srcnativelibs.Include.Tesseract.tesseract.resultiterator.h Maven / Gradle / Ivy
///////////////////////////////////////////////////////////////////////
// File: resultiterator.h
// Description: Iterator for tesseract results that is capable of
// iterating in proper reading order over Bi Directional
// (e.g. mixed Hebrew and English) text.
// Author: David Eger
// Created: Fri May 27 13:58:06 PST 2011
//
// (C) Copyright 2011, Google Inc.
// Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
///////////////////////////////////////////////////////////////////////
#ifndef TESSERACT_CCMAIN_RESULT_ITERATOR_H__
#define TESSERACT_CCMAIN_RESULT_ITERATOR_H__
#include "platform.h"
#include "ltrresultiterator.h"
template class GenericVector;
template class GenericVectorEqEq;
class BLOB_CHOICE_IT;
class WERD_RES;
class STRING;
namespace tesseract {
class Tesseract;
class TESS_API ResultIterator : public LTRResultIterator {
public:
static ResultIterator *StartOfParagraph(const LTRResultIterator &resit);
/**
* ResultIterator is copy constructible!
* The default copy constructor works just fine for us.
*/
virtual ~ResultIterator() {}
// ============= Moving around within the page ============.
/**
* Moves the iterator to point to the start of the page to begin
* an iteration.
*/
virtual void Begin();
/**
* Moves to the start of the next object at the given level in the
* page hierarchy in the appropriate reading order and returns false if
* the end of the page was reached.
* NOTE that RIL_SYMBOL will skip non-text blocks, but all other
* PageIteratorLevel level values will visit each non-text block once.
* Think of non text blocks as containing a single para, with a single line,
* with a single imaginary word.
* Calls to Next with different levels may be freely intermixed.
* This function iterates words in right-to-left scripts correctly, if
* the appropriate language has been loaded into Tesseract.
*/
virtual bool Next(PageIteratorLevel level);
/**
* IsAtBeginningOf() returns whether we're at the logical beginning of the
* given level. (as opposed to ResultIterator's left-to-right top-to-bottom
* order). Otherwise, this acts the same as PageIterator::IsAtBeginningOf().
* For a full description, see pageiterator.h
*/
virtual bool IsAtBeginningOf(PageIteratorLevel level) const;
/**
* Implement PageIterator's IsAtFinalElement correctly in a BiDi context.
* For instance, IsAtFinalElement(RIL_PARA, RIL_WORD) returns whether we
* point at the last word in a paragraph. See PageIterator for full comment.
*/
virtual bool IsAtFinalElement(PageIteratorLevel level,
PageIteratorLevel element) const;
// ============= Accessing data ==============.
/**
* Returns the null terminated UTF-8 encoded text string for the current
* object at the given level. Use delete [] to free after use.
*/
virtual char* GetUTF8Text(PageIteratorLevel level) const;
/**
* Return whether the current paragraph's dominant reading direction
* is left-to-right (as opposed to right-to-left).
*/
bool ParagraphIsLtr() const;
// ============= Exposed only for testing =============.
/**
* Yields the reading order as a sequence of indices and (optional)
* meta-marks for a set of words (given left-to-right).
* The meta marks are passed as negative values:
* kMinorRunStart Start of minor direction text.
* kMinorRunEnd End of minor direction text.
* kComplexWord The next indexed word contains both left-to-right and
* right-to-left characters and was treated as neutral.
*
* For example, suppose we have five words in a text line,
* indexed [0,1,2,3,4] from the leftmost side of the text line.
