mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 16:25:49 +08:00
117 lines
4.4 KiB
Go
117 lines
4.4 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"
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"image/color"
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"math"
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"github.com/xiaoqidun/pdfgo"
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)
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// pdfNativeImage 按源像素输出原生过程色，不分配完整显示颜色缓冲
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type pdfNativeImage struct {
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source *pdfgo.ImageProcess
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space *pdfgo.ColorSpace
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}
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// imageProcessModel 选择与页面原生过程色一致的图像输出，已等价的备用色沿用现有编码路径
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// 入参: source 源图像
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// 返回: pdfgo.Name 原生输出空间，无需重映射时为空, error 色料解析错误
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func (p *pdfImporter) imageProcessModel(source *pdfgo.Image) (pdfgo.Name, error) {
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space := p.compositeSpace
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if source.ImageMask || !space.Device() {
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return "", nil
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}
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colorants, err := source.ColorantSpace()
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if err != nil {
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return "", err
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}
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process := colorants.PrepareProcess(&pdfgo.ColorantDevice{Space: space}, space, false)
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if process == nil || process.Mask() == ([4]bool{}) || process.AlternateEquivalent() {
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return "", nil
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}
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return space.Model, nil
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}
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// imageProcess 复用源分量并保留原始分辨率，颜色变换随编码逐像素执行
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// 入参: source 源图像, model 原生设备空间
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// 返回: image.Image 只读图像, error 解码或分量映射错误
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func (p *pdfImporter) imageProcess(source *pdfgo.Image, model pdfgo.Name) (image.Image, error) {
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cache := p.compositingCache()
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space := &pdfgo.ColorSpace{Model: model}
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process, err := cache.imageProcess(p, source, space, false)
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if err != nil {
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return nil, err
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}
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if process == nil {
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return nil, fmt.Errorf("invalid native PDF image process space %s", model)
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}
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return &pdfNativeImage{source: process, space: space}, nil
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}
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// imageProcess 复用同组原生采样，仅在需要备用颜色时保留完整分量
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// 入参: importer 导入器, source 源图像, space 组混合空间, softMask 是否用于软蒙版
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// 返回: *pdfgo.ImageProcess 原生采样，需要备用色时为nil, error 解码或布局错误
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func (c *pdfCompositeCache) imageProcess(importer *pdfImporter, source *pdfgo.Image, space *pdfgo.ColorSpace, softMask bool) (*pdfgo.ImageProcess, error) {
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key := pdfImageProcessKey{image: source, space: space, softMask: softMask}
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if process, found := c.imageProcesses[key]; found {
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return process, nil
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}
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device := &pdfgo.ColorantDevice{Space: space}
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var process *pdfgo.ImageProcess
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var err error
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if components := c.images[source]; components != nil {
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process, err = components.PrepareProcess(device, space, softMask)
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} else {
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process, err = source.DecodeProcessContext(importer.ctx, device, space, softMask)
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}
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if err != nil {
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return nil, err
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}
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if c.imageProcesses == nil {
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c.imageProcesses = make(map[pdfImageProcessKey]*pdfgo.ImageProcess)
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}
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c.imageProcesses[key] = process
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return process, nil
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}
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// ColorModel 保留16位原生分量与源透明度
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// 返回: color.Model 非预乘颜色模型
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func (s *pdfNativeImage) ColorModel() color.Model { return color.NRGBA64Model }
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// Bounds 返回源图像的完整采样边界
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// 返回: image.Rectangle 原始像素边界
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func (s *pdfNativeImage) Bounds() image.Rectangle { return s.source.Bounds() }
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// At 获取按OFD输出映射的原生颜色
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// 入参: x 横坐标, y 纵坐标
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// 返回: color.Color 非预乘颜色
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func (s *pdfNativeImage) At(x, y int) color.Color { return s.NRGBA64At(x, y) }
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// NRGBA64At 按原始精度转换设备过程色，不进行页面采样或备用变换
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// 入参: x 横坐标, y 纵坐标
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// 返回: color.NRGBA64 非预乘颜色
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func (s *pdfNativeImage) NRGBA64At(x, y int) color.NRGBA64 {
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if !image.Pt(x, y).In(s.Bounds()) {
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return color.NRGBA64{}
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}
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values, alpha := s.source.ValuesAt(x, y)
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rgb, _ := pdfCompositeOutputColor(s.space, values)
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return color.NRGBA64{R: uint16(math.Round(rgb[0] * 65535)), G: uint16(math.Round(rgb[1] * 65535)), B: uint16(math.Round(rgb[2] * 65535)), A: uint16(math.Round(alpha * 65535))}
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}
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