win32: default to alphanumeric input when the IME is first initialized

Some IMEs initialize to composition mode for new windows, which is
undesirable for keyboard control.
Default to alphanumeric input to solve this.

1 files changed, 30 insertions, 0 deletions

diff --git a/video/out/w32_common.c b/video/out/w32_common.c
index d2972f9193..17a6a7ba9d 100644
--- a/video/out/w32_common.c
+++ b/video/out/w32_common.c
@@ -1220,6 +1220,20 @@ static void update_cursor_passthrough(const struct vo_w32_state *w32)
     }
 }
 
+static void set_ime_conversion_mode(const struct vo_w32_state *w32, DWORD mode)
+{
+    if (w32->parent)
+        return;
+
+    HIMC imc = ImmGetContext(w32->window);
+    if (imc) {
+        DWORD sentence_mode;
+        if (ImmGetConversionStatus(imc, NULL, &sentence_mode))
+            ImmSetConversionStatus(imc, mode, sentence_mode);
+        ImmReleaseContext(w32->window, imc);
+    }
+}
+
 static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam,
                                 LPARAM lParam)
 {
@@ -1560,6 +1574,22 @@ static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam,
         }
         break;
     }
+    case WM_CREATE:
+        // The IME can only be changed to alphanumeric input after it's initialized.
+        // Unfortunately, there is no way to know when this happens, as
+        // none of the WM_CREATE, WM_INPUTLANGCHANGE, or WM_IME_* messages work.
+        // This works if the IME is initialized within a short time after
+        // the window is created. Otherwise, fallback to setting alphanumeric mode on
+        // the first keypress.
+        SetTimer(w32->window, (UINT_PTR)WM_CREATE, 250, NULL);
+        break;
+    case WM_TIMER:
+        if (wParam == WM_CREATE) {
+            // Default to alphanumeric input when the IME is first initialized.
+            set_ime_conversion_mode(w32, IME_CMODE_ALPHANUMERIC);
+            return 0;
+        }
+        break;
     }
 
     if (message == w32->tbtn_created_msg) {