feat(编辑能力): 修复复合对象裁剪丢失，优化选区性能

ofdgo_editor_color.go

@@ -0,0 +1,171 @@
+// 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/color"
+	"maps"
+	"slices"
+	"strconv"
+	"strings"
+)
+
+// Color 解析当前文档的纯色，支持RGB、灰度、CMYK及调色板，不修改原颜色
+// 入参: value 颜色，nil表示默认黑色
+// 返回: color.NRGBA 非预乘颜色, error 错误信息
+func (e *Editor) Color(value *FillColor) (color.NRGBA, error) {
+	space := ColorSpace{Type: "RGB", BitsPerComponent: 8}
+	if value == nil {
+		return color.NRGBA{A: 255}, nil
+	}
+	if value.Pattern != nil || value.AxialShd != nil || value.RadialShd != nil || value.unsupported {
+		return color.NRGBA{}, fmt.Errorf("color is not a supported solid color")
+	}
+	id := value.ColorSpace
+	if id == "" && e.source != nil && e.source.document.CommonData.DefaultCS != 0 {
+		id = strconv.Itoa(e.source.document.CommonData.DefaultCS)
+	}
+	if id != "" {
+		var found *ColorSpace
+		if e.source != nil {
+			found = e.source.reader.colorSpaceCache[id]
+		}
+		for _, resource := range e.resources {
+			if resource.space != nil && resource.space.ID == id {
+				found = resource.space
+				break
+			}
+		}
+		if found == nil {
+			return color.NRGBA{}, fmt.Errorf("color space %q not found", id)
+		}
+		space = *found
+	}
+	bits := space.BitsPerComponent
+	if bits == 0 {
+		bits = 8
+	}
+	if bits != 1 && bits != 2 && bits != 4 && bits != 8 && bits != 16 {
+		return color.NRGBA{}, fmt.Errorf("unsupported color depth %d", bits)
+	}
+	count := 3
+	switch space.Type {
+	case "RGB":
+	case "GRAY":
+		count = 1
+	case "CMYK":
+		count = 4
+	default:
+		return color.NRGBA{}, fmt.Errorf("unsupported color space %q", space.Type)
+	}
+	text := value.Value
+	if strings.TrimSpace(text) == "" && value.Index != nil {
+		if *value.Index < 0 || *value.Index >= len(space.Palette) {
+			return color.NRGBA{}, fmt.Errorf("color palette index out of range")
+		}
+		text = space.Palette[*value.Index]
+	}
+	fields := strings.Fields(text)
+	if len(fields) != count {
+		return color.NRGBA{}, fmt.Errorf("expected %d color components", count)
+	}
+	var components [4]uint8
+	limit := 1<<bits - 1
+	for i, field := range fields {
+		v, err := parseColorComponent(field)
+		if err != nil || v < 0 || v > limit {
+			return color.NRGBA{}, fmt.Errorf("invalid color component %q", field)
+		}
+		components[i] = uint8((v*255 + limit/2) / limit)
+	}
+	r, g, b := components[0], components[1], components[2]
+	if space.Type == "GRAY" {
+		g, b = r, r
+	} else if space.Type == "CMYK" {
+		r, g, b = color.CMYKToRGB(components[0], components[1], components[2], components[3])
+	}
+	a := 255
+	if value.Alpha != nil {
+		a = *value.Alpha
+		if a < 0 || a > 255 {
+			return color.NRGBA{}, fmt.Errorf("color alpha must be between 0 and 255")
+		}
+	}
+	return color.NRGBA{R: r, G: g, B: b, A: uint8(a)}, nil
+}
+
+// RGBColor 创建浏览器等调用方使用的RGB纯色，非RGB文档按需注册独立颜色空间
+// 不修改文档默认颜色空间，未使用的新增颜色空间不写出
+// 入参: value 非预乘颜色
+// 返回: *FillColor OFD颜色, error 错误信息
+func (e *Editor) RGBColor(value color.NRGBA) (*FillColor, error) {
+	result := &FillColor{Value: fmt.Sprintf("%d %d %d", value.R, value.G, value.B)}
+	if value.A != 255 {
+		alpha := int(value.A)
+		result.Alpha = &alpha
+	}
+	if e.sourceRGB() {
+		return result, nil
+	}
+	for _, id := range slices.Sorted(maps.Keys(e.source.reader.colorSpaceCache)) {
+		space := e.source.reader.colorSpaceCache[id]
+		if space.Type == "RGB" && (space.BitsPerComponent == 0 || space.BitsPerComponent == 8) && len(space.Palette) == 0 {
+			result.ColorSpace = id
+			return result, nil
+		}
+	}
+	for _, resource := range e.resources {
+		if resource.space != nil {
+			result.ColorSpace = resource.space.ID
+			return result, nil
+		}
+	}
+	if err := e.prepareSourceIDs(); err != nil {
+		return nil, err
+	}
+	result.ColorSpace = e.nextID()
+	e.resources = append(e.resources, editorResource{space: &ColorSpace{ID: result.ColorSpace, Type: "RGB", BitsPerComponent: 8}})
+	return result, nil
+}
+
+// editorPaintable 判断文字与路径颜色能否在保留其他字段的前提下修改
+// 入参: object 图形对象
+// 返回: bool 是否支持纯色编辑
+func (e *Editor) editorPaintable(object GraphicObject) bool {
+	var fill, stroke *FillColor
+	switch object.Type {
+	case "TextObject":
+		fill, stroke = object.TextObject.FillColor, (*FillColor)(object.TextObject.StrokeColor)
+	case "PathObject":
+		fill, stroke = object.PathObject.FillColor, (*FillColor)(object.PathObject.StrokeColor)
+	default:
+		return false
+	}
+	for _, value := range []*FillColor{fill, stroke} {
+		if _, err := e.Color(value); err != nil {
+			return false
+		}
+	}
+	return true
+}
+
+// editorColor 校验当前文档的颜色空间和分量
+// 入参: value 颜色
+// 返回: error 错误信息
+func (e *Editor) editorColor(value *FillColor) error {
+	_, err := e.Color(value)
+	return err
+}