--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/textord/edgloop.cpp	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,157 @@
+/**********************************************************************
+ * File:        edgloop.cpp  (Formerly edgeloop.c)
+ * Description: Functions to clean up an outline before approximation.
+ * Author:      Ray Smith
+ *
+ * (C) Copyright 1991, Hewlett-Packard Ltd.
+ ** 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.
+ *
+ **********************************************************************/
+
+// Include automatically generated configuration file if running autoconf.
+#ifdef HAVE_CONFIG_H
+#  include "config_auto.h"
+#endif
+
+#include "scanedg.h"
+
+#include "edgloop.h"
+
+namespace tesseract {
+
+#define MINEDGELENGTH 8 // min decent length
+
+/**********************************************************************
+ * complete_edge
+ *
+ * Complete the edge by cleaning it up.
+ **********************************************************************/
+
+void complete_edge(CRACKEDGE *start, // start of loop
+                   C_OUTLINE_IT *outline_it) {
+  ScrollView::Color colour; // colour to draw in
+  int16_t looplength;       // steps in loop
+  ICOORD botleft;           // bounding box
+  ICOORD topright;
+  C_OUTLINE *outline; // new outline
+
+  // check length etc.
+  colour = check_path_legal(start);
+
+  if (colour == ScrollView::RED || colour == ScrollView::BLUE) {
+    looplength = loop_bounding_box(start, botleft, topright);
+    outline = new C_OUTLINE(start, botleft, topright, looplength);
+    // add to list
+    outline_it->add_after_then_move(outline);
+  }
+}
+
+/**********************************************************************
+ * check_path_legal
+ *
+ * Check that the outline is legal for length and for chaincode sum.
+ * The return value is RED for a normal black-inside outline,
+ * BLUE for a white-inside outline, MAGENTA if it is too short,
+ * YELLOW if it is too long, and GREEN if it is illegal.
+ * These colours are used to draw the raw outline.
+ **********************************************************************/
+
+ScrollView::Color check_path_legal( // certify outline
+    CRACKEDGE *start                // start of loop
+) {
+  int lastchain;     // last chain code
+  int chaindiff;     // chain code diff
+  int32_t length;    // length of loop
+  int32_t chainsum;  // sum of chain diffs
+  CRACKEDGE *edgept; // current point
+  constexpr ERRCODE ED_ILLEGAL_SUM("Illegal sum of chain codes");
+
+  length = 0;
+  chainsum = 0; // sum of chain codes
+  edgept = start;
+  lastchain = edgept->prev->stepdir; // previous chain code
+  do {
+    length++;
+    if (edgept->stepdir != lastchain) {
+      // chain code difference
+      chaindiff = edgept->stepdir - lastchain;
+      if (chaindiff > 2) {
+        chaindiff -= 4;
+      } else if (chaindiff < -2) {
+        chaindiff += 4;
+      }
+      chainsum += chaindiff; // sum differences
+      lastchain = edgept->stepdir;
+    }
+    edgept = edgept->next;
+  } while (edgept != start && length < C_OUTLINE::kMaxOutlineLength);
+
+  if ((chainsum != 4 && chainsum != -4) || edgept != start || length < MINEDGELENGTH) {
+    if (edgept != start) {
+      return ScrollView::YELLOW;
+    } else if (length < MINEDGELENGTH) {
+      return ScrollView::MAGENTA;
+    } else {
+      ED_ILLEGAL_SUM.error("check_path_legal", TESSLOG, "chainsum=%d", chainsum);
+      return ScrollView::GREEN;
+    }
+  }
+  // colour on inside
+  return chainsum < 0 ? ScrollView::BLUE : ScrollView::RED;
+}
+
+/**********************************************************************
+ * loop_bounding_box
+ *
+ * Find the bounding box of the edge loop.
+ **********************************************************************/
+
+int16_t loop_bounding_box( // get bounding box
+    CRACKEDGE *&start,     // edge loop
+    ICOORD &botleft,       // bounding box
+    ICOORD &topright) {
+  int16_t length;       // length of loop
+  int16_t leftmost;     // on top row
+  CRACKEDGE *edgept;    // current point
+  CRACKEDGE *realstart; // topleft start
+
+  edgept = start;
+  realstart = start;
+  botleft = topright = ICOORD(edgept->pos.x(), edgept->pos.y());
+  leftmost = edgept->pos.x();
+  length = 0; // coutn length
+  do {
+    edgept = edgept->next;
+    if (edgept->pos.x() < botleft.x()) {
+      // get bounding box
+      botleft.set_x(edgept->pos.x());
+    } else if (edgept->pos.x() > topright.x()) {
+      topright.set_x(edgept->pos.x());
+    }
+    if (edgept->pos.y() < botleft.y()) {
+      // get bounding box
+      botleft.set_y(edgept->pos.y());
+    } else if (edgept->pos.y() > topright.y()) {
+      realstart = edgept;
+      leftmost = edgept->pos.x();
+      topright.set_y(edgept->pos.y());
+    } else if (edgept->pos.y() == topright.y() && edgept->pos.x() < leftmost) {
+      // leftmost on line
+      leftmost = edgept->pos.x();
+      realstart = edgept;
+    }
+    length++; // count elements
+  } while (edgept != start);
+  start = realstart; // shift it to topleft
+  return length;
+}
+
+} // namespace tesseract