mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 08:46:55 +08:00
333 lines
11 KiB
Go
333 lines
11 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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"bytes"
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"errors"
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"fmt"
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"image"
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"image/color"
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"io"
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"math"
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"reflect"
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codecpdf "github.com/xiaoqidun/ofdgo/internal/codec/pdf"
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"github.com/xiaoqidun/pdfgo"
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)
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// pdfImageKey 区分图像流、渲染意图、原生输出空间、模板填充色及采样尺寸
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type pdfImageKey struct {
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stream *pdfgo.Stream
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intent pdfgo.Name
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process pdfgo.Name
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tint color.NRGBA64
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size image.Point
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}
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// pdfImageResource 保存图像的有效颜色空间及对应资源，避免跨资源重映射复用
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type pdfImageResource struct {
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space pdfgo.Object
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id string
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}
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// pdfImageContentKey 区分编码内容、渲染意图、原生输出空间、模板填充色及有损采样尺寸
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type pdfImageContentKey struct {
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data [32]byte
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intent pdfgo.Name
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process pdfgo.Name
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tint color.NRGBA64
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size image.Point
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}
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// pdfImageContent 保存不依赖间接资源的图像描述及已注册编号
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type pdfImageContent struct {
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source *pdfgo.Image
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id string
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}
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// image 转换图像样本，不将整页或其他对象栅格化
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// 有损编码复用已解码像素，候选容量超限时沿用原编码路径
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// 入参: mark PDF图像绘制信息
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// 返回: error 错误信息
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func (p *pdfImporter) image(mark pdfgo.ImageMark) error {
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if err := p.ctx.Err(); err != nil {
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return err
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}
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if mark.Style.BlendMode != "" && mark.Style.BlendMode != "Normal" && mark.Style.BlendMode != "Compatible" {
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return &pdfgo.UnsupportedError{Feature: "image blend mode " + string(mark.Style.BlendMode)}
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}
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if mark.Image.ImageMask && (mark.Style.Fill.Axial != nil || mark.Style.Fill.Radial != nil || mark.Style.Fill.Function != nil || mark.Style.Fill.Mesh != nil || mark.Style.Fill.Shading != nil) {
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if p.warning != nil {
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return p.compositeRegion(nil, pdfCompositeNode{image: &mark}, &pdfgo.ColorSpace{Model: "DeviceRGB"}, false)
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}
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return &pdfgo.UnsupportedError{Feature: "gradient stencil image"}
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}
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var err error
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mark.Style, err = p.maskStyle(mark.Style)
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if err != nil {
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if p.rasterMaskAllowed(err) {
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mask := mark.Style.SoftMask
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mark.Style.SoftMask = nil
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return p.rasterGroup(pdfgo.GroupMark{Alpha: 1, SoftMask: mask}, func(v pdfgo.Visitor) error { return v.Image(mark) })
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}
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return err
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}
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if mark.Style.FillOverprint {
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return &pdfgo.UnsupportedError{Feature: "image color separation overprint"}
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}
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source := mark.Image
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key := pdfImageKey{stream: source.Stream, intent: source.Intent}
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key.process, err = p.imageProcessModel(source)
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if err != nil {
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return err
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}
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if !source.ImageMask && p.compression.Mode == CompressionLossy {
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m := p.matrix.Mul(mark.Matrix)
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key.size = compressionImageSize(math.Hypot(m[0], m[1]), math.Hypot(m[2], m[3]), p.compression.ImageDPI())
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if key.size.X >= source.Width || key.size.Y >= source.Height {
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key.size = image.Point{}
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}
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}
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if source.ImageMask {
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fill := mark.Style.Fill.RGB
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if space := mark.Style.Fill.Space; space != nil {
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fill, err = space.SRGB(mark.Style.Fill.Values[:space.Components()], mark.Style.RenderingIntent)
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} else if values := mark.Style.Fill.CMYK; values != nil {
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space := &pdfgo.ColorSpace{Model: "DeviceCMYK"}
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fill, err = space.SRGB(values[:], mark.Style.RenderingIntent)
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}
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if err != nil {
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return err
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}
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key.tint = color.NRGBA64{
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R: uint16(math.Round(fill[0] * 65535)),
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G: uint16(math.Round(fill[1] * 65535)),
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B: uint16(math.Round(fill[2] * 65535)),
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A: 65535,
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}
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}
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id := ""
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for _, resource := range p.imageIDs[key] {
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if reflect.DeepEqual(resource.space, source.ColorSpace) {
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id = resource.id
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break
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}
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}
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streamCached := id != ""
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var contentKey pdfImageContentKey
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cacheable := false
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if id == "" {
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contentKey, cacheable, err = p.imageContentKey(source, key)
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if err != nil {
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return err
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}
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if cacheable {
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if p.imageContents == nil {
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p.imageContents = &renderCache[pdfImageContentKey, pdfImageContent]{limit: 8 << 20}
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}
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if cached, found := p.imageContents.get(contentKey); found && cached.matches(source) {
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id = cached.id
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}
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}
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}
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if id == "" {
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var data []byte
