Revert "fix issue tesseract-ocr#1192"

This reverts commit ce88adb.

Author: Stefanie

src/ccstruct/pageres.cpp

@@ -1292,8 +1292,7 @@ WERD_RES* PAGE_RES_IT::InsertSimpleCloneWord(const WERD_RES& clone_res,
 // Helper computes the boundaries between blobs in the word. The blob bounds
 // are likely very poor, if they come from LSTM, where it only outputs the
 // character at one pixel within it, so we find the midpoints between them.
-static void ComputeBlobEnds(const WERD_RES& word, const TBOX& clip_box,
-                            C_BLOB_LIST* next_word_blobs,
+static void ComputeBlobEnds(const WERD_RES& word, C_BLOB_LIST* next_word_blobs,
                             GenericVector<int>* blob_ends) {
   C_BLOB_IT blob_it(word.word->cblob_list());
   for (int i = 0; i < word.best_state.size(); ++i) {
@@ -1313,74 +1312,8 @@ static void ComputeBlobEnds(const WERD_RES& word, const TBOX& clip_box,
         blob_it.set_to_list(next_word_blobs);
       blob_end = (blob_box.right() + blob_it.data()->bounding_box().left()) / 2;
     }
-    blob_end = ClipToRange<int>(blob_end, clip_box.left(), clip_box.right());
     blob_ends->push_back(blob_end);
   }
-  blob_ends->back() = clip_box.right();
-}
-
-// Helper computes the bounds of a word by restricting it to existing words
-// that significantly overlap.
-static TBOX ComputeWordBounds(const tesseract::PointerVector<WERD_RES>& words,
-                              int w_index, TBOX prev_box, WERD_RES_IT w_it) {
-  constexpr int kSignificantOverlapFraction = 4;
-  TBOX clipped_box;
-  TBOX current_box = words[w_index]->word->bounding_box();
-  TBOX next_box;
-  if (w_index + 1 < words.size() && words[w_index + 1] != nullptr &&
-      words[w_index + 1]->word != nullptr)
-    next_box = words[w_index + 1]->word->bounding_box();
-  for (w_it.forward(); !w_it.at_first() && w_it.data()->part_of_combo;
-       w_it.forward()) {
-    if (w_it.data() == nullptr || w_it.data()->word == nullptr) continue;
-    TBOX w_box = w_it.data()->word->bounding_box();
-    int height_limit = std::min<int>(w_box.height(), w_box.width() / 2);
-    int width_limit = w_box.width() / kSignificantOverlapFraction;
-    int min_significant_overlap = std::max(height_limit, width_limit);
-    int overlap = w_box.intersection(current_box).width();
-    int prev_overlap = w_box.intersection(prev_box).width();
-    int next_overlap = w_box.intersection(next_box).width();
-    if (overlap > min_significant_overlap) {
-      if (prev_overlap > min_significant_overlap) {
-        // We have no choice but to use the LSTM word edge.
-        clipped_box.set_left(current_box.left());
-      } else if (next_overlap > min_significant_overlap) {
-        // We have no choice but to use the LSTM word edge.
-        clipped_box.set_right(current_box.right());
-      } else {
-        clipped_box += w_box;
-      }
-    }
-  }
-  if (clipped_box.height() <= 0) {
-    clipped_box.set_top(current_box.top());
-    clipped_box.set_bottom(current_box.bottom());
-  }
-  if (clipped_box.width() <= 0) clipped_box = current_box;
-  return clipped_box;
-}
-
-// Helper moves the blob from src to dest. If it isn't contained by clip_box,
-// the blob is replaced by a fake that is contained.
-static TBOX MoveAndClipBlob(C_BLOB_IT* src_it, C_BLOB_IT* dest_it,
-                            const TBOX& clip_box) {
-  C_BLOB* src_blob = src_it->extract();
-  TBOX box = src_blob->bounding_box();
-  if (!clip_box.contains(box)) {
-    int left =
-        ClipToRange<int>(box.left(), clip_box.left(), clip_box.right() - 1);
-    int right =
-        ClipToRange<int>(box.right(), clip_box.left() + 1, clip_box.right());
-    int top =
-        ClipToRange<int>(box.top(), clip_box.bottom() + 1, clip_box.top());
-    int bottom =
-        ClipToRange<int>(box.bottom(), clip_box.bottom(), clip_box.top() - 1);
-    box = TBOX(left, bottom, right, top);
-    delete src_blob;
-    src_blob = C_BLOB::FakeBlob(box);
-  }
-  dest_it->add_after_then_move(src_blob);
-  return box;
 }
 
