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comparison mupdf-source/thirdparty/tesseract/src/textord/cjkpitch.h @ 2:b50eed0cc0ef upstream

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ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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1 ///////////////////////////////////////////////////////////////////////
2 // File: cjkpitch.h
3 // Description: Code to determine fixed pitchness and the pitch if fixed,
4 // for CJK text.
5 // Copyright 2011 Google Inc. All Rights Reserved.
6 // Author: takenaka@google.com (Hiroshi Takenaka)
7 // Created: Mon Jun 27 12:48:35 JST 2011
8 //
9 // Licensed under the Apache License, Version 2.0 (the "License");
10 // you may not use this file except in compliance with the License.
11 // You may obtain a copy of the License at
12 // http://www.apache.org/licenses/LICENSE-2.0
13 // Unless required by applicable law or agreed to in writing, software
14 // distributed under the License is distributed on an "AS IS" BASIS,
15 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 // See the License for the specific language governing permissions and
17 // limitations under the License.
18 //
19 ///////////////////////////////////////////////////////////////////////
20 #ifndef CJKPITCH_H_
21 #define CJKPITCH_H_
22
23 #include "blobbox.h"
24
25 namespace tesseract {
26
27 // Function to test "fixed-pitchness" of the input text and estimating
28 // character pitch parameters for it, based on CJK fixed-pitch layout
29 // model.
30 //
31 // This function assumes that a fixed-pitch CJK text has following
32 // characteristics:
33 //
34 // - Most glyphs are designed to fit within the same sized square
35 // (imaginary body). Also they are aligned to the center of their
36 // imaginary bodies.
37 // - The imaginary body is always a regular rectangle.
38 // - There may be some extra space between character bodies
39 // (tracking).
40 // - There may be some extra space after punctuations.
41 // - The text is *not* space-delimited. Thus spaces are rare.
42 // - Character may consists of multiple unconnected blobs.
43 //
44 // And the function works in two passes. On pass 1, it looks for such
45 // "good" blobs that has the pitch same pitch on the both side and
46 // looks like a complete CJK character. Then estimates the character
47 // pitch for every row, based on those good blobs. If we couldn't find
48 // enough good blobs for a row, then the pitch is estimated from other
49 // rows with similar character height instead.
50 //
51 // Pass 2 is an iterative process to fit the blobs into fixed-pitch
52 // character cells. Once we have estimated the character pitch, blobs
53 // that are almost as large as the pitch can be considered to be
54 // complete characters. And once we know that some characters are
55 // complete characters, we can estimate the region occupied by its
56 // neighbors. And so on.
57 //
58 // We repeat the process until all ambiguities are resolved. Then make
59 // the final decision about fixed-pitchness of each row and compute
60 // pitch and spacing parameters.
61 //
62 // (If a row is considered to be proportional, pitch_decision for the
63 // row is set to PITCH_CORR_PROP and the later phase
64 // (i.e. Textord::to_spacing()) should determine its spacing
65 // parameters)
66 //
67 // This function doesn't provide all information required by
68 // fixed_pitch_words() and the rows need to be processed with
69 // make_prop_words() even if they are fixed pitched.
70 void compute_fixed_pitch_cjk(ICOORD page_tr, // top right
71 TO_BLOCK_LIST *port_blocks); // input list
72
73 } // namespace tesseract
74
75 #endif // CJKPITCH_H_