As you hint, you should periodically compile the font file. (“Compile” is the term used by Visual TrueType Talk, and “assemble” is the equivalent term for TrueType. For simplicity, this discussion uses “compile” except when specific to a command name.)
Compiling the main window tells Visual TrueType to (1) update the font information with all the hinting done since you last compiled and (2) update the on-screen glyph to reflect those changes. Compiling a font actually involves compiling various data tables in this order:
1. Control Program. This generates the font’s ‘cvt’ table and part of the ‘prep’ table.
2. Font program table (‘fpgm’).
3. Pre-program. This appends to code to the ‘prep’ table generated in step 1.
4. VTT Talk, which creates source code using values from the ‘cvt,’ ‘fpgm,’ and ‘prep’ tables.
5. Glyph instructions, which Visual TrueType creates from the VTT Talk source code.
While working on the glyph, you can choose a single command, described below, which executes Steps 4 and 5. It also updates the main window so your glyph shows the results of all hinting applied since you last compiled. Note that if you have set the option “Auto-compile main view” in the general options dialog (see above), then Visual TrueType will automatically execute Steps 4 and 5 each time you edit visual hints.
When you go to another glyph, Visual TrueType checks the glyph you’re leaving. If you’ve added but not compiled any links or interpolations, Visual TrueType will automatically compile your latest changes to VTT Talk and private tables (the equivalent of Steps 4 and 5). This assures that you won’t lose those hints. (Note that this does not save the changes to the file. To save changes, select Save from the File menu, or type Ctrl + S).
After entering values in the ‘cvt’ table, you should select the Control Values window and compile it with the Compile / Active Window command or type Ctrl + R. Then, save the file by selecting Save from the File menu, or typing Ctrl + R). Unless you’re an advanced user and made changes to the ‘fpgm’ and ‘prep’ tables, you don’t need to compile them.
But if you want to make sure you’ve done all the necessary compiling or if you’re an advanced user who’s modified the ‘fpgm’ and ‘prep’ tables, you can compile the entire font (Steps 1 - 3). To simplify that process, Visual TrueType provides a single command: Compile Everything. The command does Steps 1 through 3, then compiles the VTT Talk of the current glyph and the TrueType source (‘glyf’ program). Because it is a flexible tool, Visual TrueType also provides individual commands you can choose to compile in the sequence specified above.
Note Advanced users can open the VTT Talk window and enter VTT Talk commands there. If the VTT Talk contains a command that cannot be displayed visually (for example, a function call), Visual TrueType will update the on-screen glyph, reflecting the combined effects of all the function calls the advanced user may have entered. However, Visual TrueType won’t display a graphical representation of the function calls, and all tools from the Angle tool through the Delta tool will be disabled. This assures that compiling does not negate the text-based hinting.
Compiling is not the same as saving your changes to disk. You must still use the Save or Save As command on the File menu to update the disk version of the font (see “Saving the Font File” in this chapter).
To compile the current glyph
1. Select the Tools menu.
2. On the Compiler submenu, click Active Window (Ctrl + R).
OR
1. On the Compiler menu, click Compile VTT Talk.
2. On the Compiler menu, click Assemble Glyph Instructions.
OR
1. Go to another glyph.
To compile an individual table used by Visual TrueType
1. On the Compiler menu, click Assemble Pre-Program, Assemble Font Program, or Compile Control Value Table.
To compile the entire font
1. On the Compiler menu, click Compile Everything.
2. On the Compiler menu, click Compile VTT Talk of All Glyphs.
3. On the Compiler menu, click Assemble All Glyph Instructions.