gecko-dev/content/base/public/nsLineBreaker.h

230 lines
9.3 KiB
C++

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