--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/classify/normfeat.cpp	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,70 @@
+/******************************************************************************
+ ** Filename:    normfeat.c
+ ** Purpose:     Definition of char normalization features.
+ ** Author:      Dan Johnson
+ **
+ ** (c) Copyright Hewlett-Packard Company, 1988.
+ ** 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 "normfeat.h"
+
+#include "featdefs.h"
+#include "intfx.h"
+#include "mfoutline.h"
+
+namespace tesseract {
+
+/** Return the length of the outline in baseline normalized form. */
+float ActualOutlineLength(FEATURE Feature) {
+  return (Feature->Params[CharNormLength] * LENGTH_COMPRESSION);
+}
+
+/**
+ * Return the character normalization feature for a blob.
+ *
+ * The features returned are in a scale where the x-height has been
+ * normalized to live in the region y = [-0.25 .. 0.25].  Example ranges
+ * for English below are based on the Linux font collection on 2009-12-04:
+ *
+ *  - Params[CharNormY]
+ *     - The y coordinate of the grapheme's centroid.
+ *     - English: [-0.27, 0.71]
+ *
+ *  - Params[CharNormLength]
+ *     - The length of the grapheme's outline (tiny segments discarded),
+ *     divided by 10.0=LENGTH_COMPRESSION.
+ *     - English: [0.16, 0.85]
+ *
+ *  - Params[CharNormRx]
+ *     - The radius of gyration about the x axis, as measured from CharNormY.
+ *     - English: [0.011, 0.34]
+ *
+ *  - Params[CharNormRy]
+ *     - The radius of gyration about the y axis, as measured from
+ *     the x center of the grapheme's bounding box.
+ *     - English: [0.011, 0.31]
+ */
+FEATURE_SET ExtractCharNormFeatures(const INT_FX_RESULT_STRUCT &fx_info) {
+  auto feature_set = new FEATURE_SET_STRUCT(1);
+  auto feature = new FEATURE_STRUCT(&CharNormDesc);
+
+  feature->Params[CharNormY] = MF_SCALE_FACTOR * (fx_info.Ymean - kBlnBaselineOffset);
+  feature->Params[CharNormLength] = MF_SCALE_FACTOR * fx_info.Length / LENGTH_COMPRESSION;
+  feature->Params[CharNormRx] = MF_SCALE_FACTOR * fx_info.Rx;
+  feature->Params[CharNormRy] = MF_SCALE_FACTOR * fx_info.Ry;
+
+  AddFeature(feature_set, feature);
+
+  return feature_set;
+} /* ExtractCharNormFeatures */
+
+} // namespace tesseract