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📄 4.2.2 请求方式.htm

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<H3 style="TEXT-INDENT: 0cm"><FONT face=楷体_GB2312 size=4><SPAN 
style="mso-fareast-language: ZH-CN"><SPAN lang=EN-US>4.2.2 </SPAN><SPAN 
style="FONT-FAMILY: 楷体_GB2312; mso-fareast-language: ZH-CN; mso-ascii-font-family: 'Times New Roman'">请求方式</SPAN></SPAN><SPAN 
lang=EN-US style="mso-fareast-language: ZH-CN"><o:p></o:p></SPAN></FONT></H3>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0px"><SPAN 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 
size=4>此时，只有用输入方式设置命令（或语句）对相应的设备设置成需要的输入方式后，该设备才能作相应的输入处理。</FONT></SPAN><FONT 
face=楷体_GB2312 size=4><SPAN lang=EN-US>如：</SPAN></FONT></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0px"><FONT face=楷体_GB2312 
size=4><SPAN lang=EN-US>&nbsp;&nbsp;&nbsp; </SPAN></FONT><SPAN lang=EN-US><FONT 
face=楷体_GB2312 
size=4>request_locator(ws,device_code,x,y)<o:p></o:p></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0px"><SPAN 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 
size=4>该命令是把定位器置成请求输入控制方式，其中<SPAN 
lang=EN-US>x、y用来存储一个点的坐标值。在输入命令中，每一种逻辑设备所包括的参数是和输入数据类型有关的，如在请求方式下的笔划输入是：<o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN lang=EN-US 
style="mso-fareast-language: ZH-CN; mso-tab-count: 1"><FONT face=楷体_GB2312 
size=4>&nbsp;&nbsp;&nbsp; </FONT></SPAN><FONT face=楷体_GB2312 size=4><SPAN 
lang=EN-US>request_stroke(ws,device_code,n,xa,ya)<o:p></o:p></SPAN></FONT></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 size=4>这里输入的<SPAN 
lang=EN-US>n个点的坐标存放在数组xa和ya中，类似地在请求方式下的字符串输入是：<o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN lang=EN-US 
style="mso-fareast-language: ZH-CN; mso-tab-count: 1"><FONT face=楷体_GB2312 
size=4>&nbsp;&nbsp;&nbsp; </FONT></SPAN><FONT face=楷体_GB2312 size=4><SPAN 
lang=EN-US>request_string(ws,device_code,nc,text)<o:p></o:p></SPAN></FONT></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 size=4>这里<SPAN 
lang=EN-US>nc指定了输入字符串的长度（即字符个数），输入的字符串存放在字符缓存text中。为了能在应用程序中拾取到输入的图段，需要用下列命令设置图段的标志，即：<o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN lang=EN-US 
style="mso-fareast-language: ZH-CN; mso-tab-count: 1"><FONT face=楷体_GB2312 
size=4>&nbsp;&nbsp;&nbsp; </FONT></SPAN><FONT face=楷体_GB2312 size=4><SPAN 
lang=EN-US>request_pick(ws,device_code,segment-id)<o:p></o:p></SPAN></FONT></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 
size=4>用于请求方式下的输入命令还可以包括其他参数，如有些应用需要对图段中的图素设置标志，如线段、圆、矩形等；也可对图段设置标号，以加快对图段的搜索。<SPAN 
lang=EN-US><o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoBodyTextIndent><SPAN style="mso-fareast-language: ZH-CN"><FONT 
face=楷体_GB2312 size=4>请求方式的工作过程如图<SPAN 
lang=EN-US>4.2.1所示。当程序运行到request语句就向输入设备提出输入请求；同时停止运行，等待输入设备的输入数据。直到请求满足之后，程序才继续运行。当程序运行时，输入设备处于等待状态，等待程序的请求。待到程序的请求出现，输入设备立即进入工作，直到满足程序的这一请求为止。然后又重新处于等待状态。因此，在请求方式下，程序和输入设备轮流交换工作状态和等待状态，由程序支配输入设备的启动。<o:p></o:p></SPAN></FONT></SPAN></P>
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      lang=EN-US style="FONT-SIZE: 9pt"> 4.2.1 </SPAN><SPAN 
      style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">请求输入方式的工作过程</SPAN></P></DIV><![if !mso]></TD></TR></TBODY></TABLE><![endif]></v:textbox><w:wrap 
type = "square"></w:wrap></v:shape><![endif]--><![if !vml]><img width=218 height=61 src="les422.files/image003.gif" align=left hspace=12 alt="文本框: 图 4.2.1 请求输入方式的工作过程" v:shapes="_x0000_s1026"><![endif]></FONT></P>
<P class=MsoNormal><SPAN style="mso-spacerun: yes"><FONT face=楷体_GB2312 
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