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249 lines
10 KiB
C++
249 lines
10 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Novell code.
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*
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* The Initial Developer of the Original Code is Novell.
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* Portions created by the Initial Developer are Copyright (C) 2006
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Robert O'Callahan <robert@ocallahan.org> (Original Author)
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef NSLINEBREAKER_H_
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#define NSLINEBREAKER_H_
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#include "nsString.h"
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#include "nsTArray.h"
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#include "nsILineBreaker.h"
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class nsIAtom;
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class nsHyphenator;
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/**
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* A receiver of line break data.
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*/
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class nsILineBreakSink {
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public:
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/**
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* Sets the break data for a substring of the associated text chunk.
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* One or more of these calls will be performed; the union of all substrings
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* will cover the entire text chunk. Substrings may overlap (i.e., we may
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* set the break-before state of a character more than once).
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* @param aBreakBefore the break-before states for the characters in the substring.
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* These are enum values from gfxTextRun::CompressedGlyph:
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* FLAG_BREAK_TYPE_NONE - no linebreak is allowed here
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* FLAG_BREAK_TYPE_NORMAL - a normal (whitespace) linebreak
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* FLAG_BREAK_TYPE_HYPHEN - a hyphenation point
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*/
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virtual void SetBreaks(PRUint32 aStart, PRUint32 aLength, PRUint8* aBreakBefore) = 0;
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/**
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* Indicates which characters should be capitalized. Only called if
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* BREAK_NEED_CAPITALIZATION was requested.
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*/
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virtual void SetCapitalization(PRUint32 aStart, PRUint32 aLength, bool* aCapitalize) = 0;
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};
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/**
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* A line-breaking state machine. You feed text into it via AppendText calls
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* and it computes the possible line breaks. Because break decisions can
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* require a lot of context, the breaks for a piece of text are sometimes not
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* known until later text has been seen (or all text ends). So breaks are
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* returned via a call to SetBreaks on the nsILineBreakSink object passed
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* with each text chunk, which might happen during the corresponding AppendText
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* call, or might happen during a later AppendText call or even a Reset()
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* call.
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*
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* The linebreak results MUST NOT depend on how the text is broken up
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* into AppendText calls.
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*
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* The current strategy is that we break the overall text into
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* whitespace-delimited "words". Then those words are passed to the nsILineBreaker
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* service for deeper analysis if they contain a "complex" character as described
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* below.
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*
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* This class also handles detection of which characters should be capitalized
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* for text-transform:capitalize. This is a good place to handle that because
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* we have all the context we need.
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*/
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class nsLineBreaker {
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public:
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nsLineBreaker();
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~nsLineBreaker();
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static inline bool IsSpace(PRUnichar u) { return NS_IsSpace(u); }
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static inline bool IsComplexASCIIChar(PRUnichar u)
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{
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return !((0x0030 <= u && u <= 0x0039) ||
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(0x0041 <= u && u <= 0x005A) ||
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(0x0061 <= u && u <= 0x007A) ||
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(0x000a == u));
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}
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static inline bool IsComplexChar(PRUnichar u)
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{
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return IsComplexASCIIChar(u) ||
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NS_NeedsPlatformNativeHandling(u) ||
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(0x1100 <= u && u <= 0x11ff) || // Hangul Jamo
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(0x2000 <= u && u <= 0x21ff) || // Punctuations and Symbols
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(0x2e80 <= u && u <= 0xd7ff) || // several CJK blocks
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(0xf900 <= u && u <= 0xfaff) || // CJK Compatibility Idographs
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(0xff00 <= u && u <= 0xffef); // Halfwidth and Fullwidth Forms
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}
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// Break opportunities exist at the end of each run of breakable whitespace
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// (see IsSpace above). Break opportunities can also exist between pairs of
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// non-whitespace characters, as determined by nsILineBreaker. We pass a whitespace-
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// delimited word to nsILineBreaker if it contains at least one character
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// matching IsComplexChar.
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// We provide flags to control on a per-chunk basis where breaks are allowed.
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// At any character boundary, exactly one text chunk governs whether a
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// break is allowed at that boundary.
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//
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// We operate on text after whitespace processing has been applied, so
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// other characters (e.g. tabs and newlines) may have been converted to
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// spaces.
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/**
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* Flags passed with each chunk of text.
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*/
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enum {
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/*
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* Do not introduce a break opportunity at the start of this chunk of text.
