124 lines
4.5 KiB
C
124 lines
4.5 KiB
C
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#pragma option push -b -a8 -pc -A- /*P_O_Push*/
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//// bpcsuspend.h - header file for interface that allows external apps
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// to request that the bpc video server release all of its devices and
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// shutdown its directshow graph.
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// USAGE:
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// in order to request that the bpc subsystem release its devices
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// create an instance of the CBPCSuspend class
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// to check if this succeeded use the IsBPCSuspended member function. if IsBPCSuspended returns false
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// then that means that there are active bpc video clients and you must treat this as you would a
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// device busy or device open type of failure.
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// when you are done with the devices destroy the CBPCSuspend class and this will notify vidsvr
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// that it can resume using the devices and return to background data capturing
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//
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// NOTE: you must compile vidsvr.odl and include the resulting .h before including this file
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// NOTE: you must have initialized com prior on this thread prior to using this object.
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//
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// CLSID_BPCSuspend comes from the header file generated from compiling vidsvr.odl
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// IBPCSuspended comes from the header file generated from compiling vidsvr.odl
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// theory of operation:
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// by using GetActiveObject instead of CoCreateInstance we don't force vidsvr to be loaded just to find
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// out that it wasn't running in the first place.
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// by returning an object that must be released to free the devices so that vidsvr can continue background
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// data capture we utilize COM to manage this resource. this means that if the external app that requested
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// the devices crashes or leaks then the suspension object will be automatically released and
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// vidsvr can resume using the devices without requiring a system reboot or some other unfriendly intervention.
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#ifndef _MSBPCVideo_H_
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#error you must include the .h generated from compiling vidsvr.odl before including this file
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#endif
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#ifndef BPCSUSP_H
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#define BPCSUSP_H
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#pragma once
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#include <oleauto.h>
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#ifdef _CPPUNWIND
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#pragma message("bpcsusp.h using exceptions")
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#define BPCTRY try {
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#ifdef _DEBUG
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#define BPCCATCH } catch(...) { OutputDebugString("CBPCSuspend exception\r\n");}
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#else
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#define BPCCATCH } catch(...) {}
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#endif
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#define BPCNOTHROW throw()
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#else
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#define BPCTRY
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#define BPCCATCH
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#define BPCNOTHROW
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#endif
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class CBPCSuspend {
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IDispatch* m_pSuspended;
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bool m_fBPCExists;
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public:
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inline CBPCSuspend() BPCNOTHROW : m_pSuspended(NULL), m_fBPCExists(false) {
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BPCTRY
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#ifdef _DEBUG
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OutputDebugString("CBPCSuspend()::CBPCSuspend()\r\n");
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TCHAR msgtemp[256];
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#endif
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IUnknown *pUnkSuspendor = NULL;
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DWORD dwReserved;
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HRESULT hr = GetActiveObject(CLSID_BPCSuspend, &dwReserved, &pUnkSuspendor);
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if (SUCCEEDED(hr) && pUnkSuspendor) {
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IBPCSuspend *pSuspendor = NULL;
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hr = pUnkSuspendor->QueryInterface(IID_IBPCSuspend, reinterpret_cast<void **>(&pSuspendor));
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pUnkSuspendor->Release();
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if (SUCCEEDED(hr) && pSuspendor) {
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#ifdef _DEBUG
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OutputDebugString("CBPCSuspend()::CBPCSuspend() BPC exists\r\n");
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#endif
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m_fBPCExists = true;
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hr = pSuspendor->DeviceRelease(0L, &m_pSuspended);
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if (FAILED(hr) || !m_pSuspended) {
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#ifdef _DEBUG
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wsprintf(msgtemp, "CBPCSuspend()::CBPCSuspend() Suspendor->DeviceRelease() rc = %lx\r\n", hr);
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OutputDebugString(msgtemp);
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#endif
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ASSERT(!m_pSuspended);
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}
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#ifdef _DEBUG
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else {
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wsprintf(msgtemp, "CBPCSuspend()::CBPCSuspend() BPC video server suspended\r\n");
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OutputDebugString(msgtemp);
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}
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#endif
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pSuspendor->Release();
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}
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} else {
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#ifdef _DEBUG
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wsprintf(msgtemp, "CBPCSuspend()::CBPCSuspend() GetActiveObject() rc = %lx\r\n", hr);
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OutputDebugString(msgtemp);
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#endif
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}
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BPCCATCH
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}
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inline ~CBPCSuspend() BPCNOTHROW {
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BPCTRY
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if (m_fBPCExists && m_pSuspended) {
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m_pSuspended->Release();
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m_pSuspended = NULL;
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}
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BPCCATCH
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}
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inline bool IsBPCSuspended() BPCNOTHROW {
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// if m_fBPCExists but we weren't able to retrieve a suspension object then
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// there are active video clients and you must treat this as a device busy/failed to open type error
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if (m_fBPCExists && !m_pSuspended) {
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return false;
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}
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return true;
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}
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};
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#endif
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// end of file - bpcsusp.h
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#pragma option pop /*P_O_Pop*/
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