From c9aa0396950eefc189692e267b8042c613f77cc2 Mon Sep 17 00:00:00 2001
From: "Unknown W. Brackets" <checkins@unknownbrackets.org>
Date: Thu, 1 Nov 2018 21:42:12 -0700
Subject: [PATCH] Windows: Check for devices on Windows events only.

A user reported stuttering after the periodic checks, and devices failing
until unplug/replug.  Presumably, this is caused by poor drivers reacting
badly to periodic DirectInput queries, so less queries should help.
---
 Windows/DinputDevice.cpp | 6 ++++--
 Windows/DinputDevice.h   | 5 +++++
 Windows/MainWindow.cpp   | 5 +++++
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/Windows/DinputDevice.cpp b/Windows/DinputDevice.cpp
index c72b7c0dbc..5d89e4ab54 100644
--- a/Windows/DinputDevice.cpp
+++ b/Windows/DinputDevice.cpp
@@ -39,6 +39,7 @@
 unsigned int                  DinputDevice::pInstances = 0;
 LPDIRECTINPUT8                DinputDevice::pDI = NULL;
 std::vector<DIDEVICEINSTANCE> DinputDevice::devices;
+bool DinputDevice::needsCheck_ = true;
 
 // In order from 0.  There can be 128, but most controllers do not have that many.
 static const int dinput_buttons[] = {
@@ -120,7 +121,7 @@ BOOL CALLBACK DinputDevice::DevicesCallback(
 
 void DinputDevice::getDevices(bool refresh)
 {
-	if (devices.empty() || refresh)
+	if (refresh)
 	{
 		getPDI()->EnumDevices(DI8DEVCLASS_GAMECTRL, &DinputDevice::DevicesCallback, NULL, DIEDFL_ATTACHEDONLY);
 	}
@@ -368,6 +369,7 @@ void DinputDevice::ApplyButtons(DIJOYSTATE2 &state) {
 
 size_t DinputDevice::getNumPads()
 {
-	getDevices(true);
+	getDevices(needsCheck_);
+	needsCheck_ = false;
 	return devices.size();
 }
diff --git a/Windows/DinputDevice.h b/Windows/DinputDevice.h
index 366805c856..6314a055ed 100644
--- a/Windows/DinputDevice.h
+++ b/Windows/DinputDevice.h
@@ -35,6 +35,10 @@ public:
 	virtual int UpdateState();
 	virtual bool IsPad() { return true; }
 	static size_t getNumPads();
+	static void CheckDevices() {
+		needsCheck_ = true;
+	}
+
 private:
 	void ApplyButtons(DIJOYSTATE2 &state);
 	//unfortunate and unclean way to keep only one DirectInput instance around
@@ -52,6 +56,7 @@ private:
 	static unsigned int     pInstances;
 	static std::vector<DIDEVICEINSTANCE> devices;
 	static LPDIRECTINPUT8   pDI;
+	static bool needsCheck_;
 	int                     pDevNum;
 	LPDIRECTINPUTDEVICE8    pJoystick;
 	DIJOYSTATE2             pPrevState;
diff --git a/Windows/MainWindow.cpp b/Windows/MainWindow.cpp
index 848b8cb5fa..9cf3eedfd3 100644
--- a/Windows/MainWindow.cpp
+++ b/Windows/MainWindow.cpp
@@ -54,6 +54,7 @@
 #include "Windows/GEDebugger/GEDebugger.h"
 
 #include "Windows/main.h"
+#include "Windows/DinputDevice.h"
 #include "Windows/EmuThread.h"
 #include "Windows/resource.h"
 
@@ -814,6 +815,10 @@ namespace MainWindow
 		case WM_CHAR:
 			return WindowsRawInput::ProcessChar(hWnd, wParam, lParam);
 
+		case WM_DEVICECHANGE:
+			DinputDevice::CheckDevices();
+			return DefWindowProc(hWnd, message, wParam, lParam);
+
 		case WM_VERYSLEEPY_MSG:
 			switch (wParam) {
 			case VERYSLEEPY_WPARAM_SUPPORTED: