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| 1 | /* | ||
| 2 | * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package sun.font; | ||
| 27 | |||
| 28 | /* | ||
| 29 | * This class is used so that a java.awt.Font does not directly | ||
| 30 | * reference a Font2D object. This introduces occasional minor | ||
| 31 | * de-referencing overhead but increases robustness of the | ||
| 32 | * implementation when "bad fonts" are encountered. | ||
| 33 | * A handle is created by a Font2D constructor and references | ||
| 34 | * the Font2D itself. In the event that the Font2D implementation | ||
| 35 | * determines it the font resource has errors (a bad font file) | ||
| 36 | * it makes its handle point at another "stable" Font2D. | ||
| 37 | * Once all referers no longer have a reference to the Font2D it | ||
| 38 | * may be GC'd and its resources freed. | ||
| 39 | * This does not immediately help in the case that objects are | ||
| 40 | * already using a bad Font2D (ie have already dereferenced the | ||
| 41 | * handle) so there is a window for more problems. However this | ||
| 42 | * is already the case as this is the code which must detect the | ||
| 43 | * problem. | ||
| 44 | * However there is also the possibility of intercepting problems | ||
| 45 | * even when a font2D reference is already directly held. Certain | ||
| 46 | * validation points may check that font2Dhandle.font2D == font2D | ||
| 47 | * If this is not true, then this font2D is not valid. Arguably | ||
| 48 | * this check also just needs to be a de-referencing assignment : | ||
| 49 | * font2D = font2DHandle.font2D. | ||
| 50 | * The net effect of these steps is that very soon after a font | ||
| 51 | * is identified as bad, that references and uses of it will be | ||
| 52 | * eliminated. | ||
| 53 | * In the initial implementation a Font2DHandle is what is held by | ||
| 54 | * - java.awt.Font | ||
| 55 | * - FontManager.initialisedFonts map | ||
| 56 | * Font2D is held by | ||
| 57 | * - FontFamily objects | ||
| 58 | * - FontManager.registeredFonts map | ||
| 59 | * - FontInfo object on a SunGraphics2D | ||
| 60 | * | ||
| 61 | * On discovering a bad font, all but the latter remove references to | ||
| 62 | * the font. See FontManager.deRegisterBadFont(Font2D) | ||
| 63 | */ | ||
| 64 | |||
| 65 | public final class Font2DHandle { | ||
| 66 | |||
| 67 | public Font2D font2D; | ||
| 68 | |||
| 69 | public Font2DHandle(Font2D font) { | ||
| 70 | font2D = font; | ||
| 71 | } | ||
| 72 | } | ||