Fix the 3D mouse search asking every device on the PC for its name

While no 3D mouse is plugged in, which for most users is always, the
hidapi backend looks for one every 3 seconds for as long as
QElectroTech runs. It asked hidapi for every HID device,
hid_enumerate(0, 0), and on Windows hidapi reads the serial number,
manufacturer and product strings of each device that matches what it
is asked for from the device itself. So every mouse, keyboard, headset
and webcam on the PC was asked for its names every 3 seconds, on the
GUI thread. Issue #1553 reports the pointer moving by itself on Windows
since the first package with this backend; nothing else in that package
talks to devices. SDL 2.0.9 polled the same way and saw freezes and a
keyboard that kept re-initialising (libsdl-org/SDL#3071).

The scan now asks for 3Dconnexion's vendor id, and for each 3D mouse
made under Logitech's id by its product id, since most other mice and
keyboards carry Logitech's id too. That is twelve hidapi calls instead
of one, but a device that does not match is no longer asked for its
names. On Linux and macOS hidapi takes the names from the system, and
one call is cheaper than twelve (on Linux, median of 200: 5 ms against
36 ms), so the scan there is unchanged.

Where the scan is filtered, a Logitech-id device that is not one of the
eleven 3D mice on the list is no longer found, even if it reports
itself as a multi-axis controller. 3Dconnexion's own mice and keyboards,
such as the CadMouse, are still asked: their vendor id is asked for as
a whole, so that new 3D mice are found without a list.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

sources/spacemouse/hidbackend.cpp

@@ -82,16 +82,32 @@ void HidBackend::scan()
 		return;
 	}
 
-	hid_device_info *list = hid_enumerate(0, 0);
-	for (hid_device_info *info = list; info && !m_device; info = info->next)
+		//On Linux and macOS hidapi takes the name strings of the devices it
+		//lists from the system, and one call listing every device is the
+		//cheapest scan. Elsewhere, such as on Windows, it reads them from
+		//each device itself, so only 3D mice are asked for (see
+		//SpaceMouseHid::scanIds()).
+#if defined(Q_OS_LINUX) || defined(Q_OS_MACOS)
+	const QList<SpaceMouseHid::DeviceId> ids = {SpaceMouseHid::DeviceId()};
+#else
+	const QList<SpaceMouseHid::DeviceId> ids = SpaceMouseHid::scanIds();
+#endif
+	for (const SpaceMouseHid::DeviceId &id : ids)
 	{
-		if (!SpaceMouseHid::isSpaceMouse(info->vendor_id, info->product_id,
-						 info->usage_page, info->usage)) {
-			continue;
+		hid_device_info *list = hid_enumerate(id.vendor, id.product);
+		for (hid_device_info *info = list; info && !m_device; info = info->next)
+		{
+			if (!SpaceMouseHid::isSpaceMouse(info->vendor_id, info->product_id,
+							 info->usage_page, info->usage)) {
+				continue;
+			}
+			m_device = hid_open_path(info->path);
+		}
+		hid_free_enumeration(list);
+		if (m_device) {
+			break;
 		}
-		m_device = hid_open_path(info->path);
 	}
-	hid_free_enumeration(list);
 
 	if (!m_device) {
 		m_scan_timer->start();

sources/spacemouse/spacemousehid.cpp

@@ -42,7 +42,7 @@ namespace {
 	constexpr qint64 MAX_BITS = 1 << 20;
 
 		//3D mice sold under Logitech's vendor id, for the ones whose
-		//interface does not report a usage.
+		//interface does not report a usage, and for scanIds().
 	const QSet<unsigned short> LOGITECH_3D_MICE = {
 		0xc603, 0xc605, 0xc606, 0xc621, 0xc623, 0xc625,
 		0xc626, 0xc627, 0xc628, 0xc629, 0xc62b
@@ -95,6 +95,19 @@ bool SpaceMouseHid::isSpaceMouse(unsigned short vendor, unsigned short product,
 	return false;
 }
 
