githubmirror/tesseract

src/api/baseapi.h
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zdenop
Improve ABI compatibility with version 4.1.0
10 ноя 2019, 22:27
10 ноя 2019, 22:2787291ff
///////////////////////////////////////////////////////////////////////
// File:        baseapi.h
// Description: Simple API for calling tesseract.
// Author:      Ray Smith
//
// (C) Copyright 2006, 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_API_BASEAPI_H_
#define TESSERACT_API_BASEAPI_H_

#include <cstdio>
// To avoid collision with other typenames include the ABSOLUTE MINIMUM
// complexity of includes here. Use forward declarations wherever possible
// and hide includes of complex types in baseapi.cpp.
#include "apitypes.h"
#include "pageiterator.h"
#include "platform.h"
#include "publictypes.h"
#include "resultiterator.h"
#include "serialis.h"
#include "tess_version.h"
#include "tesscallback.h"
#include "thresholder.h"
#include "unichar.h"

template <typename T> class GenericVector;
class PAGE_RES;
class PAGE_RES_IT;
class ParagraphModel;
struct BlamerBundle;
class BLOCK_LIST;
class DENORM;
class MATRIX;
class ROW;
class STRING;
class WERD;
struct Pix;
struct Box;
struct Pixa;
struct Boxa;
class ETEXT_DESC;
struct OSResults;
class TBOX;
class UNICHARSET;
class WERD_CHOICE_LIST;

struct INT_FEATURE_STRUCT;
using INT_FEATURE = INT_FEATURE_STRUCT *;
struct TBLOB;

namespace tesseract {

class Dawg;
class Dict;
class EquationDetect;
class PageIterator;
class LTRResultIterator;
class ResultIterator;
class MutableIterator;
class TessResultRenderer;
class Tesseract;
class Trie;
class Wordrec;

using DictFunc = int (Dict::*)(void *, const UNICHARSET &, UNICHAR_ID, bool) const;
using ProbabilityInContextFunc = double (Dict::*)(const char *, const char *, int, const char *, int);
using ParamsModelClassifyFunc = float (Dict::*)(const char *, void *);
using FillLatticeFunc = void (Wordrec::*)(const MATRIX &, const WERD_CHOICE_LIST &, const UNICHARSET &, BlamerBundle *);
typedef TessCallback4<const UNICHARSET &, int, PageIterator *, Pix *>
    TruthCallback;

/**
 * Base class for all tesseract APIs.
 * Specific classes can add ability to work on different inputs or produce
 * different outputs.
 * This class is mostly an interface layer on top of the Tesseract instance
 * class to hide the data types so that users of this class don't have to
 * include any other Tesseract headers.
 */
class TESS_API TessBaseAPI {
 public:
  TessBaseAPI();
  virtual ~TessBaseAPI();

  /**
   * Returns the version identifier as a static string. Do not delete.
   */
  static const char* Version();

  /**
   * If compiled with OpenCL AND an available OpenCL
   * device is deemed faster than serial code, then
   * "device" is populated with the cl_device_id
   * and returns sizeof(cl_device_id)
   * otherwise *device=nullptr and returns 0.
   */
  static size_t getOpenCLDevice(void **device);

  /**
   * Writes the thresholded image to stderr as a PBM file on receipt of a
   * SIGSEGV, SIGFPE, or SIGBUS signal. (Linux/Unix only).
   */
  static void CatchSignals();

  /**
   * Set the name of the input file. Needed for training and
   * reading a UNLV zone file, and for searchable PDF output.
   */
  void SetInputName(const char* name);
  /**
   * These functions are required for searchable PDF output.
   * We need our hands on the input file so that we can include
   * it in the PDF without transcoding. If that is not possible,
   * we need the original image. Finally, resolution metadata
   * is stored in the PDF so we need that as well.
   */
  const char* GetInputName();
  // Takes ownership of the input pix.
  void SetInputImage(Pix *pix);
  Pix* GetInputImage();
  int GetSourceYResolution();
  const char* GetDatapath();

  /** Set the name of the bonus output files. Needed only for debugging. */
  void SetOutputName(const char* name);

