feat(渲染压缩): 完善三维渲染并优化转换压缩

ofdgo_pdf_image_native.go

@@ -0,0 +1,99 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+	"math"
+
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// pdfNativeImage 按源像素输出原生过程色，不分配完整显示颜色缓冲
+type pdfNativeImage struct {
+	source *pdfgo.ImageProcess
+	space  *pdfgo.ColorSpace
+}
+
+// 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
+// 入参: source 源图像
+// 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
+func (p *pdfImporter) imageProcessModel(source *pdfgo.Image) (pdfgo.Name, error) {
+	space := p.compositeSpace
+	if source.ImageMask || !space.Device() {
+		return "", nil
+	}
+	colorants, err := source.ColorantSpace()
+	if err != nil {
+		return "", err
+	}
+	process := colorants.PrepareProcess(&pdfgo.ColorantDevice{Space: space}, space, false)
+	if process == nil || process.Mask() == ([4]bool{}) || process.AlternateEquivalent() {
+		return "", nil
+	}
+	return space.Model, nil
+}
+
+// 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
+// 入参: source 源图像, model 原生设备空间
+// 返回: image.Image 只读图像, error 解码或分量映射错误
+func (p *pdfImporter) imageProcess(source *pdfgo.Image, model pdfgo.Name) (image.Image, error) {
+	cache := p.compositingCache()
+	components := cache.images[source]
+	if components == nil {
+		var err error
+		components, err = source.DecodeComponentsViewContext(p.ctx)
+		if err != nil {
+			return nil, err
+		}
+		cache.images[source] = components
+	}
+	space := &pdfgo.ColorSpace{Model: model}
+	process, err := components.PrepareProcess(&pdfgo.ColorantDevice{Space: space}, space, false)
+	if err != nil {
+		return nil, err
+	}
+	if process == nil {
+		return nil, fmt.Errorf("invalid native PDF image process space %s", model)
+	}
+	return &pdfNativeImage{source: process, space: space}, nil
+}
+
+// ColorModel 保留16位原生分量与源透明度
+// 返回: color.Model 非预乘颜色模型
+func (s *pdfNativeImage) ColorModel() color.Model { return color.NRGBA64Model }
+
+// Bounds 返回源图像的完整采样边界
+// 返回: image.Rectangle 原始像素边界
+func (s *pdfNativeImage) Bounds() image.Rectangle { return s.source.Bounds() }
+
+// At 获取按OFD输出映射的原生颜色
+// 入参: x 横坐标, y 纵坐标
+// 返回: color.Color 非预乘颜色
+func (s *pdfNativeImage) At(x, y int) color.Color { return s.NRGBA64At(x, y) }
+
+// 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
+// 入参: x 横坐标, y 纵坐标
+// 返回: color.NRGBA64 非预乘颜色
+func (s *pdfNativeImage) NRGBA64At(x, y int) color.NRGBA64 {
+	if !image.Pt(x, y).In(s.Bounds()) {
+		return color.NRGBA64{}
+	}
+	values, alpha := s.source.ValuesAt(x, y)
+	rgb, _ := pdfCompositeOutputColor(s.space, values)
+	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))}
+}