Part 3. Fonts Tool Box


 The Fonts toolbox (FONTB.BAS), included with this version of BASIC, contains
 a set of routines that perform font-management tasks such as registering,
 loading, selecting, and printing fonts on the screen.
 Nine font files are supplied. Courier fonts in COURA.FON, COURB.FON, and
 COURE.FON, Helvetica fonts in HELVA.FON, HELVB.FON and HELVE.FON, and Times
 Roman fonts in TMSRA.FON, TMSRB.FON and TMSRE.FON. Each of these files
 contains six font sizes. Besides these two font files, the Fonts toolbox
 will work with any standard Windows bitmap .FON file.

 To use the Fonts toolbox, you must compile and link the FONTASM.OBJ and
 FONTB.BAS modules into a .LIB or .QLB library file. Once this library
 exists, you can use it just like any other library. The Fonts toolbox can be
 used independently of the Presentation Graphics toolbox to draw graphics
 text.

 Several of the procedures use the font-header information defined in the
 user-defined type FontInfo. This type is defined in the FONTB.BI header
 file. This file also contains definitions for constants that can be used as
 arguments to the procedures described in this section. Using these constants
 in place of hand-coded numbers makes your program cleaner and easier to
 debug.



 Font Error Codes

 If an error occurs during the execution of a font function or sub procedure,
 the variable FontErr will contain a non-zero value.

 For non-BASIC errors, the error numbers can be tested using numerics or
 constants as defined in the FONTB.BI header file. The meaning of a non-BASIC
 error is shown in Table 3.9.

-----------------------------------------------------------------------------
 Number      Constant name                                    Type of error
 ----------------------------------------------------------------------------
 FontNum     The location of the font in the registered list
             or the loaded list.

 Ascent      The pixel distance from the character baseline
             to the top of the character box.

 Points      The point size of the current font as defined
             in the  LoadFont% function.

 Number      Constant name                                    Type of error
 ----------------------------------------------------------------------------
 
 PixWidth    The width of the character bitmap. A value of 0
             specifies a proportional font. A nonzero value
             specifies the pixel width of the characters in
             a fixed-space font.

 PixHeight   The height of the character bitmap.

 Leading     The number of blank lines at the top of the
             character definition to act as leading between
             lines.

 AvgWidth    The average width of characters in pixels.

 MaxWidth    The pixel width of the widest character in the
             font.

 FileName    The filename from which the font was loaded.
             The filename has the extension .FON.
 Number      Constant name                                    Type of error
 ----------------------------------------------------------------------------
             The filename has the extension .FON.

 FaceName    The name of the typeface (for example,
             Helvetica, Courier) taken from the filename.






 Note

 When using the  GetFontInfo procedure, be sure you have access to the .FON
 file on disk so that it can find the FontNum, FileName, and FaceName values
 for the currently selected font.

 For more information on the elements of the variable type FontInfo, see
 documentation on font file format in Chapter 7, "File Formats" in the
 Programmer's Reference, which is part of the Microsoft Windows Software
 Development Kit.