  /**
   * Set the value of an internal "parameter."
   * Supply the name of the parameter and the value as a string, just as
   * you would in a config file.
   * Returns false if the name lookup failed.
   * Eg SetVariable("tessedit_char_blacklist", "xyz"); to ignore x, y and z.
   * Or SetVariable("classify_bln_numeric_mode", "1"); to set numeric-only mode.
   * SetVariable may be used before Init, but settings will revert to
   * defaults on End().
   *
   * Note: Must be called after Init(). Only works for non-init variables
   * (init variables should be passed to Init()).
   */
  bool SetVariable(const char* name, const char* value);
  bool SetDebugVariable(const char* name, const char* value);

  /**
   * Returns true if the parameter was found among Tesseract parameters.
   * Fills in value with the value of the parameter.
   */
  bool GetIntVariable(const char *name, int *value) const;
  bool GetBoolVariable(const char *name, bool *value) const;
  bool GetDoubleVariable(const char *name, double *value) const;

  /**
   * Returns the pointer to the string that represents the value of the
   * parameter if it was found among Tesseract parameters.
   */
  const char *GetStringVariable(const char *name) const;

  /**
   * Print Tesseract parameters to the given file.
   */
  void PrintVariables(FILE *fp) const;

  /**
   * Get value of named variable as a string, if it exists.
   */
  bool GetVariableAsString(const char *name, STRING *val);

  /**
   * Instances are now mostly thread-safe and totally independent,
   * but some global parameters remain. Basically it is safe to use multiple
   * TessBaseAPIs in different threads in parallel, UNLESS:
   * you use SetVariable on some of the Params in classify and textord.
   * If you do, then the effect will be to change it for all your instances.
   *
   * Start tesseract. Returns zero on success and -1 on failure.
   * NOTE that the only members that may be called before Init are those
   * listed above here in the class definition.
   *
   * The datapath must be the name of the tessdata directory.
   * The language is (usually) an ISO 639-3 string or nullptr will default to eng.
   * It is entirely safe (and eventually will be efficient too) to call
   * Init multiple times on the same instance to change language, or just
   * to reset the classifier.
   * The language may be a string of the form [~]<lang>[+[~]<lang>]* indicating
   * that multiple languages are to be loaded. Eg hin+eng will load Hindi and
   * English. Languages may specify internally that they want to be loaded
   * with one or more other languages, so the ~ sign is available to override
   * that. Eg if hin were set to load eng by default, then hin+~eng would force
   * loading only hin. The number of loaded languages is limited only by
   * memory, with the caveat that loading additional languages will impact
   * both speed and accuracy, as there is more work to do to decide on the
   * applicable language, and there is more chance of hallucinating incorrect
   * words.
   * WARNING: On changing languages, all Tesseract parameters are reset
   * back to their default values. (Which may vary between languages.)
   * If you have a rare need to set a Variable that controls
   * initialization for a second call to Init you should explicitly
   * call End() and then use SetVariable before Init. This is only a very
   * rare use case, since there are very few uses that require any parameters
   * to be set before Init.
   *
   * If set_only_non_debug_params is true, only params that do not contain
   * "debug" in the name will be set.
   */
  int Init(const char* datapath, const char* language, OcrEngineMode mode,
           char **configs, int configs_size,
           const GenericVector<STRING> *vars_vec,
           const GenericVector<STRING> *vars_values,
           bool set_only_non_debug_params);
  int Init(const char* datapath, const char* language, OcrEngineMode oem) {
    return Init(datapath, language, oem, nullptr, 0, nullptr, nullptr, false);
  }
  int Init(const char* datapath, const char* language) {
    return Init(datapath, language, OEM_DEFAULT, nullptr, 0, nullptr, nullptr, false);
  }
  // In-memory version reads the traineddata file directly from the given
  // data[data_size] array, and/or reads data via a FileReader.
  int Init(const char* data, int data_size, const char* language,
           OcrEngineMode mode, char** configs, int configs_size,
           const GenericVector<STRING>* vars_vec,
           const GenericVector<STRING>* vars_values,
           bool set_only_non_debug_params, FileReader reader);

  /**
   * Returns the languages string used in the last valid initialization.
   * If the last initialization specified "deu+hin" then that will be
   * returned. If hin loaded eng automatically as well, then that will
   * not be included in this list. To find the languages actually
   * loaded use GetLoadedLanguagesAsVector.
   * The returned string should NOT be deleted.
   */
  const char* GetInitLanguagesAsString() const;

