The Tor Browser: comparison content/base/public/nsLineBreaker.h

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+:58a728710004
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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);
+nsAutoTArray<char16_t,100> mCurrentWord;
+// All the items that contribute to mCurrentWord
+nsAutoTArray<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_*/

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comparison: content/base/public/nsLineBreaker.h

content/base/public/nsLineBreaker.h