mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 15:06:46 +08:00
68 lines
2.0 KiB
Go
68 lines
2.0 KiB
Go
// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package pdf
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import (
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"context"
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"crypto/sha256"
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"encoding/binary"
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"math"
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"github.com/xiaoqidun/pdfgo"
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)
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// ClipPathKey 按路径完整内容与变换生成键，不依赖可变切片的地址
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// 入参: ctx 取消上下文, path 裁剪路径, matrix 页面变换
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// 返回: [32]byte 内容摘要, error 取消错误
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func ClipPathKey(ctx context.Context, path pdfgo.Path, matrix pdfgo.Matrix) ([32]byte, error) {
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hash := sha256.New()
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var value [16]byte
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for _, number := range matrix {
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binary.LittleEndian.PutUint64(value[:8], math.Float64bits(number))
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hash.Write(value[:8])
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}
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binary.LittleEndian.PutUint64(value[:8], uint64(len(path.Segments)))
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value[8] = 0
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if path.EvenOdd {
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value[8] = 1
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}
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hash.Write(value[:9])
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for _, segment := range path.Segments {
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if err := ctx.Err(); err != nil {
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return [32]byte{}, err
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}
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binary.LittleEndian.PutUint64(value[:8], uint64(len(segment.Operator)))
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binary.LittleEndian.PutUint64(value[8:], uint64(len(segment.Points)))
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hash.Write(value[:])
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hash.Write([]byte(segment.Operator))
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for index, point := range segment.Points {
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if index&255 == 0 {
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if err := ctx.Err(); err != nil {
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return [32]byte{}, err
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}
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}
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binary.LittleEndian.PutUint64(value[:8], math.Float64bits(point.X))
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binary.LittleEndian.PutUint64(value[8:], math.Float64bits(point.Y))
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hash.Write(value[:])
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}
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}
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if err := ctx.Err(); err != nil {
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return [32]byte{}, err
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}
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var key [32]byte
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hash.Sum(key[:0])
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return key, nil
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}
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