SysWin Fonts

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Fonts

Creates fonts, reads the fonts Windows uses and changes the font of a window or control.

A font is a GDI object, an HFONT. Every function on this page that returns one has created a new font, and that font is yours: delete it with DeleteObject once no window uses it any more. Giving a font to a window with WM_SETFONT does not hand it over; the window only borrows it, so delete it after the window has been destroyed.

Sizes come in two forms. A point size is what a user picks in a font dialog (10 pt). A logical height is what a LOGFONTW holds: a negative number of pixels for the character height, worked out from the vertical DPI of the display. A program that is not DPI aware always sees 96 DPI, so 10 pt is -13 there; at 175 % (168 DPI) a DPI-aware program gets -23.

Importing

#import "sys/win"
using win

Example

A window whose label shows which font Windows uses in message boxes, written in a bold font of its own, which is deleted once the window has closed:

#import "sys/win"
#import "sys/win/gui"
using win, gui

declare function WndProc( byval hwnd as HWND, byval uMsg as UINT, byval wParam as WPARAM, byval lParam as LPARAM ) as LRESULT

function main() as long
    SetProcessDpiAwareness( PROCESS_SYSTEM_DPI_AWARE )
    dim pWindow as CWindow = "FontDemo"
    dim hWin as HWND = pWindow.Create( NULL, "Fonts", @WndProc )
    SetWindowClientSizeForDpi( hWin, 420, 120 )
    CenterWindow( hWin )
    dim lf as LOGFONTW
    dim face as ustring = "(unknown)"
    if GetWindowsFontInfo( FONT_MESSAGE, @lf ) then face = lf.lfFaceName
    dim hLabel as HWND = pWindow.AddControl( "Label", hWin, 100, _
        "Message boxes use " & face & ", " & GetWindowsFontPointSize( FONT_MESSAGE ) & " pt", 20, 20, 380, 60 )
    dim hBold as HFONT = CreateFont( "Georgia", 14, -1, FW_BOLD )
    SendMessageW( hLabel, WM_SETFONT, cast( WPARAM, hBold ), true )
    dim result as long = pWindow.DoEvents( SW_NORMAL )
    DeleteObject( hBold )
    return result
end function

function WndProc( byval hwnd as HWND, byval uMsg as UINT, byval wParam as WPARAM, byval lParam as LPARAM ) as LRESULT
    select case uMsg
        case WM_DESTROY
            PostQuitMessage( 0 )
            return 0
    end select
    return DefWindowProcW( hwnd, uMsg, wParam, lParam )
end function

end main()

Functions

Function	Does
Font constants	The FONT_* values that pick a system font or a font setting.
GetWindowFontInfo	Returns the LOGFONTW of the font a window or control uses.
GetWindowsFontInfo	Reads the LOGFONTW of a font Windows uses: caption, menu, status bar, message box.
GetWindowsFontPointSize	Returns the point size of a font Windows uses.
GetFontPointSize	Converts a logical font height to a point size.
GetFontHeight	Converts a point size to a logical font height.
ModifyFontFaceName	Gives a window a copy of its font with another typeface.
ModifyFontSettings	Gives a window a copy of its font with one setting changed.
ModifyFontHeight	Gives a window a copy of its font, scaled by a percentage.
CreateFont	Creates a font from a typeface name and a point size.

Reference

Font constants

enum
   FONT_CAPTION = 1
   FONT_SMALLCAPTION
   FONT_MENU
   FONT_STATUS
   FONT_MESSAGE
   FONT_HEIGHT
   FONT_WEIGHT
   FONT_ITALIC
   FONT_UNDERLINE
   FONT_STRIKEOUT
   FONT_CHARSET
end enum

The first five name the fonts Windows draws its own parts with, for GetWindowsFontInfo and GetWindowsFontPointSize; the other six name the setting ModifyFontSettings changes.

Constant	Value	Means
FONT_CAPTION	1	the title bar font
FONT_SMALLCAPTION	2	the font of small (tool window) title bars
FONT_MENU	3	the menu bar font
FONT_STATUS	4	the font of status bars and tooltips
FONT_MESSAGE	5	the message box font
FONT_HEIGHT	6	the size, as a percentage
FONT_WEIGHT	7	the weight, 0 to 1000
FONT_ITALIC	8	italic on or off
FONT_UNDERLINE	9	underline on or off
FONT_STRIKEOUT	10	strikeout on or off
FONT_CHARSET	11	the character set

Example

print "status bar font:"; GetWindowsFontPointSize( FONT_STATUS ); " pt"

GetWindowFontInfo

function GetWindowFontInfo( byval hWin as HWND ) as LOGFONTW

Asks a window or control for its font (WM_GETFONT) and returns that font's description. A window that has never been given a font draws with the system font and answers NULL; the LOGFONTW that comes back is then all zeros.

