book_text7.htm

深入编程内幕vc++ 非常适合处学者学习

            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">总而言之，进行屏幕输出的规则如下：</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">第一 
            必须通过</SPAN><SPAN lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CDC</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">对象进行屏幕输出；</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">第二</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"> </SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">设置<SPAN 
            lang=EN-US>DC对象的输出属性；</SPAN></SPAN><SPAN lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">第三</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"> </SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">选择绘图工具</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">第四 
            用</SPAN><SPAN lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CDC</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">对象的绘图函数。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; TEXT-INDENT: 20pt; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">有关屏幕输出的内容就介绍到这里。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <H3 style="mso-line-height-alt: 1.3pt"><A name=_Toc419881636><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 15pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: Times New Roman; mso-bookmark: _Toc419740454">2．4 
            有关屏幕映射方式</SPAN></A><SPAN lang=EN-US 
            style="FONT-SIZE: 15pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'"><O:P> 
            </O:P></SPAN></H3>
            <P class=MsoBodyTextIndent3 
            style="WORD-BREAK: normal; TEXT-AUTOSPACE: ideograph-numeric; mso-line-height-alt: 1.3pt; punctuation-wrap: hanging"><SPAN 
            style="mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">在一般的情况之下，我们都以像素作为绘图的单位，我们称之为设备坐标。我们在进行绘图操作的时候，不可避免的要用到设备坐标系。</SPAN><SPAN 
            lang=EN-US style="FONT-FAMILY: 'Times New Roman'"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="TEXT-INDENT: 20pt; mso-line-height-alt: 1.3pt"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">WINDOWS</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">提供了几种映射方式，或称坐标系。可以通过它们来和设备上下文相联系。比方说不管是什么样的显示设备，如果我们需要在上面显示一个</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">2</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">英寸高，</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">2</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">英寸宽的矩形，该怎样处理呢？这就要依赖于我们所设定的坐标系。如果我们指定了</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MM_TEXT 
            </SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">方式，这时坐标原点就位于屏幕的左上角，</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">X</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">轴和</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">Y</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">轴的方向分别指向我们面对屏幕的右方和下方，它的绘图单位是像素，如果一英寸对应</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">72</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">个像素的话，我们就需要这样绘制这个矩形：</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal style="mso-line-height-alt: 1.3pt"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DC.Rectangle(CRect( 
            0,0,72*2,72*2));<O:P> </O:P></SPAN></P>
            <P class=MsoNormal 
            style="TEXT-INDENT: 20pt; mso-line-height-alt: 1.3pt"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">所以我们如果我们指定了</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MM_LOENGLISH 
            </SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">方式，那么一个绘图单位就是百分之一英寸，坐标原点仍然位于屏幕的左上角，但是</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">X</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">轴和</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">Y</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">轴</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"> </SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">的方向恰好和</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MM_TEXT</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">方式下的轴方向相反，同样完成绘制上面提到的矩形的工作，我们就需要写出这样的代码：</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal style="mso-line-height-alt: 1.3pt"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DC.Rectangle(CRect(0,0,200,_200));<O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="TEXT-INDENT: 20pt; mso-line-height-alt: 1.3pt"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">可见，坐标系的选择对我们编写程序有很大的影响。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="TEXT-INDENT: 20pt; mso-line-height-alt: 1.3pt"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">此外，在有些时候，我们需要在几个不同的坐标系下面工作，那么还需要在进行在这些坐标系之间的转换工作。所以</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"> </SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">，我们有必要在这里详细介绍以下</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">WINDOWS</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">的坐标映射方法。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="TEXT-INDENT: 20pt; mso-line-height-alt: 1.3pt"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">一般来说，最常用的就是</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">WM_TEXT</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">方式。在</SPAN><SPAN