Implemented a HINSTANCE getter function for Windows (#1213)

* Expose HINSTANCE now using a getter function

* Missing changes

* remove unused import

* Required changes for the PR

* Rust fmt

* Use GetWindowLong

* Use GetWindowLong

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
 
+- On Windows, implemented function to get HINSTANCE
 - On macOS, implement `run_return`.
 - On iOS, fix inverted parameter in `set_prefers_home_indicator_hidden`.
 - On X11, performance is improved when rapidly calling `Window::set_cursor_icon`.

src/platform/windows.rs

@@ -34,6 +34,8 @@ impl<T> EventLoopExtWindows for EventLoop<T> {
 
 /// Additional methods on `Window` that are specific to Windows.
 pub trait WindowExtWindows {
+    /// Returns the HINSTANCE of the window
+    fn hinstance(&self) -> *mut libc::c_void;
     /// Returns the native handle that is used by this window.
     ///
     /// The pointer will become invalid when the native window was destroyed.
@@ -44,6 +46,11 @@ pub trait WindowExtWindows {
 }
 
 impl WindowExtWindows for Window {
+    #[inline]
+    fn hinstance(&self) -> *mut libc::c_void {
+        self.window.hinstance() as *mut _
+    }
+
     #[inline]
     fn hwnd(&self) -> *mut libc::c_void {
         self.window.hwnd() as *mut _

src/platform_impl/windows/window.rs

@@ -14,7 +14,7 @@ use std::{
 use winapi::{
     ctypes::c_int,
     shared::{
-        minwindef::{DWORD, LPARAM, UINT, WORD, WPARAM},
+        minwindef::{DWORD, HINSTANCE, LPARAM, UINT, WORD, WPARAM},
         windef::{HWND, POINT, RECT},
     },
     um::{
@@ -358,6 +358,11 @@ impl Window {
         self.window.0
     }
 
+    #[inline]
+    pub fn hinstance(&self) -> HINSTANCE {
+        unsafe { winuser::GetWindowLongW(self.hwnd(), winuser::GWL_HINSTANCE) as *mut _ }
+    }
+
     #[inline]
     pub fn raw_window_handle(&self) -> RawWindowHandle {
         let handle = WindowsHandle {