chap11_6.htm

非常好的应用vc＋＋6.0进行相关网络程序开发的教程

      <tr>
        <td WIDTH="27%"><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">SND_MEMORY</font></td>
        <td WIDTH="73%"><font SIZE="3"><p ALIGN="JUSTIFY">播放载入到内存中的声音，此时</font><font FACE="Times New Roman" SIZE="3">pszSound</font><font SIZE="3">是指向声音数据的指针。</font></td>
      </tr>
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        <td WIDTH="27%"><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">SND_NODEFAULT</font></td>
        <td WIDTH="73%"><font SIZE="3"><p ALIGN="JUSTIFY">不播放缺省声音，若无此标志，则</font><font FACE="Times New Roman" SIZE="3">PlaySound</font><font SIZE="3">在没找到声音时会播放缺省声音。</font></td>
      </tr>
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        <td WIDTH="27%"><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">SND_NOSTOP</font></td>
        <td WIDTH="73%"><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">PlaySound</font><font SIZE="3">不打断原来的声音播出并立即返回</font><font FACE="Times New Roman" SIZE="3">FALSE</font><font SIZE="3">。</font></td>
      </tr>
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        <td WIDTH="27%"><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">SND_NOWAIT</font></td>
        <td WIDTH="73%"><font SIZE="3"><p ALIGN="JUSTIFY">如果驱动程序正忙则函数就不播放声音并立即返回。</font></td>
      </tr>
      <tr>
        <td WIDTH="27%"><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">SND_PURGE</font></td>
        <td WIDTH="73%"><font SIZE="3"><p ALIGN="JUSTIFY">停止所有与调用任务有关的声音。若参数</font><font FACE="Times New Roman" SIZE="3">pszSound</font><font SIZE="3">为</font><font FACE="Times New Roman" SIZE="3">NULL</font><font SIZE="3">，就停止所有的声音，否则，停止</font><font FACE="Times New Roman" SIZE="3">pszSound</font><font SIZE="3">指定的声音。</font></td>
      </tr>
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        <td WIDTH="27%"><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">SND_RESOURCE</font></td>
        <td WIDTH="73%"><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">pszSound</font><font SIZE="3">参数是</font><font FACE="Times New Roman" SIZE="3">WAVE</font><font SIZE="3">资源的标识符，这时要用到</font><font FACE="Times New Roman" SIZE="3">hmod</font><font SIZE="3">参数。</font></td>
      </tr>
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        <td WIDTH="27%"><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">SND_SYNC</font></td>
        <td WIDTH="73%"><font SIZE="3"><p ALIGN="JUSTIFY">同步播放声音，在播放完后</font><font FACE="Times New Roman" SIZE="3">PlaySound</font><font SIZE="3">函数才返回。</font></td>
      </tr>
    </table>
    <p><b><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font></b><font SIZE="3">在</font><font FACE="Times New Roman" SIZE="3">C:\WINDOWS\MEDIA</font><font SIZE="3">目录下有一个名为</font><font FACE="Times New Roman" SIZE="3">The Microsoft Sound.wav</font><font SIZE="3">的声音文件，在</font><font FACE="Times New Roman" SIZE="3">Windows 95</font><font SIZE="3">启动时会播放这个声音。下面我们用三种方法来调用</font><font FACE="Times New Roman" SIZE="3">PlaySound</font><font SIZE="3">函数播出</font><font FACE="Times New Roman" SIZE="3">Windows 95</font><font SIZE="3">的启动声音。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">第一种方法是直接播出声音文件，相应的代码为：</p>
    <blockquote>
      <blockquote>
        <blockquote>
          </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">PlaySound(&quot;c:\\win95\\media\\The 
          Microsoft Sound.wav&quot;, NULL, SND_FILENAME | SND_ASYNC);</p>
        </blockquote>
      </blockquote>
    </blockquote>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">注意参数中的路径使用两个连续的反斜杠转义代表一个反斜杠。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">第二种方法是把声音文件加入到资源中，然后从资源中播放声音。</font><font FACE="Times New Roman" SIZE="3">Visual C++</font><font SIZE="3">支持</font><font FACE="Times New Roman" SIZE="3">WAVE</font><font SIZE="3">型资源，用户在资源视图中单击鼠标右键并选择</font><font FACE="Times New Roman" SIZE="3">Import</font><font SIZE="3">命令，然后在文件选择对话框中选择</font><font FACE="Times New Roman" SIZE="3">The Microsoft Sound.wav</font><font SIZE="3">文件，则该文件就会被加入到</font><font FACE="Times New Roman" SIZE="3">WAVE</font><font SIZE="3">资源中。假定声音资源的</font><font FACE="Times New Roman" SIZE="3">ID</font><font SIZE="3">为</font><font FACE="Times New Roman" SIZE="3">IDR_STARTWIN</font><font SIZE="3">，则下面的调用同样会输出启动声音：</p>
