Merge pull request #3330 from Sintun/master

Enable api access to table detector results, resolves #1714

Makefile.am

@@ -271,6 +271,7 @@ noinst_HEADERS += src/ccstruct/seam.h
 noinst_HEADERS += src/ccstruct/split.h
 noinst_HEADERS += src/ccstruct/statistc.h
 noinst_HEADERS += src/ccstruct/stepblob.h
+noinst_HEADERS += src/ccstruct/tabletransfer.h
 noinst_HEADERS += src/ccstruct/werd.h
 if !DISABLED_LEGACY_ENGINE
 noinst_HEADERS += src/ccstruct/fontinfo.h

include/tesseract/baseapi.h

@@ -34,6 +34,7 @@
 
 #include <cstdio>
 #include <vector> // for std::vector
+#include <tuple>  // for std::tuple
 
 struct Pix;
 struct Pixa;
@@ -531,6 +532,28 @@ public:
    * as UTF8 and must be freed with the delete [] operator.
    */
   char *GetUTF8Text();
+  
+  size_t GetNumberOfTables();
+  
+  /// Return the i-th table bounding box coordinates
+  ///
+  ///Gives the (top_left.x, top_left.y, bottom_right.x, bottom_right.y)
+  /// coordinates of the i-th table.
+  std::tuple<int,int,int,int> GetTableBoundingBox(
+    unsigned i///< Index of the table, for upper limit \see GetNumberOfTables()
+  );
+  
+  /// Get bounding boxes of the rows of a table
+  /// return values are (top_left.x, top_left.y, bottom_right.x, bottom_right.y)
+  std::vector<std::tuple<int,int,int,int> > GetTableRows(
+    unsigned i///< Index of the table, for upper limit \see GetNumberOfTables()
+  );
+  
+  /// Get bounding boxes of the cols of a table
+  /// return values are (top_left.x, top_left.y, bottom_right.x, bottom_right.y)
+  std::vector<std::tuple<int,int,int,int> > GetTableCols(
+    unsigned i///< Index of the table, for upper limit \see GetNumberOfTables()
+  );
 
   /**
    * Make a HTML-formatted string with hOCR markup from the internal

src/api/baseapi.cpp

@@ -59,6 +59,7 @@
 #include "tesseractclass.h"  // for Tesseract
 #include "tprintf.h"         // for tprintf
 #include "werd.h"            // for WERD, WERD_IT, W_FUZZY_NON, W_FUZZY_SP
+#include "tabletransfer.h"   // for detected tables from tablefind.h
 
 #include <tesseract/baseapi.h>
 #include <tesseract/ocrclass.h>       // for ETEXT_DESC
@@ -1294,6 +1295,62 @@ char *TessBaseAPI::GetUTF8Text() {
   return result;
 }
 