Parameter	Meaning
hWin	The window or control.

Returns the LOGFONTW; lfHeight is 0 when the window has no font of its own.

Example

dim lf as LOGFONTW = GetWindowFontInfo( hCtrl )
dim face as ustring = lf.lfFaceName
print face; ","; GetFontPointSize( lf.lfHeight ); " pt"

Microsoft Learn: WM_GETFONT

GetWindowsFontInfo

function GetWindowsFontInfo( byval nType as long, byval plfw as LOGFONTW ptr ) as boolean

Reads the description of one of the fonts Windows uses for its non-client parts from the user's current settings. Use it to give your own controls the font the user sees in message boxes, or to match a status bar.

Parameter	Meaning
nType	FONT_CAPTION, FONT_SMALLCAPTION, FONT_MENU, FONT_STATUS or FONT_MESSAGE.
plfw	The LOGFONTW to fill.

Returns true on success. false when plfw is NULL, when nType is not one of the five values above, or when Windows could not be asked; in the last case GetLastError() says why.

Example

dim lf as LOGFONTW
if GetWindowsFontInfo( FONT_MESSAGE, @lf ) then
    dim hMsgFont as HFONT = CreateFontIndirectW( @lf )   ' delete it with DeleteObject
end if

Microsoft Learn: NONCLIENTMETRICSW

GetWindowsFontPointSize

function GetWindowsFontPointSize( byval nType as long ) as long

Returns the point size of one of the fonts Windows uses, worked out from its logical height and the DPI of the display. On a Windows 11 machine with default settings, FONT_MESSAGE and FONT_CAPTION both answer 9.

Parameter	Meaning
nType	FONT_CAPTION, FONT_SMALLCAPTION, FONT_MENU, FONT_STATUS or FONT_MESSAGE.

Returns the point size, rounded to a whole point; 0 for any other nType or on failure.

Example

print "menu font:"; GetWindowsFontPointSize( FONT_MENU ); " pt"

GetFontPointSize

function GetFontPointSize( byval nHeight as long ) as long

Converts a logical font height, such as lfHeight of a LOGFONTW, to a point size, using the vertical DPI of the display. The sign of nHeight does not matter. At 96 DPI, -13 gives 10 and -20 gives 15.

Returns the point size, rounded to a whole point, or 0 when the display cannot be queried.

Example

print GetFontPointSize( -13 )   ' 10 at 96 DPI

Microsoft Learn: MulDiv

GetFontHeight

function GetFontHeight( byval nPointSize as long ) as long

Converts a point size to the logical height a LOGFONTW wants: minus the number of pixels the characters are high on the display. At 96 DPI 10 pt gives -13 and 9 pt gives -12; a DPI-aware program at 175 % gets -23 and -21.

Returns the logical height (negative), or 0 when the display cannot be queried.

Example

dim lf as LOGFONTW
lf.lfHeight = GetFontHeight( 11 )
lf.lfFaceName = "Segoe UI"
dim hFont as HFONT = CreateFontIndirectW( @lf )

Microsoft Learn: LOGFONTW

ModifyFontFaceName

function ModifyFontFaceName( byval hWin as HWND, byref wszNewFaceName as wstring ) as HFONT

Makes a copy of the font a window uses with the typeface replaced, keeping its size, weight and style, and gives it to the window (WM_SETFONT, redrawn at once).

The window's previous font is not deleted: if you created it, delete it yourself, and delete the returned font once the window no longer uses it. A window without a font of its own has nothing to copy, and nothing happens.

Parameter	Meaning
hWin	The window or control.
wszNewFaceName	The typeface, such as "Consolas".

Returns the new font, or NULL when the window has no font or the font could not be made.

