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<P align=center><BR><FONT face=楷体_GB2312 size=+3>Visual C++编程技巧之七</FONT> </P>
<P><A href="http://www.vchome.net/tech/vctip7.html#tip49"><FONT 
face="Times New Roman" size=+0>49</FONT><FONT size=+0>、如何实现一个橡皮区矩形</FONT></A> 
</P>
<P><A href="http://www.vchome.net/tech/vctip7.html#tip50"><FONT 
face="Times New Roman" size=+0>50</FONT><FONT size=+0>、如何更新翻转背景颜色的文本</FONT></A> 
</P>
<P><A href="http://www.vchome.net/tech/vctip7.html#tip51"><FONT 
face="Times New Roman" size=+0>51</FONT><FONT 
size=+0>、如何创建一个具有特定点大小的字体</FONT></A> </P>
<P><A href="http://www.vchome.net/tech/vctip7.html#tip52"><FONT 
face="Times New Roman" size=+0>52</FONT><FONT size=+0>、如何计算一个串的大小</FONT></A> 
</P>
<P><A href="http://www.vchome.net/tech/vctip7.html#tip53"><FONT 
face="Times New Roman" size=+0>53</FONT><FONT size=+0>、如何显示旋转文本</FONT></A> </P>
<P><FONT face=宋体><A 
href="http://www.vchome.net/tech/vctip7.html#tip54">54、如何正确显示包含标签字符的串</A></FONT> 
</P>
<P><A href="http://www.vchome.net/tech/vctip7.html#tip55"><FONT 
face="Times New Roman" size=+0>55</FONT><FONT 
size=+0>、串太长时如何在其末尾显示一个省略号</FONT></A> </P>
<P><A href="http://www.vchome.net/tech/vctip7.html#tip56"><FONT 
face="Times New Roman" size=+0>56</FONT><FONT size=+0>、如何快速地格式化一个</FONT><FONT 
face="Times New Roman" size=+0>CString</FONT><FONT size=+0>对象</FONT></A> </P>
<P><FONT size=+2><B>　</B></FONT> </P>
<P><A name=tip49></A><B><FONT size=+2><FONT 
face="Times New Roman">49</FONT><FONT face=黑体>、如何实现一个橡皮区矩形</FONT></FONT></B> 
</P>
<P><FONT size=+0><FONT 
face="Times New Roman">CRectTracker</FONT>是一个很有用的类，可以通过调用<FONT 
face="Times New Roman">CRectTracker:: TrackRubberBand</FONT>响应<FONT 
face="Times New Roman">WM_LBUTTONDOWN</FONT>消息来创建一个橡皮区矩形。下例表明使用<FONT 
face="Times New Roman">CRectTracker</FONT>移动和重置视窗中的蓝色椭圆的大小是很容易的事情。</FONT> </P>
<P><FONT size=+0>首先，在文件档中声明一个<FONT 
face="Times New Roman">CRectTracker</FONT>数据成员：</FONT> </P>
<P><FONT face="Times New Roman" size=+0>class CSampleView : Public CView</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>{</FONT> </P>
<P><FONT size=+0>…</FONT> </P>
<P><FONT face="Times New Roman" size=+0>public :</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CrectTracker m_tracker;</FONT> </P>
<P><FONT size=+0>…</FONT> </P>
<P><FONT face="Times New Roman" size=+0>};</FONT> </P>
<P><FONT size=+0>其次，在文档类的构造函数中初始化<FONT face="Times New Roman">CRectTracker 
</FONT>对象：</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CSampleDoc:: CSampleDOC ()</FONT> </P>
<P><FONT face="Times New Roman" size=+0>{</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//Initialize tracker position, size and 
style.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>m_tracker.m_rect.SetRect (0, 0, 10, 
10);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>m_tracker.m_nStyle=CRectTracker:: 
resizeInside |</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CRectTracker:: dottedLine;</FONT> </P>
<P><FONT face="Times New Roman" size=+0>}</FONT> </P>
<P><FONT size=+0>然后，在<FONT 
face="Times New Roman">OnDraw</FONT>函数中画椭圆和踪迹矩形：</FONT> </P>
<P><FONT face="Times New Roman" size=+0>void CSampleView:: OnDraw (CDC* 
pDC)</FONT> </P>
<P><FONT face="Times New Roman" size=+0>{</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CSampleDoc* pDoc=GetDocument ();</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>ASSERT_VALID (pDoc);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//Select blue brush into device 
context.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CBrush brush (RGB (0, 0, 255));</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>CBrush* pOldBrush=pDC-&gt;SelectObject 
(&amp;brush);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//draw ellipse in tracking 
rectangle.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>Crect rcEllipse;</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDoc-&gt;m_tracker.GetTrueRect 
(rcEllipse);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDC-&gt;Ellipse (rcEllipse);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//Draw tracking rectangle.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDoc-&gt;m_tracker.Draw (pDC);</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>//Select blue brush out of device 
context.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDC-&gt;Selectobject (pOldBrush);</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>}</FONT> </P>
<P><FONT size=+0>最后，使用<FONT face="Times New Roman">ClassWizard</FONT>处理<FONT 
face="Times New Roman">WM_LBUTTONDOWN</FONT>消息，并增加下述代码。该段代码根据鼠标击键情况可以拖放、移动或者重置椭圆的大小。</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>void CSampleView::OnLButtonDown (UINT 
nFlags, CPoint point)</FONT> </P>