+size_t TessBaseAPI::GetNumberOfTables()
+{
+  return constUniqueInstance<std::vector<TessTable>>().size();
+}
+
+std::tuple<int,int,int,int> TessBaseAPI::GetTableBoundingBox(unsigned i)
+{
+  const std::vector<TessTable>& t = constUniqueInstance<std::vector<TessTable>>();
+  
+  if(i >= t.size())
+    return std::tuple<int,int,int,int>(0, 0, 0, 0);
+  
+  const int height = tesseract_->ImageHeight();
+  
+  return std::make_tuple<int,int,int,int>(
+    t[i].box.left(), height - t[i].box.top(),
+    t[i].box.right(), height - t[i].box.bottom());
+}
+
+
+std::vector<std::tuple<int,int,int,int>> TessBaseAPI::GetTableRows(unsigned i)
+{
+  const std::vector<TessTable>& t = constUniqueInstance<std::vector<TessTable>>();
+  
+  if(i >= t.size())
+    return std::vector<std::tuple<int,int,int,int>>();
+  
+  std::vector<std::tuple<int,int,int,int>> rows(t[i].rows.size());
+  const int height = tesseract_->ImageHeight();
+  
+  for(unsigned j = 0; j < t[i].rows.size(); ++j)
+    rows[j] = std::make_tuple<int,int,int,int>(
+      t[i].rows[j].left(), height - t[i].rows[j].top(),
+      t[i].rows[j].right(), height - t[i].rows[j].bottom());
+  
+  return rows;
+}
+
+std::vector<std::tuple<int,int,int,int> > TessBaseAPI::GetTableCols(unsigned i)
+{
+  const std::vector<TessTable>& t = constUniqueInstance<std::vector<TessTable>>();
+  
+  if(i >= t.size())
+    return std::vector<std::tuple<int,int,int,int>>();
+  
+  std::vector<std::tuple<int,int,int,int>> cols(t[i].cols.size());
+  const int height = tesseract_->ImageHeight();
+  
+  for(unsigned j = 0; j < t[i].cols.size(); ++j)
+    cols[j] = std::make_tuple<int,int,int,int>(
+      t[i].cols[j].left(), height - t[i].cols[j].top(),
+      t[i].cols[j].right(), height - t[i].cols[j].bottom());
+  
+  return cols;
+}
+
 static void AddBoxToTSV(const PageIterator *it, PageIteratorLevel level, std::string &text) {
   int left, top, right, bottom;
   it->BoundingBox(level, &left, &top, &right, &bottom);
@@ -2062,6 +2119,8 @@ void TessBaseAPI::ClearResults() {
     delete paragraph_models_;
     paragraph_models_ = nullptr;
   }
+
+  uniqueInstance<std::vector<TessTable>>().clear();
 }
 
 /**

src/ccstruct/tabletransfer.h

@@ -0,0 +1,66 @@
+/******************************************************************************
+ * File:        tabletransfer.h
+ * Description: Infrastructure for the transfer of table detection results
+ * Author:      Stefan Brechtken
+ *
+ * (C) Copyright 2021, Stefan Brechtken
+ * 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_CCSTRUCT_TABLETRANSFER_H_
+#define TESSERACT_CCSTRUCT_TABLETRANSFER_H_
+#include <memory>
+#include <vector>
+#include "rect.h"
+
+namespace tesseract {
+
+/// Structure for data transfer from table detector 
+struct TessTable {
+  tesseract::TBOX box;
+  std::vector<tesseract::TBOX> rows;
+  std::vector<tesseract::TBOX> cols;
+};
+
+/** \brief You can use this small template function to ensure that one and
+ *   only one object of type T exists. It implements the Singleton Pattern.
+ *
+ * T must be default-constructable.
+ * Usage examples:
+ *   A& a = uniqueInstance<A>();
+ *   a.xyz();
+ *   uniqueInstance<A>(make_unique<A>(42)); // replace instance
+ *   a.foo();
+ * or
+ *   uniqueInstance<A>().xyz();
+ */
+template<typename T>
+T& uniqueInstance(std::unique_ptr<T> new_instance = nullptr)
+{
+  static std::unique_ptr<T> _instance = std::make_unique<T>();
+
+  if(new_instance)
+    _instance = std::move(new_instance);
+
+  return *_instance.get();
+}
+
+/// return const version of \see uniqueInstance
+template<typename T>
+const T& constUniqueInstance(std::unique_ptr<T> new_instance = nullptr)
+{
+  return uniqueInstance<T>(std::move(new_instance));
+}
+
+} // namespace tesseract
+
+#endif  // TESSERACT_CCSTRUCT_TABLETRANSFER_H_

src/textord/colfind.cpp

@@ -38,6 +38,7 @@
 #include "strokewidth.h"
 #include "tablefind.h"
 #include "workingpartset.h"
+#include "tabletransfer.h"
 
 #include <algorithm>
 
@@ -1530,6 +1531,10 @@ void ColumnFinder::RotateAndReskewBlocks(bool input_is_rtl, TO_BLOCK_LIST *block
     if (textord_debug_tabfind >= 2)
       tprintf("Block median size = (%d, %d)\n", block->median_size().x(), block->median_size().y());
   }
+ 
+  std::vector<TessTable>& tables = uniqueInstance<std::vector<TessTable>>();
+  for(TessTable& mt: tables)
+    mt.box.rotate_large(reskew_);
 }
 
