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