Fix default TwainHandleManager implementation

cyanfish · Sep 5, 2024 · fb5a0c9 · fb5a0c9
1 parent 6456f1c
commit fb5a0c9
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Showing 6 changed files with 97 additions and 15 deletions.
diff --git a/NAPS2.Sdk/Platform/Windows/Win32MessagePump.cs b/NAPS2.Sdk/Platform/Windows/Win32MessagePump.cs
@@ -5,6 +5,9 @@
 
 namespace NAPS2.Platform.Windows;
 
+/// <summary>
+/// Allows creation of a Win32 event loop without any references to WinForms or WPF.
+/// </summary>
 [System.Runtime.Versioning.SupportedOSPlatform("windows")]
 internal class Win32MessagePump : IInvoker, IDisposable
 {

diff --git a/NAPS2.Sdk/Platform/Windows/Win32TwainHandleManager.cs b/NAPS2.Sdk/Platform/Windows/Win32TwainHandleManager.cs
@@ -4,6 +4,9 @@
 
 namespace NAPS2.Platform.Windows;
 
+/// <summary>
+/// TwainHandleManager implementation that uses a Win32MessagePump to get window handles to hand off to TWAIN.
+/// </summary>
 [System.Runtime.Versioning.SupportedOSPlatform("windows")]
 internal class Win32TwainHandleManager : TwainHandleManager
 {
@@ -64,6 +67,8 @@ public override MessageLoopHook CreateMessageLoopHook(IntPtr dialogParent = defa
         return new Win32MessageLoopHook(_messagePump, GetDsmHandle(dialogParent, useNativeUi));
     }
 
+    public override IInvoker Invoker => _messagePump;
+
     public override void Dispose()
     {
         if (_disposed) return;

diff --git a/NAPS2.Sdk/Scan/Internal/Twain/DefaultTwainHandleManager.cs b/NAPS2.Sdk/Scan/Internal/Twain/DefaultTwainHandleManager.cs
@@ -0,0 +1,65 @@
+#if !MAC
+using System.Threading;
+using NAPS2.Platform.Windows;
+using NTwain;
+
+namespace NAPS2.Scan.Internal.Twain;
+
+/// <summary>
+/// TwainHandleManager implementation that lazily starts a Win32MessagePump and delegates to a Win32TwainHandleManager.
+/// </summary>
+[System.Runtime.Versioning.SupportedOSPlatform("windows")]
+internal class DefaultTwainHandleManager : TwainHandleManager
+{
+    private Win32MessagePump? _messagePump;
+    private Win32TwainHandleManager? _inner;
+
+    private Win32TwainHandleManager CreateInner()
+    {
+        var mre = new ManualResetEvent(false);
+        var messageThread = new Thread(() =>
+        {
+            _messagePump = Win32MessagePump.Create();
+            mre.Set();
+            _messagePump.RunMessageLoop();
+        });
+        messageThread.SetApartmentState(ApartmentState.STA);
+        messageThread.Start();
+        mre.WaitOne();
+        return new Win32TwainHandleManager(_messagePump!);
+    }
+
+    public override IntPtr GetDsmHandle(IntPtr dialogParent, bool useNativeUi)
+    {
+        _inner ??= CreateInner();
+        return _inner.GetDsmHandle(dialogParent, useNativeUi);
+    }
+
+    public override IntPtr GetEnableHandle(IntPtr dialogParent, bool useNativeUi)
+    {
+        _inner ??= CreateInner();
+        return _inner.GetEnableHandle(dialogParent, useNativeUi);
+    }
+
+    public override MessageLoopHook CreateMessageLoopHook(IntPtr dialogParent = default, bool useNativeUi = false)
+    {
+        _inner ??= CreateInner();
+        return _inner.CreateMessageLoopHook(dialogParent, useNativeUi);
+    }
+
+    public override IInvoker Invoker
+    {
+        get
+        {
+            _inner ??= CreateInner();
+            return _inner.Invoker;
+        }
+    }
+
+    public override void Dispose()
+    {
+        _inner?.Dispose();
+        _messagePump?.Dispose();
+    }
+}
+#endif
diff --git a/NAPS2.Sdk/Scan/Internal/Twain/LocalTwainController.cs b/NAPS2.Sdk/Scan/Internal/Twain/LocalTwainController.cs
@@ -61,7 +61,8 @@ private List<ScanDevice> InternalGetDeviceList(ScanOptions options)
     {
         PlatformInfo.Current.PreferNewDSM = options.TwainOptions.Dsm != TwainDsm.Old;
         var session = new TwainSession(TwainAppId);
-        session.Open(TwainHandleManager.Factory().CreateMessageLoopHook());
+        using var handleManager = TwainHandleManager.Factory();
+        session.Open(handleManager.CreateMessageLoopHook());
         try
         {
             return session.GetSources().Select(ds => new ScanDevice(Driver.Twain, ds.Name, ds.Name)).ToList();
@@ -103,7 +104,8 @@ private ScanCaps InternalGetCaps(ScanOptions options)
     {
         PlatformInfo.Current.PreferNewDSM = options.TwainOptions.Dsm != TwainDsm.Old;
         var session = new TwainSession(TwainAppId);
-        session.Open(TwainHandleManager.Factory().CreateMessageLoopHook());
+        using var handleManager = TwainHandleManager.Factory();
+        session.Open(handleManager.CreateMessageLoopHook());
         try
         {
             var ds = session.GetSources().FirstOrDefault(ds => ds.Name == options.Device!.ID);

