在文本中顯示上下標

 【轉】在文本中顯示上下標

摘自：http://www.codeproject.com/useritems/SSTextOut.asp

Using subscripts and superscripts when showing text in the device context

By Victor Ricklefs.

• Download demo project - 36 Kb

Introduction

Recently I have been searching Code Project on how to show subscripts and superscripts in the device context (when using TextOut or ExtTextOut functions). But I could not find anything. So finally I decided to write the function myself.

Features and how to use

My function SSTextOut has the similar functionality to ExtTextOut. You need to specify the pointer to the device context, the pointer to bounding rectangle, the string itself, and the justification mode.

The string should contain special formatting codes - "^" for superscript and "_" for subscript. The next symbol after "^" or "_" wil be shown as subscript or superscript. If you need to show ^ or _ themselves - just type them twice - "^^" or "__".

Justification can be DT_CENTER, DT_LEFT, or DT_RIGHT. It affects only horizontal justification. Vertically, the text will be centered in the bounding rectangle automatically. The text outside the rectangle is clipped. The function uses the current font of the specified device context.

So, to draw the meaningless text in the image above you need to call:

SSTextOut(pDC,"ms^2/Hz+H_2O-mc^^2__4",&rect,DT_CENTER);

Source code

Below is the source code of SSTextOut:

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void SSTextOut(CDC* pDC, CString data , CRect* drawRect, int justification)
{

 //Neccessary initializations

 pDC->SaveDC();
 
 CSize sz;
 CRect outRect(0,0,0,0);

 CFont* pFont = pDC->GetCurrentFont();
 CFont* oldFont;
 pDC->SetTextAlign(TA_BOTTOM|TA_LEFT);

 LOGFONT lf;
 pFont->GetLogFont(&lf);

 CPoint sub,sup,subofs,supofs;

 // Calculate subscript/superscript size and offsets
 sub.x=lf.lfWidth/2;
 sup.x=lf.lfWidth/2;
 sub.y=lf.lfHeight/3*2;
 sup.y=lf.lfHeight/3*2;

 subofs.x=lf.lfWidth/2;
 supofs.x=lf.lfWidth/2;
 subofs.y=lf.lfHeight/6;
 supofs.y=lf.lfHeight/3;

 lf.lfWidth=sub.x;
 lf.lfHeight=sub.y;
 CFont SubFont;
 SubFont.CreateFontIndirect(&lf);
 
 lf.lfWidth=sup.x;
 lf.lfHeight=sup.y;
 CFont SupFont;
 SupFont.CreateFontIndirect(&lf);
 
 CString temp = data;
 TCHAR c;
 
 // Calculate the size of the text that needs to be displayed

 do
 {
  int x=0;
  CString s = "";
  c=' ';
  bool bFind=true;

  // Find the first "^" or "_", indicating the sub- or superscript
  while (bFind)
  {
   x=data.FindOneOf("^_");
   if (x==-1) 
   {
    bFind=false;
    x=data.GetLength();
   }
   else if (x==data.GetLength()-1) bFind=false;
   else if (data[x]!=data[x+1]) 
   {
    bFind=false; 
    c=data[x];
   }
   else x++;
   s=s+data.Left(x);
   data.Delete(0,min(x+1,data.GetLength()));
  }
  sz = pDC->GetTextExtent(s);
  outRect.right+=sz.cx;
  if (outRect.Height()<sz.cy) outRect.top=outRect.bottom-sz.cy;
  
  switch (c) 
  {
  case '^':
   oldFont = pDC->SelectObject(&SupFont);
   sz = pDC->GetTextExtent(data[0]);
   outRect.right+=sz.cx+supofs.x;
   data.Delete(0);
   pDC->SelectObject(oldFont);
   break;
  case '_':
   oldFont = pDC->SelectObject(&SubFont);
   sz = pDC->GetTextExtent(data[0]);
   outRect.right+=sz.cx+subofs.x;
   data.Delete(0);
   pDC->SelectObject(oldFont);
   break;
  }
 }
 while (c!=' ');
 
 // Adjust text position
 outRect.bottom+=2*subofs.y;
 outRect.top-=2*subofs.x;
 CPoint Origin;
 Origin.y = drawRect->Height()/2+outRect.Height()/2+drawRect->top;

 switch (justification)
 {
 case DT_CENTER:
  Origin.x = drawRect->Width()/2-outRect.Width()/2+drawRect->left;
  break;
 case DT_LEFT:
  Origin.x = drawRect->left;
  break;
 case DT_RIGHT:
  Origin.x = drawRect->right-outRect.Width();
 }

 CPoint pnt = Origin;

 data = temp;

 // Draw text
 do
 {
  int x=0;
  CString s = "";
  c=' ';
  bool bFind=true;

  // Find the first "^" or "_", indicating the sub- or superscript

  while (bFind)
  {
   x=data.FindOneOf("^_");
   if (x==-1) 
   {
    bFind=false;
    x=data.GetLength();
   }
   else if (x==data.GetLength()-1) bFind=false;
   else if (data[x]!=data[x+1]) 
   {
    bFind=false; 
    c=data[x];
   }
   else x++;
   s=s+data.Left(x);
   data.Delete(0,min(x+1,data.GetLength()));
  }
  // Draw main text
  pDC->ExtTextOut(pnt.x,pnt.y,ETO_CLIPPED,drawRect,s,NULL);
  sz = pDC->GetTextExtent(s);
  pnt.x+=sz.cx;
  
  // Draw subscript or superscript
  switch (c) 
  {
  case '^':
   oldFont = pDC->SelectObject(&SupFont);
   pDC->ExtTextOut(pnt.x+supofs.x,pnt.y-supofs.y,ETO_CLIPPED,drawRect,data[0],NULL);
   sz = pDC->GetTextExtent(data[0]);
   pnt.x+=sz.cx+supofs.x;
   data.Delete(0);
   pDC->SelectObject(oldFont);
   break;
  case '_':
   oldFont = pDC->SelectObject(&SubFont);
   pDC->ExtTextOut(pnt.x+subofs.x,pnt.y+subofs.y,ETO_CLIPPED,drawRect,data[0],NULL);
   sz = pDC->GetTextExtent(data[0]);
   pnt.x+=sz.cx+supofs.x;
   data.Delete(0);
   pDC->SelectObject(oldFont);
   break;
  }
 }
 while (c!=' ');

 // Done, restoring the device context
 pDC->RestoreDC(-1);

}