/*
* Copyright 2003 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package sun.font;
/*
* This class is used so that a java.awt.Font does not directly
* reference a Font2D object. This introduces occasional minor
* de-referencing overhead but increases robustness of the
* implementation when "bad fonts" are encountered.
* A handle is created by a Font2D constructor and references
* the Font2D itself. In the event that the Font2D implementation
* determines it the font resource has errors (a bad font file)
* it makes its handle point at another "stable" Font2D.
* Once all referers no longer have a reference to the Font2D it
* may be GC'd and its resources freed.
* This does not immediately help in the case that objects are
* already using a bad Font2D (ie have already dereferenced the
* handle) so there is a window for more problems. However this
* is already the case as this is the code which must detect the
* problem.
* However there is also the possibility of intercepting problems
* even when a font2D reference is already directly held. Certain
* validation points may check that font2Dhandle.font2D == font2D
* If this is not true, then this font2D is not valid. Arguably
* this check also just needs to be a de-referencing assignment :
* font2D = font2DHandle.font2D.
* The net effect of these steps is that very soon after a font
* is identified as bad, that references and uses of it will be
* eliminated.
* In the initial implementation a Font2DHandle is what is held by
* - java.awt.Font
* - FontManager.initialisedFonts map
* Font2D is held by
* - FontFamily objects
* - FontManager.registeredFonts map
* - FontInfo object on a SunGraphics2D
*
* On discovering a bad font, all but the latter remove references to
* the font. See FontManager.deRegisterBadFont(Font2D)
*/
public final class Font2DHandle {
public Font2D font2D;
public Font2DHandle(Font2D font) {
font2D = font;
}
}