[idd] transport: abstract LGMP implementation

Introduce transport, frame, and control interfaces with an LGMP factory
backend.

Move LGMP and IVSHMEM implementation details under transport/lgmp and
expose direct frame-buffer memory through a neutral capability.

idd/LGIdd/transport/IFrameTransport.h

@@ -0,0 +1,87 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2026 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#pragma once
+
+#include "postprocess/D12FrameFormat.h"
+#include "transport/CFrameScheduler.h"
+#include "transport/FrameBufferTypes.h"
+#include "transport/TransportTypes.h"
+
+#include <Windows.h>
+#include <stddef.h>
+#include <stdint.h>
+
+class IFrameTransport
+{
+public:
+  virtual ~IFrameTransport() = default;
+
+  virtual size_t GetMaxFrameSize() const = 0;
+
+  virtual bool FrameBufferAvailable(
+    const CFrameScheduler::Schedule& schedule,
+    bool allowReadyReplacement = true) = 0;
+  virtual bool HasPublishedFrame() const = 0;
+  virtual void ProcessDeliveries() = 0;
+  virtual bool GetPendingDeliveryTarget(
+    uint64_t now, uint64_t& target) = 0;
+  virtual bool RetryPendingDelivery(uint64_t now, bool& retry) = 0;
+  virtual PreparedFrameBuffer PrepareFrameBuffer(unsigned pitch,
+    const D12FrameFormat& srcFormat, const D12FrameFormat& dstFormat,
+    const RECT * dirtyRects, unsigned nbDirtyRects,
+    const CFrameScheduler::Schedule& schedule,
+    bool allowReadyReplacement = true) = 0;
+  virtual bool PublishFrameBuffer(unsigned frameIndex,
+    const CFrameScheduler::Schedule& schedule,
+    bool& deliveredToOwner) = 0;
+  virtual bool RepublishFrameBuffer(
+    const CFrameScheduler::Schedule& schedule) = 0;
+  virtual bool TryFrameSubmitted(unsigned frameIndex,
+    const CFrameScheduler::Schedule& schedule) = 0;
+  virtual void CommitFrameBuffer(unsigned frameIndex,
+    const CFrameScheduler::Schedule& schedule, bool periodic,
+    bool deliveredToOwner) = 0;
+  virtual void AbortFrameBuffer(unsigned frameIndex) = 0;
+  virtual void FailFrameBuffer(unsigned frameIndex) = 0;
+  virtual void CompleteFrameBuffer(
+    unsigned frameIndex, bool succeeded) = 0;
+  virtual void SetFrameTiming(unsigned frameIndex, uint64_t captureTime,
+    uint64_t postProcessTime, uint64_t copyTime, uint64_t readyTime,
+    uint64_t holdTime, const CFrameScheduler::Schedule& schedule,
+    uint64_t completedAt) = 0;
+  virtual void WriteFrameBuffer(unsigned frameIndex, void * src,
+    size_t offset, size_t len, bool setWritePos) const = 0;
+  virtual void WriteFrameBufferRows(unsigned frameIndex, void * src,
+    size_t offset, size_t rowBytes, size_t pitch,
+    unsigned rows) const = 0;
+  virtual void FinalizeFrameBuffer(unsigned frameIndex) const = 0;
+
+  virtual void ObserveFrame(uint64_t now) = 0;
+  virtual void ForceFrame() = 0;
+  virtual bool GetPublishTarget(uint64_t now, uint64_t& target,
+    CFrameScheduler::Schedule& schedule, bool& periodic,
+    bool& republish) = 0;
+  virtual void FrameMissed(const CFrameScheduler::Schedule& schedule,
+    uint64_t now, bool periodic) = 0;
+  virtual void FrameSuperseded() = 0;
+  virtual HANDLE GetFrameScheduleEvent() const = 0;
+  virtual void TryRecordFrameTiming(uint64_t duration) = 0;
+};