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<html><head><meta HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=gb2312"><meta NAME="GENERATOR" CONTENT="Microsoft FrontPage 3.0"><meta NAME="doccomm" CONTENT="sss"><meta NAME="Template" CONTENT="C:\MSOffice\Template\Sl_BOOK.dot"><meta NAME="Author" CONTENT="Cheng Jinxing"><title>Visual C++编程技巧之七</title></head><body TEXT="#000000" BGCOLOR="#CCFFFF" LINK="#0000EE" VLINK="#551A8B" ALINK="#FF0000"><p align="center"><br><font SIZE="+3" FACE="楷体_GB2312">Visual C++编程技巧之七</font> </p><p><a HREF="#tip49"><font SIZE="+0" FACE="Times New Roman">49</font><font SIZE="+0">、如何实现一个橡皮区矩形</font></a> </p><p><a HREF="#tip50"><font SIZE="+0" FACE="Times New Roman">50</font><font SIZE="+0">、如何更新翻转背景颜色的文本</font></a> </p><p><a HREF="#tip51"><font SIZE="+0" FACE="Times New Roman">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="#tip52"><font SIZE="+0" FACE="Times New Roman">52</font><font SIZE="+0">、如何计算一个串的大小</font></a> </p><p><a HREF="#tip53"><font SIZE="+0" FACE="Times New Roman">53</font><font SIZE="+0">、如何显示旋转文本</font></a> </p><p><font FACE="宋体"><a HREF="#tip54">54、如何正确显示包含标签字符的串</a></font> </p><p><a HREF="#tip55"><font SIZE="+0" FACE="Times New Roman">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="#tip56"><font SIZE="+0" FACE="Times New Roman">56</font><font SIZE="+0">、如何快速地格式化一个</font><fontSIZE="+0" FACE="Times New Roman">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><fontFACE="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<fontFACE="Times New Roman">CRectTracker:: TrackRubberBand</font>响应<fontFACE="Times New Roman">WM_LBUTTONDOWN</font>消息来创建一个橡皮区矩形。下例表明使用<fontFACE="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 SIZE="+0" FACE="Times New Roman">class CSampleView : Public CView</font> </p><p><font SIZE="+0" FACE="Times New Roman">{</font> </p><p><font SIZE="+0">…</font> </p><p><font SIZE="+0" FACE="Times New Roman">public :</font> </p><p><font SIZE="+0" FACE="Times New Roman">CrectTracker m_tracker;</font> </p><p><font SIZE="+0">…</font> </p><p><font SIZE="+0" FACE="Times New Roman">};</font> </p><p><font SIZE="+0">其次，在文档类的构造函数中初始化<fontFACE="Times New Roman">CRectTracker </font>对象：</font> </p><p><font SIZE="+0" FACE="Times New Roman">CSampleDoc:: CSampleDOC ()</font> </p><p><font SIZE="+0" FACE="Times New Roman">{</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Initialize tracker position, size and style.</font> </p><p><font SIZE="+0" FACE="Times New Roman">m_tracker.m_rect.SetRect (0, 0, 10, 10);</font> </p><p><font SIZE="+0" FACE="Times New Roman">m_tracker.m_nStyle=CRectTracker:: resizeInside |</font> </p><p><font SIZE="+0" FACE="Times New Roman">CRectTracker:: dottedLine;</font> </p><p><font SIZE="+0" FACE="Times New Roman">}</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 SIZE="+0" FACE="Times New Roman">void CSampleView:: OnDraw (CDC* pDC)</font> </p><p><font SIZE="+0" FACE="Times New Roman">{</font> </p><p><font SIZE="+0" FACE="Times New Roman">CSampleDoc* pDoc=GetDocument ();</font> </p><p><font SIZE="+0" FACE="Times New Roman">ASSERT_VALID (pDoc);</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Select blue brush into device context.</font> </p><p><font SIZE="+0" FACE="Times New Roman">CBrush brush (RGB (0, 0, 255));</font> </p><p><font SIZE="+0" FACE="Times New Roman">CBrush* pOldBrush=pDC->SelectObject (&brush);</font> </p><p><font SIZE="+0" FACE="Times New Roman">//draw ellipse in tracking rectangle.</font> </p><p><font SIZE="+0" FACE="Times New Roman">Crect rcEllipse;</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDoc->m_tracker.GetTrueRect (rcEllipse);</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDC->Ellipse (rcEllipse);</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Draw tracking rectangle.</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDoc->m_tracker.Draw (pDC);</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Select blue brush out of device context.</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDC->Selectobject (pOldBrush);</font> </p><p><font SIZE="+0" FACE="Times New Roman">}</font> </p><p><font SIZE="+0">最后，使用<font FACE="Times New Roman">ClassWizard</font>处理<fontFACE="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 SIZE="+0" FACE="Times New Roman">void CSampleView::OnLButtonDown (UINT nFlags, CPoint point)</font> </p><p><font SIZE="+0" FACE="Times New Roman">{</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Get pointer to document.