{
* This Source Code Form is subject to the terms of the Mozilla Public License,
* v. 2.0. If a copy of the MPL was not distributed with this file, You can
* obtain one at http://mozilla.org/MPL/2.0/
*
* Copyright (C) 2006-2013, Peter Johnson (www.delphidabbler.com).
*
* $Rev$
* $Date$
*
* Implements a static class used to assist when working with fonts.
}
unit UFontHelper;
interface
uses
// Delphi
Classes, Graphics,
// Project
UBaseObjects;
type
/// <summary>Container for methods for assisting with font related
/// operations.</summary>
TFontHelper = class(TNoConstructObject)
public
/// <summary>Checks if a font with the given name exists on the system.
/// </summary>
class function FontExists(const FontName: string): Boolean;
/// <summary>Returns an array containing the names of all mono-spaced fonts
/// that are installed on the system.</summary>
class function ListMonoSpaceFonts: TArray<string>;
/// <summary>Sets the given font object to the default UI font for the
/// underlying operating system.</summary>
class procedure SetDefaultFont(const Font: TFont);
/// <summary>Sets all the given font objects to the default UI font for the
/// underlying operating system.</summary>
class procedure SetDefaultFonts(const Fonts: array of TFont);
/// <summary>Updates the given font object to have the same font name as
/// the default UI font of the underlying operating system.</summary>
class procedure SetDefaultBaseFont(const BaseFont: TFont);
/// <summary>Updates all the given font object to have the same font name
/// as the default UI font of the underlying operating system.</summary>
class procedure SetDefaultBaseFonts(const Fonts: array of TFont);
/// <summary>Sets the given font object to an appropriate content font for
/// the underlying operating system.</summary>
class procedure SetContentFont(const Font: TFont);
/// <summary>Sets the given font object to the program's default mono-space
/// font.</summary>
class procedure SetDefaultMonoFont(const Font: TFont);
/// <summary>Returns the name of the program's default mono-spaced font.
/// </summary>
class function GetDefaultMonoFontName: string;
/// <summary>Clones the font with the given font handle and returns the
/// handle of the cloned font.</summary>
/// <remarks>The caller is responsible for releasing the returned handle.
/// </remarks>
class function CloneFontHandle(const Handle: THandle): THandle;
strict private
const
/// <summary>Font name used when preferred font is not available.
/// </summary>
FallbackUIFontName = 'Arial';
/// <summary>UI font size used when preferred font is not available.
/// </summary>
FallbackUIFontSize = 8;
/// <summary>Content font name used when preferred font is not available.
/// </summary>
FallbackContentFontName = FallbackUIFontName;
/// <summary>Content font size used when preferred font is not available.
/// </summary>
FallbackContentFontSize = FallbackUIFontSize;
/// <summary>UI font name used on Windows Vista and later.</summary>
VistaUIFontName = 'Segoe UI';
/// <summary>UI font size used on Windows Vista and later.</summary>
VistaUIFontSize = 9;
/// <summary>Content font name used on Windows Vista and later.</summary>
VistaContentFontName = 'Calibri';
/// <summary>Content font size used on Windows Vista and later.</summary>
VistaContentFontSize = 10;
/// <summary>UI font name used on Windows XP and earlier.</summary>
PreVistaUIFontName = 'Tahoma';
/// <summary>UI font size used on Windows XP and earlier.</summary>
PreVistaUIFontSize = 8;
/// <summary>Content font name used on Windows XP and earlier.</summary>
PreVistaContentFontName = 'Verdana';
/// <summary>Content font size used on Windows XP and earlier.</summary>
PreVistaContentFontSize = PreVistaUIFontSize;
/// <summary>Mono spaced font name used on all OSs.</summary>
DefaultMonoFontName = 'Courier New';
/// <summary>Mono spaced font name used on all OSs.</summary>
DefaultMonoFontSize = 8;
end;
implementation
uses
// Delphi
SysUtils, Windows, Forms,
// Project
UGraphicUtils, UStrUtils, USystemInfo;
/// <summary>EnumFontFamilies() callback function used to add mono-spaced fonts
/// to a string list.</summary>
/// <remarks>For more info about this callback see
/// http://msdn.microsoft.com/en-us/library/aa911409.aspx</remarks>
function MonoFontFamilyProc(PLF: PEnumLogFont; PNTM: PNewTextMetric;
FontType: Integer; List: TStrings): Integer; stdcall;
begin
// check for fixed pitch font and filter out all "vertical" fonts that start
// with "@" (see http://tinyurl.com/6ul6rfo for details of vertical fonts).
