Fix broken feedback for the arrow keys in the virtual MIDI keyboard if it opens when REAPER starts. (#1217)

Previously, if the virtual MIDI keyboard was configured to open when REAPER starts, this feedback would fail to work until REAPER was restarted with the keyboard closed.
To fix this, always register the hook as soon as OSARA loads.

Author: jcsteh

Diff for: src/reaper_osara.cpp

@@ -2459,6 +2459,85 @@ void postMidiResets(int command) {
 	}
 }
 
+// The virtual MIDI keyboard dialog HWND.
+HWND vkbHwnd = nullptr;
+// This is called from translateAccel. This is necessary because REAPER
+// registers its own accelerator hook for the virtual MIDI keyboard when the
+// keyboard first opens and we need to be ahead of that hook in order to be
+// called. This might happen right at startup if the virtual keyboard is
+// configured  to open then. REAPER never unregisters its hook once registered.
+int vkbTranslateAccel(MSG* msg, accelerator_register_t* accelReg) {
+	if (!vkbHwnd) {
+		// The window probably isn't open.
+		return 0; // Normal handling.
+	}
+	if (!IsWindow(vkbHwnd)) {
+		vkbHwnd = nullptr;
+		return 0;
+	}
+	if (msg->message != WM_KEYDOWN ||
+			(msg->hwnd != vkbHwnd && GetParent(msg->hwnd) != vkbHwnd)) {
+		// This key isn't for us.
+		return 0;
+	}
+	if (isClassName(msg->hwnd, "Edit") || isClassName(msg->hwnd, "ComboBox")) {
+		// Don't trap arrow keys in these controls.
+		return 0;
+	}
+	if (isShortcutHelpEnabled) {
+		switch (msg->wParam) {
+			case VK_RIGHT:
+				outputMessage(translate("Octave up"));
+				return 1; // Eat the key.
+			case VK_LEFT:
+				outputMessage(translate("Octave down"));
+				return 1;
+			case VK_UP:
+				outputMessage(translate("Increase MIDI channel"));
+				return 1;
+			case VK_DOWN:
+				outputMessage(translate("Decrease MIDI channel"));
+				return 1;
+		default:
+			break;
+		}
+		return 0;
+	}
+	switch (msg->wParam) {
+		case VK_RIGHT:
+		case VK_LEFT:
+			// We need to wait until this executes before we can report the new value.
+			CallLater([] {
+				constexpr long WCID_CENTER_NOTE = 1239;
+				char note[10];
+				if (GetDlgItemText(vkbHwnd, WCID_CENTER_NOTE, note, sizeof(note)) != 0) {
+					outputMessage(note);
+				}
+			}, 0);
+			return 0;
+		case VK_UP:
+		case VK_DOWN:
+			CallLater([] {
+				constexpr long WCID_CHANNEL = 1377;
+				char channel[10];
+				if (GetDlgItemText(vkbHwnd, WCID_CHANNEL, channel, sizeof(channel)) != 0) {
+					outputMessage(channel);
+				}
+			}, 0);
+			return 0;
+		default:
+			break;
+	}
+	return 0;
+}
+
+void postVirtualMidiKeyboard(int command) {
+	if (GetToggleCommandState(command)) {
+		// The window has just been shown. Store its HWND for vkbTranslateAccel.
+		vkbHwnd = GetForegroundWindow();
+	}
+}
+
 void postMExplorerChangeVolume(int cmd, HWND hwnd) {
 	HWND w = GetDlgItem(hwnd, 997);
 	if(!w) {// support Reaper versions before 6.65
@@ -2710,9 +2789,10 @@ PostCommand POST_COMMANDS[] = {
 	{24866, postMomentarilySetOverrideToAltN}, // Main action section: Momentarily set override to alt-14
 	{24867, postMomentarilySetOverrideToAltN}, // Main action section: Momentarily set override to alt-15
 	{24868, postMomentarilySetOverrideToAltN}, // Main action section: Momentarily set override to alt-16
-		{41175, postMidiResets}, // Reset all MIDI devices
-		{42348, postMidiResets}, // Reset all MIDI control surface devices
-		{40345, postMidiResets}, // Send all-notes-off and all-sounds-off to all MIDI outputs/plug-ins
+	{41175, postMidiResets}, // Reset all MIDI devices
+	{42348, postMidiResets}, // Reset all MIDI control surface devices
+	{40345, postMidiResets}, // Send all-notes-off and all-sounds-off to all MIDI outputs/plug-ins
+	{40377, postVirtualMidiKeyboard}, // View: Show virtual MIDI keyboard
 	{0},
 };
 MidiPostCommand MIDI_POST_COMMANDS[] = {
@@ -5213,89 +5293,6 @@ void cmdJumpToTime(Command* command) {
 	}, 50);
 }
 