 // Computes the rotations for the block (to make textlines horizontal) and

src/textord/tablefind.cpp

@@ -28,6 +28,7 @@
 
 #include "colpartitionset.h"
 #include "tablerecog.h"
+#include "tabletransfer.h"
 
 namespace tesseract {
 
@@ -263,12 +264,13 @@ void TableFinder::LocateTables(ColPartitionGrid *grid, ColPartitionSet **all_col
 
 #ifndef GRAPHICS_DISABLED
   if (textord_show_tables) {
-    ScrollView *table_win = MakeWindow(0, 300, "Column Partitions & Neighbors");
+    ScrollView *table_win = MakeWindow(0, 300,
+                                       "Step 1: Column Partitions & Neighbors");
     DisplayColPartitions(table_win, &clean_part_grid_, ScrollView::BLUE);
     DisplayColPartitions(table_win, &leader_and_ruling_grid_, ScrollView::AQUAMARINE);
     DisplayColPartitionConnections(table_win, &clean_part_grid_, ScrollView::ORANGE);
 
-    table_win = MakeWindow(100, 300, "Fragmented Text");
+    table_win = MakeWindow(100, 300, "Step 2: Fragmented Text");
     DisplayColPartitions(table_win, &fragmented_text_grid_, ScrollView::BLUE);
   }
 #endif // !GRAPHICS_DISABLED
@@ -303,7 +305,8 @@ void TableFinder::LocateTables(ColPartitionGrid *grid, ColPartitionSet **all_col
 
 #ifndef GRAPHICS_DISABLED
   if (textord_tablefind_show_mark) {
-    ScrollView *table_win = MakeWindow(1200, 300, "Table Columns and Regions");
+    ScrollView *table_win = MakeWindow(1200, 300,
+                                       "Step 7: Table Columns and Regions");
     DisplayColSegments(table_win, &table_columns, ScrollView::DARK_TURQUOISE);
     DisplayColSegments(table_win, &table_regions, ScrollView::YELLOW);
   }
@@ -325,7 +328,8 @@ void TableFinder::LocateTables(ColPartitionGrid *grid, ColPartitionSet **all_col
 
 #ifndef GRAPHICS_DISABLED
     if (textord_show_tables) {
-      ScrollView *table_win = MakeWindow(1200, 300, "Detected Table Locations");
+      ScrollView *table_win = MakeWindow(1200, 300,
+                                         "Step 8: Detected Table Locations");
       DisplayColPartitions(table_win, &clean_part_grid_, ScrollView::BLUE);
       DisplayColSegments(table_win, &table_columns, ScrollView::KHAKI);
       table_grid_.DisplayBoxes(table_win);
@@ -339,8 +343,10 @@ void TableFinder::LocateTables(ColPartitionGrid *grid, ColPartitionSet **all_col
 
 #ifndef GRAPHICS_DISABLED
     if (textord_show_tables) {
-      ScrollView *table_win = MakeWindow(1400, 600, "Recognized Tables");
-      DisplayColPartitions(table_win, &clean_part_grid_, ScrollView::BLUE, ScrollView::BLUE);
+      ScrollView *table_win = MakeWindow(1400, 600,
+                                         "Step 10: Recognized Tables");
+      DisplayColPartitions(table_win, &clean_part_grid_,
+                           ScrollView::BLUE, ScrollView::BLUE);
       table_grid_.DisplayBoxes(table_win);
     }
 #endif // !GRAPHICS_DISABLED
@@ -353,8 +359,9 @@ void TableFinder::LocateTables(ColPartitionGrid *grid, ColPartitionSet **all_col
 
