From 199cad52f0599872e57a2fcb391a459e48146be0 Mon Sep 17 00:00:00 2001
From: David Faure <faure@kde.org>
Date: Sun, 31 Jan 2021 20:59:41 +0100
Subject: [PATCH] Compress notifications about new mouse/keyboard.

When resuming from suspend, I get 5 "new pointer" and 5 "new keyboard"
events (on a laptop with USB mouse/keyboard, but also stuff like
"Thinkpad Extra Buttons" adds more notifications than one would expect)

KGlobalAccelImpl::x11MappingNotify is still called 15 times, but
that's better than 145 times...

"new pointer" notifications end up calling `kcminit mouse`, better
also compress that.
---
 kcms/keyboard/xinput_helper.cpp | 30 +++++++++++++++++++++++++-----
 kcms/keyboard/xinput_helper.h   |  5 ++++-
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/kcms/keyboard/xinput_helper.cpp b/kcms/keyboard/xinput_helper.cpp
index 14974ada7..bade5ea33 100644
--- a/kcms/keyboard/xinput_helper.cpp
+++ b/kcms/keyboard/xinput_helper.cpp
@@ -23,6 +23,7 @@
 #include <QCoreApplication>
 #include <QX11Info>
 #include <QDebug>
+#include <QTimer>
 
 #include <X11/X.h>
 #include <X11/Xlib.h>
@@ -56,9 +57,21 @@ static const int DEVICE_POINTER = 2;
 XInputEventNotifier::XInputEventNotifier(QWidget* parent):
 	XEventNotifier(), //TODO: destruct properly?
 	xinputEventType(-1),
-	udevNotifier(nullptr)
+	udevNotifier(nullptr),
+	keyboardNotificationTimer(new QTimer(this)),
+	mouseNotificationTimer(new QTimer(this))
 {
-  Q_UNUSED(parent)
+	Q_UNUSED(parent)
+
+	// emit signal only once, even after X11 re-enables N keyboards after resuming from suspend
+	keyboardNotificationTimer->setSingleShot(true);
+	keyboardNotificationTimer->setInterval(500);
+	connect(keyboardNotificationTimer, &QTimer::timeout, this, &XInputEventNotifier::newKeyboardDevice);
+
+	// same for mouse
+	mouseNotificationTimer->setSingleShot(true);
+	mouseNotificationTimer->setInterval(500);
+	connect(mouseNotificationTimer, &QTimer::timeout, this, &XInputEventNotifier::newPointerDevice);
 }
 
 void XInputEventNotifier::start()
@@ -83,11 +96,18 @@ bool XInputEventNotifier::processOtherEvents(xcb_generic_event_t* event)
 {
 	int newDeviceType = getNewDeviceEventType(event);
 	if( newDeviceType == DEVICE_KEYBOARD ) {
-		emit(newKeyboardDevice());
+		if (!keyboardNotificationTimer->isActive()) {
+			keyboardNotificationTimer->start();
+		}
 	}
 	else if( newDeviceType == DEVICE_POINTER ) {
-		emit(newPointerDevice());
-		emit(newKeyboardDevice());	// arghhh, looks like X resets xkb map even when only pointer device is connected
+		if (!mouseNotificationTimer->isActive()) {
+			mouseNotificationTimer->start();
+		}
+		// arghhh, looks like X resets xkb map even when only pointer device is connected
+		if (!keyboardNotificationTimer->isActive()) {
+			keyboardNotificationTimer->start();
+		}
 	}
 	return true;
 }
diff --git a/kcms/keyboard/xinput_helper.h b/kcms/keyboard/xinput_helper.h
index e29fdc22a..52b6a12b4 100644
--- a/kcms/keyboard/xinput_helper.h
+++ b/kcms/keyboard/xinput_helper.h
@@ -25,13 +25,14 @@
 #include <X11/Xlib.h>
 #include <fixx11h.h>
 
+class QTimer;
 class UdevDeviceNotifier;
 
 class XInputEventNotifier: public XEventNotifier {
 	Q_OBJECT
 
 public:
-	XInputEventNotifier(QWidget* parent=nullptr);
+	explicit XInputEventNotifier(QWidget* parent=nullptr);
 
 	void start() override;
 	void stop() override;
@@ -51,6 +52,8 @@ private:
 	int xinputEventType;
 	Display* display;
 	UdevDeviceNotifier *udevNotifier;
+	QTimer* keyboardNotificationTimer;
+	QTimer* mouseNotificationTimer;
 };
 
 #endif /* XINPUT_HELPER_H_ */
-- 
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