/////////////////////////////////////////////////////////////////////// // File: pageiterator.h // Description: Iterator for tesseract page structure that avoids using // tesseract internal data structures. // Author: Ray Smith // Created: Fri Feb 26 11:01:06 PST 2010 // // (C) Copyright 2010, 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_PAGEITERATOR_H__ #define TESSERACT_CCMAIN_PAGEITERATOR_H__ #include "publictypes.h" #include "platform.h" struct BlamerBundle; class C_BLOB_IT; class PAGE_RES; class PAGE_RES_IT; class WERD; struct Pix; struct Pta; namespace tesseract { class Tesseract; /** * Class to iterate over tesseract page structure, providing access to all * levels of the page hierarchy, without including any tesseract headers or * having to handle any tesseract structures. * 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. * See apitypes.h for the definition of PageIteratorLevel. * See also ResultIterator, derived from PageIterator, which adds in the * ability to access OCR output with text-specific methods. */ class TESS_API PageIterator { public: /** * page_res and tesseract come directly from the BaseAPI. * The rectangle parameters are copied indirectly from the Thresholder, * via the BaseAPI. They represent the coordinates of some rectangle in an * original image (in top-left-origin coordinates) and therefore the top-left * needs to be added to any output boxes in order to specify coordinates * in the original image. See TessBaseAPI::SetRectangle. * The scale and scaled_yres are in case the Thresholder scaled the image * rectangle prior to thresholding. Any coordinates in tesseract's image * must be divided by scale before adding (rect_left, rect_top). * The scaled_yres indicates the effective resolution of the binary image * that tesseract has been given by the Thresholder. * After the constructor, Begin has already been called. */ PageIterator(PAGE_RES* page_res, Tesseract* tesseract, int scale, int scaled_yres, int rect_left, int rect_top, int rect_width, int rect_height); virtual ~PageIterator(); /** * Page/ResultIterators may be copied! This makes it possible to iterate over * all the objects at a lower level, while maintaining an iterator to * objects at a higher level. These constructors DO NOT CALL Begin, so * iterations will continue from the location of src. */ PageIterator(const PageIterator& src); const PageIterator& operator=(const PageIterator& src); /** Are we positioned at the same location as other? */ bool PositionedAtSameWord(const PAGE_RES_IT* other) const; // ============= Moving around within the page ============. /** * Moves the iterator to point to the start of the page to begin an * iteration. */ virtual void Begin(); /** * Moves the iterator to the beginning of the paragraph. * This class implements this functionality by moving it to the zero indexed * blob of the first (leftmost) word on the first row of the paragraph. */ virtual void RestartParagraph(); /** * Return whether this iterator points anywhere in the first textline of a * paragraph. */ bool IsWithinFirstTextlineOfParagraph() const; /** * Moves the iterator to the beginning of the text line. * This class implements this functionality by moving it to the zero indexed * blob of the first (leftmost) word of the row. */ virtual void RestartRow(); /** * Moves to the start of the next object at the given level in the * page hierarchy, 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); /** * Returns true if the iterator is at the start of an object at the given * level. * * For instance, suppose an iterator it is pointed to the first symbol of the * first word of the third line of the second paragraph of the first block in * a page, then: * it.IsAtBeginningOf(RIL_BLOCK) = false * it.IsAtBeginningOf(RIL_PARA) = false * it.IsAtBeginningOf(RIL_TEXTLINE) = true * it.IsAtBeginningOf(RIL_WORD) = true * it.IsAtBeginningOf(RIL_SYMBOL) = true */ virtual bool IsAtBeginningOf(PageIteratorLevel level) const; /** * Returns whether the iterator is positioned at the last element in a * given level. (e.g. the last word in a line, the last line in a block) * * Here's some two-paragraph example * text. It starts off innocuously * enough but quickly turns bizarre. * The author inserts a cornucopia * of words to guard against confused * references. * * Now take an iterator it pointed to the start of "bizarre." * it.IsAtFinalElement(RIL_PARA, RIL_SYMBOL) = false * it.IsAtFinalElement(RIL_PARA, RIL_WORD) = true * it.IsAtFinalElement(RIL_BLOCK, RIL_WORD) = false */ virtual bool IsAtFinalElement(PageIteratorLevel level, PageIteratorLevel element) const; /** * Returns whether this iterator is positioned * before other: -1 * equal to other: 0 * after other: 1 */ int Cmp(const PageIterator &other) const; // ============= Accessing data ==============. // Coordinate system: // Integer coordinates are at the cracks between the pixels. // The top-left corner of the top-left pixel in the image is at (0,0). // The bottom-right corner of the bottom-right pixel in the image is at // (width, height). // Every bounding box goes from the top-left of the top-left contained // pixel to the bottom-right of the bottom-right contained pixel, so // the bounding box of the single top-left pixel in the image is: // (0,0)->(1,1). // If an image rectangle has been set in the API, then returned coordinates // relate to the original (full) image, rather than the rectangle. /** * Returns the bounding rectangle of the current object at the given level. * See comment on coordinate system above. * Returns false if there is no such object at the current position. * The returned bounding box is guaranteed to match the size and position * of the image returned by GetBinaryImage, but may clip foreground pixels * from a grey image. The padding argument to GetImage can be used to expand * the image to