 #ifndef GRAPHICS_DISABLED
     if (textord_show_tables) {
-      ScrollView *table_win = MakeWindow(1500, 300, "Detected Tables");
-      DisplayColPartitions(table_win, &clean_part_grid_, ScrollView::BLUE, ScrollView::BLUE);
+      ScrollView *table_win = MakeWindow(1500, 300, "Step 11: Detected Tables");
+      DisplayColPartitions(table_win, &clean_part_grid_,
+                           ScrollView::BLUE, ScrollView::BLUE);
       table_grid_.DisplayBoxes(table_win);
     }
 #endif // !GRAPHICS_DISABLED
@@ -773,7 +780,8 @@ void TableFinder::MarkTablePartitions() {
   MarkPartitionsUsingLocalInformation();
 #ifndef GRAPHICS_DISABLED
   if (textord_tablefind_show_mark) {
-    ScrollView *table_win = MakeWindow(300, 300, "Initial Table Partitions");
+    ScrollView *table_win = MakeWindow(300, 300,
+                                       "Step 3: Initial Table Partitions");
     DisplayColPartitions(table_win, &clean_part_grid_, ScrollView::BLUE);
     DisplayColPartitions(table_win, &leader_and_ruling_grid_, ScrollView::AQUAMARINE);
   }
@@ -781,7 +789,8 @@ void TableFinder::MarkTablePartitions() {
   FilterFalseAlarms();
 #ifndef GRAPHICS_DISABLED
   if (textord_tablefind_show_mark) {
-    ScrollView *table_win = MakeWindow(600, 300, "Filtered Table Partitions");
+    ScrollView *table_win = MakeWindow(600, 300,
+                                       "Step 4: Filtered Table Partitions");
     DisplayColPartitions(table_win, &clean_part_grid_, ScrollView::BLUE);
     DisplayColPartitions(table_win, &leader_and_ruling_grid_, ScrollView::AQUAMARINE);
   }
@@ -789,7 +798,8 @@ void TableFinder::MarkTablePartitions() {
   SmoothTablePartitionRuns();
 #ifndef GRAPHICS_DISABLED
   if (textord_tablefind_show_mark) {
-    ScrollView *table_win = MakeWindow(900, 300, "Smoothed Table Partitions");
+    ScrollView *table_win = MakeWindow(900, 300,
+                                       "Step 5: Smoothed Table Partitions");
     DisplayColPartitions(table_win, &clean_part_grid_, ScrollView::BLUE);
     DisplayColPartitions(table_win, &leader_and_ruling_grid_, ScrollView::AQUAMARINE);
   }
@@ -797,7 +807,8 @@ void TableFinder::MarkTablePartitions() {
   FilterFalseAlarms();
 #ifndef GRAPHICS_DISABLED
   if (textord_tablefind_show_mark || textord_show_tables) {
-    ScrollView *table_win = MakeWindow(900, 300, "Final Table Partitions");
+    ScrollView *table_win = MakeWindow(900, 300,
+                                       "Step 6: Final Table Partitions");
     DisplayColPartitions(table_win, &clean_part_grid_, ScrollView::BLUE);
     DisplayColPartitions(table_win, &leader_and_ruling_grid_, ScrollView::AQUAMARINE);
   }
@@ -1774,7 +1785,7 @@ void TableFinder::RecognizeTables() {
   ScrollView *table_win = nullptr;
 #ifndef GRAPHICS_DISABLED
   if (textord_show_tables) {
-    table_win = MakeWindow(0, 0, "Table Structure");
+    table_win = MakeWindow(0, 0, "Step 9: Table Structure");
     DisplayColPartitions(table_win, &fragmented_text_grid_, ScrollView::BLUE,
                          ScrollView::LIGHT_BLUE);
     // table_grid_.DisplayBoxes(table_win);
@@ -1925,6 +1936,25 @@ void TableFinder::DisplayColPartitionConnections(ScrollView *win, ColPartitionGr
 // assigned to any table to their original types.
 void TableFinder::MakeTableBlocks(ColPartitionGrid *grid, ColPartitionSet **all_columns,
                                   WidthCallback width_cb) {
+#ifndef GRAPHICS_DISABLED
+  ScrollView* table_win = nullptr;
+  if (textord_show_tables) {
+    table_win = MakeWindow(0, 0, "Step 12: Final tables");
+    DisplayColPartitions(table_win, &fragmented_text_grid_,
+                         ScrollView::BLUE, ScrollView::LIGHT_BLUE);
+  }
+#endif  // GRAPHICS_DISABLED
+  
+  // initializing recognizer in order to extract table row and columnd info
+  TableRecognizer recognizer;
+  {
+    recognizer.Init();
+    recognizer.set_line_grid(&leader_and_ruling_grid_);
+    recognizer.set_text_grid(&fragmented_text_grid_);
+    recognizer.set_max_text_height(global_median_xheight_ * 2.0);
+    recognizer.set_min_height(1.5 * gridheight());
+  }
+  
   // Since we have table blocks already, remove table tags from all
   // colpartitions
   GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT> gsearch(grid);
@@ -1978,8 +2008,30 @@ void TableFinder::MakeTableBlocks(ColPartitionGrid *grid, ColPartitionSet **all_
       table_partition->set_flow(BTFT_CHAIN);
       table_partition->SetBlobTypes();
       grid->InsertBBox(true, true, table_partition);
+      
+      // Insert table columns and rows into an api accessible object
+      StructuredTable* table_structure = recognizer.RecognizeTable(table_box);
+      if (table_structure != nullptr) {
+#ifndef GRAPHICS_DISABLED
+      if (textord_show_tables) {
+        table_structure->Display(table_win, ScrollView::LIME_GREEN);
+      }
+#endif  // GRAPHICS_DISABLED
+
+        std::vector<TessTable>& tables = uniqueInstance<std::vector<TessTable>>();
+        tables.push_back(TessTable{table_box, table_structure->getRows(),
+                                            table_structure->getCols()});
+        
+        delete table_structure;
+      }
     }
   }
+  
+#ifndef GRAPHICS_DISABLED
+  if (textord_show_tables) {
+    table_grid_.DisplayBoxes(table_win);
+  }
+#endif  // GRAPHICS_DISABLED
 }
 