    <blockquote>
      <blockquote>
        <blockquote>
          </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">PlaySound((LPCTSTR)IDR_STARTWIN, 
          AfxGetInstanceHandle(), SND_RESOURCE | SND_ASYNC);</p>
        </blockquote>
      </blockquote>
    </blockquote>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">第三种方法是用</font><font FACE="Times New Roman" SIZE="3">PlaySound</font><font SIZE="3">播放系统声音，</font><font FACE="Times New Roman" SIZE="3">Windows</font><font SIZE="3">启动的声音是由</font><font FACE="Times New Roman" SIZE="3">SystemStart</font><font SIZE="3">定义的系统声音，因此可以用下面的方法播放启动声音：</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">PlaySound(&quot;SystemStart&quot;,NULL,SND_ALIAS|SND_ASYNC);</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">函数</font><font FACE="Times New Roman" SIZE="3">sndPlaySound</font><font SIZE="3">的功能与</font><font FACE="Times New Roman" SIZE="3">PlaySound</font><font SIZE="3">类似，但少了一个参数。函数的声明为：</p>
    <blockquote>
      <blockquote>
        <blockquote>
          </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">BOOL sndPlaySound(LPCSTR 
          lpszSound, UINT fuSound);</font></p>
        </blockquote>
      </blockquote>
    </blockquote>
    <p><font SIZE="3">　</p>
    <p ALIGN="JUSTIFY">除了不能指定资源名字外，参数</font><font FACE="Times New Roman" SIZE="3">lpszSound</font><font SIZE="3">与</font><font FACE="Times New Roman" SIZE="3">PlaySound</font><font SIZE="3">的是一样的。参数</font><font FACE="Times New Roman" SIZE="3">fuSound</font><font SIZE="3">是如何播放声音的标志，可以是</font><font FACE="Times New Roman" SIZE="3">SND_ASYNC</font><font SIZE="3">、</font><font FACE="Times New Roman" SIZE="3">SND_LOOP</font><font SIZE="3">、</font><font FACE="Times New Roman" SIZE="3">SND_MEMORY</font><font SIZE="3">、</font><font FACE="Times New Roman" SIZE="3">SND_NODEFAULT</font><font SIZE="3">、</font><font FACE="Times New Roman" SIZE="3">SND_NOSTOP</font><font SIZE="3">和</font><font FACE="Times New Roman" SIZE="3">SND_SYNC</font><font SIZE="3">的组合，这些标志的含义与</font><font FACE="Times New Roman" SIZE="3">PlaySound</font><font SIZE="3">的一样。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">可以看出，</font><font FACE="Times New Roman" SIZE="3">sndPlaySound</font><font SIZE="3">不能直接播放声音资源。要用该函数播放</font><font FACE="Times New Roman" SIZE="3">WAVE</font><font SIZE="3">文件，可按下面的方式调用：</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">sndPlaySound(</font><font SIZE="3">“</font><font FACE="Times New Roman" SIZE="3">MYSOUND.WAV</font><font SIZE="3">”</font><font FACE="Times New Roman" SIZE="3">,SND_ASYNC);</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <b><p ALIGN="JUSTIFY"></b><font color="#3973DE">11.6.2 MCI</font></p>
    <p ALIGN="JUSTIFY">MCI(Media Control Interface</font><font SIZE="3">，媒体控制接口</font><font FACE="Times New Roman" SIZE="3">)</font><font SIZE="3">向</font><font FACE="Times New Roman" SIZE="3">Windows</font><font SIZE="3">程序提供了在高层次上控制媒体设备接口的能力。程序不必关心具体设备，就可以对激光唱机（</font><font FACE="Times New Roman" SIZE="3">CD</font><font SIZE="3">）、视盘机、波形音频设备、视频播放设备和</font><font FACE="Times New Roman" SIZE="3">MIDI</font><font SIZE="3">设备等媒体设备进行控制。对于程序员来说，可以把</font><font FACE="Times New Roman" SIZE="3">MCI</font><font SIZE="3">理解为设备面板上的一排按键，通过选择不同的按键（发送不同的</font><font FACE="Times New Roman" SIZE="3">MCI</font><font SIZE="3">命令）可以让设备完成各种功能，而不必关心设备内部实现。比如，对于</font><font FACE="Times New Roman" SIZE="3">play</font><font SIZE="3">，视盘机和</font><font FACE="Times New Roman" SIZE="3">CD</font><font SIZE="3">机有不同的反应（一个是播放视频，一个播放音频），而对用户来说却只需要按同一按钮。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">应用程序通过向</font><font FACE="Times New Roman" SIZE="3">MCI</font><font SIZE="3">发送命令来控制媒体设备。</font><font FACE="Times New Roman" SIZE="3">MCI</font><font SIZE="3">命令接口分命令字符串和命令消息两种，两者具有相同的功能。命令字符串具有使用简单的特点，但是它的执行效率不如命令消息。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">所有的</font><font FACE="Times New Roman" SIZE="3">MCI</font><font SIZE="3">命令字符串都是通过多媒体</font><font FACE="Times New Roman" SIZE="3">API</font><font SIZE="3">函数</font><font FACE="Times New Roman" SIZE="3">mciSendString</font><font SIZE="3">传递给</font><font FACE="Times New Roman" SIZE="3">MCI</font><font SIZE="3">的，该函数的声明为：</p>
