📄 book_text7.htm
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<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'">下面介绍绘图操作的源程序使您对设备上下文的使用有一个大致的了解。</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'">首先生成一个设备上下文。</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CPaintDC</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">是</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MFC</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">提供的一个从</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'">继承出来的类。使用它有什么好处呢</SPAN><SPAN
lang=EN-US
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'">如果</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">直接使用</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: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">的话，</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">我们需要首先调用</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CWnd</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">的</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">BeginPaint</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">函数为重绘工作做一些准备工作，在完成绘制之还要用<SPAN
lang=EN-US>EndPaint函数表示结束绘制工作。所有的绘图操作都必须在这两个函数之间完成。</SPAN></SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CPaintDC</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">封装了这两个函数，自动地对它们进行调用，使用者无须再去进行这些调用。<SPAN
lang=EN-US><O:P> </O:P></SPAN></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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">CPaintDC
dc(this);<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">BITMAP
bm;<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">m_bitmap_>GetBitmap(&bm);<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black"> <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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">CDC
dcImage;<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">if
(!dcImage.CreateCompatibleDC(&dc))<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black"><SPAN
style="mso-tab-count: 1"> </SPAN>return;<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">CBitmap*
pOldBitmap = dcImage.SelectObject(m_bitmap);<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">dc.BitBlt(0,
0, bm.bmWidth, bm.bmHeight, <O:P></O:P></SPAN></P>
<P class=MsoNormal
style="MARGIN-LEFT: 2cm; WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">&dcImage,
0, 0, SRCCOPY);<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'">以上这段代码完成向屏幕上面输出位图的工作。首先根据资源生成一个位图对象，然后生成成一个和<SPAN
lang=EN-US>C</SPAN></SPAN><SPAN lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">PaintDC</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">一致的内存</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DC</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'">对象，在</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">内存</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DC</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">当中选择这个位图。<SPAN
lang=EN-US>BITMAP是一个</SPAN></SPAN><SPAN lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">WIN32</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">提供的位图结构，我们将这幅位图的信息保存在这个结构当中。这样做的原因是由于在使用到位图的位置及大小信息。<SPAN
lang=EN-US>BITMAP结构的定义如下：<O:P> </O:P></SPAN></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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">typedef
struct tagBITMAP {<SPAN style="mso-spacerun: yes"> </SPAN>/*
bm */<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black"><SPAN
style="mso-spacerun: yes"> </SPAN>int<SPAN
style="mso-spacerun: yes">
</SPAN>bmType;<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black"><SPAN
style="mso-spacerun: yes"> </SPAN>int<SPAN
style="mso-spacerun: yes">
</SPAN>bmWidth;<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black"><SPAN
style="mso-spacerun: yes"> </SPAN>int<SPAN
style="mso-spacerun: yes">
</SPAN>bmHeight;<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
lang=EN-US
style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black"><SPAN
style="mso-spacerun: yes"> </SPAN>int<SPAN
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