mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 08:46:55 +08:00
108 lines
3.3 KiB
Go
108 lines
3.3 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 ofdgo
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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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// pdfClipPath 保存导入器只读的裁剪几何，不缓存对象位移或文字裁剪
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type pdfClipPath struct {
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box Box
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data string
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path *[1]PathObject
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}
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// pdfClipPathKey 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 pdfClipPathKey(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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// clipPath 复用页面内重复路径编码，按估算字节预算淘汰且不缓存错误
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// 入参: path 裁剪路径
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// 返回: pdfClipPath 变换后的边界及编码, error 取消错误
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func (p *pdfImporter) clipPath(path pdfgo.Path) (pdfClipPath, error) {
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key, err := pdfClipPathKey(p.ctx, path, p.matrix)
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if err != nil {
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return pdfClipPath{}, err
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}
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if p.clipPaths == nil {
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p.clipPaths = &renderCache[[32]byte, pdfClipPath]{limit: 8 << 20}
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}
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if cached, ok := p.clipPaths.get(key); ok {
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return cached, nil
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}
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box, err := p.pathBoundsContext(p.ctx, path)
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if err != nil {
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return pdfClipPath{}, err
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}
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data, err := p.pathDataContext(p.ctx, path, box)
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if err != nil {
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return pdfClipPath{}, err
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}
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rule := "NonZero"
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if path.EvenOdd {
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rule = "Even-Odd"
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}
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boundary := pdfBoundary(box)
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fill, stroke := true, false
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result := pdfClipPath{box: box, data: data, path: &[1]PathObject{{Boundary: boundary, AbbreviatedData: data, Rule: rule, Fill: &fill, Stroke: &stroke}}}
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p.clipPaths.put(key, result, len(data)+len(boundary)+512)
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return result, nil
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}
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