<P><FONT face="Times New Roman" size=+0>{</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//Get pointer to document.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CSampleDoc* pDoc=GetDocument ();</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>ASSERT_VALID (pDoc);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//If clicked on ellipse, drag or resize 
it. Otherwise create a</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//rubber-band rectangle nd create a new 
ellipse.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>BOOL bResult=pDoc-&gt;m_tracker.HitTest 
(point)!=</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CRectTracker::hitNothing;</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//Tracker rectangle changed so update 
views.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>if (bResult)</FONT> </P>
<P><FONT face="Times New Roman" size=+0>{</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDoc-&gt;m_tracker.Track 
(this,point,TRue);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDoc-&gt;SetModifiedFlag ();</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDoc-&gt;UpdateAllViews (NULL);</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>}</FONT> </P>
<P><FONT face="Times New Roman" size=+0>else</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDoc-&gt;m-tracker.TrackRubberBand 
(this,point,TRUE);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CView:: onLButtonDown 
(nFlags,point);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>}</FONT> </P>
<P><A name=tip50></A><B><FONT size=+2><FONT 
face="Times New Roman">50</FONT><FONT face=黑体>、如何更新翻转背景颜色的文本</FONT></FONT></B> 
</P>
<P><FONT size=+0>调用<FONT face="Times New Roman">CDC:: SetBkmode</FONT>并传送<FONT 
face="Times New Roman">OPAQUE</FONT>用当前的背景颜色填充背景，或者调用<FONT 
face="Times New Roman">CDC::SetBkMode</FONT>并传送<FONT 
face="Times New Roman">TRANSPAARENT</FONT>使背景保持不变，这两种方法都可以设置背景模式。下例设置背景模式为<FONT 
face="Times New Roman">TRANSPARENT</FONT>，可以两次更新串，用花色带黑阴影更新文本。黑色串在红色串之后，但由于设置了背景模式仍然可见。</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>void CSampleView:: OnDraw (CDC* 
pDC)</FONT> </P>
<P><FONT face="Times New Roman" size=+0>{</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//Determint size of view.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CRect rcView;</FONT> </P>
<P><FONT face="Times New Roman" size=+0>GetClientRect (rcVieew);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//Create sample string to 
display.</FONT> </P>
<P><FONT size=+0><FONT face="Times New Roman">CString str (_T ("Awesome Shadow 
Text</FONT>．．．<FONT face="Times New Roman">"));</FONT></FONT> </P>
<P><FONT face="Times New Roman" size=+0>//Set the background mode to 
transparent.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDC-&gt;SetBKMode (TRANSPARENT);</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>//Draw black shadow text.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>rcView.OffsetRect (1, 1);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDc-&gt;SetTextColor (RGB (0, 0, 
0));</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDC-&gt;DrawText (str, str.GetLength (), 
rcView,</FONT> </P>
<P><FONT face="Times New Roman" size=+0>DT_SINGLELINE | DT_CENTER | 
DT_VCENTER);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>//Draw red text.</FONT> </P>
<P><FONT face="Times New Roman" size=+0>rcView.OffsetRect (-1,-1);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDc-&gt;SetTextColor (RGB (255, 0, 
0));</FONT> </P>
<P><FONT face="Times New Roman" size=+0>pDC-&gt;DrawText (str, str.GetLength (), 
rcView,</FONT> </P>
<P><FONT face="Times New Roman" size=+0>DT_SINGLELINE | DT_CENTER | 
DT_VCENTER);</FONT> </P>
<P><FONT face="Times New Roman" size=+0>}</FONT> </P>
<P><A name=tip51></A><B><FONT size=+2><FONT 
face="Times New Roman">51</FONT><FONT 
face=黑体>、如何创建一个具有特定点大小的字体</FONT></FONT></B> </P>
<P><FONT size=+0>可以指定字体逻辑单位的大小，但有时指定字体的点的大小可能会更方便一些。可以如下将字体的点转换为字体的高度：</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>int nHeigth=mulDiv (nPointSize, 
-dc.GetDeviceCaps (LOGPIXELSY), 72);</FONT> </P>
<P><FONT size=+0>下例创建了一个<FONT face="Times New Roman">8</FONT>点的<FONT 
face="Times New Roman">Apial</FONT>字体：</FONT> </P>
<P><FONT face="Times New Roman" size=+0>CClientDC dc (AqfxGetMainWnd ());</FONT> 
</P>
<P><FONT face="Times New Roman" size=+0>m_font. CreateFont (MulDiv (8, 
-dc.GetDeviceCaps (LOGPIXELSY),</FONT> </P>
<P><FONT face="Times New Roman" 
size=+0>72),0,0,0,FW_NORMAL,0,0,0,ANSI_CHARSET,</FONT> </P>
<P><FONT face="Times New Roman" 
size=+0>OUT_STROKE_PRECIS,CLIP_STROKE_PRECIS,DRAFT_QUALITY,</FONT> </P>
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