w32_common: drop TLS usage

This was added in 3f268cc4f2a4 because it wasn't clear whether
WM_NCCREATE could be used to send a context pointer from CreateWindowEx
to the window procedure. WM_NCCREATE isn't always the first message sent
to a window, but this seems to be because of an undocumented but
well-known bug where, for top-level overlapped windows, a spurious
WM_GETMINMAXINFO arrives first instead. The WM_GETMINMAXINFO can be
safely ignored, so it is still okay to pass the context struct in
WM_NCCREATE.

1 files changed, 21 insertions, 20 deletions

diff --git a/video/out/w32_common.c b/video/out/w32_common.c
index ce9ff771b7..42d0135f74 100644
--- a/video/out/w32_common.c
+++ b/video/out/w32_common.c
@@ -62,8 +62,6 @@ typedef enum MONITOR_DPI_TYPE {
 } MONITOR_DPI_TYPE;
 #endif
 
-static __thread struct vo_w32_state *w32_thread_context;
-
 struct w32_api {
     HRESULT (WINAPI *pGetDpiForMonitor)(HMONITOR, MONITOR_DPI_TYPE, UINT*, UINT*);
 };
@@ -874,11 +872,21 @@ static void reinit_window_state(struct vo_w32_state *w32)
 static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam,
                                 LPARAM lParam)
 {
-    assert(w32_thread_context);
-    struct vo_w32_state *w32 = w32_thread_context;
-    if (!w32->window)
-        w32->window = hWnd; // can happen during CreateWindow*!
-    assert(w32->window == hWnd);
+    struct vo_w32_state *w32 = (void*)GetWindowLongPtrW(hWnd, GWLP_USERDATA);
+    if (!w32) {
+        // WM_NCCREATE is supposed to be the first message that a window
+        // receives. It allows struct vo_w32_state to be passed from
+        // CreateWindow's lpParam to the window procedure. However, as a
+        // longstanding Windows bug, overlapped top-level windows will get a
+        // WM_GETMINMAXINFO before WM_NCCREATE. This can be ignored.
+        if (message != WM_NCCREATE)
+            return DefWindowProcW(hWnd, message, wParam, lParam);
+
+        CREATESTRUCTW *cs = (CREATESTRUCTW *)lParam;
+        w32 = cs->lpCreateParams;
+        w32->window = hWnd;
+        SetWindowLongPtrW(hWnd, GWLP_USERDATA, (LONG_PTR)w32);
+    }
 
     switch (message) {
     case WM_USER:
@@ -1321,8 +1329,6 @@ static void *gui_thread(void *ptr)
     w32_api_load(w32);
     thread_disable_ime();
 
-    w32_thread_context = w32;
-
     if (w32->opts->WinID >= 0)
         w32->parent = (HWND)(intptr_t)(w32->opts->WinID);
 
@@ -1330,20 +1336,17 @@ static void *gui_thread(void *ptr)
     if (w32->parent) {
         RECT r;
         GetClientRect(w32->parent, &r);
-        w32->window = CreateWindowExW(WS_EX_NOPARENTNOTIFY,
-                                      (LPWSTR)MAKEINTATOM(cls), L"mpv",
-                                      WS_CHILD | WS_VISIBLE,
-                                      0, 0, r.right, r.bottom,
-                                      w32->parent, 0, HINST_THISCOMPONENT, NULL);
+        CreateWindowExW(WS_EX_NOPARENTNOTIFY, (LPWSTR)MAKEINTATOM(cls), L"mpv",
+                        WS_CHILD | WS_VISIBLE, 0, 0, r.right, r.bottom,
+                        w32->parent, 0, HINST_THISCOMPONENT, w32);
 
         // Install a hook to get notifications when the parent changes size
         if (w32->window)
             install_parent_hook(w32);
     } else {
-        w32->window = CreateWindowExW(0, (LPWSTR)MAKEINTATOM(cls), L"mpv",
-                                      update_style(w32, 0),
-                                      CW_USEDEFAULT, SW_HIDE, 100, 100,
-                                      0, 0, HINST_THISCOMPONENT, NULL);
+        CreateWindowExW(0, (LPWSTR)MAKEINTATOM(cls), L"mpv",
+                        update_style(w32, 0), CW_USEDEFAULT, SW_HIDE, 100, 100,
+                        0, 0, HINST_THISCOMPONENT, w32);
     }
 
     if (!w32->window) {
@@ -1423,8 +1426,6 @@ done:
     if (ole_ok)
         OleUninitialize();
     SetThreadExecutionState(ES_CONTINUOUS);
-
-    w32_thread_context = NULL;
     return NULL;
 }