if ((PLF.elfLogFont.lfPitchAndFamily and $F) = FIXED_PITCH)
and not StrStartsStr('@', PLF.elfLogFont.lfFaceName) then
List.Add(PLF.elfLogFont.lfFaceName);
Result := 1;
end;
{ TFontHelper }
class function TFontHelper.CloneFontHandle(const Handle: THandle): THandle;
var
LogFont: TLogFont; // logical font info for memo control's font
begin
Result := 0;
if GetObject(Handle, SizeOf(LogFont), @LogFont) > 0 then
Result := CreateFontIndirect(LogFont);
Assert(Result <> 0, ClassName + '.CloneFontHandle: Can''t clone handle');
end;
class function TFontHelper.FontExists(const FontName: string): Boolean;
begin
Result := Screen.Fonts.IndexOf(FontName) >= 0;
end;
class function TFontHelper.GetDefaultMonoFontName: string;
begin
Result := DefaultMonoFontName;
end;
class function TFontHelper.ListMonoSpaceFonts: TArray<string>;
var
DC: HDC; // device context required for API call
FontNames: TStrings; // receives list of font names
begin
FontNames := TStringList.Create;
try
// Get a device context needed for API call
DC := GetDC(0);
try
// Enumerate all font families: handle each font in MonoFontFamilyProc()
EnumFontFamilies(DC, nil, @MonoFontFamilyProc, LPARAM(FontNames));
finally
ReleaseDC(0, DC);
end;
Result := FontNames.ToStringArray;
finally
FontNames.Free;
end
end;
class procedure TFontHelper.SetContentFont(const Font: TFont);
begin
// Set default content font, size and style
Font.Name := FallbackContentFontName;
Font.Size := FallbackContentFontSize;
Font.Style := [];
if TOSInfo.CheckReportedOS(TOSInfo.WinVista) then
begin
// We have Vista or later - use Calibri if installed
if FontExists(VistaContentFontName) then
begin
Font.Name := VistaContentFontName;
Font.Size := VistaContentFontSize;
end;
end
else
begin
// Earlier OS than Vista (i.e. 2000 or XP)
if FontExists(PreVistaContentFontName) then
begin
Font.Name := PreVistaContentFontName;
Font.Size := PreVistaContentFontSize;
end;
end;
end;
class procedure TFontHelper.SetDefaultBaseFont(const BaseFont: TFont);
var
DefaultFont: TFont; // default font per OS
FontDelta: Integer; // amount to increment font size by
begin
// Create default font
DefaultFont := TFont.Create;
try
SetDefaultFont(DefaultFont);
// font delta is difference between normal default font size and that used
// on a specific OS (e.g. Vista uses Segoe UI 9 rather than MS Sans Serif 8)
FontDelta := DefaultFont.Size - FallbackUIFontSize;
// change base font name and size as required
BaseFont.Name := DefaultFont.Name;
BaseFont.Size := BaseFont.Size + FontDelta;
finally
DefaultFont.Free;
end;
end;
class procedure TFontHelper.SetDefaultBaseFonts(const Fonts: array of TFont);
var
Font: TFont;
begin
for Font in Fonts do
SetDefaultBaseFont(Font);
end;
class procedure TFontHelper.SetDefaultFont(const Font: TFont);
begin
// Set default font, size and style
Font.Name := FallbackUIFontName;
Font.Size := FallbackUIFontSize;
Font.Style := [];
if TOSInfo.CheckReportedOS(TOSInfo.WinVista) then
begin
// Vista or later
if FontExists(VistaUIFontName) then
begin
Font.Name := VistaUIFontName;
Font.Size := VistaUIFontSize;
end;
end
else
begin
// Earlier OS than Vista (i.e. 2000 or XP)
if FontExists(PreVistaUIFontName) then
begin
Font.Name := PreVistaUIFontName;
Font.Size := PreVistaUIFontSize;
end;
end;
end;
class procedure TFontHelper.SetDefaultFonts(const Fonts: array of TFont);
var
Font: TFont;
begin
for Font in Fonts do
SetDefaultFont(Font);
end;
class procedure TFontHelper.SetDefaultMonoFont(const Font: TFont);
begin
Font.Name := GetDefaultMonoFontName;
Font.Size := DefaultMonoFontSize;
Font.Style := [];
end;
end.
