/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
/*
*
* (C) Copyright IBM Corp. 2003 - All Rights Reserved
*/
package sun.font;
/**
* Iterates over runs of fonts in a CompositeFont, optionally taking script runs into account.
*/
public final class FontRunIterator {
CompositeFont font;
char[] text;
int start;
int limit;
CompositeGlyphMapper mapper; // handy cache
int slot = -1;
int pos;
public void init(CompositeFont font, char[] text, int start, int limit) {
if (font == null || text == null || start < 0 || limit < start || limit > text.length) {
throw new IllegalArgumentException();
}
this.font = font;
this.text = text;
this.start = start;
this.limit = limit;
this.mapper = (CompositeGlyphMapper)font.getMapper();
this.slot = -1;
this.pos = start;
}
public PhysicalFont getFont() {
return slot == -1 ? null : font.getSlotFont(slot);
}
public int getGlyphMask() {
return slot << 24;
}
public int getPos() {
return pos;
}
/*
* characters that are in the 'common' script become part of the
* surrounding script run. we want to fetch these from the same font
* used to get surrounding characters, where possible. but we don't
* want to force non-common characters to come from other than their
* standard font.
*
* what we really want to do is this:
* 1) fetch a code point from the text.
* 2) get its 'native' script code
* 3) determine its 'resolved' script code
* 4) if its native script is COMMON, and its resolved script is the same as the previous
* code point's, then see if the previous font supports this code point. if so, use it.
* 5) otherwise resolve the font as usual
* 6) break the run when either the physical font or the resolved script changes.
*
* problems: we optimize latin-1 and cjk text assuming a fixed
* width for each character. since latin-1 digits and punctuation
* are common, following this algorithm they will change to match
* the fonts used for the preceeding text, and potentially change metrics.
*
* this also seems to have the potential for changing arbitrary runs of text, e.g.
* any number of digits and spaces can change depending on the preceeding (or following!)
* non-COMMON character's font assignment. this is not good.
*
* since the goal is to enable layout to be performed using as few physical fonts as
* possible, and the primary cause of switching fonts is to handle spaces, perhaps
* we should just special-case spaces and assign them from the current font, whatever
* it may be.
*
* One could also argue that the job of the composite font is to assign physical fonts
* to text runs, however it wishes. we don't necessarily have to provide script info
* to let it do this. it can determine based on whatever. so having a special 'next'
* function that takes script (and limit) is redundant. It can fetch the script again
* if need be.
*
* both this and the script iterator are turning char sequences into code point
* sequences. maybe it would be better to feed a single code point into each iterator-- push
* the data instead of pull it?
*/
public boolean next(int script, int lim) {
if (pos == lim) {
return false;
}
int ch = nextCodePoint(lim);
int sl = mapper.charToGlyph(ch) & CompositeGlyphMapper.SLOTMASK;
slot = sl >>> 24;
while ((ch = nextCodePoint(lim)) != DONE && (mapper.charToGlyph(ch) & CompositeGlyphMapper.SLOTMASK) == sl);
pushback(ch);
return true;
}
public boolean next() {
return next(Script.COMMON, limit);
}
static final int SURROGATE_START = 0x10000;
static final int LEAD_START = 0xd800;
static final int LEAD_LIMIT = 0xdc00;
static final int TAIL_START = 0xdc00;
static final int TAIL_LIMIT = 0xe000;
static final int LEAD_SURROGATE_SHIFT = 10;
static final int SURROGATE_OFFSET = SURROGATE_START - (LEAD_START << LEAD_SURROGATE_SHIFT) - TAIL_START;
static final int DONE = -1;
final int nextCodePoint() {
return nextCodePoint(limit);
}
final int nextCodePoint(int lim) {
if (pos >= lim) {
return DONE;
}
int ch = text[pos++];
if (ch >= LEAD_START && ch < LEAD_LIMIT && pos < lim) {
int nch = text[pos];
if (nch >= TAIL_START && nch < TAIL_LIMIT) {
++pos;
ch = (ch << LEAD_SURROGATE_SHIFT) + nch + SURROGATE_OFFSET;
}
}
return ch;
}
final void pushback(int ch) {
if (ch >= 0) {
if (ch >= 0x10000) {
pos -= 2;
} else {
pos -= 1;
}
}
}
}