m: Fix pointers and thread safety

Signed-off-by: John Nunley <dev@notgull.net>

src/backends/win32.rs

@@ -49,7 +49,7 @@ impl Drop for Buffer {
 impl Buffer {
  fn new(window_dc: Gdi::HDC, width: NonZeroI32, height: NonZeroI32) -> Self {
  let dc = Allocator::get().allocate(window_dc);
- assert!(dc != 0);
+ assert!(!dc.is_null());
 
  // Create a new bitmap info struct.
  let bitmap_info = BitmapInfo {
@@ -92,11 +92,11 @@ impl Buffer {
  &bitmap_info as *const BitmapInfo as *const _,
  Gdi::DIB_RGB_COLORS,
  &mut pixels as *mut *mut u32 as _,
- 0,
+ ptr::null_mut(),
  0,
  )
  };
- assert!(bitmap != 0);
+ assert!(!bitmap.is_null());
  let pixels = NonNull::new(pixels).unwrap();
 
  unsafe {
@@ -137,10 +137,10 @@ impl Buffer {
 /// The handle to a window for software buffering.
 pub struct Win32Impl<D: ?Sized, W> {
  /// The window handle.
- window: HWND,
+ window: OnlyUsedFromOrigin<HWND>,
 
  /// The device context for the window.
- dc: Gdi::HDC,
+ dc: OnlyUsedFromOrigin<Gdi::HDC>,
 
  /// The buffer used to hold the image.
  buffer: Option<Buffer>,
@@ -159,7 +159,7 @@ pub struct Win32Impl<D: ?Sized, W> {
 impl<D: ?Sized, W> Drop for Win32Impl<D, W> {
  fn drop(&mut self) {
  // Release our resources.
- Allocator::get().release(self.window, self.dc);
+ Allocator::get().release(self.window.0, self.dc.0);
  }
 }
 
@@ -184,11 +184,21 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> Win32Impl<D, W> {
  ))
  })()
  .ok_or(SoftBufferError::DamageOutOfRange { rect })?;
- Gdi::BitBlt(self.dc, x, y, width, height, buffer.dc, x, y, Gdi::SRCCOPY);
+ Gdi::BitBlt(
+ self.dc.0,
+ x,
+ y,
+ width,
+ height,
+ buffer.dc,
+ x,
+ y,
+ Gdi::SRCCOPY,
+ );
  }
 
  // Validate the window.
- Gdi::ValidateRect(self.window, ptr::null_mut());
+ Gdi::ValidateRect(self.window.0, ptr::null_mut());
  }
  buffer.presented = true;
 
@@ -214,7 +224,7 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> SurfaceInterface<D, W> for Win32Im
  let dc = Allocator::get().get_dc(hwnd);
 
  // GetDC returns null if there is a platform error.
- if dc == 0 {
+ if dc.is_null() {
  return Err(SoftBufferError::PlatformError(
  Some("Device Context is null".into()),
  Some(Box::new(io::Error::last_os_error())),
@@ -223,8 +233,8 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> SurfaceInterface<D, W> for Win32Im
  }
 
  Ok(Self {
- dc,
- window: hwnd,
+ dc: dc.into(),
+ window: hwnd.into(),
  buffer: None,
  handle: window,
  _display: PhantomData,
@@ -250,7 +260,7 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> SurfaceInterface<D, W> for Win32Im
  }
  }
 
- self.buffer = Some(Buffer::new(self.dc, width, height));
+ self.buffer = Some(Buffer::new(self.dc.0, width, height));
 
  Ok(())
  }
@@ -411,6 +421,8 @@ enum Command {
  },
 }
 
+unsafe impl Send for Command {}
+
 impl Command {
  /// Handle this command.
  ///
@@ -445,3 +457,12 @@ impl Command {
  }
  }
 }
+
+struct OnlyUsedFromOrigin<T>(T);
+unsafe impl<T> Send for OnlyUsedFromOrigin<T> {}
+
+impl<T> From<T> for OnlyUsedFromOrigin<T> {
+ fn from(t: T) -> Self {
+ Self(t)
+ }
+}