mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 14:31:12 +08:00
118 lines
3.9 KiB
Go
118 lines
3.9 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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basegeom "github.com/xiaoqidun/ofdgo/internal/base/geom"
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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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// ClipContainsBoundary 判断单一矩形裁剪是否完整覆盖对象边界，不近似曲线或斜边
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// 入参: path PDF裁剪路径, matrix 页面变换, boundary OFD对象边界
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// 返回: bool 是否可由对象边界代替裁剪
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func ClipContainsBoundary(path pdfgo.Path, matrix pdfgo.Matrix, boundary basegeom.Box) bool {
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if len(path.Text) != 0 || len(path.Segments) < 4 || len(path.Segments) > 6 || !finite(boundary.X) || !finite(boundary.Y) || !finite(boundary.W) || !finite(boundary.H) || boundary.W <= 0 || boundary.H <= 0 {
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return false
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}
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var points [4]pdfgo.Point
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for index := range 4 {
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segment := path.Segments[index]
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operator := "L"
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if index == 0 {
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operator = "M"
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}
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if segment.Operator != operator || len(segment.Points) != 1 {
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return false
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}
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points[index] = matrix.Apply(segment.Points[0])
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if !finite(points[index].X) || !finite(points[index].Y) {
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return false
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}
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}
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end := 4
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if end < len(path.Segments) && path.Segments[end].Operator == "L" {
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segment := path.Segments[end]
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if len(segment.Points) != 1 || matrix.Apply(segment.Points[0]) != points[0] {
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return false
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}
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end++
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}
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if end < len(path.Segments) {
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segment := path.Segments[end]
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if segment.Operator != "C" || len(segment.Points) != 0 {
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return false
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}
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end++
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}
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if end != len(path.Segments) {
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return false
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}
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a, b, c, d := points[0], points[1], points[2], points[3]
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if !(a.Y == b.Y && b.X == c.X && c.Y == d.Y && d.X == a.X || a.X == b.X && b.Y == c.Y && c.X == d.X && d.Y == a.Y) {
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return false
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}
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left, right := math.Min(a.X, c.X), math.Max(a.X, c.X)
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top, bottom := math.Min(a.Y, c.Y), math.Max(a.Y, c.Y)
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return left < right && top < bottom && boundary.X >= left && boundary.Y >= top && boundary.X+boundary.W <= right && boundary.Y+boundary.H <= bottom
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}
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