  /**
   * Returns the loaded languages in the vector of STRINGs.
   * Includes all languages loaded by the last Init, including those loaded
   * as dependencies of other loaded languages.
   */
  void GetLoadedLanguagesAsVector(GenericVector<STRING>* langs) const;

  /**
   * Returns the available languages in the sorted vector of STRINGs.
   */
  void GetAvailableLanguagesAsVector(GenericVector<STRING>* langs) const;

  /**
   * Init only the lang model component of Tesseract. The only functions
   * that work after this init are SetVariable and IsValidWord.
   * WARNING: temporary! This function will be removed from here and placed
   * in a separate API at some future time.
   */
  int InitLangMod(const char* datapath, const char* language);

  /**
   * Init only for page layout analysis. Use only for calls to SetImage and
   * AnalysePage. Calls that attempt recognition will generate an error.
   */
  void InitForAnalysePage();

  /**
   * Read a "config" file containing a set of param, value pairs.
   * Searches the standard places: tessdata/configs, tessdata/tessconfigs
   * and also accepts a relative or absolute path name.
   * Note: only non-init params will be set (init params are set by Init()).
   */
  void ReadConfigFile(const char* filename);
  /** Same as above, but only set debug params from the given config file. */
  void ReadDebugConfigFile(const char* filename);

  /**
   * Set the current page segmentation mode. Defaults to PSM_SINGLE_BLOCK.
   * The mode is stored as an IntParam so it can also be modified by
   * ReadConfigFile or SetVariable("tessedit_pageseg_mode", mode as string).
   */
  void SetPageSegMode(PageSegMode mode);

  /** Return the current page segmentation mode. */
  PageSegMode GetPageSegMode() const;

  /**
   * Recognize a rectangle from an image and return the result as a string.
   * May be called many times for a single Init.
   * Currently has no error checking.
   * Greyscale of 8 and color of 24 or 32 bits per pixel may be given.
   * Palette color images will not work properly and must be converted to
   * 24 bit.
   * Binary images of 1 bit per pixel may also be given but they must be
   * byte packed with the MSB of the first byte being the first pixel, and a
   * 1 represents WHITE. For binary images set bytes_per_pixel=0.
   * The recognized text is returned as a char* which is coded
   * as UTF8 and must be freed with the delete [] operator.
   *
   * Note that TesseractRect is the simplified convenience interface.
   * For advanced uses, use SetImage, (optionally) SetRectangle, Recognize,
   * and one or more of the Get*Text functions below.
   */
  char* TesseractRect(const unsigned char* imagedata,
                      int bytes_per_pixel, int bytes_per_line,
                      int left, int top, int width, int height);

  /**
   * Call between pages or documents etc to free up memory and forget
   * adaptive data.
   */
  void ClearAdaptiveClassifier();

  /**
   * @defgroup AdvancedAPI Advanced API
   * The following methods break TesseractRect into pieces, so you can
   * get hold of the thresholded image, get the text in different formats,
   * get bounding boxes, confidences etc.
   */
   /* @{ */

  /**
   * Provide an image for Tesseract to recognize. Format is as
   * TesseractRect above. Copies the image buffer and converts to Pix.
   * SetImage clears all recognition results, and sets the rectangle to the
   * full image, so it may be followed immediately by a GetUTF8Text, and it
   * will automatically perform recognition.
   */
  void SetImage(const unsigned char* imagedata, int width, int height,
                int bytes_per_pixel, int bytes_per_line);

  /**
   * Provide an image for Tesseract to recognize. As with SetImage above,
   * Tesseract takes its own copy of the image, so it need not persist until
   * after Recognize.
   * Pix vs raw, which to use?
   * Use Pix where possible. Tesseract uses Pix as its internal representation
   * and it is therefore more efficient to provide a Pix directly.
   */
  void SetImage(Pix* pix);

  /**
   * Set the resolution of the source image in pixels per inch so font size
   * information can be calculated in results.  Call this after SetImage().
   */
  void SetSourceResolution(int ppi);

  /**
   * Restrict recognition to a sub-rectangle of the image. Call after SetImage.
   * Each SetRectangle clears the recogntion results so multiple rectangles
   * can be recognized with the same image.
   */
  void SetRectangle(int left, int top, int width, int height);

