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Enumerating the Installed Fonts

In some instances, an application must be able to enumerate the available fonts and select the one most appropriate for a particular operation. An application can enumerate the available fonts by calling the EnumFonts or EnumFontFamilies function. These functions send information about the available fonts to a callback function that the application supplies. The callback function receives information in LOGFONT and NEWTEXTMETRIC structures. (The NEWTEXTMETRIC structure contains information about a TrueType font. When the callback function receives information about a non-TrueType font, the information is contained in a TEXTMETRIC structure.) By using this information, an application can limit the user's choices to only those fonts that are available.

The EnumFontFamilies function is similar to the EnumFonts function but includes some extra functionality. EnumFontFamilies allows an application to take advantage of styles available with TrueType fonts. New and upgraded applications should use EnumFontFamilies instead of EnumFonts.

TrueType fonts are organized around a typeface name (for example, Courier New) and style names (for example, italic, bold, and extra-bold). The EnumFontFamilies function enumerates all the styles associated with a specified family name, not simply the bold and italic attributes. For example, when the system includes a TrueType font called Courier New Extra-Bold, EnumFontFamilies lists it with the other Courier New fonts. The capabilities of EnumFontFamilies are helpful for fonts with many or unusual styles and for fonts that cross international borders.

If an application does not supply a typeface name, the EnumFonts and EnumFontFamilies functions supply information about one font in each available family. To enumerate all the fonts in a device context, the application can specify NULL for the typeface name, compile a list of the available typefaces, and then enumerate each font in each typeface.

The following example uses the EnumFontFamilies function to retrieve the number of available raster, vector, and TrueType font families.



    UINT uAlignPrev; 
    int aFontCount[] = { 0, 0, 0 }; 
    char szCount[8];
        HRESULT hr;
        size_t * pcch; 
 
    EnumFontFamilies(hdc, (LPCTSTR) NULL, 
        (FONTENUMPROC) EnumFamCallBack, (LPARAM) aFontCount); 
 
    uAlignPrev = SetTextAlign(hdc, TA_UPDATECP); 
 
    MoveToEx(hdc, 10, 50, (LPPOINT)NULL); 
    TextOut(hdc, 0, 0, "Number of raster fonts: ", 24); 
    itoa(aFontCount[0], szCount, 10); 
        
        hr = StringCchLength(szCount, 9, pcch);
        if (FAILED(hr))
        {
        // TODO: write error handler 
        }
    TextOut(hdc, 0, 0, szCount, *pcch); 
 
    MoveToEx(hdc, 10, 75, (LPPOINT)NULL); 
    TextOut(hdc, 0, 0, "Number of vector fonts: ", 24); 
    itoa(aFontCount[1], szCount, 10);
        hr = StringCchLength(szCount, 9, pcch);
        if (FAILED(hr))
        {
        // TODO: write error handler 
        } 
    TextOut(hdc, 0, 0, szCount, *pcch); 
 
    MoveToEx(hdc, 10, 100, (LPPOINT)NULL); 
    TextOut(hdc, 0, 0, "Number of TrueType fonts: ", 26); 
    itoa(aFontCount[2], szCount, 10);
        hr = StringCchLength(szCount, 9, pcch);
        if (FAILED(hr))
        {
        // TODO: write error handler 
        }
    TextOut(hdc, 0, 0, szCount, *pcch); 
 
    SetTextAlign(hdc, uAlignPrev); 
 
BOOL CALLBACK EnumFamCallBack(LPLOGFONT lplf, LPNEWTEXTMETRIC lpntm, DWORD FontType, LPVOID aFontCount) 
{ 
    int far * aiFontCount = (int far *) aFontCount; 
 
    // Record the number of raster, TrueType, and vector  
    // fonts in the font-count array.  
 
    if (FontType & RASTER_FONTTYPE) 
        aiFontCount[0]++; 
    else if (FontType & TRUETYPE_FONTTYPE) 
        aiFontCount[2]++; 
    else 
        aiFontCount[1]++; 
 
    if (aiFontCount[0] || aiFontCount[1] || aiFontCount[2]) 
        return TRUE; 
    else 
        return FALSE; 
 
    UNREFERENCED_PARAMETER( lplf ); 
    UNREFERENCED_PARAMETER( lpntm ); 
} 


This example uses two masks, RASTER_FONTTYPE and TRUETYPE_FONTTYPE, to determine the type of font being enumerated. If the RASTER_FONTTYPE bit is set, the font is a raster font. If the TRUETYPE_FONTTYPE bit is set, the font is a TrueType font. If neither bit is set, the font is a vector font. A third mask, DEVICE_FONTTYPE, is set when a device (for example, a laser printer) supports downloading TrueType fonts; it is zero if the device is a display adapter, dot-matrix printer, or other raster device. An application can also use the DEVICE_FONTTYPE mask to distinguish GDI-supplied raster fonts from device-supplied fonts. The system can simulate bold, italic, underline, and strikeout attributes for GDI-supplied raster fonts, but not for device-supplied fonts.

An application can also check bits 1 and 2 in the tmPitchAndFamily member of the NEWTEXTMETRIC structure to identify a TrueType font. If bit 1 is 0 and bit 2 is 1, the font is a TrueType font.

Vector fonts are categorized as OEM_CHARSET instead of ANSI_CHARSET. Some applications identify vector fonts by using this information, checking the tmCharSet member of the NEWTEXTMETRIC structure. This categorization usually prevents the font mapper from choosing vector fonts unless they are specifically requested. (Most applications no longer use vector fonts because their strokes are single lines and they take longer to draw than TrueType fonts, which offer many of the same scaling and rotation features that required vector fonts.)

 

 

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