[idd] resend the last captured frame if a new client connects

idd/LGIdd/CIndirectDeviceContext.cpp

@@ -165,11 +165,12 @@ void CIndirectDeviceContext::FinishInit(UINT connectorIndex)
     return;
   }
 
-  auto * wrapper = WdfObjectGet_CIndirectMonitorContextWrapper(createOut.MonitorObject);
+  m_monitor = createOut.MonitorObject;
-  wrapper->context = new CIndirectMonitorContext(createOut.MonitorObject, this);
+  auto * wrapper = WdfObjectGet_CIndirectMonitorContextWrapper(m_monitor);
+  wrapper->context = new CIndirectMonitorContext(m_monitor, this);
 
   IDARG_OUT_MONITORARRIVAL out;
-  status = IddCxMonitorArrival(createOut.MonitorObject, &out);
+  status = IddCxMonitorArrival(m_monitor, &out);
 }
 
 bool CIndirectDeviceContext::SetupLGMP()
@@ -366,6 +367,13 @@ void CIndirectDeviceContext::LGMPTimer()
 
     lgmpHostAckData(m_pointerQueue);
   }
+
+  if (lgmpHostQueueNewSubs(m_frameQueue) && m_monitor)
+  {
+    auto* wrapper = WdfObjectGet_CIndirectMonitorContextWrapper(m_monitor);
+    if (wrapper)
+      wrapper->context->ResendLastFrame();
+  }
 }
 
 void CIndirectDeviceContext::SendFrame(int width, int height, int pitch, DXGI_FORMAT format, void* data)
@@ -373,11 +381,12 @@ void CIndirectDeviceContext::SendFrame(int width, int height, int pitch, DXGI_FO
   if (!m_lgmp || !m_frameQueue)
     return;
 
-  if (m_width != width || m_height != height || m_format != format)
+  if (m_width != width || m_height != height || m_pitch != pitch || m_format != format)
   {
     m_width  = width;
     m_height = height;
     m_format = format;
+    m_pitch  = pitch;
     ++m_formatVer;
   }
 

idd/LGIdd/CIndirectDeviceContext.h

@@ -19,6 +19,8 @@ class CIndirectDeviceContext
 private:
   WDFDEVICE     m_wdfDevice;
   IDDCX_ADAPTER m_adapter = nullptr;
+  IDDCX_MONITOR m_monitor = nullptr;
+
   CIVSHMEM      m_ivshmem;
 
   PLGMPHost      m_lgmp         = nullptr;
@@ -36,7 +38,9 @@ private:
 
   int         m_width  = 0;
   int         m_height = 0;
+  int         m_pitch  = 0;
   DXGI_FORMAT m_format = DXGI_FORMAT_UNKNOWN;
+  void      * m_data   = nullptr;
 
   bool SetupLGMP();
 

idd/LGIdd/CIndirectMonitorContext.h

@@ -22,6 +22,12 @@ public:
   
   void AssignSwapChain(IDDCX_SWAPCHAIN swapChain, LUID renderAdapter, HANDLE newFrameEvent);
   void UnassignSwapChain();
+
+  inline void ResendLastFrame()
+  {
+    if (m_thread)
+      m_thread->ResendLastFrame();
+  }
 };
 
 struct CIndirectMonitorContextWrapper

idd/LGIdd/CSwapChainProcessor.cpp

@@ -3,11 +3,16 @@
 #include <avrt.h>
 #include "Debug.h"
 
-#define LOCK_CONTEXT() \
+#define LOCK(lock) \
-  while (InterlockedCompareExchange((volatile LONG*)&m_contextLock, 1, 0) != 0) {};
+  while (InterlockedCompareExchange((volatile LONG*)&(lock), 1, 0) != 0) {};
 
-#define UNLOCK_CONTEXT() \
+#define UNLOCK(lock) \
-  InterlockedExchange((volatile LONG*)&m_contextLock, 0);
+  InterlockedExchange((volatile LONG*)&(lock), 0);
+
+#define LOCK_CONTEXT()   LOCK(m_contextLock);
+#define UNLOCK_CONTEXT() UNLOCK(m_contextLock);
+#define LOCK_ST(st)      LOCK((st).lock);
+#define UNLOCK_ST(st)    UNLOCK((st).lock);
 
 CSwapChainProcessor::CSwapChainProcessor(CIndirectDeviceContext* devContext, IDDCX_SWAPCHAIN hSwapChain,
     std::shared_ptr<Direct3DDevice> device, HANDLE newFrameEvent) :
@@ -197,6 +202,7 @@ void CSwapChainProcessor::FrameThread()
     }
 
     StagingTexture & st = m_cpuTex[m_texRIndex];
+    LOCK(st);
 
     LOCK_CONTEXT();
     HRESULT status = m_device->m_context->Map(st.tex.Get(), 0, D3D11_MAP_READ,
@@ -205,6 +211,7 @@ void CSwapChainProcessor::FrameThread()
 
     if (FAILED(status))
     {
+      UNLOCK(st);
       if (status == DXGI_ERROR_WAS_STILL_DRAWING)
         continue;
 
@@ -219,8 +226,11 @@ void CSwapChainProcessor::FrameThread()
 
     m_devContext->SendFrame(st.width, st.height, st.map.RowPitch, st.format, st.map.pData);
     InterlockedAdd(&m_copyCount, -1);
+    m_lastIndex = m_texRIndex;
     if (++m_texRIndex == STAGING_TEXTURES)
       m_texRIndex = 0;
+
+    UNLOCK(st);
   }
 }
 
@@ -255,3 +265,20 @@ bool CSwapChainProcessor::SetupStagingTexture(StagingTexture & st, int width, in
 
   return true;
 }
+
+void CSwapChainProcessor::ResendLastFrame()
+{
+  LOCK_CONTEXT()
+  StagingTexture & st = m_cpuTex[m_lastIndex];
+  LOCK_ST(st);
+  UNLOCK_CONTEXT();
+
+  if (!st.map.pData)
+  {
+    UNLOCK_ST(st);
+    return;
+  }
+
+  m_devContext->SendFrame(st.width, st.height, st.map.RowPitch, st.format, st.map.pData);
+  UNLOCK_ST(st);
+}

idd/LGIdd/CSwapChainProcessor.h

@@ -34,6 +34,8 @@ private:
 
   struct StagingTexture
   {
+    volatile LONG lock = 0;
+
     int         width  = 0;
     int         height = 0;
     DXGI_FORMAT format = DXGI_FORMAT_UNKNOWN;
@@ -46,6 +48,7 @@ private:
   volatile LONG m_contextLock = 0;
   int m_texRIndex = 0;
   int m_texWIndex = 0;
+  int m_lastIndex = 0;
 
   bool SetupStagingTexture(StagingTexture & st, int width, int height, DXGI_FORMAT format);
 
@@ -53,4 +56,6 @@ public:
   CSwapChainProcessor(CIndirectDeviceContext * devContext, IDDCX_SWAPCHAIN hSwapChain,
     std::shared_ptr<Direct3DDevice> device, HANDLE newFrameEvent);
   ~CSwapChainProcessor();
+
+  void ResendLastFrame();
 };