  /**
   * In extreme cases only, usually with a subclass of Thresholder, it
   * is possible to provide a different Thresholder. The Thresholder may
   * be preloaded with an image, settings etc, or they may be set after.
   * Note that Tesseract takes ownership of the Thresholder and will
   * delete it when it it is replaced or the API is destructed.
   */
  void SetThresholder(ImageThresholder* thresholder) {
    delete thresholder_;
    thresholder_ = thresholder;
    ClearResults();
  }

  /**
   * Get a copy of the internal thresholded image from Tesseract.
   * Caller takes ownership of the Pix and must pixDestroy it.
   * May be called any time after SetImage, or after TesseractRect.
   */
  Pix* GetThresholdedImage();

  /**
   * Get the result of page layout analysis as a leptonica-style
   * Boxa, Pixa pair, in reading order.
   * Can be called before or after Recognize.
   */
  Boxa* GetRegions(Pixa** pixa);

  /**
   * Get the textlines as a leptonica-style
   * Boxa, Pixa pair, in reading order.
   * Can be called before or after Recognize.
   * If raw_image is true, then extract from the original image instead of the
   * thresholded image and pad by raw_padding pixels.
   * If blockids is not nullptr, the block-id of each line is also returned as an
   * array of one element per line. delete [] after use.
   * If paraids is not nullptr, the paragraph-id of each line within its block is
   * also returned as an array of one element per line. delete [] after use.
   */
  Boxa* GetTextlines(bool raw_image, int raw_padding,
                     Pixa** pixa, int** blockids, int** paraids);
  /*
     Helper method to extract from the thresholded image. (most common usage)
  */
  Boxa* GetTextlines(Pixa** pixa, int** blockids) {
    return GetTextlines(false, 0, pixa, blockids, nullptr);
  }

  /**
   * Get textlines and strips of image regions as a leptonica-style Boxa, Pixa
   * pair, in reading order. Enables downstream handling of non-rectangular
   * regions.
   * Can be called before or after Recognize.
   * If blockids is not nullptr, the block-id of each line is also returned as an
   * array of one element per line. delete [] after use.
   */
  Boxa* GetStrips(Pixa** pixa, int** blockids);

  /**
   * Get the words as a leptonica-style
   * Boxa, Pixa pair, in reading order.
   * Can be called before or after Recognize.
   */
  Boxa* GetWords(Pixa** pixa);

  /**
   * Gets the individual connected (text) components (created
   * after pages segmentation step, but before recognition)
   * as a leptonica-style Boxa, Pixa pair, in reading order.
   * Can be called before or after Recognize.
   * Note: the caller is responsible for calling boxaDestroy()
   * on the returned Boxa array and pixaDestroy() on cc array.
   */
  Boxa* GetConnectedComponents(Pixa** cc);

  /**
   * Get the given level kind of components (block, textline, word etc.) as a
   * leptonica-style Boxa, Pixa pair, in reading order.
   * Can be called before or after Recognize.
   * If blockids is not nullptr, the block-id of each component is also returned
   * as an array of one element per component. delete [] after use.
   * If blockids is not nullptr, the paragraph-id of each component with its block
   * is also returned as an array of one element per component. delete [] after
   * use.
   * If raw_image is true, then portions of the original image are extracted
   * instead of the thresholded image and padded with raw_padding.
   * If text_only is true, then only text components are returned.
   */
  Boxa* GetComponentImages(PageIteratorLevel level,
                           bool text_only, bool raw_image,
                           int raw_padding,
                           Pixa** pixa, int** blockids, int** paraids);
  // Helper function to get binary images with no padding (most common usage).
  Boxa* GetComponentImages(const PageIteratorLevel level,
                           const bool text_only,
                           Pixa** pixa, int** blockids) {
    return GetComponentImages(level, text_only, false, 0, pixa, blockids, nullptr);
  }

  /**
   * Returns the scale factor of the thresholded image that would be returned by
   * GetThresholdedImage() and the various GetX() methods that call
   * GetComponentImages().
   * Returns 0 if no thresholder has been set.
   */
  int GetThresholdedImageScaleFactor() const;

