feat(功能强化): 新增全文搜索与结果定位，优化搜索框及翻页按钮显示

ofdgo_search.go

@@ -0,0 +1,178 @@
+// 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 (
+	"math"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"github.com/tdewolff/canvas"
+)
+
+// PageText 页面文字，按绘制顺序保留文本对象，不包含图像和签名外观
+type PageText struct {
+	Runs []TextRun `json:"runs"`
+}
+
+// TextRun 文本对象原文及逐字符区域，坐标以页面左上角为原点，单位为毫米
+// Boxes与Text的Unicode字符一一对应，缺少字体时使用文本对象区域
+type TextRun struct {
+	ID    string `json:"id"`
+	Text  string `json:"text"`
+	Boxes []Box  `json:"boxes"`
+}
+
+// TextMatch 文字匹配结果，Run为文本对象索引，Start和End为原文Unicode字符区间
+type TextMatch struct {
+	Run    int    `json:"run"`
+	Start  int    `json:"start"`
+	End    int    `json:"end"`
+	Before string `json:"before"`
+	Text   string `json:"text"`
+	After  string `json:"after"`
+	Boxes  []Box  `json:"boxes"`
+}
+
+// PageText 提取页面及启用注释的原文，复用当前字体配置和渲染位置计算
+// 入参: page 页面内容
+// 返回: *PageText 页面文字, error 错误信息
+func (r *Renderer) PageText(page *PageContent) (*PageText, error) {
+	box, err := r.GetPageBox(page)
+	if err != nil {
+		return nil, err
+	}
+	renderer := *r
+	renderer.pageText = &PageText{}
+	if err := renderer.renderPageToContext(canvas.NewContext(canvas.New(box.W, box.H)), page, false); err != nil {
+		return nil, err
+	}
+	return renderer.pageText, nil
+}
+
+// Search 按原文进行忽略大小写的字面匹配，不跨文本对象拼接或识别图像
+// 入参: query 搜索文字
+// 返回: []TextMatch 匹配结果及上下文
+func (p *PageText) Search(query string) []TextMatch {
+	var matches []TextMatch
+	if query == "" {
+		return matches
+	}
+	query = foldText(query)
+	length := utf8.RuneCountInString(query)
+	for index, run := range p.Runs {
+		text := foldText(run.Text)
+		runes := []rune(run.Text)
+		codeOffset := 0
+		for offset := 0; offset < len(text); {
+			found := strings.Index(text[offset:], query)
+			if found < 0 {
+				break
+			}
+			start := codeOffset + utf8.RuneCountInString(text[offset:offset+found])
+			offset += found
+			end := start + length
+			match := TextMatch{
+				Run: index, Start: start, End: end,
+				Before: string(runes[max(0, start-16):start]),
+				Text:   string(runes[start:end]),
+				After:  string(runes[end:min(len(runes), end+16)]),
+			}
+			for _, box := range run.Boxes[start:end] {
+				if box.W > 0 && box.H > 0 && (len(match.Boxes) == 0 || match.Boxes[len(match.Boxes)-1] != box) {
+					match.Boxes = append(match.Boxes, box)
+				}
+			}
+			matches = append(matches, match)
+			offset += len(query)
+			codeOffset = end
+		}
+	}
+	return matches
+}
+
+// foldText 统一Unicode大小写等价字符，保留字符数量
+// 入参: text 原文
+// 返回: string 匹配用文字
+func foldText(text string) string {
+	return strings.Map(func(char rune) rune {
+		folded := char
+		for next := unicode.SimpleFold(char); next != char; next = unicode.SimpleFold(next) {
+			folded = min(folded, next)
+		}
+		return folded
+	}, text)
+}
+
+// addRun 收集原始文本，字形索引不替代Unicode原文
+// 入参: obj 文本对象
+// 返回: *TextRun 文本及待填充的字符区域
+func (p *PageText) addRun(obj TextObject) *TextRun {
+	var text strings.Builder
+	for _, code := range obj.TextCode {
+		if code.Index == "" {
+			text.WriteString(string(textCodeRunes(code.Value)))
+		} else {
+			text.WriteRune('\uFFFC')
+		}
+	}
+	p.Runs = append(p.Runs, TextRun{ID: obj.ID, Text: text.String(), Boxes: make([]Box, utf8.RuneCountInString(text.String()))})
+	return &p.Runs[len(p.Runs)-1]
+}
+
+// textGlyphSpans 将绘制字形映射到原文字符区间
+// 入参: runes 原文字符, transforms 字形变换, offset 文本编码偏移
+// 返回: [][2]int 每个字形对应的字符起止位置
+func textGlyphSpans(runes []rune, transforms map[int]textGlyphTransform, offset int) [][2]int {
+	spans := make([][2]int, 0, len(runes))
+	for i := 0; i < len(runes); {
+		if transform, ok := transforms[offset+i]; ok && i+transform.CodeCount <= len(runes) {
+			for range transform.Glyphs {
+				spans = append(spans, [2]int{i, i + transform.CodeCount})
+			}
+			i += transform.CodeCount
+		} else {
+			spans = append(spans, [2]int{i, i + 1})
+			i++
+		}
+	}
+	return spans
+}
+
+// textPathBox 将字形轮廓转换为页面区域
+// 入参: path 字形轮廓, pageH 页面高度
+// 返回: Box 字符区域
+func textPathBox(path *canvas.Path, pageH float64) Box {
+	if path.Empty() {
+		return Box{}
+	}
+	bounds := path.Bounds()
+	return Box{X: bounds.X0, Y: pageH - bounds.Y1, W: bounds.X1 - bounds.X0, H: bounds.Y1 - bounds.Y0}
+}
+
+// unionTextBox 合并同一字符的字形区域
+// 入参: a 已有区域, b 新区域
+// 返回: Box 合并区域
+func unionTextBox(a, b Box) Box {
+	if a.W <= 0 || a.H <= 0 {
+		return b
+	}
+	if b.W <= 0 || b.H <= 0 {
+		return a
+	}
+	x, y := math.Min(a.X, b.X), math.Min(a.Y, b.Y)
+	return Box{X: x, Y: y, W: math.Max(a.X+a.W, b.X+b.W) - x, H: math.Max(a.Y+a.H, b.Y+b.H) - y}
+}