From 520320535e41988a8c8fc15535de5b213625508c Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Thu, 2 Mar 2023 22:01:14 +1000
Subject: [PATCH] Qt: Clear all keyboard bind states when focus is lost

---
 pcsx2-qt/QtHost.cpp             |  9 ++++-
 pcsx2/Frontend/InputManager.cpp | 65 +++++++++++++++++++++++++++++++++
 pcsx2/Frontend/InputManager.h   |  3 ++
 3 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/pcsx2-qt/QtHost.cpp b/pcsx2-qt/QtHost.cpp
index 51fbdb4055..97a542b2a3 100644
--- a/pcsx2-qt/QtHost.cpp
+++ b/pcsx2-qt/QtHost.cpp
@@ -795,17 +795,22 @@ void EmuThread::onDisplayWindowResized(int width, int height, float scale)
 void EmuThread::onApplicationStateChanged(Qt::ApplicationState state)
 {
 	// NOTE: This is executed on the emu thread, not UI thread.
-	if (!m_pause_on_focus_loss || !VMManager::HasValidVM())
+	if (!VMManager::HasValidVM())
 		return;
 
 	const bool focus_loss = (state != Qt::ApplicationActive);
 	if (focus_loss)
 	{
-		if (!m_was_paused_by_focus_loss && VMManager::GetState() == VMState::Running)
+		if (m_pause_on_focus_loss && !m_was_paused_by_focus_loss && VMManager::GetState() == VMState::Running)
 		{
 			m_was_paused_by_focus_loss = true;
 			VMManager::SetPaused(true);
 		}
+
+		// Clear the state of all keyboard binds.
+		// That way, if we had a key held down, and lost focus, the bind won't be stuck enabled because we never
+		// got the key release message, because it happened in another window which "stole" the event.
+		InputManager::ClearBindStateFromSource(InputManager::MakeHostKeyboardKey(0));
 	}
 	else
 	{
diff --git a/pcsx2/Frontend/InputManager.cpp b/pcsx2/Frontend/InputManager.cpp
index c6eddc592a..3700172e2f 100644
--- a/pcsx2/Frontend/InputManager.cpp
+++ b/pcsx2/Frontend/InputManager.cpp
@@ -923,6 +923,71 @@ bool InputManager::ProcessEvent(InputBindingKey key, float value, bool skip_butt
 	return true;
 }
 
+void InputManager::ClearBindStateFromSource(InputBindingKey key)
+{
+	// Why are we doing it this way? Because any of the bindings could cause a reload and invalidate our iterators :(.
+	// Axis handlers should be fine, so we'll do those as a first pass.
+	for (const auto& [match_key, binding] : s_binding_map)
+	{
+		if (key.source_type != match_key.source_type || key.source_subtype != match_key.source_subtype ||
+			key.source_index != match_key.source_index || !IsAxisHandler(binding->handler))
+		{
+			continue;
+		}
+
+		for (u32 i = 0; i < binding->num_keys; i++)
+		{
+			if (binding->keys[i].MaskDirection() != match_key)
+				continue;
+
+			std::get<InputAxisEventHandler>(binding->handler)(0.0f);
+			break;
+		}
+	}
+
+	// Now go through the button handlers, and pick them off.
+	bool matched;
+	do
+	{
+		matched = false;
+
+		for (const auto& [match_key, binding] : s_binding_map)
+		{
+			if (key.source_type != match_key.source_type || key.source_subtype != match_key.source_subtype ||
+				key.source_index != match_key.source_index || IsAxisHandler(binding->handler))
+			{
+				continue;
+			}
+
+			for (u32 i = 0; i < binding->num_keys; i++)
+			{
+				if (binding->keys[i].MaskDirection() != match_key)
+					continue;
+
+				// Skip if we weren't pressed.
+				const u8 bit = static_cast<u8>(1) << i;
+				if ((binding->current_mask & bit) == 0)
+					continue;
+
+				// Only fire handler if we're changing from active state.
+				const u8 current_mask = binding->current_mask;
+				binding->current_mask &= ~bit;
+
+				if (current_mask == binding->full_mask)
+				{
+					std::get<InputButtonEventHandler>(binding->handler)(0.0f);
+					matched = true;
+					break;
+				}
+			}
+
+			// Need to start again, might've reloaded.
+			if (matched)
+				break;
+		}
+	} while (matched);
+}
+
 bool InputManager::PreprocessEvent(InputBindingKey key, float value, GenericInputBinding generic_key)
 {
 	// does imgui want the event?
diff --git a/pcsx2/Frontend/InputManager.h b/pcsx2/Frontend/InputManager.h
index afd8424768..894af7e650 100644
--- a/pcsx2/Frontend/InputManager.h
+++ b/pcsx2/Frontend/InputManager.h
@@ -257,6 +257,9 @@ namespace InputManager
 	/// Returns true if anything was bound to this key, otherwise false.
 	bool InvokeEvents(InputBindingKey key, float value, GenericInputBinding generic_key = GenericInputBinding::Unknown);
 
+	/// Clears internal state for any binds with a matching source/index.
+	void ClearBindStateFromSource(InputBindingKey key);
+
 	/// Sets a hook which can be used to intercept events before they're processed by the normal bindings.
 	/// This is typically used when binding new controls to detect what gets pressed.
 	void SetHook(InputInterceptHook::Callback callback);