Inherits From: NSObject
Conforms To: NSObject (NSObject)
Declared In: AppKit/NSFontManager.h
NSFontManager declares the programmatic interface to objects that manage font conversion in an application. NSFontManager is the center of activity for font conversion. NSFontManager accepts messages from font conversion user-interface objects such as the Font menu or the Font panel (see NSFontPanel for more details) and appropriately converts the current font in the selection by sending a changeFont: message up the responder chain.
When an object receives a changeFont: message, it should message NSFontManager (by sending it a convertFont: message), asking it to convert the font in whatever way the user has specified. Thus, any object containing a font that can be changed should respond to the changeFont: message by sending a convertFont: message back to the NSFontManager for each font in the selection.
To use NSFontManager, you simply insert a Font menu into your application's menu using the appropriate interface construction tools (such as Interface Builder). You can also obtain a Font menu by sending a getFontMenu: message to NSFontManager and then inserting the menu it returns into the application's main menu. Once the Font menu is installed, your application automatically gains the functionality of both the Font menu and the Font panel.
NSFontManager's delegate can restrict which font names will appear in the Font Panel. See Methods Implemented by the Delegate at the end of this class specification for more information.
NSFontManager can be used to convert a font or find out the attributes of a font. It can also be overridden to convert fonts in some application-specific manner. The default implementation of font conversion is very conservative: The font isn't converted unless all traits of the font can be maintained across the conversion.
Generally, you obtain an instance of NSFontManager by sending a sharedFontManager message to the NSFontManager class object. NSFontManager will return a font manager object that is shared within your application. NSFontManager normally returns a pre-defined font manager object, but the actual object which is returned can be changed by previously invoking the setFontManagerFactory factory to some other kind of object.
Fonts work mainly in terms of traits, or characteristics, such as bold, italic, condensed, and so on. Traits are described by a collection of constants such as NSItalicFontMask, NSBoldFontMask, and so on. The full complement of traits are defined in AppKit/NSFontManager.h. The values of traits are defined in bitwise form so they can be or'ed together, although some traits, such as NSBoldFontMask and NSUnboldFontMask naturally conflict and have the effect of turning each other off. You use one of the convertFont1/4 methods to obtain a font of the desired characteristics from an existing font.
The convertFont:toHaveTrait: and the convertFont:toNotHaveTrait: methods deal with only one trait at a time. To convert a font to have (or not have) multiple traits, you must invoke these methods for each separate trait you wish to add to or remove from the font. Alternatively, use the fontWithFamily:traits:weight:size: method to specify multiple traits in one invocation.
The size of a font in the method definitions below is defined in points, which, in the current milieu, are actually PostScript unitsa PostScript unit being defined as 1/72 of an inch, or 0.0139 of an inch. In metric equivalents, a PostScript unit is 0.3528 millimetres. PostScript points are minimally different from printer's points, so for all intents and purposes you can think of PostScript units and points as interchangeable.
The weight of a font as used in these methods is simply a value representing a point in a continuum of font weights from lightest to heaviest. There's no simple one-to-one mapping of some integer value to, say, a bold weight. If you query the font for its weight value, increment the value, and use it as a new weight, you'll not necessarily obtain a different face (such as a transition from medium to bold) in a new instance of the font.
Managing the FontManager