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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 | } | ||