include more foreground pixels. See GetImage below. */ bool BoundingBox(PageIteratorLevel level, int* left, int* top, int* right, int* bottom) const; bool BoundingBox(PageIteratorLevel level, const int padding, int* left, int* top, int* right, int* bottom) const; /** * Returns the bounding rectangle of the object in a coordinate system of the * working image rectangle having its origin at (rect_left_, rect_top_) with * respect to the original image and is scaled by a factor scale_. */ bool BoundingBoxInternal(PageIteratorLevel level, int* left, int* top, int* right, int* bottom) const; /** Returns whether there is no object of a given level. */ bool Empty(PageIteratorLevel level) const; /** * Returns the type of the current block. See apitypes.h for * PolyBlockType. */ PolyBlockType BlockType() const; /** * Returns the polygon outline of the current block. The returned Pta must * be ptaDestroy-ed after use. Note that the returned Pta lists the vertices * of the polygon, and the last edge is the line segment between the last * point and the first point. NULL will be returned if the iterator is * at the end of the document or layout analysis was not used. */ Pta* BlockPolygon() const; /** * Returns a binary image of the current object at the given level. * The position and size match the return from BoundingBoxInternal, and so * this could be upscaled with respect to the original input image. * Use pixDestroy to delete the image after use. */ Pix* GetBinaryImage(PageIteratorLevel level) const; /** * Returns an image of the current object at the given level in greyscale * if available in the input. To guarantee a binary image use BinaryImage. * NOTE that in order to give the best possible image, the bounds are * expanded slightly over the binary connected component, by the supplied * padding, so the top-left position of the returned image is returned * in (left,top). These will most likely not match the coordinates * returned by BoundingBox. * If you do not supply an original image, you will get a binary one. * Use pixDestroy to delete the image after use. */ Pix* GetImage(PageIteratorLevel level, int padding, Pix* original_img, int* left, int* top) const; /** * Returns the baseline of the current object at the given level. * The baseline is the line that passes through (x1, y1) and (x2, y2). * WARNING: with vertical text, baselines may be vertical! * Returns false if there is no baseline at the current position. */ bool Baseline(PageIteratorLevel level, int* x1, int* y1, int* x2, int* y2) const; /** * Returns orientation for the block the iterator points to. * orientation, writing_direction, textline_order: see publictypes.h * deskew_angle: after rotating the block so the text orientation is * upright, how many radians does one have to rotate the * block anti-clockwise for it to be level? * -Pi/4 <= deskew_angle <= Pi/4 */ void Orientation(tesseract::Orientation *orientation, tesseract::WritingDirection *writing_direction, tesseract::TextlineOrder *textline_order, float *deskew_angle) const; /** * Returns information about the current paragraph, if available. * * justification - * LEFT if ragged right, or fully justified and script is left-to-right. * RIGHT if ragged left, or fully justified and script is right-to-left. * unknown if it looks like source code or we have very few lines. * is_list_item - * true if we believe this is a member of an ordered or unordered list. * is_crown - * true if the first line of the paragraph is aligned with the other * lines of the paragraph even though subsequent paragraphs have first * line indents. This typically indicates that this is the continuation * of a previous paragraph or that it is the very first paragraph in * the chapter. * first_line_indent - * For LEFT aligned paragraphs, the first text line of paragraphs of * this kind are indented this many pixels from the left edge of the * rest of the paragraph. * for RIGHT aligned paragraphs, the first text line of paragraphs of * this kind are indented this many pixels from the right edge of the * rest of the paragraph. * NOTE 1: This value may be negative. * NOTE 2: if *is_crown == true, the first line of this paragraph is * actually flush, and first_line_indent is set to the "common" * first_line_indent for subsequent paragraphs in this block * of text. */ void ParagraphInfo(tesseract::ParagraphJustification *justification, bool *is_list_item, bool *is_crown, int *first_line_indent) const; // If the current WERD_RES (it_->word()) is not NULL, sets the BlamerBundle // of the current word to the given pointer (takes ownership of the pointer) // and returns true. // Can only be used when iterating on the word level. bool SetWordBlamerBundle(BlamerBundle *blamer_bundle); protected: /** * Sets up the internal data for iterating the blobs of a new word, then * moves the iterator to the given offset. */ TESS_LOCAL void BeginWord(int offset); /** Pointer to the page_res owned by the API. */ PAGE_RES* page_res_; /** Pointer to the Tesseract object owned by the API. */ Tesseract* tesseract_; /** * The iterator to the page_res_. Owned by this ResultIterator. * A pointer just to avoid dragging in Tesseract includes. */ PAGE_RES_IT* it_; /** * The current input WERD being iterated. If there is an output from OCR, * then word_ is NULL. Owned by the API */ WERD* word_; /** The length of the current word_. */ int word_length_; /** The current blob index within the word. */ int blob_index_; /** * Iterator to the blobs within the word. If NULL, then we are iterating * OCR results in the box_word. * Owned by this ResultIterator. */ C_BLOB_IT* cblob_it_; /** Parameters saved from the Thresholder. Needed to rebuild coordinates.*/ int scale_; int scaled_yres_; int rect_left_; int rect_top_; int rect_width_; int rect_height_; }; } // namespace tesseract. #endif // TESSERACT_CCMAIN_PAGEITERATOR_H__