  /**
   * Runs page layout analysis in the mode set by SetPageSegMode.
   * May optionally be called prior to Recognize to get access to just
   * the page layout results. Returns an iterator to the results.
   * If merge_similar_words is true, words are combined where suitable for use
   * with a line recognizer. Use if you want to use AnalyseLayout to find the
   * textlines, and then want to process textline fragments with an external
   * line recognizer.
   * Returns nullptr on error or an empty page.
   * The returned iterator must be deleted after use.
   * WARNING! This class points to data held within the TessBaseAPI class, and
   * therefore can only be used while the TessBaseAPI class still exists and
   * has not been subjected to a call of Init, SetImage, Recognize, Clear, End
   * DetectOS, or anything else that changes the internal PAGE_RES.
   */
  PageIterator* AnalyseLayout();
  PageIterator* AnalyseLayout(bool merge_similar_words);

  /**
   * Recognize the image from SetAndThresholdImage, generating Tesseract
   * internal structures. Returns 0 on success.
   * Optional. The Get*Text functions below will call Recognize if needed.
   * After Recognize, the output is kept internally until the next SetImage.
   */
  int Recognize(ETEXT_DESC* monitor);

  /**
   * Methods to retrieve information after SetAndThresholdImage(),
   * Recognize() or TesseractRect(). (Recognize is called implicitly if needed.)
   */

  #ifndef DISABLED_LEGACY_ENGINE
  /** Variant on Recognize used for testing chopper. */
  int RecognizeForChopTest(ETEXT_DESC* monitor);
  #endif

  /**
   * Turns images into symbolic text.
   *
   * filename can point to a single image, a multi-page TIFF,
   * or a plain text list of image filenames.
   *
   * retry_config is useful for debugging. If not nullptr, you can fall
   * back to an alternate configuration if a page fails for some
   * reason.
   *
   * timeout_millisec terminates processing if any single page
   * takes too long. Set to 0 for unlimited time.
   *
   * renderer is responible for creating the output. For example,
   * use the TessTextRenderer if you want plaintext output, or
   * the TessPDFRender to produce searchable PDF.
   *
   * If tessedit_page_number is non-negative, will only process that
   * single page. Works for multi-page tiff file, or filelist.
   *
   * Returns true if successful, false on error.
   */
  bool ProcessPages(const char* filename, const char* retry_config,
                    int timeout_millisec, TessResultRenderer* renderer);
  // Does the real work of ProcessPages.
  bool ProcessPagesInternal(const char* filename, const char* retry_config,
                            int timeout_millisec, TessResultRenderer* renderer);

  /**
   * Turn a single image into symbolic text.
   *
   * The pix is the image processed. filename and page_index are
   * metadata used by side-effect processes, such as reading a box
   * file or formatting as hOCR.
   *
   * See ProcessPages for desciptions of other parameters.
   */
  bool ProcessPage(Pix* pix, int page_index, const char* filename,
                   const char* retry_config, int timeout_millisec,
                   TessResultRenderer* renderer);

  /**
   * Get a reading-order iterator to the results of LayoutAnalysis and/or
   * Recognize. The returned iterator must be deleted after use.
   * WARNING! This class points to data held within the TessBaseAPI class, and
   * therefore can only be used while the TessBaseAPI class still exists and
   * has not been subjected to a call of Init, SetImage, Recognize, Clear, End
   * DetectOS, or anything else that changes the internal PAGE_RES.
   */
  ResultIterator* GetIterator();

  /**
   * Get a mutable iterator to the results of LayoutAnalysis and/or Recognize.
   * The returned iterator must be deleted after use.
   * WARNING! This class points to data held within the TessBaseAPI class, and
   * therefore can only be used while the TessBaseAPI class still exists and
   * has not been subjected to a call of Init, SetImage, Recognize, Clear, End
   * DetectOS, or anything else that changes the internal PAGE_RES.
   */
  MutableIterator* GetMutableIterator();

  /**
   * The recognized text is returned as a char* which is coded
   * as UTF8 and must be freed with the delete [] operator.
   */
  char* GetUTF8Text();

  /**
   * Make a HTML-formatted string with hOCR markup from the internal
   * data structures.
   * page_number is 0-based but will appear in the output as 1-based.
   * monitor can be used to
   *  cancel the recognition
   *  receive progress callbacks
   * Returned string must be freed with the delete [] operator.
   */
  char* GetHOCRText(ETEXT_DESC* monitor, int page_number);

