Add option to focus game window on injection (#4)

Some games don't play audio or render at reduced frame rate when
their window is not in focus. Switching active window when VR session is
started is a hassle.

This commit adds an option to automatically focus game window post
injection making UEVR experience more streamlined.

UEVR/MainWindow.xaml

@@ -158,6 +158,10 @@
                                     <ToggleButton x:Name="m_nullifyVRPluginsCheckbox" HorizontalAlignment="Left"/>
                                     <TextBlock TextWrapping="Wrap" Text="Nullify VR Plugins"/>
                                 </StackPanel>
+                                <StackPanel Orientation="Horizontal">
+                                    <ToggleButton x:Name="m_focusGameOnInjectionCheckbox" HorizontalAlignment="Left" IsChecked="True"/>
+                                    <TextBlock TextWrapping="Wrap" Text="Focus game on injection"/>
+                                </StackPanel>
                             </StackPanel>
                             <TextBlock x:Name="m_connectionStatus" TextWrapping="Wrap" Text="Unknown status"/>
                         </StackPanel>

UEVR/MainWindow.xaml.cs

@@ -150,6 +150,7 @@ public class ValueTemplateSelector : DataTemplateSelector {
             }
         }
     }
+
     public partial class MainWindow : Window {
         // variables
         // process list
@@ -173,6 +174,9 @@ public partial class MainWindow : Window {
         private string? m_commandLineAttachExe = null;
         private bool m_ignoreFutureVDWarnings = false;
 
+        [System.Runtime.InteropServices.DllImport("user32.dll")]
+        public static extern void SwitchToThisWindow(IntPtr hWnd, bool fAltTab);
+
         public MainWindow() {
             InitializeComponent();
 
@@ -204,6 +208,7 @@ private void MainWindow_Loaded(object sender, RoutedEventArgs e) {
             m_openxrRadio.IsChecked = m_mainWindowSettings.OpenXRRadio;
             m_nullifyVRPluginsCheckbox.IsChecked = m_mainWindowSettings.NullifyVRPluginsCheckbox;
             m_ignoreFutureVDWarnings = m_mainWindowSettings.IgnoreFutureVDWarnings;
+            m_focusGameOnInjectionCheckbox.IsChecked = m_mainWindowSettings.FocusGameOnInjection;
 
             m_updateTimer.Tick += (sender, e) => Dispatcher.Invoke(MainWindow_Update);
             m_updateTimer.Start();
@@ -351,6 +356,10 @@ private void Update_InjectStatus() {
                     m_lastAutoInjectTime = now;
                     m_commandLineAttachExe = null; // no need anymore.
                     FillProcessList();
+                    if (m_focusGameOnInjectionCheckbox.IsChecked == true)
+                    {
+                        SwitchToThisWindow(process.MainWindowHandle, true);
+                    }
                 }
             }
         }
@@ -574,6 +583,7 @@ private void MainWindow_Closing(object sender, System.ComponentModel.CancelEvent
             m_mainWindowSettings.OpenVRRadio = m_openvrRadio.IsChecked == true;
             m_mainWindowSettings.NullifyVRPluginsCheckbox = m_nullifyVRPluginsCheckbox.IsChecked == true;
             m_mainWindowSettings.IgnoreFutureVDWarnings = m_ignoreFutureVDWarnings;
+            m_mainWindowSettings.FocusGameOnInjection = m_focusGameOnInjectionCheckbox.IsChecked == true;
 
             m_mainWindowSettings.Save();
         }
@@ -1040,6 +1050,11 @@ private void Inject_Clicked(object sender, RoutedEventArgs e) {
 
                 Injector.InjectDll(process.Id, "UEVRBackend.dll");
             }
+
+            if (m_focusGameOnInjectionCheckbox.IsChecked == true)
+            {
+                SwitchToThisWindow(process.MainWindowHandle, true);
+            }
         }
 
         private string GenerateProcessName(Process p) {

UEVR/MainWindowSettings.cs

@@ -34,5 +34,13 @@ public bool IgnoreFutureVDWarnings {
             get { return (bool)this["IgnoreFutureVDWarnings"]; }
             set { this["IgnoreFutureVDWarnings"] = value; }
         }
+
+        [UserScopedSettingAttribute()]
+        [DefaultSettingValueAttribute("true")]
+        public bool FocusGameOnInjection
+        {
+            get { return (bool)this["FocusGameOnInjection"]; }
+            set { this["FocusGameOnInjection"] = value; }
+        }
     }
 }