From 51669f36f3ad216591aaf43c9a8da77dd89b437b Mon Sep 17 00:00:00 2001
From: tomcw <tomcw@users.noreply.github.com>
Date: Sat, 16 Jun 2018 10:24:05 +0100
Subject: [PATCH] Hook system keys: (#556) . added -no-hook-system-key to
 prevent hooking system keys . updated help . HookFilter.dll: changed to
 directly send virtual key code

---
 HookFilter/HookFilter.cpp | 10 +++-------
 help/CommandLine.html     |  2 ++
 source/Applewin.cpp       | 37 ++++++++++++++++++++++++++-----------
 3 files changed, 31 insertions(+), 18 deletions(-)

diff --git a/HookFilter/HookFilter.cpp b/HookFilter/HookFilter.cpp
index 0ec04004..fcf3bf33 100644
--- a/HookFilter/HookFilter.cpp
+++ b/HookFilter/HookFilter.cpp
@@ -20,28 +20,24 @@ extern "C" __declspec(dllexport) LRESULT CALLBACK LowLevelKeyboardProc(
 		UINT newMsg = pKbdLlHookStruct->flags & LLKHF_UP ? WM_KEYUP : WM_KEYDOWN;
 		LPARAM newlParam = newMsg == WM_KEYUP ? 3<<30 : 0;	// b31:transition state, b30:previous key state
 
-		// Note about PostMessage() and use of VkKeyScan():
-		// . Convert the ascii code to virtual key code, so that the message pump can do TranslateMessage()
-		// . NB. From MSDN for "WM_KEYDOWN" && "WM_KEYUP" : "Applications must pass wParam to TranslateMessage without altering it at all."
-
 		// Suppress alt-tab
 		if (pKbdLlHookStruct->vkCode == VK_TAB && (pKbdLlHookStruct->flags & LLKHF_ALTDOWN))
 		{
-			PostMessage(g_hFrameWindow, newMsg, LOBYTE(VkKeyScan(0x09)), newlParam);
+			PostMessage(g_hFrameWindow, newMsg, VK_TAB, newlParam);
 			suppress = true;
 		}
 
 		// Suppress alt-escape
 		if (pKbdLlHookStruct->vkCode == VK_ESCAPE && (pKbdLlHookStruct->flags & LLKHF_ALTDOWN))
 		{
-			PostMessage(g_hFrameWindow, newMsg, LOBYTE(VkKeyScan(0x1B)), newlParam);
+			PostMessage(g_hFrameWindow, newMsg, VK_ESCAPE, newlParam);
 			suppress = true;
 		}
 
 		// Suppress alt-space
 		if (pKbdLlHookStruct->vkCode == VK_SPACE && (pKbdLlHookStruct->flags & LLKHF_ALTDOWN))
 		{
-			PostMessage(g_hFrameWindow, newMsg, LOBYTE(VkKeyScan(0x20)), newlParam);
+			PostMessage(g_hFrameWindow, newMsg, VK_SPACE, newlParam);
 			suppress = true;
 		}
 
diff --git a/help/CommandLine.html b/help/CommandLine.html
index 0d48ca57..f8c17778 100644
--- a/help/CommandLine.html
+++ b/help/CommandLine.html
@@ -42,6 +42,8 @@
 		Enable the dialog box to display the last file saved to<br><br>
 		-no-printscreen-key<br>
 		Prevent the PrintScreen key from being registered<br><br>
+		-no-hook-system-key<br>
+		Prevent certain system key combinations from being hooked (to prevent the emulator from trapping ALT+ESC, ALT+SPACE, ALT+TAB and CTRL+ESC). This means that the equivalent Open Apple+&lt;key&gt; combinations won't work within the emulator.<br><br>
 		-use-real-printer<br>
 		Enables Advanced configuration control to allow dumping to a real printer<br><br>
 		-noreg<br>
diff --git a/source/Applewin.cpp b/source/Applewin.cpp
index 188ab1b7..de24d066 100644
--- a/source/Applewin.cpp
+++ b/source/Applewin.cpp
@@ -78,6 +78,8 @@ TCHAR     g_sProgramDir[MAX_PATH] = TEXT(""); // Directory of where AppleWin exe
 TCHAR     g_sDebugDir  [MAX_PATH] = TEXT(""); // TODO: Not currently used
 TCHAR     g_sScreenShotDir[MAX_PATH] = TEXT(""); // TODO: Not currently used
 bool      g_bCapturePrintScreenKey = true;
+static bool g_bHookSystemKey = true;
+
 TCHAR     g_sCurrentDir[MAX_PATH] = TEXT(""); // Also Starting Dir.  Debugger uses this when load/save
 bool      g_bRestart = false;
 bool      g_bRestartFullScreen = false;
@@ -871,7 +873,7 @@ static HINSTANCE g_hinstDLL = 0;
 static HHOOK g_hhook = 0;
 
