From bb537fe9969e490b74548738f16173d5b9d84c63 Mon Sep 17 00:00:00 2001
From: Amr Bashir <amr.bashir2015@gmail.com>
Date: Sat, 4 Jan 2025 17:20:20 +0200
Subject: [PATCH] fix(windows): fix set_size doing nothing for undecorated
 window with shadows (#1039)

closes tauri-apps/tauri#12168
---
 .../windows-set-size-undecorated-window.md    |  5 ++++
 src/platform_impl/windows/window.rs           | 24 ++++++++++++-------
 2 files changed, 20 insertions(+), 9 deletions(-)
 create mode 100644 .changes/windows-set-size-undecorated-window.md

diff --git a/.changes/windows-set-size-undecorated-window.md b/.changes/windows-set-size-undecorated-window.md
new file mode 100644
index 000000000..d25a934ce
--- /dev/null
+++ b/.changes/windows-set-size-undecorated-window.md
@@ -0,0 +1,5 @@
+---
+"tao": "patch"
+---
+
+On Windows, fix regression that caused `Window::set_size` to have no effect at all for undecorated window with shadows.
\ No newline at end of file
diff --git a/src/platform_impl/windows/window.rs b/src/platform_impl/windows/window.rs
index 7e2dabd29..e53837387 100644
--- a/src/platform_impl/windows/window.rs
+++ b/src/platform_impl/windows/window.rs
@@ -287,7 +287,7 @@ impl Window {
   #[inline]
   pub fn set_inner_size(&self, size: Size) {
     let scale_factor = self.scale_factor();
-    let (mut width, mut height) = size.to_physical::<i32>(scale_factor).into();
+    let (mut desired_width, mut desired_height) = size.to_physical::<i32>(scale_factor).into();
 
     let window_state = Arc::clone(&self.window_state);
 
@@ -300,13 +300,19 @@ impl Window {
       if unsafe { ClientToScreen(self.hwnd(), &mut pt) }.as_bool() == true {
         let mut window_rc: RECT = unsafe { mem::zeroed() };
         if unsafe { GetWindowRect(self.hwnd(), &mut window_rc) }.is_ok() {
-          let left_b = pt.x - window_rc.left;
-          let right_b = pt.x + width - window_rc.right;
-          let top_b = pt.y - window_rc.top;
-          let bottom_b = pt.y + height - window_rc.bottom;
-
-          width = width + (left_b - right_b);
-          height = height + (top_b - bottom_b);
+          let mut client_rc: RECT = unsafe { mem::zeroed() };
+          if unsafe { GetClientRect(self.hwnd(), &mut client_rc) }.is_ok() {
+            let curr_width = client_rc.right - client_rc.left;
+            let curr_height = client_rc.bottom - client_rc.top;
+
+            let left_b = pt.x - window_rc.left;
+            let right_b: i32 = (pt.x + curr_width) - window_rc.right;
+            let top_b = pt.y - window_rc.top;
+            let bottom_b: i32 = (pt.y + curr_height) - window_rc.bottom;
+
+            desired_width = desired_width + left_b + right_b.abs();
+            desired_height = desired_height + top_b + bottom_b.abs();
+          }
         }
       }
     }
@@ -318,7 +324,7 @@ impl Window {
       });
     });
 
-    util::set_inner_size_physical(self.window.0, width, height, is_decorated);
+    util::set_inner_size_physical(self.window.0, desired_width, desired_height, is_decorated);
   }
 
   #[inline]