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/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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/*
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*
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* (C) Copyright IBM Corp. 2003 - All Rights Reserved
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*/
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package sun.font;
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/**
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* Iterates over runs of fonts in a CompositeFont, optionally taking script runs into account.
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*/
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public final class FontRunIterator {
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CompositeFont font;
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char[] text;
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int start;
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int limit;
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CompositeGlyphMapper mapper; // handy cache
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int slot = -1;
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int pos;
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public void init(CompositeFont font, char[] text, int start, int limit) {
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if (font == null || text == null || start < 0 || limit < start || limit > text.length) {
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throw new IllegalArgumentException();
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}
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this.font = font;
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this.text = text;
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this.start = start;
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this.limit = limit;
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this.mapper = (CompositeGlyphMapper)font.getMapper();
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this.slot = -1;
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this.pos = start;
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}
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public PhysicalFont getFont() {
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return slot == -1 ? null : font.getSlotFont(slot);
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}
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public int getGlyphMask() {
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return slot << 24;
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}
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public int getPos() {
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return pos;
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}
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/*
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* characters that are in the 'common' script become part of the
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* surrounding script run. we want to fetch these from the same font
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* used to get surrounding characters, where possible. but we don't
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* want to force non-common characters to come from other than their
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* standard font.
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*
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* what we really want to do is this:
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* 1) fetch a code point from the text.
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* 2) get its 'native' script code
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* 3) determine its 'resolved' script code
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* 4) if its native script is COMMON, and its resolved script is the same as the previous
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* code point's, then see if the previous font supports this code point. if so, use it.
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* 5) otherwise resolve the font as usual
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* 6) break the run when either the physical font or the resolved script changes.
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*
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* problems: we optimize latin-1 and cjk text assuming a fixed
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* width for each character. since latin-1 digits and punctuation
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* are common, following this algorithm they will change to match
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* the fonts used for the preceeding text, and potentially change metrics.
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*
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* this also seems to have the potential for changing arbitrary runs of text, e.g.
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* any number of digits and spaces can change depending on the preceeding (or following!)
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* non-COMMON character's font assignment. this is not good.
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*
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* since the goal is to enable layout to be performed using as few physical fonts as
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* possible, and the primary cause of switching fonts is to handle spaces, perhaps
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* we should just special-case spaces and assign them from the current font, whatever
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* it may be.
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*
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* One could also argue that the job of the composite font is to assign physical fonts
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* to text runs, however it wishes. we don't necessarily have to provide script info
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* to let it do this. it can determine based on whatever. so having a special 'next'
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* function that takes script (and limit) is redundant. It can fetch the script again
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* if need be.
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*
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* both this and the script iterator are turning char sequences into code point
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* sequences. maybe it would be better to feed a single code point into each iterator-- push
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* the data instead of pull it?
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*/
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public boolean next(int script, int lim) {
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if (pos == lim) {
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return false;
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}
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int ch = nextCodePoint(lim);
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int sl = mapper.charToGlyph(ch) & CompositeGlyphMapper.SLOTMASK;
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slot = sl >>> 24;
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while ((ch = nextCodePoint(lim)) != DONE && (mapper.charToGlyph(ch) & CompositeGlyphMapper.SLOTMASK) == sl);
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pushback(ch);
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return true;
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}
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public boolean next() {
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return next(Script.COMMON, limit);
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}
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static final int SURROGATE_START = 0x10000;
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static final int LEAD_START = 0xd800;
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static final int LEAD_LIMIT = 0xdc00;
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static final int TAIL_START = 0xdc00;
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static final int TAIL_LIMIT = 0xe000;
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static final int LEAD_SURROGATE_SHIFT = 10;
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static final int SURROGATE_OFFSET = SURROGATE_START - (LEAD_START << LEAD_SURROGATE_SHIFT) - TAIL_START;
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static final int DONE = -1;
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final int nextCodePoint() {
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return nextCodePoint(limit);
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}
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final int nextCodePoint(int lim) {
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if (pos >= lim) {
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return DONE;
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}
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int ch = text[pos++];
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if (ch >= LEAD_START && ch < LEAD_LIMIT && pos < lim) {
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int nch = text[pos];
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if (nch >= TAIL_START && nch < TAIL_LIMIT) {
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++pos;
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ch = (ch << LEAD_SURROGATE_SHIFT) + nch + SURROGATE_OFFSET;
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}
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}
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return ch;
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}
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final void pushback(int ch) {
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if (ch >= 0) {
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if (ch >= 0x10000) {
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pos -= 2;
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} else {
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pos -= 1;
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}
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}
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}
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}
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