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249 lines
9.0 KiB
C++
249 lines
9.0 KiB
C++
///////////////////////////////////////////////////////////////////////
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// File: resultiterator.h
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// Description: Iterator for tesseract results that is capable of
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// iterating in proper reading order over Bi Directional
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// (e.g. mixed Hebrew and English) text.
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// Author: David Eger
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// Created: Fri May 27 13:58:06 PST 2011
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//
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// (C) Copyright 2011, Google Inc.
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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///////////////////////////////////////////////////////////////////////
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#ifndef TESSERACT_CCMAIN_RESULT_ITERATOR_H_
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#define TESSERACT_CCMAIN_RESULT_ITERATOR_H_
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#include "platform.h"
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#include "ltrresultiterator.h"
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template <typename T> class GenericVector;
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template <typename T> class GenericVectorEqEq;
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class BLOB_CHOICE_IT;
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class WERD_RES;
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class STRING;
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namespace tesseract {
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class Tesseract;
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class TESS_API ResultIterator : public LTRResultIterator {
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public:
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static ResultIterator *StartOfParagraph(const LTRResultIterator &resit);
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/**
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* ResultIterator is copy constructible!
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* The default copy constructor works just fine for us.
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*/
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virtual ~ResultIterator() {}
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// ============= Moving around within the page ============.
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/**
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* Moves the iterator to point to the start of the page to begin
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* an iteration.
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*/
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virtual void Begin();
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/**
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* Moves to the start of the next object at the given level in the
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* page hierarchy in the appropriate reading order and returns false if
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* the end of the page was reached.
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* NOTE that RIL_SYMBOL will skip non-text blocks, but all other
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* PageIteratorLevel level values will visit each non-text block once.
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* Think of non text blocks as containing a single para, with a single line,
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* with a single imaginary word.
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* Calls to Next with different levels may be freely intermixed.
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* This function iterates words in right-to-left scripts correctly, if
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* the appropriate language has been loaded into Tesseract.
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*/
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virtual bool Next(PageIteratorLevel level);
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/**
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* IsAtBeginningOf() returns whether we're at the logical beginning of the
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* given level. (as opposed to ResultIterator's left-to-right top-to-bottom
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* order). Otherwise, this acts the same as PageIterator::IsAtBeginningOf().
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* For a full description, see pageiterator.h
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*/
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virtual bool IsAtBeginningOf(PageIteratorLevel level) const;
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/**
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* Implement PageIterator's IsAtFinalElement correctly in a BiDi context.
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* For instance, IsAtFinalElement(RIL_PARA, RIL_WORD) returns whether we
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* point at the last word in a paragraph. See PageIterator for full comment.
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*/
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virtual bool IsAtFinalElement(PageIteratorLevel level,
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PageIteratorLevel element) const;
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// ============= Functions that refer to words only ============.
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// Returns the number of blanks before the current word.
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int BlanksBeforeWord() const;
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// ============= Accessing data ==============.
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/**
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* Returns the null terminated UTF-8 encoded text string for the current
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* object at the given level. Use delete [] to free after use.
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*/
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virtual char* GetUTF8Text(PageIteratorLevel level) const;
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/**
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* Return whether the current paragraph's dominant reading direction
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* is left-to-right (as opposed to right-to-left).
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*/
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bool ParagraphIsLtr() const;
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// ============= Exposed only for testing =============.
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/**
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* Yields the reading order as a sequence of indices and (optional)
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* meta-marks for a set of words (given left-to-right).
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* The meta marks are passed as negative values:
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* kMinorRunStart Start of minor direction text.
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* kMinorRunEnd End of minor direction text.
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* kComplexWord The next indexed word contains both left-to-right and
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* right-to-left characters and was treated as neutral.
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*
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* For example, suppose we have five words in a text line,
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* indexed [0,1,2,3,4] from the leftmost side of the text line.