</font> </p><p><font SIZE="+0" FACE="Times New Roman">CSampleDoc* pDoc=GetDocument ();</font> </p><p><font SIZE="+0" FACE="Times New Roman">ASSERT_VALID (pDoc);</font> </p><p><font SIZE="+0" FACE="Times New Roman">//If clicked on ellipse, drag or resize it. Otherwise create a</font> </p><p><font SIZE="+0" FACE="Times New Roman">//rubber-band rectangle nd create a new ellipse.</font> </p><p><font SIZE="+0" FACE="Times New Roman">BOOL bResult=pDoc->m_tracker.HitTest (point)!=</font> </p><p><font SIZE="+0" FACE="Times New Roman">CRectTracker::hitNothing;</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Tracker rectangle changed so update views.</font> </p><p><font SIZE="+0" FACE="Times New Roman">if (bResult)</font> </p><p><font SIZE="+0" FACE="Times New Roman">{</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDoc->m_tracker.Track (this,point,TRue);</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDoc->SetModifiedFlag ();</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDoc->UpdateAllViews (NULL);</font> </p><p><font SIZE="+0" FACE="Times New Roman">}</font> </p><p><font SIZE="+0" FACE="Times New Roman">else</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDoc->m-tracker.TrackRubberBand (this,point,TRUE);</font> </p><p><font SIZE="+0" FACE="Times New Roman">CView:: onLButtonDown (nFlags,point);</font> </p><p><font SIZE="+0" FACE="Times New Roman">}</font> </p><p><a NAME="tip50"></a><b><font SIZE="+2"><font FACE="Times New Roman">50</font><fontFACE="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<fontFACE="Times New Roman">OPAQUE</font>用当前的背景颜色填充背景，或者调用<fontFACE="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<fontFACE="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 SIZE="+0" FACE="Times New Roman">void CSampleView:: OnDraw (CDC* pDC)</font> </p><p><font SIZE="+0" FACE="Times New Roman">{</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Determint size of view.</font> </p><p><font SIZE="+0" FACE="Times New Roman">CRect rcView;</font> </p><p><font SIZE="+0" FACE="Times New Roman">GetClientRect (rcVieew);</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Create sample string to display.</font> </p><p><font SIZE="+0"><font FACE="Times New Roman">CString str (_T ("Awesome Shadow Text</font>．．．<fontFACE="Times New Roman">"));</font></font> </p><p><font SIZE="+0" FACE="Times New Roman">//Set the background mode to transparent.</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDC->SetBKMode (TRANSPARENT);</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Draw black shadow text.</font> </p><p><font SIZE="+0" FACE="Times New Roman">rcView.OffsetRect (1, 1);</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDc->SetTextColor (RGB (0, 0, 0));</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDC->DrawText (str, str.GetLength (), rcView,</font> </p><p><font SIZE="+0" FACE="Times New Roman">DT_SINGLELINE | DT_CENTER | DT_VCENTER);</font> </p><p><font SIZE="+0" FACE="Times New Roman">//Draw red text.</font> </p><p><font SIZE="+0" FACE="Times New Roman">rcView.OffsetRect (-1,-1);</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDc->SetTextColor (RGB (255, 0, 0));</font> </p><p><font SIZE="+0" FACE="Times New Roman">pDC->DrawText (str, str.GetLength (), rcView,</font> </p><p><font SIZE="+0" FACE="Times New Roman">DT_SINGLELINE | DT_CENTER | DT_VCENTER);</font> </p><p><font SIZE="+0" FACE="Times New Roman">}</font> </p><p><a NAME="tip51"></a><b><font SIZE="+2"><font FACE="Times New Roman">51</font><fontFACE="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 SIZE="+0" FACE="Times New Roman">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<fontFACE="Times New Roman">Apial</font>字体：</font> </p><p><font SIZE="+0" FACE="Times New Roman">CClientDC dc (AqfxGetMainWnd ());</font> </p><p><font SIZE="+0" FACE="Times New Roman">m_font. CreateFont (MulDiv (8, -dc.GetDeviceCaps (LOGPIXELSY),</font> </p><p><font SIZE="+0" FACE="Times New Roman">72),0,0,0,FW_NORMAL,0,0,0,ANSI_CHARSET,</font> </p><p><font SIZE="+0" FACE="Times New Roman">OUT_STROKE_PRECIS,CLIP_STROKE_PRECIS,DRAFT_QUALITY,</font> </p>⌨️ 快捷键说明
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