 // Pre: g_hFrameWindow must be valid
-void HookFilterForKeyboard()
+bool HookFilterForKeyboard()
 {
 	g_hinstDLL = LoadLibrary(TEXT("HookFilter.dll"));
 
@@ -890,16 +892,17 @@ void HookFilterForKeyboard()
 						g_hinstDLL,
 						0);
 
-	if (g_hhook == 0 || g_hFrameWindow == 0)
-	{
-		std::string msg("Failed to install hook filter for system keys");
+	if (g_hhook != 0 && g_hFrameWindow != 0)
+		return true;
 
-		DWORD dwErr = GetLastError();
-		MessageBox(GetDesktopWindow(), msg.c_str(), "Warning", MB_ICONASTERISK | MB_OK);
+	std::string msg("Failed to install hook filter for system keys");
 
-		msg += "\n";
-		LogFileOutput(msg.c_str());
-	}
+	DWORD dwErr = GetLastError();
+	MessageBox(GetDesktopWindow(), msg.c_str(), "Warning", MB_ICONASTERISK | MB_OK);
+
+	msg += "\n";
+	LogFileOutput(msg.c_str());
+	return false;
 }
 
 void UnhookFilterForKeyboard()
@@ -1227,6 +1230,10 @@ int APIENTRY WinMain(HINSTANCE passinstance, HINSTANCE, LPSTR lpCmdLine, int)
 		{
 			g_bShowPrintScreenWarningDialog = false;
 		}
+		else if (strcmp(lpCmdLine, "-no-hook-system-key") == 0)		// Don't hook the System keys (eg. Left-ALT+ESC/SPACE/TAB) GH#556
+		{
+			g_bHookSystemKey = false;
+		}
 		else if (strcmp(lpCmdLine, "-spkr-inc") == 0)
 		{
 			lpCmdLine = GetCurrArg(lpNextArg);
@@ -1419,7 +1426,11 @@ int APIENTRY WinMain(HINSTANCE passinstance, HINSTANCE, LPSTR lpCmdLine, int)
 			LogFileOutput("Main: RegisterHotKeys()\n");
 		}
 
-		HookFilterForKeyboard();	// needs valid g_hFrameWindow (for message pump)
+		if (g_bHookSystemKey)
+		{
+			if (HookFilterForKeyboard())	// needs valid g_hFrameWindow (for message pump)
+				LogFileOutput("Main: HookFilterForKeyboard()\n");
+		}
 
 		// Need to test if it's safe to call ResetMachineState(). In the meantime, just call DiskReset():
 		DiskReset();	// Switch from a booting A][+ to a non-autostart A][, so need to turn off floppy motor
@@ -1527,7 +1538,11 @@ int APIENTRY WinMain(HINSTANCE passinstance, HINSTANCE, LPSTR lpCmdLine, int)
 		DSUninit();
 		LogFileOutput("Main: DSUninit()\n");
 
-		UnhookFilterForKeyboard();
+		if (g_bHookSystemKey)
+		{
+			UnhookFilterForKeyboard();
+			LogFileOutput("Main: UnhookFilterForKeyboard()\n");
+		}
 	}
 	while (g_bRestart);