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* The following are all believable reading_orders:
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*
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* Left-to-Right (in ltr paragraph):
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* { 0, 1, 2, 3, 4 }
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* Left-to-Right (in rtl paragraph):
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* { kMinorRunStart, 0, 1, 2, 3, 4, kMinorRunEnd }
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* Right-to-Left (in rtl paragraph):
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* { 4, 3, 2, 1, 0 }
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* Left-to-Right except for an RTL phrase in words 2, 3 in an ltr paragraph:
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* { 0, 1, kMinorRunStart, 3, 2, kMinorRunEnd, 4 }
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*/
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static void CalculateTextlineOrder(
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bool paragraph_is_ltr,
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const GenericVector<StrongScriptDirection> &word_dirs,
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GenericVectorEqEq<int> *reading_order);
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static const int kMinorRunStart;
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static const int kMinorRunEnd;
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static const int kComplexWord;
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protected:
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/**
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* We presume the data associated with the given iterator will outlive us.
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* NB: This is private because it does something that is non-obvious:
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* it resets to the beginning of the paragraph instead of staying wherever
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* resit might have pointed.
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*/
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TESS_LOCAL explicit ResultIterator(const LTRResultIterator &resit);
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private:
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/**
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* Calculates the current paragraph's dominant writing direction.
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* Typically, members should use current_paragraph_ltr_ instead.
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*/
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bool CurrentParagraphIsLtr() const;
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/**
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* Returns word indices as measured from resit->RestartRow() = index 0
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* for the reading order of words within a textline given an iterator
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* into the middle of the text line.
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* In addition to non-negative word indices, the following negative values
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* may be inserted:
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* kMinorRunStart Start of minor direction text.
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* kMinorRunEnd End of minor direction text.
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* kComplexWord The previous word contains both left-to-right and
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* right-to-left characters and was treated as neutral.
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*/
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void CalculateTextlineOrder(bool paragraph_is_ltr,
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const LTRResultIterator &resit,
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GenericVectorEqEq<int> *indices) const;
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/** Same as above, but the caller's ssd gets filled in if ssd != NULL. */
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void CalculateTextlineOrder(bool paragraph_is_ltr,
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const LTRResultIterator &resit,
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GenericVector<StrongScriptDirection> *ssd,
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GenericVectorEqEq<int> *indices) const;
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/**
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* What is the index of the current word in a strict left-to-right reading
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* of the row?
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*/
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int LTRWordIndex() const;
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/**
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* Given an iterator pointing at a word, returns the logical reading order
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* of blob indices for the word.
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*/
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void CalculateBlobOrder(GenericVector<int> *blob_indices) const;
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/** Precondition: current_paragraph_is_ltr_ is set. */
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void MoveToLogicalStartOfTextline();
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/**
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* Precondition: current_paragraph_is_ltr_ and in_minor_direction_
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* are set.
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*/
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void MoveToLogicalStartOfWord();
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/** Are we pointing at the final (reading order) symbol of the word? */
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bool IsAtFinalSymbolOfWord() const;
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/** Are we pointing at the first (reading order) symbol of the word? */
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bool IsAtFirstSymbolOfWord() const;
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/**
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* Append any extra marks that should be appended to this word when printed.
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* Mostly, these are Unicode BiDi control characters.
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*/
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void AppendSuffixMarks(STRING *text) const;
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/** Appends the current word in reading order to the given buffer.*/
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void AppendUTF8WordText(STRING *text) const;
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/**
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* Appends the text of the current text line, *assuming this iterator is
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* positioned at the beginning of the text line* This function
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* updates the iterator to point to the first position past the text line.
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* Each textline is terminated in a single newline character.
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* If the textline ends a paragraph, it gets a second terminal newline.
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*/
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void IterateAndAppendUTF8TextlineText(STRING *text);
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/**
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* Appends the text of the current paragraph in reading order
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* to the given buffer.
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* Each textline is terminated in a single newline character, and the
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* paragraph gets an extra newline at the end.
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*/
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void AppendUTF8ParagraphText(STRING *text) const;
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/** Returns whether the bidi_debug flag is set to at least min_level. */
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bool BidiDebug(int min_level) const;
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bool current_paragraph_is_ltr_;
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/**
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* Is the currently pointed-at character at the beginning of
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* a minor-direction run?
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*/
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bool at_beginning_of_minor_run_;
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/** Is the currently pointed-at character in a minor-direction sequence? */
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bool in_minor_direction_;
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/**
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* Should detected inter-word spaces be preserved, or "compressed" to a single
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* space character (default behavior).
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*/
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bool preserve_interword_spaces_;
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};
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} // namespace tesseract.
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#endif // TESSERACT_CCMAIN_RESULT_ITERATOR_H_
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