fix: Fix Windows 32-bit build errors (#223)

Author: mwcampbell

platforms/windows/src/adapter.rs

@@ -195,7 +195,7 @@ impl Adapter {
         // than the client area of the window. DefWindowProc can handle those.
         // First, cast the lparam to i32, to handle inconsistent conversion
         // behavior in senders.
-        let objid: i32 = (lparam.0 & 0xFFFFFFFF) as _;
+        let objid = normalize_objid(lparam);
         if objid < 0 && objid != UiaRootObjectId && objid != OBJID_CLIENT.0 {
             return None;
         }
@@ -210,6 +210,15 @@ impl Adapter {
     }
 }
 
+#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
+fn normalize_objid(lparam: LPARAM) -> i32 {
+    (lparam.0 & 0xFFFFFFFF) as _
+}
+#[cfg(not(any(target_arch = "x86_64", target_arch = "aarch64")))]
+fn normalize_objid(lparam: LPARAM) -> i32 {
+    lparam.0 as _
+}
+
 struct WmGetObjectResult {
     hwnd: HWND,
     wparam: WPARAM,

platforms/windows/src/subclass.rs

@@ -13,6 +13,13 @@ use windows::{
 
 use crate::{Adapter, QueuedEvents, UiaInitMarker};
 
+// Work around a difference between the SetWindowLongPtrW API definition
+// in windows-rs on 32-bit and 64-bit Windows.
+#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
+type LongPtr = isize;
+#[cfg(not(any(target_arch = "x86_64", target_arch = "aarch64")))]
+type LongPtr = i32;
+
 const PROP_NAME: PCWSTR = w!("AccessKitAdapter");
 
 type LazyAdapter = Lazy<Adapter, Box<dyn FnOnce() -> Adapter>>;
@@ -70,7 +77,7 @@ impl SubclassImpl {
             let result: Result<()> = Err(Error::from_win32());
             result.unwrap();
         }
-        self.prev_wnd_proc = unsafe { transmute::<isize, WNDPROC>(result) };
+        self.prev_wnd_proc = unsafe { transmute::<LongPtr, WNDPROC>(result) };
     }
 
     fn uninstall(&self) {
@@ -81,7 +88,7 @@ impl SubclassImpl {
             SetWindowLongPtrW(
                 self.hwnd,
                 GWLP_WNDPROC,
-                transmute::<WNDPROC, isize>(self.prev_wnd_proc),
+                transmute::<WNDPROC, LongPtr>(self.prev_wnd_proc),
             )
         };
         if result == 0 {