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5 - Looking Over The Calls
The constructor and destructor are very straightforward, setting our variables and cleaning up afterwards: paLabel::paLabel(U16 uid,const char *label,const FONT *font,int width)
: CLabel(uid,"",font),
m_width(-1),
m_origText(0),
m_dispText(0),
m_font(font)
{
Width(width);
SetLabel(label);
}
paLabel::~paLabel(void)
{
delete[] m_origText;
}
Notice we only have one array to delete in
the destructor, m_origText. We actually allocate
one character array twice the length of the
original text string. Halfway into this string,
we set the pointer m_dispText. The reason
is to reduce the calls to new[]. While not
good programming practice, on a small class
like this it is a timesaving tradeoff that
can be worth the extra management.SetLabel() shows this array allocation in action, setting up enough room for two full strings, and then setting the m_dispText pointer:
void paLabel::SetLabel( const char *buff )
{
unsigned int newLen=strlen(buff)+1;
if ( NULL==m_origText || newLen>strlen(m_origText))
{
m_origText=new char[newLen+newLen+8];
m_dispText=&m_origText[newLen];
}
strcpy(m_origText,buff);
ResizeText();
}
Setting the width and the font are very similar,
in that the calls make their adjustments and then
finish up by calling ResizeText():
void paLabel::Width(int width)
{
if (width!=m_width) // changed width?
{
m_width=width;
ResizeText();
}
}
void paLabel::SetFont(const FONT *font)
{
m_font=font;
CLabel::SetFont(m_font); // change base class font as well
ResizeText();
}
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