--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/textord/blkocc.cpp	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,159 @@
+/*****************************************************************************
+ *
+ * File:         blkocc.cpp  (Formerly blockocc.c)
+ * Description:  Block Occupancy routines
+ * Author:       Chris Newton
+ *
+ * (c) Copyright 1991, Hewlett-Packard Company.
+ ** 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 "blkocc.h"
+
+#include "drawtord.h"
+#include "errcode.h"
+
+#include <cctype>
+#include <cmath>
+
+#include "helpers.h"
+
+namespace tesseract {
+
+double_VAR(textord_underline_threshold, 0.5, "Fraction of width occupied");
+
+// Forward declarations of static functions
+static void horizontal_cblob_projection(C_BLOB *blob,  // blob to project
+                                        STATS *stats); // output
+static void horizontal_coutline_projection(C_OUTLINE *outline,
+                                           STATS *stats); // output
+
+/**
+ * test_underline
+ *
+ * Check to see if the blob is an underline.
+ * Return true if it is.
+ */
+
+bool test_underline(  // look for underlines
+    bool testing_on,  ///< drawing blob
+    C_BLOB *blob,     ///< blob to test
+    int16_t baseline, ///< coords of baseline
+    int16_t xheight   ///< height of line
+) {
+  TDimension occ;
+  STATS projection;
+
+  auto blob_box = blob->bounding_box();
+  auto blob_width = blob->bounding_box().width();
+  projection.set_range(blob_box.bottom(), blob_box.top());
+  if (testing_on) {
+    //              blob->plot(to_win,GOLDENROD,GOLDENROD);
+    //              line_color_index(to_win,GOLDENROD);
+    //              move2d(to_win,blob_box.left(),baseline);
+    //              draw2d(to_win,blob_box.right(),baseline);
+    //              move2d(to_win,blob_box.left(),baseline+xheight);
+    //              draw2d(to_win,blob_box.right(),baseline+xheight);
+    tprintf("Testing underline on blob at (%d,%d)->(%d,%d), base=%d\nOccs:",
+            blob->bounding_box().left(), blob->bounding_box().bottom(),
+            blob->bounding_box().right(), blob->bounding_box().top(), baseline);
+  }
+  horizontal_cblob_projection(blob, &projection);
+  int32_t desc_occ = 0;
+  for (occ = blob_box.bottom(); occ < baseline; occ++) {
+    if (occ <= blob_box.top() && projection.pile_count(occ) > desc_occ) {
+      // max in region
+      desc_occ = projection.pile_count(occ);
+    }
+  }
+  int32_t x_occ = 0;
+  for (occ = baseline; occ <= baseline + xheight; occ++) {
+    if (occ >= blob_box.bottom() && occ <= blob_box.top() && projection.pile_count(occ) > x_occ) {
+      // max in region
+      x_occ = projection.pile_count(occ);
+    }
+  }
+  int32_t asc_occ = 0;
+  for (occ = baseline + xheight + 1; occ <= blob_box.top(); occ++) {
+    if (occ >= blob_box.bottom() && projection.pile_count(occ) > asc_occ) {
+      asc_occ = projection.pile_count(occ);
+    }
+  }
+  if (testing_on) {
+    tprintf("%d %d %d\n", desc_occ, x_occ, asc_occ);
+  }
+  if (desc_occ == 0 && x_occ == 0 && asc_occ == 0) {
+    tprintf("Bottom=%d, top=%d, base=%d, x=%d\n", blob_box.bottom(), blob_box.top(), baseline,
+            xheight);
+    projection.print();
+  }
+  if (desc_occ > x_occ + x_occ && desc_occ > blob_width * textord_underline_threshold) {
+    return true; // real underline
+  }
+  return asc_occ > x_occ + x_occ && asc_occ > blob_width * textord_underline_threshold; // overline
+                                                                                        // neither
+}
+
+/**
+ * horizontal_cblob_projection
+ *
+ * Compute the horizontal projection of a cblob from its outlines
+ * and add to the given STATS.
+ */
+
+static void horizontal_cblob_projection( // project outlines
+    C_BLOB *blob,                        ///< blob to project
+    STATS *stats                         ///< output
+) {
+  // outlines of blob
+  C_OUTLINE_IT out_it = blob->out_list();
+
+  for (out_it.mark_cycle_pt(); !out_it.cycled_list(); out_it.forward()) {
+    horizontal_coutline_projection(out_it.data(), stats);
+  }
+}
+
+/**
+ * horizontal_coutline_projection
+ *
+ * Compute the horizontal projection of an outline from its outlines
+ * and add to the given STATS.
+ */
+
+static void horizontal_coutline_projection( // project outlines
+    C_OUTLINE *outline,                     ///< outline to project
+    STATS *stats                            ///< output
+) {
+  ICOORD pos;        // current point
+  ICOORD step;       // edge step
+  int32_t length;    // of outline
+  int16_t stepindex; // current step
+  C_OUTLINE_IT out_it = outline->child();
+
+  pos = outline->start_pos();
+  length = outline->pathlength();
+  for (stepindex = 0; stepindex < length; stepindex++) {
+    step = outline->step(stepindex);
+    if (step.y() > 0) {
+      stats->add(pos.y(), pos.x());
+    } else if (step.y() < 0) {
+      stats->add(pos.y() - 1, -pos.x());
+    }
+    pos += step;
+  }
+
+  for (out_it.mark_cycle_pt(); !out_it.cycled_list(); out_it.forward()) {
+    horizontal_coutline_projection(out_it.data(), stats);
+  }
+}
+
+} // namespace tesseract