Advanced MFC Programming

Chapter 9. Font
9.2 Enumerating Fonts in the System
Font Types
There are three type of fonts in Windows system: raster font, vector font and True Type font. The
difference among them is how the character glyph is stored for each type of fonts. For raster fonts, the
glyph is simply a bitmap; for vector fonts, the glyph is a collection of end points that define the line
segments; for true type fonts, the glyph is a collection of line and curve commands. The raster fonts can not
be drawn in a scaled size, they are device dependent (the size of the output depends on the resolution of the
device). The vector fonts and true Type Fonts are device independent because they are scalable, however,
drawing True Type fonts is faster than drawing vector fonts. This is because the glyph of True Type fonts
contains commands and hints.
Enumerating Font Family
We can find out all the font families installed in a system by calling API function
::EnumFontFamilies(…), which has the following format:
int EnumFontFamilies
(
HDC hdc, LPCTSTR lpszFamily, FONTENUMPROC lpEnumFontFamProc, LPARAM lParam
);
The first parameter hdc is the handle to a device context, which can be obtained from any window.
The second parameter lpszFamily specifies the font family name that will be enumerated, it could be
any of “Decorative”, “Dontcare”, “Modern”, “Roman”, “Script” and “Swiss”. To enumerate all fonts in the
system, we just need to pass NULL to it.
The third parameter is a pointer to callback function, which will be used to implement the actual
enumeration. This function must be provided by the programmer.
The final parameter lParam is a user-defined parameter that allows us to send information to the
callback function.
The callback function must have the following format:
int CALLBACK EnumFontFamProc
(
ENUMLOGFONT FAR *lpelf, NEWTEXTMETRIC FAR *lpntm, int FontType, LPARAM lParam
);
Each time a new font family is enumerated, this function is called by the system. So the function will
be called for all the available font types (e.g. if there are three types of fonts in the system, this funciton
will be called three times by the system). The font’s information is stored in an ENUMLOGFONT type object
that is pointed by lpelf, and the font type is specified by FontType parameter. We can check
RASTER_FONTTYPE or TRUETYPE_FONTTYPE bit of FontType to judge if the font is a raster font or a true type
font. The final parameter lParam will be used to store the information that is passed through the user
defined parameter (lParam in the function ::EnumFontFamilies(…)).
Sample 9.2\GDI demonstrates how to enumerate all the valid fonts in the system. It is a standard SDI
application generated by Application Wizard. The application will display all the available fonts in the
client window after it is executed. Because there are many types of fonts, the view class of this application
is derived from CScrollView (This can be set in the final step of Application Wizard).
First, an int type array is declared in class CGDIView:
……
class CGDIView : public CScrollView
{
protected:
int m_nFontCount[3];
}
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