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72 lines
3.2 KiB
C
72 lines
3.2 KiB
C
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///////////////////////////////////////////////////////////////////////
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// File: cjkpitch.h
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// Description: Code to determine fixed pitchness and the pitch if fixed,
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// for CJK text.
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// Copyright 2011 Google Inc. All Rights Reserved.
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// Author: takenaka@google.com (Hiroshi Takenaka)
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// Created: Mon Jun 27 12:48:35 JST 2011
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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///////////////////////////////////////////////////////////////////////
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#ifndef CJKPITCH_H_
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#define CJKPITCH_H_
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#include "blobbox.h"
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// Function to test "fixed-pitchness" of the input text and estimating
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// character pitch parameters for it, based on CJK fixed-pitch layout
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// model.
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//
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// This function assumes that a fixed-pitch CJK text has following
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// characteristics:
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//
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// - Most glyphs are designed to fit within the same sized square
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// (imaginary body). Also they are aligned to the center of their
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// imaginary bodies.
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// - The imaginary body is always a regular rectangle.
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// - There may be some extra space between character bodies
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// (tracking).
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// - There may be some extra space after punctuations.
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// - The text is *not* space-delimited. Thus spaces are rare.
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// - Character may consists of multiple unconnected blobs.
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//
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// And the function works in two passes. On pass 1, it looks for such
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// "good" blobs that has the pitch same pitch on the both side and
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// looks like a complete CJK character. Then estimates the character
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// pitch for every row, based on those good blobs. If we couldn't find
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// enough good blobs for a row, then the pitch is estimated from other
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// rows with similar character height instead.
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//
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// Pass 2 is an iterative process to fit the blobs into fixed-pitch
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// character cells. Once we have estimated the character pitch, blobs
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// that are almost as large as the pitch can be considered to be
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// complete characters. And once we know that some characters are
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// complete characters, we can estimate the region occupied by its
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// neighbors. And so on.
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//
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// We repeat the process until all ambiguities are resolved. Then make
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// the final decision about fixed-pitchness of each row and compute
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// pitch and spacing parameters.
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//
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// (If a row is considered to be propotional, pitch_decision for the
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// row is set to PITCH_CORR_PROP and the later phase
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// (i.e. Textord::to_spacing()) should determine its spacing
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// parameters)
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//
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// This function doesn't provide all information required by
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// fixed_pitch_words() and the rows need to be processed with
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// make_prop_words() even if they are fixed pitched.
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void compute_fixed_pitch_cjk(ICOORD page_tr, // top right
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TO_BLOCK_LIST *port_blocks); // input list
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#endif // CJKPITCH_H_
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