📄 csdn_文档中心_视频捕获 之 如何使用系统设备枚举器.htm
字号:
face="Times New Roman">CoCreateInstance</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">生成系统设备枚举器。类标识（</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">CLSID</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）为</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">CLSID_SystemDeviceEnum</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。</SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt 21.75pt; TEXT-INDENT: -21.75pt; mso-list: l0 level1 lfo1; tab-stops: list 21.75pt"><SPAN
lang=EN-US style="mso-fareast-font-family: 'Times New Roman'"><SPAN
style="mso-list: Ignore"><FONT face="Times New Roman">2．<SPAN
style="FONT: 7pt 'Times New Roman'"><FONT size=3>
</FONT></SPAN></FONT></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">调用</SPAN><SPAN
lang=EN-US><A
href="mk:@MSITStore:D:\DXSDK\Doc\DirectX9\DirectX9_c.chm::/directx/htm/icreatedevenumcreateclassenumerator.htm"><SPAN
style="COLOR: windowtext; TEXT-DECORATION: none; text-underline: none"><FONT
face="Times New Roman">ICreateDevEnum::CreateClassEnumerator</FONT></SPAN></A></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法生成类型枚举器，参数为你想要得到的类型的</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">CLSID</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，该方法返回一个</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">IEnumMoniker</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">接口指针，如果指定的类型（是空的）或不存在，函数</SPAN><SPAN
lang=EN-US><A
href="mk:@MSITStore:D:\DXSDK\Doc\DirectX9\DirectX9_c.chm::/directx/htm/icreatedevenumcreateclassenumerator.htm"><SPAN
style="COLOR: windowtext; TEXT-DECORATION: none; text-underline: none"><FONT
face="Times New Roman">ICreateDevEnum::CreateClassEnumerator</FONT></SPAN></A></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">将返回</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">S_FALSE</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">而不是错误代码，同时</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">IEnumMoniker</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">指针（译注：通过参数返回）也是空的，这就要求我们在调用</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">CreateClassEnumerator</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的时候明确用</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">S_OK</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">进行比较而不是使用宏</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">SUCCEEDED</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。</SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt 21.75pt; TEXT-INDENT: -21.75pt; mso-list: l0 level1 lfo1; tab-stops: list 21.75pt"><SPAN
lang=EN-US style="mso-fareast-font-family: 'Times New Roman'"><SPAN
style="mso-list: Ignore"><FONT face="Times New Roman">3．<SPAN
style="FONT: 7pt 'Times New Roman'"><FONT size=3>
</FONT></SPAN></FONT></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">使用</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">IEnumMoniker::Next</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法依次得到</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">IEnumMoniker</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">指针中的每个</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">moniker</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。该方法返回一个</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">IMoniker</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">接口指针。当</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Next</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">到达枚举的底部，它的返回值仍然是</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">S_FALSE</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，这里我们仍需要用</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">S_OK</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">来进行检验。</SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt 21.75pt; TEXT-INDENT: -21.75pt; mso-list: l0 level1 lfo1; tab-stops: list 21.75pt"><SPAN
lang=EN-US style="mso-fareast-font-family: 'Times New Roman'"><SPAN
style="mso-list: Ignore"><FONT face="Times New Roman">4．<SPAN
style="FONT: 7pt 'Times New Roman'"><FONT size=3>
</FONT></SPAN></FONT></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">想要得到该设备较为友好的名称（例如想要在用户界面中进行显示），调用</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">IMoniker::BindToStorage</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法。</SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt 21.75pt; TEXT-INDENT: -21.75pt; mso-list: l0 level1 lfo1; tab-stops: list 21.75pt"><SPAN
lang=EN-US style="mso-fareast-font-family: 'Times New Roman'"><SPAN
style="mso-list: Ignore"><FONT face="Times New Roman">5．<SPAN
style="FONT: 7pt 'Times New Roman'"><FONT size=3>
</FONT></SPAN></FONT></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">如果想要生成并初始化管理该设备的</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Filter</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">调用</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">3</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">返回指针的</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">IMonitor::BindToObject</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法，接下来调用</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">IFilterGraph::AddFilter</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">把该</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Filter</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">添加到视图中。</SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">下图说明了上述步骤：</SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
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style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">下面的代码示例了如何枚举用户系统中的视频压缩器，为了简化，只给出了很少的错误检查。</SPAN></P>
<P>
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