Using Subscripts and Superscripts When Showing Text in the Device Context






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Extended version of ExtTextOut supporting subscripts and superscripts

Introduction
Recently I have been searching The 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 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 _
will 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
The source code of SSTextOut
is shown below:
void SSTextOut(CDC* pDC, CString data , CRect* drawRect, int justification)
{
//Necessary 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);
}