FontScaler.java revision 1686
3681N/A * Copyright 2007 Sun Microsystems, Inc. All Rights Reserved. 342N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 342N/A * This code is free software; you can redistribute it and/or modify it 342N/A * under the terms of the GNU General Public License version 2 only, as 342N/A * published by the Free Software Foundation. Sun designates this 342N/A * particular file as subject to the "Classpath" exception as provided 342N/A * by Sun in the LICENSE file that accompanied this code. 342N/A * This code is distributed in the hope that it will be useful, but WITHOUT 342N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 342N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 342N/A * version 2 for more details (a copy is included in the LICENSE file that 342N/A * accompanied this code). 342N/A * You should have received a copy of the GNU General Public License version 342N/A * 2 along with this work; if not, write to the Free Software Foundation, 1472N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 1472N/A * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 342N/A * CA 95054 USA or visit www.sun.com if you need additional information or 2591N/A/* FontScaler is "internal interface" to font rasterizer library. 2591N/A * Access to native rasterizers without going through this interface is 2591N/A * strongly discouraged. In particular, this is important because native 2591N/A * data could be disposed due to runtime font processing error at any time. 2591N/A * FontScaler represents combination of particular rasterizer implementation 2591N/A * and particular font. It does not include rasterization attributes such as 2591N/A * transform. These attributes are part of native scalerContext object. 2591N/A * This approach allows to share same scaler for different requests related 2591N/A * Note that scaler may throw FontScalerException on any operation. 2591N/A * Generally this means that runtime error had happened and scaler is not 2591N/A * usable. Subsequent calls to this scaler should not cause crash but will 2591N/A * likely cause exceptions to be thrown again. 2591N/A * It is recommended that callee should replace its reference to the scaler 342N/A * with something else. For instance it could be FontManager.getNullScaler(). 3863N/A * Note that NullScaler is trivial and will not actually rasterize anything. 342N/A * Alternatively, callee can use more sophisticated error recovery strategies 2591N/A * and for instance try to substitute failed scaler with new scaler instance 2591N/A * Note that in case of error there is no need to call dispose(). Moreover, 2591N/A * dispose() generally is called by Disposer thread and explicit calls to 2591N/A * dispose might have unexpected sideeffects because scaler can be shared. 3681N/A * Current disposing logic is the following: 342N/A * - scaler is registered in the Disposer by the FontManager (on creation) 2591N/A * - scalers are disposed when associated Font2D object (e.g. TruetypeFont) 2591N/A * is garbage collected. That's why this object implements DisposerRecord 2591N/A * interface directly (as it is not used as indicator when it is safe 2591N/A * to release native state) and that's why we have to use WeakReference 2591N/A * - Majority of Font2D objects are linked from various mapping arrays 2591N/A * (e.g. FontManager.localeFullNamesToFont). So, they are not collected. 3681N/A * This logic only works for fonts created with Font.createFont() 2591N/A * - Eventually we may consider releasing some of the scaler resources if 3681N/A * it was not used for a while but we do not want to be too aggressive on 342N/A * this (and this is probably more important for Type1 fonts). 2591N/A //Find preferred font scaler 3681N/A //NB: we can allow property based preferences 342N/A // (theoretically logic can be font type specific) 342N/A boolean.
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2591N/A //NB: rewrite using factory? constructor is ugly way 2591N/A /* This is the only place to instantiate new FontScaler. 2591N/A * Therefore this is very convinient place to register 2591N/A * scaler with Disposer as well as trigger deregistring bad font 2591N/A * in case when scaler reports this. 2591N/A //if we can not instantiate scaler assume bad font 2591N/A //NB: technically it could be also because of internal scaler 2591N/A // error but here we are assuming scaler is ok. 2591N/A * At the moment it is harmless to create 2 null scalers so, technically, 2591N/A * syncronized keyword is not needed. 342N/A * But it is safer to keep it to avoid subtle problems if we will be adding 2591N/A * checks like whether scaler is null scaler. * Returns pointer to native GlyphInfo object. * Callee is responsible for freeing this memory. * currently this method has to return not 0L but pointer to valid * GlyphInfo object. Because Strike and drawing releated logic does * In the future we may want to rework this to allow 0L here. /* Used by Java2D disposer to ensure native resources are released. Note: this method does not release any of created scaler context objects! */ /* At the moment these 3 methods are needed for Type1 fonts only. * For Truetype fonts we extract required info outside of scaler /* This method returns table cache used by native layout engine. * This cache is essentially just small collection of * pointers to various truetype tables. See definition of TTLayoutTableCache * in the fontscalerdefs.h for more details. * Note that tables themselves have same format as defined in the truetype * specification, i.e. font scaler do not need to perform any preprocessing. * Probably it is better to have API to request pointers to each table * separately instead of requesting pointer to some native structure. * (then there is not need to share its definition by different * implementations of scaler). * However, this means multiple JNI calls and potential impact on performance. * Note: return value 0 is legal. * This means tables are not available (e.g. type1 font). /* Used by the OpenType engine for mark positioning. */ /* Returns pointer to native structure describing rasterization attributes. Format of this structure is scaler-specific. Callee is responsible for freeing scaler context (using free()). Context is tightly associated with strike and it is actually freed when corresponding strike is being released. /* Marks context as invalid because native scaler is invalid. - pointer itself is still valid and has to be released - if pointer to native scaler was cached it should not be neither disposed nor used. it is very likely it is already disposed by this moment. */