Implement centered message box.

1 files changed, 45 insertions, 0 deletions

diff --git a/c/common.cpp b/c/common.cpp
index d503133..2259b69 100644
--- a/c/common.cpp
+++ b/c/common.cpp
@@ -57,3 +57,48 @@ Library::~Library()
 {
 	FreeLibrary(m_hModule);
 }
+
+/* Move message box to center of main window. */
+static LRESULT CALLBACK CBTProc(const int nCode, const WPARAM wParam, const LPARAM lParam)
+{
+	extern HWND g_hWnd;
+	if (!g_hWnd || nCode < 0 || nCode != HCBT_ACTIVATE)
+		return CallNextHookEx(0, nCode, wParam, lParam);
+
+	HWND hWnd = (HWND)wParam;
+	if (long lStyle = GetWindowLong(hWnd, GWL_STYLE))
+		if (lStyle & WS_POPUP) {
+			RECT rcMain, rcMsg;
+			GetWindowRect(g_hWnd, &rcMain);
+			GetWindowRect(hWnd, &rcMsg);
+			SetWindowPos(hWnd, NULL,
+			    rcMain.left+(rcMain.right-rcMain.left)/2-(rcMsg.right-rcMsg.left)/2,
+			    rcMain.top+(rcMain.bottom-rcMain.top)/2-(rcMsg.bottom-rcMsg.top)/2,
+			    -1, -1,
+			    SWP_NOZORDER|SWP_NOSIZE|SWP_NOACTIVATE);
+		}
+
+	return 0;
+}
+
+int EBMessageBox(const TCHAR* const tszText, const TCHAR* const tszCaption, const unsigned uType)
+{
+	extern HWND g_hWnd;
+	HHOOK hHook = SetWindowsHookEx(WH_CBT, CBTProc, 0, GetCurrentThreadId());
+	if (!hHook) return 0;
+	MessageBox(g_hWnd, tszText, tszCaption, uType);
+	UnhookWindowsHookEx(hHook);
+	if (!hHook) throw Win32Error(GetLastError());
+	return 0;
+}
+
+int EBMessageBoxA(const char* const szText, const char* const szCaption, const unsigned uType)
+{
+	extern HWND g_hWnd;
+	HHOOK hHook = SetWindowsHookEx(WH_CBT, CBTProc, 0, GetCurrentThreadId());
+	if (!hHook) return 0;
+	MessageBoxA(g_hWnd, szText, szCaption, uType);
+	UnhookWindowsHookEx(hHook);
+	if (!hHook) throw Win32Error(GetLastError());
+	return 0;
+}