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if !source.ImageMask && key.process == "" && p.compression.Mode != CompressionLossy {
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data, err = codecpdf.EncodeCMYKTIFF(p.ctx, source)
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if err != nil {
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return err
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}
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}
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var jbig2Original, jpegOriginal []byte
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var decoded image.Image
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if len(data) == 0 {
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if key.process != "" {
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decoded, err = p.imageProcess(source, key.process)
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if err != nil {
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return err
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}
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if key.size != (image.Point{}) {
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decoded, err = pdfgo.ResizeImage(p.ctx, decoded, key.size)
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if err != nil {
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return err
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}
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}
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} else {
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jbig2Original, err = source.JBIG2FileContext(p.ctx)
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if err != nil {
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return err
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}
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jpegOriginal, err = source.JPEGFileContext(p.ctx)
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if err != nil {
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return err
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}
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if len(jbig2Original) == 0 && len(jpegOriginal) == 0 && (source.ImageMask || key.size != (image.Point{})) {
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decoded, err = source.DecodeImageSizeContext(p.ctx, key.size)
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if err != nil {
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return err
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}
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}
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}
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if source.ImageMask {
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decoded = &codecpdf.StencilImage{Source: decoded, Fill: key.tint}
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}
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data = jbig2Original
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if len(data) == 0 {
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data = jpegOriginal
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}
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}
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optimized := false
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if len(data) == 0 && decoded != nil && !source.ImageMask && p.compression.Mode == CompressionLossy {
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data, err = pdfgo.EncodeImageResource(p.ctx, decoded, p.compression)
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if err != nil && !errors.Is(err, io.ErrShortBuffer) {
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return err
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}
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optimized = err == nil
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}
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if len(data) == 0 {
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var encoded bytes.Buffer
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if decoded != nil {
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err = pdfgo.EncodePNG(p.ctx, &encoded, decoded)
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} else {
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err = source.EncodePNGContext(p.ctx, &encoded)
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}
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if err != nil {
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return err
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}
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data = encoded.Bytes()
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}
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if !source.ImageMask && p.compression.Mode == CompressionLossy {
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if !optimized {
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data, err = pdfgo.OptimizeImageResource(p.ctx, data, p.compression, key.size)
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if err != nil {
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return err
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}
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}
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decoded = nil
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}
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id, err = p.editor.addDecodedImageContext(p.ctx, data, decoded)
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if err != nil {
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return err
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}
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if cacheable {
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p.imageContents.put(contentKey, pdfImageContent{source: source, id: id}, len(source.Stream.Data)+65536)
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}
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}
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if !streamCached {
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if p.imageIDs == nil {
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p.imageIDs = map[pdfImageKey][]pdfImageResource{}
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}
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p.imageIDs[key] = append(p.imageIDs[key], pdfImageResource{space: source.ColorSpace, id: id})
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}
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return p.appendImage(mark, id)
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}
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// appendImage 定位已注册的图像资源，保留透明度与裁剪
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// 入参: mark 图像绘制信息, id 资源编号
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// 返回: error 裁剪错误
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func (p *pdfImporter) appendImage(mark pdfgo.ImageMark, id string) error {
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m := p.matrix.Mul(mark.Matrix).Mul(pdfgo.Matrix{1, 0, 0, -1, 0, 1})
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box := pdfBounds([]pdfgo.Point{m.Apply(pdfgo.Point{}), m.Apply(pdfgo.Point{X: 1}), m.Apply(pdfgo.Point{Y: 1}), m.Apply(pdfgo.Point{X: 1, Y: 1})})
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alpha := int(math.Round(mark.Style.Fill.Alpha * 255))
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clips, err := p.clips(mark.Style.Clips, box)
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if err != nil {
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return err
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}
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object := ImageObject{Boundary: pdfBoundary(box), ResourceID: id, CTM: pdfNumbers(m[0], m[1], m[2], m[3], m[4]-box.X, m[5]-box.Y), Alpha: &alpha, Clips: clips}
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p.appendSequenceObject(GraphicObject{Type: "ImageObject", ImageObject: object}, mark.Sequence)
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p.report.ImageObjects++
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return nil
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}
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// imageContentKey 对无间接依赖的小图像生成内容键，超大图像仍沿用流缓存
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// 入参: source 图像描述, key 流缓存键
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// 返回: pdfImageContentKey 内容键, bool 是否可复用, error 取消错误
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func (p *pdfImporter) imageContentKey(source *pdfgo.Image, key pdfImageKey) (pdfImageContentKey, bool, error) {
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digest, reusable, err := codecpdf.ImageDigest(p.ctx, source)
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if !reusable {
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return pdfImageContentKey{}, reusable, err
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}
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return pdfImageContentKey{data: digest, intent: key.intent, process: key.process, tint: key.tint, size: key.size}, true, err
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}
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// matches 核对完整编码与有效图像属性，不以摘要相同代替内容相同
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// 入参: source 待复用图像
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// 返回: bool 是否可使用同一图像资源
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func (c pdfImageContent) matches(source *pdfgo.Image) bool {
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return codecpdf.SameImage(c.source, source)
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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 &codecpdf.NativeImage{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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