diff --git a/NAPS2.Sdk/Scan/Internal/Twain/TwainHandleManager.cs b/NAPS2.Sdk/Scan/Internal/Twain/TwainHandleManager.cs
@@ -3,23 +3,31 @@
 
 namespace NAPS2.Scan.Internal.Twain;
 
-internal class TwainHandleManager : IDisposable
+/// <summary>
+/// Abstracts how HWND handles are obtained for use with TWAIN.
+/// </summary>
+internal abstract class TwainHandleManager : IDisposable
 {
-    public static Func<TwainHandleManager> Factory { get; set; } = () => new TwainHandleManager();
+    public static Func<TwainHandleManager> Factory { get; set; } = () =>
+    {
+#if NET6_0_OR_GREATER
+        if (!OperatingSystem.IsWindows()) throw new NotSupportedException();
+#endif
+        return new DefaultTwainHandleManager();
+    };
 
     protected TwainHandleManager()
     {
     }
 
-    public virtual IntPtr GetDsmHandle(IntPtr dialogParent, bool useNativeUi) => dialogParent;
+    public abstract IntPtr GetDsmHandle(IntPtr dialogParent, bool useNativeUi);
 
-    public virtual IntPtr GetEnableHandle(IntPtr dialogParent, bool useNativeUi) => dialogParent;
+    public abstract IntPtr GetEnableHandle(IntPtr dialogParent, bool useNativeUi);
 
-    public virtual MessageLoopHook CreateMessageLoopHook(IntPtr dialogParent = default, bool useNativeUi = false) =>
-        throw new NotSupportedException();
+    public abstract MessageLoopHook CreateMessageLoopHook(IntPtr dialogParent = default, bool useNativeUi = false);
 
-    public virtual void Dispose()
-    {
-    }
+    public abstract IInvoker Invoker { get; }
+
+    public abstract void Dispose();
 }
 #endif
diff --git a/NAPS2.Sdk/Scan/Internal/Twain/TwainScanRunner.cs b/NAPS2.Sdk/Scan/Internal/Twain/TwainScanRunner.cs
@@ -52,8 +52,7 @@ public TwainScanRunner(ILogger logger, TWIdentity twainAppId, TwainDsm dsm, Scan
 
     public Task Run()
     {
-        // TODO: Work around needing Invoker (maybe pass in SyncContext or something?) and move it to NAPS2.Lib
-        Invoker.Current.InvokeDispatch(Init);
+        _handleManager.Invoker.InvokeDispatch(Init);
         return _tcs.Task;
     }
 
@@ -99,8 +98,8 @@ private void Init()
                 throw GetExceptionForStatus(_source.GetStatus());
             }
 
-            _cancelToken.Register(() => Invoker.Current.Invoke(FinishWithCancellation));
-            _sourceDisabledTcs.Task.ContinueWith(_ => Invoker.Current.Invoke(FinishWithCompletion)).AssertNoAwait();
+            _cancelToken.Register(() => _handleManager.Invoker.Invoke(FinishWithCancellation));
+            _sourceDisabledTcs.Task.ContinueWith(_ => _handleManager.Invoker.Invoke(FinishWithCompletion)).AssertNoAwait();
         }
         catch (Exception ex)
         {