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*/
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BREAK_SUPPRESS_INITIAL = 0x01,
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/**
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* Do not introduce a break opportunity in the interior of this chunk of text.
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* Also, whitespace in this chunk is treated as non-breakable.
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*/
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BREAK_SUPPRESS_INSIDE = 0x02,
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/**
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* The sink currently is already set up to have no breaks in it;
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* if no breaks are possible, nsLineBreaker does not need to call
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* SetBreaks on it. This is useful when handling large quantities of
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* preformatted text; the textruns will never have any breaks set on them,
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* and there is no need to ever actually scan the text for breaks, except
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* at the end of textruns in case context is needed for following breakable
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* text.
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*/
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BREAK_SKIP_SETTING_NO_BREAKS = 0x04,
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/**
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* We need to be notified of characters that should be capitalized
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* (as in text-transform:capitalize) in this chunk of text.
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*/
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BREAK_NEED_CAPITALIZATION = 0x08,
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/**
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* Auto-hyphenation is enabled, so we need to get a hyphenator
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* (if available) and use it to find breakpoints.
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*/
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BREAK_USE_AUTO_HYPHENATION = 0x10
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};
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/**
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* Append "invisible whitespace". This acts like whitespace, but there is
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* no actual text associated with it. Only the BREAK_SUPPRESS_INSIDE flag
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* is relevant here.
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*/
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nsresult AppendInvisibleWhitespace(PRUint32 aFlags);
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/**
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* Feed Unicode text into the linebreaker for analysis. aLength must be
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* nonzero.
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* @param aSink can be null if the breaks are not actually needed (we may
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* still be setting up state for later breaks)
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*/
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nsresult AppendText(nsIAtom* aLangGroup, const PRUnichar* aText, PRUint32 aLength,
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PRUint32 aFlags, nsILineBreakSink* aSink);
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/**
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* Feed 8-bit text into the linebreaker for analysis. aLength must be nonzero.
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* @param aSink can be null if the breaks are not actually needed (we may
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* still be setting up state for later breaks)
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*/
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nsresult AppendText(nsIAtom* aLangGroup, const PRUint8* aText, PRUint32 aLength,
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PRUint32 aFlags, nsILineBreakSink* aSink);
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/**
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* Reset all state. This means the current run has ended; any outstanding
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* calls through nsILineBreakSink are made, and all outstanding references to
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* nsILineBreakSink objects are dropped.
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* After this call, this linebreaker can be reused.
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* This must be called at least once between any call to AppendText() and
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* destroying the object.
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* @param aTrailingBreak this is set to true when there is a break opportunity
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* at the end of the text. This will normally only be declared true when there
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* is breakable whitespace at the end.
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*/
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nsresult Reset(bool* aTrailingBreak);
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private:
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// This is a list of text sources that make up the "current word" (i.e.,
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// run of text which does not contain any whitespace). All the mLengths
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// are are nonzero, these cannot overlap.
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struct TextItem {
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TextItem(nsILineBreakSink* aSink, PRUint32 aSinkOffset, PRUint32 aLength,
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PRUint32 aFlags)
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: mSink(aSink), mSinkOffset(aSinkOffset), mLength(aLength), mFlags(aFlags) {}
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nsILineBreakSink* mSink;
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PRUint32 mSinkOffset;
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PRUint32 mLength;
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PRUint32 mFlags;
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};
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// State for the nonwhitespace "word" that started in previous text and hasn't
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// finished yet.
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// When the current word ends, this computes the linebreak opportunities
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// *inside* the word (excluding either end) and sets them through the
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// appropriate sink(s). Then we clear the current word state.
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nsresult FlushCurrentWord();
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void UpdateCurrentWordLangGroup(nsIAtom *aLangGroup);
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void FindHyphenationPoints(nsHyphenator *aHyphenator,
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const PRUnichar *aTextStart,
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const PRUnichar *aTextLimit,
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PRUint8 *aBreakState);
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nsAutoTArray<PRUnichar,100> mCurrentWord;
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// All the items that contribute to mCurrentWord
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nsAutoTArray<TextItem,2> mTextItems;
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nsIAtom* mCurrentWordLangGroup;
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bool mCurrentWordContainsMixedLang;
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bool mCurrentWordContainsComplexChar;
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// True if the previous character was breakable whitespace
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bool mAfterBreakableSpace;
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// True if a break must be allowed at the current position because
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// a run of breakable whitespace ends here
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bool mBreakHere;
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};
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#endif /*NSLINEBREAKER_H_*/
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