ) -> Option<Rc<dyn IExternalObjectsWrappedGpuHandle>>;
    fn wrap_semaphore_handle_on_any_thread(
        &self,
        handle: &Rc<dyn IPlatformHandle>,
    ) -> Option<Rc<dyn IExternalObjectsWrappedGpuHandle>>;
}

Expand description

This interface allows proper management of ref-counted platform handles. If we immediately wrap the handle, the caller can destroy its copy immediately after the call This is needed for MoltenVK-based users that can e.g. get an MTLSharedEvent from a VkSemaphore. This does NOT actually increase the ref-counter of MTLSharedEvent, since it’s declared as __unsafe_unretained in vulkan headers. Same happens with exporting an IOSurfaceRef from a VkImage. So in a case when the VkSemaphore or VkImage is destroyed, the “handle” which is actually a pointer will be pointing to a dead object. To prevent this we need to increase the reference counter in a handle-specific means synchronously before returning control back to the user.

This is not needed for fds or DXGI handles, since those are created on demand as proper NT handles