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| 1 | +/* | |
| 2 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 3 | + * | |
| 4 | + * This code is free software; you can redistribute it and/or modify it | |
| 5 | + * under the terms of the GNU General Public License version 2 only, as | |
| 6 | + * published by the Free Software Foundation. Oracle designates this | |
| 7 | + * particular file as subject to the "Classpath" exception as provided | |
| 8 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 9 | + * | |
| 10 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 11 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 12 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 13 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 14 | + * accompanied this code). | |
| 15 | + * | |
| 16 | + * You should have received a copy of the GNU General Public License version | |
| 17 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 18 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 19 | + * | |
| 20 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 21 | + * or visit www.oracle.com if you need additional information or have any | |
| 22 | + * questions. | |
| 23 | + * | |
| 24 | + */ | |
| 25 | + | |
| 26 | +/* | |
| 27 | + * | |
| 28 | + * (C) Copyright IBM Corp. 2003 - All Rights Reserved | |
| 29 | + */ | |
| 30 | + | |
| 31 | +package sun.font; | |
| 32 | + | |
| 33 | +/** | |
| 34 | + * Iterates over runs of fonts in a CompositeFont, optionally taking script runs into account. | |
| 35 | + */ | |
| 36 | +public final class FontRunIterator { | |
| 37 | + CompositeFont font; | |
| 38 | + char[] text; | |
| 39 | + int start; | |
| 40 | + int limit; | |
| 41 | + | |
| 42 | + CompositeGlyphMapper mapper; // handy cache | |
| 43 | + | |
| 44 | + int slot = -1; | |
| 45 | + int pos; | |
| 46 | + | |
| 47 | + public void init(CompositeFont font, char[] text, int start, int limit) { | |
| 48 | + if (font == null || text == null || start < 0 || limit < start || limit > text.length) { | |
| 49 | + throw new IllegalArgumentException(); | |
| 50 | + } | |
| 51 | + | |
| 52 | + this.font = font; | |
| 53 | + this.text = text; | |
| 54 | + this.start = start; | |
| 55 | + this.limit = limit; | |
| 56 | + | |
| 57 | + this.mapper = (CompositeGlyphMapper)font.getMapper(); | |
| 58 | + this.slot = -1; | |
| 59 | + this.pos = start; | |
| 60 | + } | |
| 61 | + | |
| 62 | + public PhysicalFont getFont() { | |
| 63 | + return slot == -1 ? null : font.getSlotFont(slot); | |
| 64 | + } | |
| 65 | + | |
| 66 | + public int getGlyphMask() { | |
| 67 | + return slot << 24; | |
| 68 | + } | |
| 69 | + | |
| 70 | + public int getPos() { | |
| 71 | + return pos; | |
| 72 | + } | |
| 73 | + | |
| 74 | + /* | |
| 75 | + * characters that are in the 'common' script become part of the | |
| 76 | + * surrounding script run. we want to fetch these from the same font | |
| 77 | + * used to get surrounding characters, where possible. but we don't | |
| 78 | + * want to force non-common characters to come from other than their | |
| 79 | + * standard font. | |
| 80 | + * | |
| 81 | + * what we really want to do is this: | |
| 82 | + * 1) fetch a code point from the text. | |
| 83 | + * 2) get its 'native' script code | |
| 84 | + * 3) determine its 'resolved' script code | |
| 85 | + * 4) if its native script is COMMON, and its resolved script is the same as the previous | |
| 86 | + * code point's, then see if the previous font supports this code point. if so, use it. | |
| 87 | + * 5) otherwise resolve the font as usual | |
| 88 | + * 6) break the run when either the physical font or the resolved script changes. | |
| 89 | + * | |