  /**
   * Make a HTML-formatted string with hOCR markup from the internal
   * data structures.
   * page_number is 0-based but will appear in the output as 1-based.
   * Returned string must be freed with the delete [] operator.
   */
  char* GetHOCRText(int page_number);

  /**
   * Make an XML-formatted string with Alto markup from the internal
   * data structures.
   */
  char* GetAltoText(ETEXT_DESC* monitor, int page_number);


  /**
   * Make an XML-formatted string with Alto markup from the internal
   * data structures.
   */
  char* GetAltoText(int page_number);

  /**
   * Make a TSV-formatted string from the internal data structures.
   * page_number is 0-based but will appear in the output as 1-based.
   * Returned string must be freed with the delete [] operator.
   */
  char* GetTSVText(int page_number);

  /**
   * Make a box file for LSTM training from the internal data structures.
   * Constructs coordinates in the original image - not just the rectangle.
   * page_number is a 0-based page index that will appear in the box file.
   * Returned string must be freed with the delete [] operator.
   */
  char* GetLSTMBoxText(int page_number);

  /**
   * The recognized text is returned as a char* which is coded in the same
   * format as a box file used in training.
   * Constructs coordinates in the original image - not just the rectangle.
   * page_number is a 0-based page index that will appear in the box file.
   * Returned string must be freed with the delete [] operator.
   */
  char* GetBoxText(int page_number);

  /**
   * The recognized text is returned as a char* which is coded in the same
   * format as a WordStr box file used in training.
   * page_number is a 0-based page index that will appear in the box file.
   * Returned string must be freed with the delete [] operator.
   */
  char* GetWordStrBoxText(int page_number);

  /**
   * The recognized text is returned as a char* which is coded
   * as UNLV format Latin-1 with specific reject and suspect codes.
   * Returned string must be freed with the delete [] operator.
   */
  char* GetUNLVText();

  /**
   * Detect the orientation of the input image and apparent script (alphabet).
   * orient_deg is the detected clockwise rotation of the input image in degrees
   * (0, 90, 180, 270)
   * orient_conf is the confidence (15.0 is reasonably confident)
   * script_name is an ASCII string, the name of the script, e.g. "Latin"
   * script_conf is confidence level in the script
   * Returns true on success and writes values to each parameter as an output
   */
  bool DetectOrientationScript(int* orient_deg, float* orient_conf,
                               const char** script_name, float* script_conf);

  /**
   * The recognized text is returned as a char* which is coded
   * as UTF8 and must be freed with the delete [] operator.
   * page_number is a 0-based page index that will appear in the osd file.
   */
  char* GetOsdText(int page_number);

  /** Returns the (average) confidence value between 0 and 100. */
  int MeanTextConf();
  /**
   * Returns all word confidences (between 0 and 100) in an array, terminated
   * by -1.  The calling function must delete [] after use.
   * The number of confidences should correspond to the number of space-
   * delimited words in GetUTF8Text.
   */
  int* AllWordConfidences();

#ifndef DISABLED_LEGACY_ENGINE
  /**
   * Applies the given word to the adaptive classifier if possible.
   * The word must be SPACE-DELIMITED UTF-8 - l i k e t h i s , so it can
   * tell the boundaries of the graphemes.
   * Assumes that SetImage/SetRectangle have been used to set the image
   * to the given word. The mode arg should be PSM_SINGLE_WORD or
   * PSM_CIRCLE_WORD, as that will be used to control layout analysis.
   * The currently set PageSegMode is preserved.
   * Returns false if adaption was not possible for some reason.
   */
  bool AdaptToWordStr(PageSegMode mode, const char* wordstr);
#endif  //  ndef DISABLED_LEGACY_ENGINE

  /**
   * Free up recognition results and any stored image data, without actually
   * freeing any recognition data that would be time-consuming to reload.
   * Afterwards, you must call SetImage or TesseractRect before doing
   * any Recognize or Get* operation.
   */
  void Clear();

  /**
   * Close down tesseract and free up all memory. End() is equivalent to
   * destructing and reconstructing your TessBaseAPI.
   * Once End() has been used, none of the other API functions may be used
   * other than Init and anything declared above it in the class definition.
   */
  void End();

  /**
   * Clear any library-level memory caches.
   * There are a variety of expensive-to-load constant data structures (mostly
   * language dictionaries) that are cached globally -- surviving the Init()
   * and End() of individual TessBaseAPI's.  This function allows the clearing
   * of these caches.
   **/
  static void ClearPersistentCache();