+QList<SpaceMouseHid::DeviceId> SpaceMouseHid::scanIds()
+{
+	QList<DeviceId> ids;
+	ids.append({VENDOR_3DCONNEXION, 0});
+
+	QList<unsigned short> logitech(LOGITECH_3D_MICE.cbegin(), LOGITECH_3D_MICE.cend());
+	std::sort(logitech.begin(), logitech.end());
+	for (const unsigned short product : std::as_const(logitech)) {
+		ids.append({VENDOR_LOGITECH, product});
+	}
+	return ids;
+}
+
 bool SpaceMouseHid::Layout::hasAxes() const
 {
 	for (const Field &f : axes) {

sources/spacemouse/spacemousehid.h

@@ -45,6 +45,21 @@ namespace SpaceMouseHid
 	bool isSpaceMouse(unsigned short vendor, unsigned short product,
 			  unsigned short usage_page, unsigned short usage);
 
+		/// A vendor and product id as hid_enumerate() takes them, where 0
+		/// matches every vendor or every product.
+	struct DeviceId
+	{
+		unsigned short vendor = 0;
+		unsigned short product = 0;
+	};
+
+		/// @return what a scan asks hidapi for where hidapi reads each
+		/// matching device's name strings from the device itself, as on
+		/// Windows (issue #1553): every 3Dconnexion device, and Logitech's
+		/// 3D mice by product id, since most other mice and keyboards carry
+		/// Logitech's id too.
+	QList<DeviceId> scanIds();
+
 		/// Where one value sits in the reports, per the report descriptor.
 	struct Field
 	{

tests/qttest/tst_spacemousehid.cpp

@@ -74,6 +74,8 @@ class TstSpaceMouseHid : public QObject
 	private slots:
 		void recognisesOnly3DMice_data();
 		void recognisesOnly3DMice();
+		void scanAsksOnlyFor3DMice_data();
+		void scanAsksOnlyFor3DMice();
 		void parsesTheClassicDescriptor();
 		void parsesADescriptorWithoutReportIds();
 		void survivesBrokenDescriptors_data();
@@ -115,6 +117,41 @@ void TstSpaceMouseHid::recognisesOnly3DMice()
 	QCOMPARE(isSpaceMouse(vendor, product, page, usage), match);
 }
 
+	// Where hidapi reads the name strings of every device a scan asks for
+	// from the device itself, as on Windows, the other devices on the PC
+	// must never be asked for at all (issue #1553).
+void TstSpaceMouseHid::scanAsksOnlyFor3DMice_data()
+{
+	QTest::addColumn<int>("vendor");
+	QTest::addColumn<int>("product");
+	QTest::addColumn<bool>("asked");
+	QTest::newRow("3Dconnexion SpaceMouse Compact") << 0x256f << 0xc635 << true;
+	QTest::newRow("3Dconnexion receiver") << 0x256f << 0xc652 << true;
+	QTest::newRow("Logitech SpaceNavigator") << 0x046d << 0xc626 << true;
+	QTest::newRow("Logitech SpacePilot Pro") << 0x046d << 0xc629 << true;
+	QTest::newRow("Logitech receiver") << 0x046d << 0xc52b << false;
+	QTest::newRow("Logitech mouse") << 0x046d << 0xc077 << false;
+	QTest::newRow("Microsoft keyboard") << 0x045e << 0x07f8 << false;
+	QTest::newRow("HP mouse") << 0x03f0 << 0x094a << false;
+}
+
+void TstSpaceMouseHid::scanAsksOnlyFor3DMice()
+{
+	QFETCH(int, vendor);
+	QFETCH(int, product);
+	QFETCH(bool, asked);
+
+		// hid_enumerate()'s own rule: an id of 0 matches every id.
+	bool matched = false;
+	for (const DeviceId &id : scanIds()) {
+		if ((id.vendor == 0 || id.vendor == vendor)
+				&& (id.product == 0 || id.product == product)) {
+			matched = true;
+		}
+	}
+	QCOMPARE(matched, asked);
+}
+
 void TstSpaceMouseHid::parsesTheClassicDescriptor()
 {
 	const Layout layout = parseDescriptor(classicDescriptor(true));