* The following are all believable reading_orders:
*
* Left-to-Right (in ltr paragraph):
* { 0, 1, 2, 3, 4 }
* Left-to-Right (in rtl paragraph):
* { kMinorRunStart, 0, 1, 2, 3, 4, kMinorRunEnd }
* Right-to-Left (in rtl paragraph):
* { 4, 3, 2, 1, 0 }
* Left-to-Right except for an RTL phrase in words 2, 3 in an ltr paragraph:
* { 0, 1, kMinorRunStart, 3, 2, kMinorRunEnd, 4 }
*/
static void CalculateTextlineOrder(
bool paragraph_is_ltr,
const GenericVector &word_dirs,
GenericVectorEqEq *reading_order);
static const int kMinorRunStart;
static const int kMinorRunEnd;
static const int kComplexWord;
protected:
/**
* We presume the data associated with the given iterator will outlive us.
* NB: This is private because it does something that is non-obvious:
* it resets to the beginning of the paragraph instead of staying wherever
* resit might have pointed.
*/
TESS_LOCAL explicit ResultIterator(const LTRResultIterator &resit);
private:
/**
* Calculates the current paragraph's dominant writing direction.
* Typically, members should use current_paragraph_ltr_ instead.
*/
bool CurrentParagraphIsLtr() const;
/**
* Returns word indices as measured from resit->RestartRow() = index 0
* for the reading order of words within a textline given an iterator
* into the middle of the text line.
* In addition to non-negative word indices, the following negative values
* may be inserted:
* kMinorRunStart Start of minor direction text.
* kMinorRunEnd End of minor direction text.
* kComplexWord The previous word contains both left-to-right and
* right-to-left characters and was treated as neutral.
*/
void CalculateTextlineOrder(bool paragraph_is_ltr,
const LTRResultIterator &resit,
GenericVectorEqEq *indices) const;
/** Same as above, but the caller's ssd gets filled in if ssd != NULL. */
void CalculateTextlineOrder(bool paragraph_is_ltr,
const LTRResultIterator &resit,
GenericVector *ssd,
GenericVectorEqEq *indices) const;
/**
* What is the index of the current word in a strict left-to-right reading
* of the row?
*/
int LTRWordIndex() const;
/**
* Given an iterator pointing at a word, returns the logical reading order
* of blob indices for the word.
*/
void CalculateBlobOrder(GenericVector *blob_indices) const;
/** Precondition: current_paragraph_is_ltr_ is set. */
void MoveToLogicalStartOfTextline();
/**
* Precondition: current_paragraph_is_ltr_ and in_minor_direction_
* are set.
*/
void MoveToLogicalStartOfWord();
/** Are we pointing at the final (reading order) symbol of the word? */
bool IsAtFinalSymbolOfWord() const;
/** Are we pointing at the first (reading order) symbol of the word? */
bool IsAtFirstSymbolOfWord() const;
/**
* Append any extra marks that should be appended to this word when printed.
* Mostly, these are Unicode BiDi control characters.
*/
void AppendSuffixMarks(STRING *text) const;
/** Appends the current word in reading order to the given buffer.*/
void AppendUTF8WordText(STRING *text) const;
/**
* Appends the text of the current text line, *assuming this iterator is
* positioned at the beginning of the text line* This function
* updates the iterator to point to the first position past the text line.
* Each textline is terminated in a single newline character.
* If the textline ends a paragraph, it gets a second terminal newline.
*/
void IterateAndAppendUTF8TextlineText(STRING *text);
/**
* Appends the text of the current paragraph in reading order
* to the given buffer.
* Each textline is terminated in a single newline character, and the
* paragraph gets an extra newline at the end.
*/
void AppendUTF8ParagraphText(STRING *text) const;
/** Returns whether the bidi_debug flag is set to at least min_level. */
bool BidiDebug(int min_level) const;
bool current_paragraph_is_ltr_;
/**
* Is the currently pointed-at character at the beginning of
* a minor-direction run?
*/
bool at_beginning_of_minor_run_;
/** Is the currently pointed-at character in a minor-direction sequence? */
bool in_minor_direction_;
};
} // namespace tesseract.
#endif // TESSERACT_CCMAIN_RESULT_ITERATOR_H__
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