  /**
   * Check whether a word is valid according to Tesseract's language model
   * @return 0 if the word is invalid, non-zero if valid.
   * @warning temporary! This function will be removed from here and placed
   * in a separate API at some future time.
   */
  int IsValidWord(const char *word);
  // Returns true if utf8_character is defined in the UniCharset.
  bool IsValidCharacter(const char *utf8_character);


  bool GetTextDirection(int* out_offset, float* out_slope);

  /** Sets Dict::letter_is_okay_ function to point to the given function. */
  void SetDictFunc(DictFunc f);

  /** Sets Dict::probability_in_context_ function to point to the given
   * function.
   */
  void SetProbabilityInContextFunc(ProbabilityInContextFunc f);

  /**
   * Estimates the Orientation And Script of the image.
   * @return true if the image was processed successfully.
   */
  bool DetectOS(OSResults*);

  /**
   * Return text orientation of each block as determined by an earlier run
   * of layout analysis.
   */
  void GetBlockTextOrientations(int** block_orientation,
                                bool** vertical_writing);


  #ifndef DISABLED_LEGACY_ENGINE

  /** Sets Wordrec::fill_lattice_ function to point to the given function. */
  void SetFillLatticeFunc(FillLatticeFunc f);

  /** Find lines from the image making the BLOCK_LIST. */
  BLOCK_LIST* FindLinesCreateBlockList();

  /**
   * Delete a block list.
   * This is to keep BLOCK_LIST pointer opaque
   * and let go of including the other headers.
   */
  static void DeleteBlockList(BLOCK_LIST* block_list);

  /** Returns a ROW object created from the input row specification. */
  static ROW *MakeTessOCRRow(float baseline, float xheight,
                             float descender, float ascender);

  /** Returns a TBLOB corresponding to the entire input image. */
  static TBLOB *MakeTBLOB(Pix *pix);

  /**
   * This method baseline normalizes a TBLOB in-place. The input row is used
   * for normalization. The denorm is an optional parameter in which the
   * normalization-antidote is returned.
   */
  static void NormalizeTBLOB(TBLOB *tblob, ROW *row, bool numeric_mode);

  /** This method returns the features associated with the input image. */
  void GetFeaturesForBlob(TBLOB* blob, INT_FEATURE_STRUCT* int_features,
                          int* num_features, int* feature_outline_index);

  /**
   * This method returns the row to which a box of specified dimensions would
   * belong. If no good match is found, it returns nullptr.
   */
  static ROW* FindRowForBox(BLOCK_LIST* blocks, int left, int top,
                            int right, int bottom);

  /**
   * Method to run adaptive classifier on a blob.
   * It returns at max num_max_matches results.
   */
  void RunAdaptiveClassifier(TBLOB* blob,
                             int num_max_matches,
                             int* unichar_ids,
                             float* ratings,
                             int* num_matches_returned);
#endif  // ndef DISABLED_LEGACY_ENGINE

  /** This method returns the string form of the specified unichar. */
  const char* GetUnichar(int unichar_id);

  /** Return the pointer to the i-th dawg loaded into tesseract_ object. */
  const Dawg *GetDawg(int i) const;

  /** Return the number of dawgs loaded into tesseract_ object. */
  int NumDawgs() const;

  Tesseract* tesseract() const { return tesseract_; }

  OcrEngineMode oem() const { return last_oem_requested_; }

  void InitTruthCallback(TruthCallback *cb) { truth_cb_ = cb; }

  void set_min_orientation_margin(double margin);
 /* @} */

 protected:

  /** Common code for setting the image. Returns true if Init has been called. */
  TESS_LOCAL bool InternalSetImage();

  /**
   * Run the thresholder to make the thresholded image. If pix is not nullptr,
   * the source is thresholded to pix instead of the internal IMAGE.
   */
  TESS_LOCAL virtual bool Threshold(Pix** pix);

  /**
   * Find lines from the image making the BLOCK_LIST.
   * @return 0 on success.
   */
  TESS_LOCAL int FindLines();

  /** Delete the pageres and block list ready for a new page. */
  void ClearResults();

