71 lines
2.7 KiB
C#
71 lines
2.7 KiB
C#
 
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using System.Runtime.InteropServices;
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namespace RemSound.App;
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/// <summary>
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/// Tolk-backed <see cref="IScreenReaderOutput"/>. Tolk (https://github.com/dkager/tolk, LGPL-3.0) is a
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/// screen-reader abstraction DLL that auto-detects whichever reader is running (NVDA, JAWS, Window-Eyes,
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/// SuperNova, System Access, ZoomText) and falls back to SAPI, then routes speech to it. The native
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/// <c>Tolk.dll</c> plus its helpers (<c>nvdaControllerClient64.dll</c>, <c>SAAPI64.dll</c>) ship flat
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/// next to the exe (see the .csproj Content items) — Tolk.dll loads those helpers from the same folder.
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///
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/// Loaded lazily on the first <see cref="Speak"/> and never re-attempted once it fails, so a missing DLL
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/// or absent screen reader just means silence, never an exception. All entry points are wrapped in
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/// try/catch and guarded by a lock, so it's safe to call from any thread (e.g. a hotkey callback).
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/// </summary>
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internal sealed class TolkScreenReaderOutput : IScreenReaderOutput
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{
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private readonly object sync = new();
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private bool loadAttempted;
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private bool loaded;
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public bool Speak(string text, bool interrupt = true)
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{
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if (string.IsNullOrWhiteSpace(text)) return false;
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if (!EnsureLoaded()) return false;
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try { return Tolk_Output(text, interrupt); }
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catch { return false; }
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}
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public void Shutdown()
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{
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lock (sync)
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{
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if (!loaded) return;
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try { Tolk_Unload(); } catch { /* best-effort */ }
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loaded = false;
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loadAttempted = false;
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}
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}
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/// <summary>Load Tolk once. Succeeds only if Tolk loads AND reports a working speech channel, so a
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/// machine with the DLLs present but no screen reader running stays silent instead of half-init'd.</summary>
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private bool EnsureLoaded()
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{
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lock (sync)
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{
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if (loaded) return true;
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if (loadAttempted) return false; // already tried and failed — don't spam load attempts
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loadAttempted = true;
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try { loaded = Tolk_Load() && Tolk_HasSpeech(); }
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catch { loaded = false; }
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return loaded;
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}
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}
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[DllImport("Tolk.dll", CharSet = CharSet.Unicode)]
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[return: MarshalAs(UnmanagedType.Bool)]
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private static extern bool Tolk_Load();
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[DllImport("Tolk.dll")]
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private static extern void Tolk_Unload();
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[DllImport("Tolk.dll")]
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[return: MarshalAs(UnmanagedType.Bool)]
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private static extern bool Tolk_HasSpeech();
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[DllImport("Tolk.dll", CharSet = CharSet.Unicode)]
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[return: MarshalAs(UnmanagedType.Bool)]
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private static extern bool Tolk_Output(string text, [MarshalAs(UnmanagedType.Bool)] bool interrupt);
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}
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