 //////// ColSegment code

src/textord/tablerecog.cpp

@@ -301,6 +301,37 @@ void StructuredTable::Display(ScrollView *window, ScrollView::Color color) {
 
 #endif
 
+std::vector<TBOX> StructuredTable::getRows()
+{
+  if(cell_y_.size() < 2)
+    return std::vector<TBOX>();
+  
+  std::vector<TBOX> rows(cell_y_.size() - 1);
+  unsigned ct = cell_y_.size() - 2;
+  for(unsigned i = 0; i + 1 < cell_y_.size(); i++) {
+    const ICOORD left(bounding_box_.left(), cell_y_[i]);
+    const ICOORD right(bounding_box_.right(), cell_y_[i + 1]);
+    rows[ct - i] = TBOX(left, right);
+  }
+ 
+  return rows;
+}
+
+std::vector<TBOX> StructuredTable::getCols()
+{
+  if(cell_x_.size() < 2)
+    return std::vector<TBOX>();
+  
+  std::vector<TBOX> cols(cell_x_.size() - 1);
+  for(unsigned i = 0; i + 1 < cell_x_.size(); i++) {
+    const ICOORD top(cell_x_[i], bounding_box_.top());
+    const ICOORD bot(cell_x_[i+1], bounding_box_.bottom());
+    cols[i] = TBOX(top, bot);
+  }
+ 
+  return cols;
+}
+
 // Clear structure information.
 void StructuredTable::ClearStructure() {
   cell_x_.clear();

src/textord/tablerecog.h

@@ -21,6 +21,7 @@
 #define TABLERECOG_H_
 
 #include "colpartitiongrid.h"
+#include <vector>
 
 namespace tesseract {
 
@@ -134,6 +135,11 @@ public:
   // Debug display, draws the table in the given color. If the table is not
   // valid, the table and "best" grid lines are still drawn in the given color.
   void Display(ScrollView *window, ScrollView::Color color);
+  
+  /// Calculate bounding boxes of the rows and return them.
+  std::vector<TBOX> getRows();
+  /// Calculate bounding boxes of the columns and return them.
+  std::vector<TBOX> getCols();
 
 protected:
   // Clear the structure information.