feat(归并文件): 归并文件下沉通用能力

ofdgo_action.go

@@ -17,9 +17,10 @@ package ofdgo
 import (
 	"encoding/xml"
 	"fmt"
-	basegeom "github.com/xiaoqidun/ofdgo/internal/base/geom"
 	"net/url"
 	"strconv"
+
+	basegeom "github.com/xiaoqidun/ofdgo/internal/base/geom"
 )
 
 // Action 动作
@@ -548,3 +549,92 @@ func resolveActionURI(action URI) string {
 	}
 	return base.ResolveReference(target).String()
 }
+
+// MarshalXML 按标准属性写入目标，书签和动作采用相同格式
+// 入参: encoder XML编码器, start 起始节点
+// 返回: error 参数或编码错误
+func (dest Dest) MarshalXML(encoder *xml.Encoder, start xml.StartElement) error {
+	attrs, err := dest.attributes()
+	if err != nil {
+		return err
+	}
+	start.Attr = attrs
+	if err := encoder.EncodeToken(start); err != nil {
+		return err
+	}
+	return encoder.EncodeToken(start.End())
+}
+
+// effective 应用省略属性的默认值，不改变原始声明
+// 返回: Dest 生效的目标参数
+func (dest Dest) effective() Dest {
+	if dest.OmitLeft {
+		dest.Left = 0
+	}
+	if dest.OmitTop {
+		dest.Top = 0
+	}
+	if dest.OmitZoom {
+		dest.Zoom = 0
+	}
+	return dest
+}
+
+// attributes 校验并生成目标属性，缩放为0表示沿用当前比例
+// 返回: ofdAttrs 标准属性, error 模式或参数错误
+func (dest Dest) attributes() (ofdAttrs, error) {
+	dest = dest.effective()
+	attrs := ofdAttrs{{Name: xml.Name{Local: "Type"}, Value: dest.Type}, {Name: xml.Name{Local: "PageID"}, Value: dest.PageID}}
+	if dest.PageID == "" {
+		return nil, fmt.Errorf("missing destination page")
+	}
+	add := func(name string, value float64, omit bool) error {
+		if !finite(value) {
+			return fmt.Errorf("invalid destination %s", name)
+		}
+		if !omit {
+			attrs.add(name, ofdNumber(value))
+		}
+		return nil
+	}
+	switch dest.Type {
+	case "XYZ":
+		if dest.Zoom != 0 && (dest.Zoom < 0.1 || dest.Zoom > 64) {
+			return nil, fmt.Errorf("destination zoom must be zero or between 0.1 and 64")
+		}
+		if err := add("Zoom", dest.Zoom, dest.OmitZoom); err != nil {
+			return nil, err
+		}
+		fallthrough
+	case "FitR":
+		if err := add("Left", dest.Left, dest.OmitLeft); err != nil {
+			return nil, err
+		}
+		if err := add("Top", dest.Top, dest.OmitTop); err != nil {
+			return nil, err
+		}
+		if dest.Type == "FitR" {
+			if dest.Right <= dest.Left || dest.Bottom <= dest.Top {
+				return nil, fmt.Errorf("empty destination rectangle")
+			}
+			if err := add("Right", dest.Right, false); err != nil {
+				return nil, err
+			}
+			if err := add("Bottom", dest.Bottom, false); err != nil {
+				return nil, err
+			}
+		}
+	case "FitH":
+		if err := add("Top", dest.Top, dest.OmitTop); err != nil {
+			return nil, err
+		}
+	case "FitV":
+		if err := add("Left", dest.Left, dest.OmitLeft); err != nil {
+			return nil, err
+		}
+	case "Fit":
+	default:
+		return nil, fmt.Errorf("invalid destination type %q", dest.Type)
+	}
+	return attrs, nil
+}