Free Look: Add background input setting (disabled by default)

Before, Free Look would accept background input by default, which means it was easy to accidentally move the camera while typing in another window. (This is because HotkeyScheduler::Run sets the input gate to `true` after it's copied the hotkey state, supposedly for other threads (though `SetInputGate` uses a `thread_local` variable so I'm not 100% sure that's correct) and for the GBA windows (which always accept unfocused input, presumably because they won't be focused normally).

Source/Core/Core/Config/FreeLookSettings.cpp

@@ -12,6 +12,8 @@ namespace Config
 {
 // Configuration Information
 const Info<bool> FREE_LOOK_ENABLED{{System::FreeLook, "General", "Enabled"}, false};
+const Info<bool> FREE_LOOK_BACKGROUND_INPUT{{System::FreeLook, "General", "BackgroundInput"},
+                                            false};
 
 // FreeLook.Controller1
 const Info<FreeLook::ControlType> FL1_CONTROL_TYPE{{System::FreeLook, "Camera1", "ControlType"},

Source/Core/Core/Config/FreeLookSettings.h

@@ -15,6 +15,7 @@ namespace Config
 // Configuration Information
 
 extern const Info<bool> FREE_LOOK_ENABLED;
+extern const Info<bool> FREE_LOOK_BACKGROUND_INPUT;
 
 // FreeLook.Controller1
 extern const Info<FreeLook::ControlType> FL1_CONTROL_TYPE;

Source/Core/Core/FreeLookManager.cpp

@@ -6,10 +6,14 @@
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
 #include "Common/Config/Config.h"
+#include "Common/ScopeGuard.h"
 
+#include "Core/Config/FreeLookSettings.h"
 #include "Core/ConfigManager.h"
+#include "Core/Core.h"
 #include "Core/FreeLookConfig.h"
 
+#include "InputCommon/ControlReference/ControlReference.h"
 #include "InputCommon/ControllerEmu/ControlGroup/Buttons.h"
 #include "InputCommon/ControllerEmu/ControlGroup/IMUGyroscope.h"
 #include "InputCommon/InputConfig.h"
@@ -226,6 +230,11 @@ void FreeLookController::Update()
 void FreeLookController::UpdateInput(CameraControllerInput* camera_controller)
 {
   const auto lock = GetStateLock();
+  // Preserve the old controller gate state
+  const auto old_gate = ControlReference::GetInputGate();
+  Common::ScopeGuard gate_guard{[old_gate] { ControlReference::SetInputGate(old_gate); }};
+  // Switch to the free look focus gate
+  Core::UpdateInputGate(!Config::Get(Config::FREE_LOOK_BACKGROUND_INPUT));
 
   float dt = 1.0;
   if (m_last_free_look_rotate_time)

Source/Core/DolphinQt/Config/FreeLookWidget.cpp

@@ -61,6 +61,9 @@ void FreeLookWidget::CreateLayout()
   description->setTextInteractionFlags(Qt::TextBrowserInteraction);
   description->setOpenExternalLinks(true);
 
+  m_freelook_background_input = new QCheckBox(tr("Background Input"));
+  m_freelook_background_input->setChecked(Config::Get(Config::FREE_LOOK_BACKGROUND_INPUT));
+
   auto* hlayout = new QHBoxLayout();
   hlayout->addWidget(new QLabel(tr("Camera 1")));
   hlayout->addWidget(m_freelook_control_type);
@@ -68,6 +71,7 @@ void FreeLookWidget::CreateLayout()
 
   layout->addWidget(m_enable_freelook);
   layout->addLayout(hlayout);
+  layout->addWidget(m_freelook_background_input);
   layout->addWidget(description);
 
   setLayout(layout);
@@ -78,6 +82,7 @@ void FreeLookWidget::ConnectWidgets()
   connect(m_freelook_controller_configure_button, &QPushButton::clicked, this,
           &FreeLookWidget::OnFreeLookControllerConfigured);
   connect(m_enable_freelook, &QCheckBox::clicked, this, &FreeLookWidget::SaveSettings);
+  connect(m_freelook_background_input, &QCheckBox::clicked, this, &FreeLookWidget::SaveSettings);
   connect(&Settings::Instance(), &Settings::ConfigChanged, this, [this] {
     const QSignalBlocker blocker(this);
     LoadSettings();
@@ -101,12 +106,16 @@ void FreeLookWidget::LoadSettings()
   m_enable_freelook->setChecked(checked);
   m_freelook_control_type->setEnabled(checked);
   m_freelook_controller_configure_button->setEnabled(checked);
+  m_freelook_background_input->setEnabled(checked);
 }
 
 void FreeLookWidget::SaveSettings()
 {
   const bool checked = m_enable_freelook->isChecked();
   Config::SetBaseOrCurrent(Config::FREE_LOOK_ENABLED, checked);
+  Config::SetBaseOrCurrent(Config::FREE_LOOK_BACKGROUND_INPUT,
+                           m_freelook_background_input->isChecked());
   m_freelook_control_type->setEnabled(checked);
   m_freelook_controller_configure_button->setEnabled(checked);
+  m_freelook_background_input->setEnabled(checked);
 }

Source/Core/DolphinQt/Config/FreeLookWidget.h

@@ -6,6 +6,7 @@
 #include <QWidget>
 
 class GraphicsChoice;
+class QCheckBox;
 class QPushButton;
 class ToolTipCheckBox;
 
@@ -26,4 +27,5 @@ private:
   ToolTipCheckBox* m_enable_freelook;
   GraphicsChoice* m_freelook_control_type;
   QPushButton* m_freelook_controller_configure_button;
+  QCheckBox* m_freelook_background_input;
 };