-void cmdVirtualMidiKeyboard(Command* command) {
-	static accelerator_register_t accelReg = {0};
-	if (GetToggleCommandState(command->gaccel.accel.cmd)) {
-		// The virtual keyboard is showing. Run the command to hide it.
-		Main_OnCommand(command->gaccel.accel.cmd, 0);
-		return;
-	}
-	const bool isRegistered = !!accelReg.translateAccel;
-	accelReg.translateAccel = [](MSG* msg, accelerator_register_t* accelReg) -> int {
-		HWND dialog = (HWND)accelReg->user;
-		if (dialog && !IsWindow(dialog)) {
-			// The dialog is dead. Ideally, we would unregister. However, if we do,
-			// subsequent registrations of our hook never intercept key presses in the
-			// virtual keyboard. So, we just have to leave this registered.
-			accelReg->user = nullptr;
-			return 0; // Normal handling.
-		}
-		if (msg->message != WM_KEYDOWN ||
-				(msg->hwnd != dialog && GetParent(msg->hwnd) != dialog)) {
-			// This key isn't for us.
-			return 0;
-		}
-		if (isClassName(msg->hwnd, "Edit") || isClassName(msg->hwnd, "ComboBox")) {
-			// Don't trap arrow keys in these controls.
-			return 0;
-		}
-		if (isShortcutHelpEnabled) {
-			switch (msg->wParam) {
-				case VK_RIGHT:
-					outputMessage(translate("Octave up"));
-					return 1; // Eat the key.
-				case VK_LEFT:
-					outputMessage(translate("Octave down"));
-					return 1;
-				case VK_UP:
-					outputMessage(translate("Increase MIDI channel"));
-					return 1;
-				case VK_DOWN:
-					outputMessage(translate("Decrease MIDI channel"));
-					return 1;
-			default:
-				break;
-			}
-			return 0;
-		}
-		switch (msg->wParam) {
-			case VK_RIGHT:
-			case VK_LEFT:
-				// We need to wait until this executes before we can report the new value.
-				CallLater([dialog] {
-					constexpr long WCID_CENTER_NOTE = 1239;
-					char note[10];
-					if (GetDlgItemText(dialog, WCID_CENTER_NOTE, note, sizeof(note)) != 0) {
-						outputMessage(note);
-					}
-				}, 0);
-				return 0;
-			case VK_UP:
-			case VK_DOWN:
-				CallLater([dialog] {
-					constexpr long WCID_CHANNEL = 1377;
-					char channel[10];
-					if (GetDlgItemText(dialog, WCID_CHANNEL, channel, sizeof(channel)) != 0) {
-						outputMessage(channel);
-					}
-				}, 0);
-				return 0;
-			default:
-				break;
-		}
-		return 0;
-	};
-	accelReg.isLocal = true;
-	accelReg.user = nullptr;
-	if (!isRegistered) {
-		// We must register the hook before the window appears or it won't work.
-		plugin_register("accelerator", &accelReg);
-	}
-	// Show the window.
-	Main_OnCommand(command->gaccel.accel.cmd, 0);
-	accelReg.user = GetForegroundWindow(); // The dialog.
-}
-
 #define DEFACCEL {0, 0, 0}
 
 Command COMMANDS[] = {
@@ -5399,7 +5396,6 @@ Command COMMANDS[] = {
 	{MAIN_SECTION, {{0, 0, 42207}, nullptr}, nullptr, cmdAddAutoItems}, // Envelope: Convert all project automation to automation items
 	{MAIN_SECTION, {{0, 0, 42089}, nullptr}, nullptr, cmdGlueAutoItems}, // Envelope: Glue automation items
 	{MAIN_SECTION, {{0, 0, 40069}, nullptr}, nullptr, cmdJumpToTime}, // View: Jump (go) to time window
-	{MAIN_SECTION, {{0, 0, 40377}, nullptr}, nullptr, cmdVirtualMidiKeyboard}, // View: Show virtual MIDI keyboard
 	{MIDI_EDITOR_SECTION, {{0, 0, 40036}, nullptr}, nullptr, cmdMidiMoveCursor}, // View: Go to start of file
 	{MIDI_EVENT_LIST_SECTION, {{0, 0, 40036}, nullptr}, nullptr, cmdMidiMoveCursor}, // View: Go to start of file
 	{MIDI_EDITOR_SECTION, {{0, 0, 40037}, nullptr}, nullptr, cmdMidiMoveCursor}, // View: Go to end of file
@@ -5968,6 +5964,12 @@ HWINEVENTHOOK winEventHook = nullptr;
 
 #endif // _WIN32
 
+// This accelerator hook is registered at startup and remains registered until
+// REAPER exits.
+int translateAccel(MSG* msg, accelerator_register_t* accelReg) {
+	return vkbTranslateAccel(msg, accelReg);
+}
+
 extern "C" {
 
 REAPER_PLUGIN_DLL_EXPORT int REAPER_PLUGIN_ENTRYPOINT(REAPER_PLUGIN_HINSTANCE hInstance, reaper_plugin_info_t* rec) {
@@ -6021,6 +6023,12 @@ REAPER_PLUGIN_DLL_EXPORT int REAPER_PLUGIN_ENTRYPOINT(REAPER_PLUGIN_HINSTANCE hI
 #ifdef _WIN32
 		keyboardHook = SetWindowsHookEx(WH_KEYBOARD, keyboardHookProc, nullptr, guiThread);
 #endif
+
+		static accelerator_register_t accelReg;
+		accelReg.translateAccel = translateAccel;
+		accelReg.isLocal = true;
+		accelReg.user = nullptr;
+		plugin_register("accelerator", &accelReg);
 		return 1;
 
 	} else {