 // Replaces the current WERD/WERD_RES with the given words. The given words
@@ -1431,45 +1364,66 @@ void PAGE_RES_IT::ReplaceCurrentWord(
   src_b_it.sort(&C_BLOB::SortByXMiddle);
   C_BLOB_IT rej_b_it(input_word->word->rej_cblob_list());
   rej_b_it.sort(&C_BLOB::SortByXMiddle);
-  TBOX clip_box;
   for (int w = 0; w < words->size(); ++w) {
     WERD_RES* word_w = (*words)[w];
-    clip_box = ComputeWordBounds(*words, w, clip_box, wr_it_of_current_word);
     // Compute blob boundaries.
     GenericVector<int> blob_ends;
     C_BLOB_LIST* next_word_blobs =
         w + 1 < words->size() ? (*words)[w + 1]->word->cblob_list() : nullptr;
-    ComputeBlobEnds(*word_w, clip_box, next_word_blobs, &blob_ends);
-    // Remove the fake blobs on the current word, but keep safe for back-up if
-    // no blob can be found.
-    C_BLOB_LIST fake_blobs;
-    C_BLOB_IT fake_b_it(&fake_blobs);
-    fake_b_it.add_list_after(word_w->word->cblob_list());
-    fake_b_it.move_to_first();
+    ComputeBlobEnds(*word_w, next_word_blobs, &blob_ends);
+    // Delete the fake blobs on the current word.
     word_w->word->cblob_list()->clear();
     C_BLOB_IT dest_it(word_w->word->cblob_list());
     // Build the box word as we move the blobs.
     tesseract::BoxWord* box_word = new tesseract::BoxWord;
-    for (int i = 0; i < blob_ends.size(); ++i, fake_b_it.forward()) {
+    for (int i = 0; i < blob_ends.size(); ++i) {
       int end_x = blob_ends[i];
       TBOX blob_box;
       // Add the blobs up to end_x.
       while (!src_b_it.empty() &&
              src_b_it.data()->bounding_box().x_middle() < end_x) {
-        blob_box += MoveAndClipBlob(&src_b_it, &dest_it, clip_box);
+        blob_box += src_b_it.data()->bounding_box();
+        dest_it.add_after_then_move(src_b_it.extract());
         src_b_it.forward();
       }
       while (!rej_b_it.empty() &&
              rej_b_it.data()->bounding_box().x_middle() < end_x) {
-        blob_box += MoveAndClipBlob(&rej_b_it, &dest_it, clip_box);
+        blob_box += rej_b_it.data()->bounding_box();
+        dest_it.add_after_then_move(rej_b_it.extract());
         rej_b_it.forward();
       }
-      if (blob_box.null_box()) {
-        // Use the original box as a back-up.
-        blob_box = MoveAndClipBlob(&fake_b_it, &dest_it, clip_box);
-      }
+      // Clip to the previously computed bounds. Although imperfectly accurate,
+      // it is good enough, and much more complicated to determine where else
+      // to clip.
+      if (i > 0 && blob_box.left() < blob_ends[i - 1])
+        blob_box.set_left(blob_ends[i - 1]);
+      if (blob_box.right() > end_x)
+        blob_box.set_right(end_x);
       box_word->InsertBox(i, blob_box);
     }
+    // Fix empty boxes. If a very joined blob sits over multiple characters,
+    // then we will have some empty boxes from using the middle, so look for
+    // overlaps.
+    for (int i = 0; i < box_word->length(); ++i) {
+      TBOX box = box_word->BlobBox(i);
+      if (box.null_box()) {
+        // Nothing has its middle in the bounds of this blob, so use anything
+        // that overlaps.
+        for (dest_it.mark_cycle_pt(); !dest_it.cycled_list();
+             dest_it.forward()) {
+          TBOX blob_box = dest_it.data()->bounding_box();
+          if (blob_box.left() < blob_ends[i] &&
+              (i == 0 || blob_box.right() >= blob_ends[i - 1])) {
+            if (i > 0 && blob_box.left() < blob_ends[i - 1])
+              blob_box.set_left(blob_ends[i - 1]);
+            if (blob_box.right() > blob_ends[i])
+              blob_box.set_right(blob_ends[i]);
+            box_word->ChangeBox(i, blob_box);
+            break;
+          }
+        }
+      }
+    }
     delete word_w->box_word;
     word_w->box_word = box_word;
     if (!input_word->combination) {
@@ -1590,7 +1544,6 @@ void PAGE_RES_IT::ResetWordIterator() {
       }
     }
     ASSERT_HOST(!word_res_it.cycled_list());
-    wr_it_of_next_word = word_res_it;
     word_res_it.forward();
   } else {
     // word_res_it is OK, but reset word_res and prev_word_res if needed.
@@ -1628,7 +1581,6 @@ WERD_RES *PAGE_RES_IT::internal_forward(bool new_block, bool empty_ok) {
   block_res = next_block_res;
   row_res = next_row_res;
   word_res = next_word_res;
-  wr_it_of_current_word = wr_it_of_next_word;
   next_block_res = nullptr;
   next_row_res = nullptr;
   next_word_res = nullptr;
@@ -1657,7 +1609,6 @@ WERD_RES *PAGE_RES_IT::internal_forward(bool new_block, bool empty_ok) {
         next_block_res = block_res_it.data();
         next_row_res = row_res_it.data();
         next_word_res = word_res_it.data();
-        wr_it_of_next_word = word_res_it;
         word_res_it.forward();
         goto foundword;
       }

src/ccstruct/pageres.h

@@ -787,9 +787,5 @@ class PAGE_RES_IT {
   BLOCK_RES_IT block_res_it;   // iterators
   ROW_RES_IT row_res_it;
   WERD_RES_IT word_res_it;
-  // Iterators used to get the state of word_res_it for the current word.
-  // Since word_res_it is 2 words further on, this is otherwise hard to do.
-  WERD_RES_IT wr_it_of_current_word;
-  WERD_RES_IT wr_it_of_next_word;
 };
 #endif