mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 08:46:55 +08:00
136 lines
4.8 KiB
Go
136 lines
4.8 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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"fmt"
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"image/color"
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"math"
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"slices"
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"strconv"
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"strings"
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"github.com/xiaoqidun/pdfgo"
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)
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// colorProfile 保存包内配置的不可变解析结果，不跨阅读器或文档共享
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type colorProfile struct {
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space *pdfgo.ColorSpace
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err error
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}
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// colorProfileUsed 判断新增ICC文件是否被颜色空间引用，不作为资源XML登记
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// 入参: spaces 当前使用的新增颜色空间
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// 返回: bool 是否保留文件
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func (r editorResource) colorProfileUsed(spaces []ColorSpace) bool {
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return r.space != nil && r.name != "" && r.space.Profile != "" && slices.ContainsFunc(spaces, func(space ColorSpace) bool { return space.Profile == r.space.Profile })
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}
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// parseColorProfile 验证OFD模型与ICC源模型一致，不以设备色替代声明的配置
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// 入参: kind OFD颜色模型, data ICC文件
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// 返回: *colorProfile 解析结果, error 模型或配置错误
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func parseColorProfile(kind string, data []byte) (*colorProfile, error) {
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model := map[string]string{"GRAY": "GRAY", "RGB": "RGB ", "CMYK": "CMYK"}[strings.ToUpper(kind)]
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if len(data) < 132 || model == "" || string(data[16:20]) != model {
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return nil, fmt.Errorf("ICC source model does not match OFD color space %q", kind)
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}
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space, err := pdfgo.NewICCColorSpace(data)
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if err != nil {
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return nil, err
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}
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return &colorProfile{space: space}, nil
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}
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// colorProfile 按文件及模型复用只读配置，读取失败也保留结果以免重复读取
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// 入参: space 颜色空间
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// 返回: *colorProfile 配置，未声明时为nil, error 读取或配置错误
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func (r *Reader) colorProfile(space *ColorSpace) (*colorProfile, error) {
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if space == nil || space.Profile == "" {
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return nil, nil
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}
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if space.profile != nil {
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return space.profile, space.profile.err
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}
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if r == nil {
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return nil, fmt.Errorf("color profile %q is unavailable", space.Profile)
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}
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name := r.ResPath(space.Profile)
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for _, other := range r.colorSpaceCache {
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if other != nil && other.profile != nil && strings.EqualFold(other.Type, space.Type) && r.ResPath(other.Profile) == name {
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space.profile = other.profile
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return space.profile, space.profile.err
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}
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}
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data, err := r.readFile(name)
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if err == nil {
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space.profile, err = parseColorProfile(space.Type, data)
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}
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if err != nil {
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space.profile = &colorProfile{err: fmt.Errorf("color profile %q: %w", space.Profile, err)}
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}
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return space.profile, space.profile.err
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}
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// colorDefinition 获取显式或文档默认颜色空间，统一资源标识别名
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// 入参: id 颜色空间标识
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// 返回: *ColorSpace 已加载定义，未声明时为nil
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func (r *Renderer) colorDefinition(id string) *ColorSpace {
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if r.Reader == nil {
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return nil
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}
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if id == "" && r.Reader.doc != nil {
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id = strconv.Itoa(r.Reader.doc.CommonData.DefaultCS)
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}
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space, _ := resourceValue(r.Reader.colorSpaceCache, id)
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return space
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}
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// srgb 转换归一化源分量，不在ICC变换前量化为8位
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// 入参: values 源分量
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// 返回: [3]float64 sRGB分量, error 变换错误
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func (p *colorProfile) srgb(values [4]float64) ([3]float64, error) {
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return p.space.SRGB(values[:p.space.Components()], p.space.DefaultIntent())
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}
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// displayColor 按源模型及配置转换显示颜色，保持源分量精度
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// 入参: kind 源模型, values 归一化分量, profile 可选ICC配置
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// 返回: [3]float64 sRGB分量, error 模型或转换错误
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func displayColor(kind string, values [4]float64, profile *colorProfile) ([3]float64, error) {
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if profile != nil {
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return profile.srgb(values)
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}
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var model pdfgo.Name
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switch kind {
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case "GRAY":
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model = "DeviceGray"
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case "RGB":
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model = "DeviceRGB"
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case "CMYK":
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model = "DeviceCMYK"
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default:
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return [3]float64{}, fmt.Errorf("unsupported color space %q", kind)
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}
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space := pdfgo.ColorSpace{Model: model}
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return space.SRGB(values[:space.Components()], "RelativeColorimetric")
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}
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// profileColor 将显示分量一次量化并按透明度预乘
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// 入参: rgb sRGB分量, alpha 非预乘透明度
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// 返回: color.RGBA 预乘颜色
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func profileColor(rgb [3]float64, alpha float64) color.RGBA {
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alpha = math.Max(0, math.Min(1, alpha))
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return color.RGBA{meshByte(rgb[0] * alpha), meshByte(rgb[1] * alpha), meshByte(rgb[2] * alpha), meshByte(alpha)}
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}
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