  /**
   * Return an LTR Result Iterator -- used only for training, as we really want
   * to ignore all BiDi smarts at that point.
   * delete once you're done with it.
   */
  TESS_LOCAL LTRResultIterator* GetLTRIterator();

  /**
   * Return the length of the output text string, as UTF8, assuming
   * one newline per line and one per block, with a terminator,
   * and assuming a single character reject marker for each rejected character.
   * Also return the number of recognized blobs in blob_count.
   */
  TESS_LOCAL int TextLength(int* blob_count);

  //// paragraphs.cpp ////////////////////////////////////////////////////
  TESS_LOCAL void DetectParagraphs(bool after_text_recognition);

  #ifndef DISABLED_LEGACY_ENGINE

  /** @defgroup ocropusAddOns ocropus add-ons */
  /* @{ */

  /**
   * Adapt to recognize the current image as the given character.
   * The image must be preloaded and be just an image of a single character.
   */
  TESS_LOCAL void AdaptToCharacter(const char *unichar_repr,
                                   int length,
                                   float baseline,
                                   float xheight,
                                   float descender,
                                   float ascender);

  /** Recognize text doing one pass only, using settings for a given pass. */
  TESS_LOCAL PAGE_RES* RecognitionPass1(BLOCK_LIST* block_list);

  TESS_LOCAL PAGE_RES* RecognitionPass2(BLOCK_LIST* block_list,
                                        PAGE_RES* pass1_result);

  /**
   * Extract the OCR results, costs (penalty points for uncertainty),
   * and the bounding boxes of the characters.
   */
  TESS_LOCAL static int TesseractExtractResult(char** text,
                                    int** lengths,
                                    float** costs,
                                    int** x0,
                                    int** y0,
                                    int** x1,
                                    int** y1,
                                    PAGE_RES* page_res);

  TESS_LOCAL const PAGE_RES* GetPageRes() const { return page_res_; }
  /* @} */
#endif  // ndef DISABLED_LEGACY_ENGINE

 protected:
  Tesseract*        tesseract_;       ///< The underlying data object.
  Tesseract*        osd_tesseract_;   ///< For orientation & script detection.
  EquationDetect*   equ_detect_;      ///<The equation detector.
  FileReader reader_;                 ///< Reads files from any filesystem.
  ImageThresholder* thresholder_;     ///< Image thresholding module.
  GenericVector<ParagraphModel *>* paragraph_models_;
  BLOCK_LIST*       block_list_;      ///< The page layout.
  PAGE_RES*         page_res_;        ///< The page-level data.
  STRING*           input_file_;      ///< Name used by training code.
  STRING*           output_file_;     ///< Name used by debug code.
  STRING*           datapath_;        ///< Current location of tessdata.
  STRING*           language_;        ///< Last initialized language.
  OcrEngineMode last_oem_requested_;  ///< Last ocr language mode requested.
  bool          recognition_done_;   ///< page_res_ contains recognition data.
  TruthCallback *truth_cb_;           /// fxn for setting truth_* in WERD_RES

  /**
   * @defgroup ThresholderParams Thresholder Parameters
   * Parameters saved from the Thresholder. Needed to rebuild coordinates.
   */
  /* @{ */
  int rect_left_;
  int rect_top_;
  int rect_width_;
  int rect_height_;
  int image_width_;
  int image_height_;
  /* @} */

 private:
  // A list of image filenames gets special consideration
  bool ProcessPagesFileList(FILE *fp,
                            STRING *buf,
                            const char* retry_config, int timeout_millisec,
                            TessResultRenderer* renderer,
                            int tessedit_page_number);
  // TIFF supports multipage so gets special consideration.
  bool ProcessPagesMultipageTiff(const unsigned char *data,
                                 size_t size,
                                 const char* filename,
                                 const char* retry_config,
                                 int timeout_millisec,
                                 TessResultRenderer* renderer,
                                 int tessedit_page_number);
  // There's currently no way to pass a document title from the
  // Tesseract command line, and we have multiple places that choose
  // to set the title to an empty string. Using a single named
  // variable will hopefully reduce confusion if the situation changes
  // in the future.
  const char *unknown_title_ = "";
};  // class TessBaseAPI.

/** Escape a char string - remove &<>"' with HTML codes. */
STRING HOcrEscape(const char* text);
}  // namespace tesseract.

#endif  // TESSERACT_API_BASEAPI_H_