feat(文字图像): 修复文字定位及图像导出

ofdgo_renderer_pdf_canvas.go

@@ -17,15 +17,19 @@ package ofdgo
 import (
 	"fmt"
 	"image"
+	"image/color"
 
 	"github.com/tdewolff/canvas"
+	cimage "github.com/tdewolff/canvas/image"
 	"github.com/tdewolff/canvas/renderers/pdf"
 )
 
 // pdfRenderer PDF渲染器
 type pdfRenderer struct {
 	*pdf.PDF
-	glyphPaths map[*canvas.Path]*canvas.Path
+	glyphPaths  map[*canvas.Path]*canvas.Path
+	images      [][]image.Image
+	exactImages bool
 }
 
 // pdfNavigation PDF导航信息
@@ -58,6 +62,27 @@ type pdfOutline struct {
 // RenderImage 在图像局部保存状态前同步不透明画笔，避免恢复后的透明度与后端缓存不一致
 // 入参: img 图像, matrix 图像变换
 func (r *pdfRenderer) RenderImage(img image.Image, matrix canvas.Matrix) {
+	if len(r.images) != 0 {
+		var original image.Image
+		opaque := false
+		if source, ok := img.(interface{ Opaque() bool }); ok {
+			opaque = source.Opaque()
+		}
+		switch img.ColorModel() {
+		case color.GrayModel, color.CMYKModel:
+		case color.RGBAModel, color.NRGBAModel, color.AlphaModel:
+			if !opaque {
+				original = img
+			}
+		default:
+			if source, ok := img.(*cimage.Image); !ok || source.Mimetype != "image/jpeg" || source.Mask != nil {
+				original = img
+			}
+		}
+		r.exactImages = r.exactImages || original != nil
+		last := len(r.images) - 1
+		r.images[last] = append(r.images[last], original)
+	}
 	style := canvas.DefaultStyle
 	style.Fill = canvas.Paint{Color: canvas.White}
 	style.Stroke = canvas.Paint{Color: canvas.Black}