Example

dim hOld as HFONT = cast( HFONT, SendMessageW( hCtrl, WM_GETFONT, 0, 0 ) )
dim hNew as HFONT = ModifyFontFaceName( hCtrl, "Consolas" )
if hNew then DeleteObject( hOld )   ' only if hOld was a font you created

Microsoft Learn: WM_SETFONT

ModifyFontSettings

function ModifyFontSettings( byval hWin as HWND, byval nSetting as long, byval nValue as long ) as HFONT

Makes a copy of the font a window uses with one setting changed and gives it to the window (WM_SETFONT, redrawn at once). As with ModifyFontFaceName, the previous font is not deleted and the returned font is yours to delete.

nSetting	nValue
FONT_HEIGHT	A percentage of the current size: 120 makes it 20 % larger, 80 20 % smaller. The current size is first rounded to a whole point.
FONT_WEIGHT	0 to 1000: FW_NORMAL (400), FW_BOLD (700) … 0 lets the font mapper choose.
FONT_ITALIC, FONT_UNDERLINE, FONT_STRIKEOUT	1 to turn it on, 0 to turn it off.
FONT_CHARSET	A character set such as DEFAULT_CHARSET, SYMBOL_CHARSET or GREEK_CHARSET.

The copy reads the current font's description through the ANSI form of GetObject, so the typeface name it carries over is the ANSI bytes of the name packed into wide characters: the new font asks for a typeface that does not exist and the font mapper substitutes one. Follow the call with ModifyFontFaceName to put the right typeface back, as the example does.

Parameter	Meaning
hWin	The window or control.
nSetting	One of the six settings above.
nValue	The new value.

Returns the new font, or NULL when hWin is not a window, the window has no font, or nSetting is not one of the six settings.

Example

dim face as ustring = GetWindowFontInfo( hCtrl ).lfFaceName
dim hBold as HFONT = ModifyFontSettings( hCtrl, FONT_WEIGHT, FW_BOLD )
dim hFixed as HFONT = ModifyFontFaceName( hCtrl, face )
if hBold then DeleteObject( hBold )

Microsoft Learn: CreateFontIndirectW

ModifyFontHeight

function ModifyFontHeight( byval hWin as HWND, byval nValue as long ) as HFONT

The same as ModifyFontSettings( hWin, FONT_HEIGHT, nValue ): 150 makes a 10 pt font 15 pt. The typeface name is carried over the same way as there, so restore it with ModifyFontFaceName.

Returns the new font, which is yours to delete, or NULL on failure.

Example

dim face as ustring = GetWindowFontInfo( hCtrl ).lfFaceName
dim hBig as HFONT = ModifyFontHeight( hCtrl, 150 )
dim hFixed as HFONT = ModifyFontFaceName( hCtrl, face )
if hBig then DeleteObject( hBig )

CreateFont

function CreateFont overload( byref wszFaceName as wstring, byval lPointSize as long, byval DPI as long = 96, byval lWeight as long = 0, byval bItalic as ubyte = false, byval bUnderline as ubyte = false, byval bStrikeOut as ubyte = false, byval bCharSet as ubyte = DEFAULT_CHARSET ) as HFONT

Creates a TrueType-preferring font from a typeface name and a point size. The Windows function of the same name, with fourteen arguments, is still there.

DPI says which display the size is meant for:

• -1 sizes the font for the display the program sees: 10 pt is -13 pixels at 96 DPI and -23 at 175 % in a DPI-aware program. Use this in a DPI-aware program.
• 96, the default, keeps the font the pixel size it would have at 96 DPI. The point size is first scaled down in whole points (10 pt becomes 5 pt at 168 DPI, which gives -12 rather than -13), so on a scaled display the font can come out a pixel or so smaller.
• Any other positive value works the same way for that DPI.

A program that is not DPI aware sees 96 DPI, and every choice gives the same font.

Parameter	Meaning
wszFaceName	The typeface, such as "Segoe UI".
lPointSize	The size in points.
DPI	-1, or the DPI the size is meant for; see above.
lWeight	0 to 1000; FW_NORMAL (400), FW_BOLD (700). 0 lets the font mapper choose.
bItalic, bUnderline, bStrikeOut	Nonzero turns the style on.
bCharSet	The character set; SYMBOL_CHARSET for a symbol font such as Marlett.

Returns the font, which you delete with DeleteObject, or NULL on failure.

Example

dim hFont as HFONT = CreateFont( "Segoe UI", 10, -1, FW_BOLD )
SendMessageW( hCtrl, WM_SETFONT, cast( WPARAM, hFont ), true )

Microsoft Learn: CreateFontIndirectW

See also

• Category: sys/win
• Display, screen and DPI for the DPI these conversions use
• Units for points, pixels and the other units
• CWindow, whose CreateFont and SetFont members size fonts for the window's DPI