| 90 | + * problems: we optimize latin-1 and cjk text assuming a fixed | |
| 91 | + * width for each character. since latin-1 digits and punctuation | |
| 92 | + * are common, following this algorithm they will change to match | |
| 93 | + * the fonts used for the preceeding text, and potentially change metrics. | |
| 94 | + * | |
| 95 | + * this also seems to have the potential for changing arbitrary runs of text, e.g. | |
| 96 | + * any number of digits and spaces can change depending on the preceeding (or following!) | |
| 97 | + * non-COMMON character's font assignment. this is not good. | |
| 98 | + * | |
| 99 | + * since the goal is to enable layout to be performed using as few physical fonts as | |
| 100 | + * possible, and the primary cause of switching fonts is to handle spaces, perhaps | |
| 101 | + * we should just special-case spaces and assign them from the current font, whatever | |
| 102 | + * it may be. | |
| 103 | + * | |
| 104 | + * One could also argue that the job of the composite font is to assign physical fonts | |
| 105 | + * to text runs, however it wishes. we don't necessarily have to provide script info | |
| 106 | + * to let it do this. it can determine based on whatever. so having a special 'next' | |
| 107 | + * function that takes script (and limit) is redundant. It can fetch the script again | |
| 108 | + * if need be. | |
| 109 | + * | |
| 110 | + * both this and the script iterator are turning char sequences into code point | |
| 111 | + * sequences. maybe it would be better to feed a single code point into each iterator-- push | |
| 112 | + * the data instead of pull it? | |
| 113 | + */ | |
| 114 | + | |
| 115 | + public boolean next(int script, int lim) { | |
| 116 | + if (pos == lim) { | |
| 117 | + return false; | |
| 118 | + } | |
| 119 | + | |
| 120 | + int ch = nextCodePoint(lim); | |
| 121 | + int sl = mapper.charToGlyph(ch) & CompositeGlyphMapper.SLOTMASK; | |
| 122 | + slot = sl >>> 24; | |
| 123 | + while ((ch = nextCodePoint(lim)) != DONE && (mapper.charToGlyph(ch) & CompositeGlyphMapper.SLOTMASK) == sl); | |
| 124 | + pushback(ch); | |
| 125 | + | |
| 126 | + return true; | |
| 127 | + } | |
| 128 | + | |
| 129 | + public boolean next() { | |
| 130 | + return next(Script.COMMON, limit); | |
| 131 | + } | |
| 132 | + | |
| 133 | + static final int SURROGATE_START = 0x10000; | |
| 134 | + static final int LEAD_START = 0xd800; | |
| 135 | + static final int LEAD_LIMIT = 0xdc00; | |
| 136 | + static final int TAIL_START = 0xdc00; | |
| 137 | + static final int TAIL_LIMIT = 0xe000; | |
| 138 | + static final int LEAD_SURROGATE_SHIFT = 10; | |
| 139 | + static final int SURROGATE_OFFSET = SURROGATE_START - (LEAD_START << LEAD_SURROGATE_SHIFT) - TAIL_START; | |
| 140 | + | |
| 141 | + static final int DONE = -1; | |
| 142 | + | |
| 143 | + final int nextCodePoint() { | |
| 144 | + return nextCodePoint(limit); | |
| 145 | + } | |
| 146 | + | |
| 147 | + final int nextCodePoint(int lim) { | |
| 148 | + if (pos >= lim) { | |
| 149 | + return DONE; | |
| 150 | + } | |
| 151 | + int ch = text[pos++]; | |
| 152 | + if (ch >= LEAD_START && ch < LEAD_LIMIT && pos < lim) { | |
| 153 | + int nch = text[pos]; | |
| 154 | + if (nch >= TAIL_START && nch < TAIL_LIMIT) { | |
| 155 | + ++pos; | |
| 156 | + ch = (ch << LEAD_SURROGATE_SHIFT) + nch + SURROGATE_OFFSET; | |
| 157 | + } | |
| 158 | + } | |
| 159 | + return ch; | |
| 160 | + } | |
| 161 | + | |
| 162 | + final void pushback(int ch) { | |
| 163 | + if (ch >= 0) { | |
| 164 | + if (ch >= 0x10000) { | |
| 165 | + pos -= 2; | |
| 166 | + } else { | |
| 167 | + pos -= 1; | |
| 168 | + } | |
| 169 | + } | |
| 170 | + } | |
| 171 | +} | |