feat(文件拆分): 拆分PDF格式适配模块

internal/codec/pdf/geometry.go

@@ -0,0 +1,101 @@
+// 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 pdf
+
+import (
+	"context"
+	"fmt"
+
+	basegeom "github.com/xiaoqidun/ofdgo/internal/base/geom"
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// GeometryPath 直接转换PDF路径坐标，不经文本编码或曲线展平
+// 入参: ctx 取消上下文, source PDF路径, matrix 坐标变换
+// 返回: basegeom.Path 独立几何路径, error 指令、坐标或取消错误
+func GeometryPath(ctx context.Context, source pdfgo.Path, matrix pdfgo.Matrix) (basegeom.Path, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	path := make(basegeom.Path, len(source.Segments))
+	for i, segment := range source.Segments {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
+		var count int
+		switch segment.Operator {
+		case "M":
+			path[i].Verb, count = basegeom.Move, 1
+		case "L":
+			path[i].Verb, count = basegeom.Line, 1
+		case "B":
+			path[i].Verb, count = basegeom.Cubic, 3
+		case "C":
+			path[i].Verb = basegeom.ClosePath
+		default:
+			return nil, fmt.Errorf("invalid PDF path operator %q", segment.Operator)
+		}
+		if len(segment.Points) != count {
+			return nil, fmt.Errorf("invalid PDF path operands for %s", segment.Operator)
+		}
+		var points [3]basegeom.Point
+		for j, point := range segment.Points {
+			point = matrix.Apply(point)
+			points[j] = basegeom.Point{X: point.X, Y: point.Y}
+		}
+		if count != 0 {
+			path[i].End = points[count-1]
+		}
+		if count == 3 {
+			path[i].Control1, path[i].Control2 = points[0], points[1]
+		}
+	}
+	if err := path.Validate(); err != nil {
+		return nil, err
+	}
+	return path, ctx.Err()
+}
+
+// GlyphPath 将字形轮廓变换到PDF页面坐标，二次曲线精确转换为三次曲线
+// 入参: outline 字形轮廓, matrix 字形到页面的变换
+// 返回: pdfgo.Path 页面路径, error 非字体轮廓指令
+func GlyphPath(outline basegeom.Path, matrix pdfgo.Matrix) (pdfgo.Path, error) {
+	path := pdfgo.Path{Segments: make([]pdfgo.Segment, 0, len(outline))}
+	var current, start basegeom.Point
+	point := func(p basegeom.Point) pdfgo.Point { return matrix.Apply(pdfgo.Point{X: p.X, Y: p.Y}) }
+	for _, segment := range outline {
+		switch segment.Verb {
+		case basegeom.Move:
+			start = segment.End
+			path.Segments = append(path.Segments, pdfgo.Segment{Operator: "M", Points: []pdfgo.Point{point(segment.End)}})
+		case basegeom.Line:
+			path.Segments = append(path.Segments, pdfgo.Segment{Operator: "L", Points: []pdfgo.Point{point(segment.End)}})
+		case basegeom.Quad:
+			c1 := basegeom.Point{X: current.X + (segment.Control1.X-current.X)*2/3, Y: current.Y + (segment.Control1.Y-current.Y)*2/3}
+			c2 := basegeom.Point{X: segment.End.X + (segment.Control1.X-segment.End.X)*2/3, Y: segment.End.Y + (segment.Control1.Y-segment.End.Y)*2/3}
+			path.Segments = append(path.Segments, pdfgo.Segment{Operator: "B", Points: []pdfgo.Point{point(c1), point(c2), point(segment.End)}})
+		case basegeom.Cubic:
+			path.Segments = append(path.Segments, pdfgo.Segment{Operator: "B", Points: []pdfgo.Point{point(segment.Control1), point(segment.Control2), point(segment.End)}})
+		case basegeom.ClosePath:
+			path.Segments = append(path.Segments, pdfgo.Segment{Operator: "C"})
+			current = start
+			continue
+		default:
+			return pdfgo.Path{}, fmt.Errorf("unsupported PDF glyph geometry verb %d", segment.Verb)
+		}
+		current = segment.End
+	}
+	return path, nil
+}