XMonoFontDialog - Customizing CFontDialog Part II: Selecting Monospaced Fonts

• Download demo project - 59 Kb

Introduction

When I took a closer look, I realized that Visual Studio relies on information stored in the font file at the time the font is created, concerning whether the font is monospaced. Programmatically, you can check if font is monospaced (fixed pitch, aka fixed width) by testing the flag bit TMPF_FIXED_PITCH that is returned in TEXTMETRIC structure member tmPitchAndFamily. However, there is no requirement that the font must be marked as being monospaced, and Visual Studio incorrectly reports the pitch of some fonts:

Since information in font file is not reliable, how can you be certain that a font is monospaced? After researching font file data structures, I came to conclusion that there is only one reliable method: to compare width of uppercase 'W' with width of '!' character. In normal fonts, these will always be different, but in monospaced fonts, they will always be same (obviously, other character pairs would also work, but these are what I chose).

Demo Application

This is what XMonoFontDialog looks like:

Both the blue MONOSPACED label and the use of bold typeface for monospaced fonts can be controlled programmatically.

I took demo app from my XFontDialog article and modified it to allow for additional features:

XMonoFontDialog Features

	Similar to standard CFontDialog but with only font list, font sizes, and sample text controls.
	Same basic APIs as CFontDialog
	Font filters to select specific groups of fonts to display
	Optional visual indication of monospaced fonts (blue MONOSPACED label)
	Optional use of bold typeface for monospaced fonts in combobox list
	APIs to check if selected font is monospaced, symbol, OpenType, or TrueType
	API to set caption of font dialog
	API to set sample text of font dialog
	More detailed information returned about selected font

Implementation Notes

typedef struct tagNEWTEXTMETRIC { 
    LONG   tmHeight; 
    LONG   tmAscent; 
    LONG   tmDescent; 
    LONG   tmInternalLeading; 
    LONG   tmExternalLeading; 
    LONG   tmAveCharWidth; 
    LONG   tmMaxCharWidth; 
    LONG   tmWeight; 
    LONG   tmOverhang; 
    LONG   tmDigitizedAspectX; 
    LONG   tmDigitizedAspectY; 
    TCHAR  tmFirstChar; 
    TCHAR  tmLastChar; 
    TCHAR  tmDefaultChar; 
    TCHAR  tmBreakChar; 
    BYTE   tmItalic; 
    BYTE   tmUnderlined; 
    BYTE   tmStruckOut; 
    BYTE   tmPitchAndFamily; 
    BYTE   tmCharSet; 
    DWORD  ntmFlags;
    UINT   ntmSizeEM; 
    UINT   ntmCellHeight; 
    UINT   ntmAvgWidth; 
} NEWTEXTMETRIC, *PNEWTEXTMETRIC;

As it turned out, there were other good reasons to abandon the custom template approach. Since I was going to be doing all the drawing for the font combobox, I needed to know not just whether a font was monospaced, but also whether it was TrueType, OpenType, or something else, so I could draw the correct glyph for the font type. In another article, I looked up the font in the registry, found the filepath for the font file, opened the font file, and looked for certain tables in the file, to determine if the font was TrueType or OpenType. I discovered that all of this would be unnecessary as soon as I started to write the code to fill the combobox with font names.

The standard way to get the list of fonts installed on a system is to use the Win32 EnumFonts function. The callback function provides you with a LOGFONT struct and a TEXTMETRIC struct, which give you all the standard font information. However, neither of these structs tell you anything about whether the font is TrueType or OpenType. The good news is that there is another API: EnumFontFamiliesEx(), which tells you everything you want to know about a font. The callback function returns a NEWTEXTMETRIC struct, which is a superset of the TEXTMETRIC struct, and which is only returned via the EnumFontFamiliesEx() callback function - there is no other way to obtain it, as far as I can determine. Its ntmFlags member contains flags that specify whether the font is OpenType, and you can use that in combination with other information returned via the callback function to determine exactly what type of font it is. This is a major improvement over scanning font files. Now I knew whether a font was OpenType, TrueType, or something else, and I could compare two character widths (as I described above) to see if the font was monospaced.

The only remaining thing I needed was the TrueType () and OpenType () glyphs. In another article I loaded these glyphs from bitmap resources, but this time I knew a secret: the glyphs could be dynamically extracted from bitmap resource #38 in COMDLG32.DLL:

So this is what I did, and set up a CImageList so the glyphs can be drawn directly in the combobox list.

When a font is selected in the font combobox, a selection message gets sent to the parent dialog, which then enumerates the sizes for that font, and fills the size combobox. (This enumeration only happens for fonts that are not TrueType, OpenType, or vector; for these three font types, a "standard" set of 16 sizes is used, ranging from 8 to 72 points.)

How To Use

To integrate CXMonoFontDialog into your app, you first need to add following files to your project:

• XMonoFontDialog.cpp
• XMonoFontDialog.h
• XFontSize.cpp
• XFontSize.h
• XMonoFontListCombo.cpp
• XMonoFontListCombo.h
• XMonoFontListComboEdit.cpp
• XMonoFontListComboEdit.h
• XMonoFontDialog.rc
• XMonoFontDialogRes.h

You also need to add XMonoFontDialog.rc to project rc file - go to View | Resource Includes... and in the bottom listbox, scroll down to the end. Insert #include "XMonoFontDialog.rc" right before the #endif:

Next, include header file XMonoFontDialog.h in appropriate project files. Now you are ready to start using CXMonoFontDialog. The file XMonoFontDialogTestDlg.cpp gives an example:

CXMonoFontDialog dlg(&lf);
dlg.SetFontFilter(dwFonts)
   .SetCaption(_T("XMonoFontDialog"))
   .SetSampleText(m_strSampleText)
   .ShowMonospacedLabel(m_bShowMonospacedLabel)
   .ShowMonospacedAsBold(m_bShowMonospacedAsBold);

if (dlg.DoModal() == IDOK)
.
.
.

Revision History

Version 1.1 - 2008 October 29

• Fixed problem with small point sizes.

Version 1.0 - 2008 October 23

• Initial public release.

Usage

This software is released into the public domain. You are free to use it in any way you like, except that you may not sell this source code. If you modify it or extend it, please to consider posting new code here for everyone to share. This software is provided "as is" with no expressed or implied warranty. I accept no liability for any damage or loss of business that this software may cause.