feat(转换能力): 完善转换渲染，优化字体加载

ofdgo_pdf_shading.go

@@ -16,72 +16,61 @@ package ofdgo
 
 import (
 	"math"
-	"slices"
 
 	"github.com/xiaoqidun/pdfgo"
 )
 
-// pdfGradientSegments 将线性源颜色及设备四色的截断点表达为OFD分段
+// gradientSegments 保留线性源颜色的设备分量，校准颜色经源空间转换
 // 入参: stops 源颜色分段, space 源颜色空间
-// 返回: []ShdSegment 等价RGB分段, error 不可线性表达的变换
-func pdfGradientSegments(stops []pdfgo.GradientStop, space *pdfgo.ColorSpace) ([]ShdSegment, error) {
-	if len(stops) == 0 {
-		return nil, &pdfgo.UnsupportedError{Feature: "nonlinear gradient conversion"}
+// 返回: []ShdSegment OFD颜色分段, error 不可线性表达的变换
+func (p *pdfImporter) gradientSegments(stops []pdfgo.GradientStop, space *pdfgo.ColorSpace) ([]ShdSegment, error) {
+	if err := pdfGradientStopsError(stops, space); err != nil {
+		return nil, err
 	}
-	calibrated := space != nil && space.Calibrated() && !space.SRGBEquivalent()
 	cmyk := space != nil && space.Model == "DeviceCMYK" && !space.Calibrated()
-	segments := make([]ShdSegment, 0, len(stops))
-	appendStop := func(position float64, rgb [3]float64) {
-		segments = append(segments, ShdSegment{Position: position, Color: ShdColor{Value: pdfNumbers(math.Round(rgb[0]*255), math.Round(rgb[1]*255), math.Round(rgb[2]*255))}})
-	}
-	for i, b := range stops {
-		if i > 0 {
-			a := stops[i-1]
-			if a.Position != b.Position && a.Values != b.Values {
-				if calibrated {
-					return nil, &pdfgo.UnsupportedError{Feature: "nonlinear ICC gradient conversion"}
-				}
-				if cmyk {
-					var crossings []float64
-					for c := 0; c < 3; c++ {
-						start, end := a.Values[c]+a.Values[3], b.Values[c]+b.Values[3]
-						if start != end {
-							if t := (1 - start) / (end - start); t > 0 && t < 1 {
-								crossings = append(crossings, t)
-							}
-						}
-					}
-					slices.Sort(crossings)
-					for _, t := range slices.Compact(crossings) {
-						var values [4]float64
-						for c := range values {
-							values[c] = a.Values[c]*(1-t) + b.Values[c]*t
-						}
-						rgb, err := space.RGB(values[:], "RelativeColorimetric")
-						if err != nil {
-							return nil, err
-						}
-						appendStop(a.Position+(b.Position-a.Position)*t, rgb)
-					}
-				}
-			}
+	segments := make([]ShdSegment, len(stops))
+	for i, stop := range stops {
+		paint := pdfgo.Paint{RGB: stop.RGB, Alpha: 1}
+		if cmyk {
+			paint.CMYK = &stop.Values
 		}
-		appendStop(b.Position, b.RGB)
+		color := p.color(paint)
+		segments[i] = ShdSegment{Position: stop.Position, Color: ShdColor{Value: color.Value, ColorSpace: color.ColorSpace}}
 	}
 	return segments, nil
 }
 
+// pdfGradientStopsError 检查源颜色分段是否可由OFD基本颜色表达
+// 入参: stops 源颜色分段, space 源颜色空间
+// 返回: error 不可线性表达的变换
+func pdfGradientStopsError(stops []pdfgo.GradientStop, space *pdfgo.ColorSpace) error {
+	if len(stops) == 0 {
+		return &pdfgo.UnsupportedError{Feature: "nonlinear gradient conversion"}
+	}
+	calibrated := space != nil && space.Calibrated() && !space.SRGBEquivalent()
+	if calibrated {
+		for i := 1; i < len(stops); i++ {
+			a, b := stops[i-1], stops[i]
+			if a.Position != b.Position && a.Values != b.Values {
+				return &pdfgo.UnsupportedError{Feature: "nonlinear ICC gradient conversion"}
+			}
+		}
+	}
+	return nil
+}
+
 // pdfGradientError 检查渐变能否精确映射为OFD线性分段
 // 入参: paint 画刷
 // 返回: error 不可等价表达的渐变
 func pdfGradientError(paint pdfgo.Paint) error {
+	if paint.Mesh != nil {
+		return &pdfgo.UnsupportedError{Feature: "bicubic mesh conversion"}
+	}
 	if paint.Axial != nil {
-		_, err := pdfGradientSegments(paint.Axial.Stops, paint.Axial.Space)
-		return err
+		return pdfGradientStopsError(paint.Axial.Stops, paint.Axial.Space)
 	}
 	if paint.Radial != nil {
-		_, err := pdfGradientSegments(paint.Radial.Stops, paint.Radial.Space)
-		return err
+		return pdfGradientStopsError(paint.Radial.Stops, paint.Radial.Space)
 	}
 	return nil
 }
@@ -90,7 +79,30 @@ func pdfGradientError(paint pdfgo.Paint) error {
 // 入参: mark 路径绘制信息
 // 返回: error 几何或着色错误
 func (p *pdfImporter) gradientPath(mark pdfgo.PathMark) error {
-	return p.compositeRegion(nil, pdfCompositeNode{path: &mark}, &pdfgo.ColorSpace{Model: "DeviceRGB"}, false)
+	cmyk := true
+	for i, paint := range []pdfgo.Paint{mark.Style.Fill, mark.Style.Stroke} {
+		if i == 0 && !mark.Fill || i == 1 && !mark.Stroke {
+			continue
+		}
+		space := paint.Space
+		switch {
+		case paint.Axial != nil:
+			space = paint.Axial.Space
+		case paint.Radial != nil:
+			space = paint.Radial.Space
+		case paint.Mesh != nil:
+			space = paint.Mesh.Space
+		}
+		if paint.CMYK == nil && (space == nil || space.Model != "DeviceCMYK" || space.Calibrated()) {
+			cmyk = false
+			break
+		}
+	}
+	space := &pdfgo.ColorSpace{Model: "DeviceRGB"}
+	if cmyk {
+		space.Model = "DeviceCMYK"
+	}
+	return p.compositeRegion(nil, pdfCompositeNode{path: &mark}, space, false)
 }
 
 // pdfShadingPosition 计算渐变参数，未延伸区域及不存在非负圆半径的位置不着色
@@ -103,6 +115,13 @@ func pdfShadingPosition(paint pdfgo.Paint, point pdfgo.Point) (float64, bool) {
 		return t, finite(t) && (t >= 0 || g.Extend[0]) && (t <= 1 || g.Extend[1])
 	}
 	g := paint.Radial
+	if g.Matrix != (pdfgo.Matrix{}) {
+		inverse, ok := g.Matrix.Inverse()
+		if !ok {
+			return 0, false
+		}
+		point = inverse.Apply(point)
+	}
 	dx, dy, dr := g.End.X-g.Start.X, g.End.Y-g.Start.Y, g.EndRadius-g.StartRadius
 	px, py := point.X-g.Start.X, point.Y-g.Start.Y
 	a, b, c := dx*dx+dy*dy-dr*dr, -2*(px*dx+py*dy+g.StartRadius*dr), px*px+py*py-g.StartRadius*g.StartRadius