From d9c68cd32d40009f9d70954197130a9cdfc0f0a9 Mon Sep 17 00:00:00 2001
From: Philosoph228 <philosoph228@gmail.com>
Date: Mon, 24 Mar 2025 03:21:19 +0500
Subject: [PATCH] Fix CreateWindow client size CreateWindow(Ex) size parameters
 actually accepts outer window dimensions containing caption and border, which
 we can calculate with AdjustWindowRect by giving client size window
 dimensions.

---
 examples/win32_gdi/main.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/examples/win32_gdi/main.c b/examples/win32_gdi/main.c
index 761c59e..c28fbd3 100644
--- a/examples/win32_gdi/main.c
+++ b/examples/win32_gdi/main.c
@@ -26,6 +26,9 @@ void CenterWindow(HWND hWnd);
 long lastMsgTime = 0;
 bool ui_debug_mode;
 
+#define RECTWIDTH(rc)   ((rc).right - (rc).left)
+#define RECTHEIGHT(rc)  ((rc).bottom - (rc).top)
+
 LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
 
@@ -165,6 +168,10 @@ int APIENTRY WinMain(
     if (FALSE == RegisterClass(&wc))
         return 0;
 
+    // Calculate window rectangle by given client size
+    // TODO: AdjustWindowRectExForDpi for DPI support
+    RECT rcWindow = { .right = 800, .bottom = 600 };
+    AdjustWindowRect(&rcWindow, WS_OVERLAPPEDWINDOW, FALSE);
 
     hwnd = CreateWindow(
         szAppName,
@@ -172,8 +179,8 @@ int APIENTRY WinMain(
         WS_OVERLAPPEDWINDOW | WS_VISIBLE,
         CW_USEDEFAULT,
         CW_USEDEFAULT,
-        800, // CW_USEDEFAULT,
-        600, // CW_USEDEFAULT,
+        RECTWIDTH(rcWindow), // CW_USEDEFAULT,
+        RECTHEIGHT(rcWindow), // CW_USEDEFAULT,
         0,
         0,
         hInstance,