From dd8c2d1993b5dc5c3ffd29095dc9e3071ed3b28d Mon Sep 17 00:00:00 2001
From: WIndFate <windfate@vip.qq.com>
Date: Fri, 19 Jun 2026 05:38:43 +0900
Subject: [PATCH] feat(d3d11): implement SwapDeviceContextState

SwapDeviceContextState was UNIMPLEMENTED. Callers such as Direct2D interop
use it to swap their own pipeline state in and the application's state out
around a render pass, so any such render loop aborted at the first call.

MTLD3D11DeviceContextState gains a D3D11ContextState saved_state slot. The
swap saves the current state_ into the returned previous-state token,
activates the incoming token's saved state, then resets encoding state and
invalidates the render pipeline so the Metal side follows the new state.

With this, a Direct2D render loop (BeginDraw/Clear/draw/EndDraw) runs
cleanly with EndDraw returning S_OK.
---
 src/d3d11/d3d11_context_impl.cpp  | 21 ++++++++++++++++++++-
 src/d3d11/d3d11_context_state.hpp |  5 +++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/d3d11/d3d11_context_impl.cpp b/src/d3d11/d3d11_context_impl.cpp
index 6d3595207..795cbbe43 100644
--- a/src/d3d11/d3d11_context_impl.cpp
+++ b/src/d3d11/d3d11_context_impl.cpp
@@ -1884,7 +1884,26 @@ template <typename ContextInternalState> class MTLD3D11DeviceContextImplBase : p
   void
   STDMETHODCALLTYPE
   SwapDeviceContextState(ID3DDeviceContextState *pState, ID3DDeviceContextState **ppPreviousState) override {
-    UNIMPLEMENTED("SwapDeviceContextState");
+    // Callers (e.g. Direct2D interop) swap their own pipeline state in and the
+    // application's state out around a render pass. Save the current pipeline
+    // state into the returned previous-state token, then activate the incoming
+    // token's saved state.
+    if (!pState) {
+      if (ppPreviousState)
+        *ppPreviousState = nullptr;
+      return;
+    }
+    std::lock_guard<mutex_t> lock(mutex);
+    auto incoming = static_cast<MTLD3D11DeviceContextState *>(pState);
+    if (ppPreviousState) {
+      auto previous = new MTLD3D11DeviceContextState(device);
+      previous->saved_state = std::move(state_);
+      *ppPreviousState = ref(previous);
+    }
+    state_ = std::move(incoming->saved_state);
+    incoming->saved_state = {};
+    ResetEncodingContextState();
+    InvalidateRenderPipeline();
   }
 
   void
diff --git a/src/d3d11/d3d11_context_state.hpp b/src/d3d11/d3d11_context_state.hpp
index 3484bda07..cb1bcb9bb 100644
--- a/src/d3d11/d3d11_context_state.hpp
+++ b/src/d3d11/d3d11_context_state.hpp
@@ -211,6 +211,11 @@ class MTLD3D11DeviceContextState
 
     return E_NOINTERFACE;
   }
+
+  // Saved pipeline state for SwapDeviceContextState. A newly created token
+  // carries default (empty) state, giving the caller a clean context to render
+  // into; swapping back restores the previously saved state.
+  D3D11ContextState saved_state = {};
 };
 
 } // namespace dxmt
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