    <blockquote>
      </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">MCIERROR mciSendString(</p>
      <p ALIGN="JUSTIFY">LPCTSTR lpszCommand, //MCI</font><font SIZE="3">命令字符串</p>
      </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">LPTSTR lpszReturnString, 
      //</font><font SIZE="3">存放反馈信息的缓冲区</p>
      </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">UINT cchReturn, //</font><font SIZE="3">缓冲区的长度</p>
      </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">HANDLE hwndCallback //</font><font SIZE="3">回调窗口的句柄，一般为</font><font FACE="Times New Roman" SIZE="3">NULL</p>
      <p ALIGN="JUSTIFY">); //</font><font SIZE="3">若成功则返回</font><font FACE="Times New Roman" SIZE="3">0</font><font SIZE="3">，否则返回错误码。</font></p>
    </blockquote>
    <p><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">该函数返回的错误码可以用</font><font FACE="Times New Roman" SIZE="3">mciGetErrorString</font><font SIZE="3">函数进行分析，该函数的声明为：</p>
    <blockquote>
      </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">BOOL mciGetErrorString(</p>
      <p ALIGN="JUSTIFY">DWORD fdwError, //</font><font SIZE="3">函数</font><font FACE="Times New Roman" SIZE="3">mciSendString</font><font SIZE="3">或</font><font FACE="Times New Roman" SIZE="3">mciSendCommand</font><font SIZE="3">返回的错误码</p>
      </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">LPTSTR lpszErrorText, //</font><font SIZE="3">接收描述错误的字符串的缓冲区</p>
      </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">UINT cchErrorText //</font><font SIZE="3">缓冲区的长度</p>
      </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">);</p>
    </blockquote>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">下面是使用</font><font FACE="Times New Roman" SIZE="3">mciSendString</font><font SIZE="3">函数的一个简单例子：</p>
    <blockquote>
      </font><font FACE="Times New Roman" SIZE="3"><p ALIGN="JUSTIFY">char buf[50];</p>
      <p ALIGN="JUSTIFY">MCIERROR mciError;</p>
      <p ALIGN="JUSTIFY">mciError=mciSendString(</font><font SIZE="3">“</font><font FACE="Times New Roman" SIZE="3">open cdaudio</font><font SIZE="3">”</font><font FACE="Times New Roman" SIZE="3">,buf,strlen(buf),NULL);</p>
      <p ALIGN="JUSTIFY">if(mciError)</p>
      <p ALIGN="JUSTIFY">{</p>
      <p ALIGN="JUSTIFY">mciGetErrorString(mciError,buf,strlen(buf));</p>
      <p ALIGN="JUSTIFY">AfxMessageBox(buf);</p>
      <p ALIGN="JUSTIFY">return;</p>
      <p ALIGN="JUSTIFY">}</p>
    </blockquote>
    <p ALIGN="JUSTIFY">open cdaudio</font><font SIZE="3">命令打开</font><font FACE="Times New Roman" SIZE="3">CD</font><font SIZE="3">播放器，如果出错（如驱动器内没有</font><font FACE="Times New Roman" SIZE="3">CD</font><font SIZE="3">）则返回错误码，此时可以用</font><font FACE="Times New Roman" SIZE="3">mciGetErrorString</font><font SIZE="3">函数取得错误信息字符串。</font><font FACE="Times New Roman" SIZE="3">open</font><font SIZE="3">是</font><font FACE="Times New Roman" SIZE="3">MCI</font><font SIZE="3">打开设备的命令，</font><font FACE="Times New Roman" SIZE="3">cdaudio</font><font SIZE="3">是</font><font FACE="Times New Roman" SIZE="3">MCI</font><font SIZE="3">设备名。</font><font FACE="Times New Roman" SIZE="3">MCI</font><font SIZE="3">的设备类型在表</font><font FACE="Times New Roman" SIZE="3">11.6</font><font SIZE="3">列出。</font><b><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="CENTER"></font><font SIZE="3">　</p>
    <p ALIGN="CENTER">表</font><font FACE="Times New Roman" SIZE="3">11.6 MCI</font><font SIZE="3">设备类型</font></b></p>
    <table BORDER="1" CELLSPACING="1" CELLPADDING="1" WIDTH="579">
      <tr>
        <td WIDTH="24%"><font SIZE="3"><b><p ALIGN="JUSTIFY">设备类型</b></font></td>
        <td WIDTH="76%"><font SIZE="3"><b><p ALIGN="JUSTIFY">描述</b></font></td>
      </tr>
      <tr>