nsLineBreaker.h
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef NSLINEBREAKER_H_
#define NSLINEBREAKER_H_
#include "nsString.h"
#include "nsTArray.h"
#include "nsILineBreaker.h"
class nsIAtom;
class nsHyphenator;
/**
* 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.
* These are enum values from gfxTextRun::CompressedGlyph:
* FLAG_BREAK_TYPE_NONE - no linebreak is allowed here
* FLAG_BREAK_TYPE_NORMAL - a normal (whitespace) linebreak
* FLAG_BREAK_TYPE_HYPHEN - a hyphenation point
*/
virtual void SetBreaks(uint32_t aStart, uint32_t aLength, uint8_t* aBreakBefore) = 0;
/**
* Indicates which characters should be capitalized. Only called if
* BREAK_NEED_CAPITALIZATION was requested.
*/
virtual void SetCapitalization(uint32_t aStart, uint32_t aLength, bool* 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 bool IsSpace(char16_t u) { return NS_IsSpace(u); }
static inline bool IsComplexASCIIChar(char16_t u)
{
return !((0x0030 <= u && u <= 0x0039) ||
(0x0041 <= u && u <= 0x005A) ||
(0x0061 <= u && u <= 0x007A) ||
(0x000a == u));
}
static inline bool IsComplexChar(char16_t 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,
/**
* Auto-hyphenation is enabled, so we need to get a hyphenator
* (if available) and use it to find breakpoints.
*/
BREAK_USE_AUTO_HYPHENATION = 0x10
};
/**
* 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(uint32_t 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* aHyphenationLanguage, const char16_t* aText, uint32_t aLength,
uint32_t 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* aHyphenationLanguage, const uint8_t* aText, uint32_t aLength,
uint32_t 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(bool* aTrailingBreak);
/*
* Set word-break mode for linebreaker. This is set by word-break property.
* @param aMode is nsILineBreaker::kWordBreak_* value.
*/
void SetWordBreak(uint8_t aMode) { mWordBreak = aMode; }
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, uint32_t aSinkOffset, uint32_t aLength,
uint32_t aFlags)
: mSink(aSink), mSinkOffset(aSinkOffset), mLength(aLength), mFlags(aFlags) {}
nsILineBreakSink* mSink;
uint32_t mSinkOffset;
uint32_t mLength;
uint32_t 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();
void UpdateCurrentWordLanguage(nsIAtom *aHyphenationLanguage);
void FindHyphenationPoints(nsHyphenator *aHyphenator,
const char16_t *aTextStart,
const char16_t *aTextLimit,
uint8_t *aBreakState);
AutoTArray<char16_t,100> mCurrentWord;
// All the items that contribute to mCurrentWord
AutoTArray<TextItem,2> mTextItems;
nsIAtom* mCurrentWordLanguage;
bool mCurrentWordContainsMixedLang;
bool mCurrentWordContainsComplexChar;
// True if the previous character was breakable whitespace
bool mAfterBreakableSpace;
// True if a break must be allowed at the current position because
// a run of breakable whitespace ends here
bool mBreakHere;
// line break mode by "word-break" style
uint8_t mWordBreak;
};
#endif /*NSLINEBREAKER_H_*/
