ndk/native_window: Use release/acquire fns for Drop and Clone

Much like ALooper and AHardwareBuffer the reference counter of
ANativeWindow must be properly incremented on `Clone`, in turn allowing
us to also `_release` the window as soon as it is dropped.

ndk-glue/src/lib.rs

@@ -167,7 +167,7 @@ pub unsafe fn init(
 
     let activity = NativeActivity::from_ptr(activity);
     ndk_context::initialize_android_context(activity.vm().cast(), activity.activity().cast());
-    NATIVE_ACTIVITY = Some(activity);
+    NATIVE_ACTIVITY.replace(activity);
 
     let mut logpipe: [RawFd; 2] = Default::default();
     libc::pipe(logpipe.as_mut_ptr());
@@ -207,7 +207,7 @@ pub unsafe fn init(
 
         {
             let mut locked_looper = LOOPER.lock().unwrap();
-            *locked_looper = Some(foreign);
+            locked_looper.replace(foreign);
             signal_looper_ready.notify_one();
         }
 
@@ -274,7 +274,10 @@ unsafe extern "C" fn on_window_focus_changed(
 }
 
 unsafe extern "C" fn on_window_created(activity: *mut ANativeActivity, window: *mut ANativeWindow) {
-    *NATIVE_WINDOW.write().unwrap() = Some(NativeWindow::from_ptr(NonNull::new(window).unwrap()));
+    NATIVE_WINDOW
+        .write()
+        .unwrap()
+        .replace(NativeWindow::clone_from_ptr(NonNull::new(window).unwrap()));
     wake(activity, Event::WindowCreated);
 }
 
@@ -299,7 +302,7 @@ unsafe extern "C" fn on_window_destroyed(
     wake(activity, Event::WindowDestroyed);
     let mut native_window_guard = NATIVE_WINDOW.write().unwrap();
     assert_eq!(native_window_guard.as_ref().unwrap().ptr().as_ptr(), window);
-    *native_window_guard = None;
+    native_window_guard.take();
 }
 
 unsafe extern "C" fn on_input_queue_created(
@@ -312,7 +315,7 @@ unsafe extern "C" fn on_input_queue_created(
     // future code cleans it up and sets it back to `None` again.
     let looper = locked_looper.as_ref().expect("Looper does not exist");
     input_queue.attach_looper(looper, NDK_GLUE_LOOPER_INPUT_QUEUE_IDENT);
-    *INPUT_QUEUE.write().unwrap() = Some(input_queue);
+    INPUT_QUEUE.write().unwrap().replace(input_queue);
     wake(activity, Event::InputQueueCreated);
 }
 
@@ -325,7 +328,7 @@ unsafe extern "C" fn on_input_queue_destroyed(
     assert_eq!(input_queue_guard.as_ref().unwrap().ptr().as_ptr(), queue);
     let input_queue = InputQueue::from_ptr(NonNull::new(queue).unwrap());
     input_queue.detach_looper();
-    *input_queue_guard = None;
+    input_queue_guard.take();
 }
 
 unsafe extern "C" fn on_content_rect_changed(activity: *mut ANativeActivity, rect: *const ARect) {

ndk/CHANGELOG.md

@@ -3,6 +3,7 @@
 - ndk/hardware_buffer: Make `HardwareBuffer::as_ptr()` public for interop with Vulkan.
 - **Breaking:** `Configuration::country()` now returns `None` when the country is unset (akin to `Configuration::language()`)
 - Add `MediaCodec` and `MediaFormat` bindings ([#216](https://github.com/rust-windowing/android-ndk-rs/pull/216))
+- ndk/native_window: Use `release`/`acquire` for `Drop` and `Clone` respectively
 
 # 0.6.0 (2022-01-05)
 

ndk/src/media/media_codec.rs

@@ -380,13 +380,13 @@ impl MediaCodec {
     }
 
     #[cfg(feature = "api-level-26")]
-    pub fn set_input_surface(&self, surface: NativeWindow) -> Result<()> {
+    pub fn set_input_surface(&self, surface: &NativeWindow) -> Result<()> {
         let status =
             unsafe { ffi::AMediaCodec_setInputSurface(self.as_ptr(), surface.ptr().as_ptr()) };
         NdkMediaError::from_status(status)
     }
 
-    pub fn set_output_surface(&self, surface: NativeWindow) -> Result<()> {
+    pub fn set_output_surface(&self, surface: &NativeWindow) -> Result<()> {
         let status =
             unsafe { ffi::AMediaCodec_setOutputSurface(self.as_ptr(), surface.ptr().as_ptr()) };
         NdkMediaError::from_status(status)

ndk/src/native_window.rs

@@ -1,21 +1,47 @@
-//! Bindings for `ANativeWindow`
+//! Bindings for [`ffi::ANativeWindow`]
 use std::ptr::NonNull;
 
-#[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
+#[derive(Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 pub struct NativeWindow {
     ptr: NonNull<ffi::ANativeWindow>,
 }
 
 unsafe impl Send for NativeWindow {}
 unsafe impl Sync for NativeWindow {}
 
+impl Drop for NativeWindow {
+    fn drop(&mut self) {
+        unsafe { ffi::ANativeWindow_release(self.ptr.as_ptr()) }
+    }
+}
+
+impl Clone for NativeWindow {
+    fn clone(&self) -> Self {
+        unsafe {
+            ffi::ANativeWindow_acquire(self.ptr.as_ptr());
+            Self { ptr: self.ptr }
+        }
+    }
+}
+
 impl NativeWindow {
+    /// Assumes ownership of `ptr`
+    ///
     /// # Safety
-    /// `ptr` must be a valid pointer to an Android `ANativeWindow`.
+    /// `ptr` must be a valid pointer to an Android [`ffi::ANativeWindow`].
     pub unsafe fn from_ptr(ptr: NonNull<ffi::ANativeWindow>) -> Self {
         Self { ptr }
     }
 
+    /// Acquires ownership of `ptr`
+    ///
+    /// # Safety
+    /// `ptr` must be a valid pointer to an Android [`ffi::ANativeWindow`].
+    pub unsafe fn clone_from_ptr(ptr: NonNull<ffi::ANativeWindow>) -> Self {
+        ffi::ANativeWindow_acquire(ptr.as_ptr());
+        Self::from_ptr(ptr)
+    }
+
     pub fn ptr(&self) -> NonNull<ffi::ANativeWindow> {
         self.ptr
     }