mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 17:27:08 +08:00
284 lines
8.8 KiB
Go
284 lines
8.8 KiB
Go
// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ofdgo
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import (
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"fmt"
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"image/color"
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"strings"
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"github.com/go-text/typesetting/segmenter"
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)
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// MissingGlyphError 字体缺字错误，FontID为OFD字体资源标识，Characters按首次出现顺序保留不重复的缺失字符
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// 可通过errors.As从编辑错误中取得，不表示字体缺失或文件损坏
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type MissingGlyphError struct {
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FontID string `json:"fontID"`
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Characters string `json:"characters"`
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}
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// Error 返回缺失字符的Unicode码点
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// 返回: string 错误描述
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func (e *MissingGlyphError) Error() string {
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var codes []string
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for _, char := range e.Characters {
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codes = append(codes, fmt.Sprintf("U+%04X", char))
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}
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return fmt.Sprintf("font %q does not contain %s", e.FontID, strings.Join(codes, ", "))
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}
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// missingGlyphError 汇总缺失字符，无缺字时返回nil
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// 入参: id 字体资源标识, characters 缺失字符
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// 返回: error 缺字诊断
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func missingGlyphError(id string, characters []rune) error {
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if len(characters) == 0 {
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return nil
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}
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seen := make(map[rune]bool)
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var value strings.Builder
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for _, char := range characters {
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if !seen[char] {
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seen[char] = true
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value.WriteRune(char)
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}
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}
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return &MissingGlyphError{FontID: id, Characters: value.String()}
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}
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// TextLayout 本地横向段落选项，Wrap按CTM变换前的边界宽度折行，Align为left、center、right或justify
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// LineHeight为毫米单位的基线间距，0使用字体度量；LetterSpacing为字素间的附加毫米间距，可为负
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// LeftIndent和RightIndent为左右缩进，FirstLineIndent为每段首行相对左缩进的偏移，单位为毫米
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// 零值保持显式换行和左对齐
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type TextLayout struct {
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Wrap bool
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Align string
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LineHeight float64
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LetterSpacing float64
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LeftIndent float64
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RightIndent float64
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FirstLineIndent float64
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}
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// TextStyle 文字样式增量，Font和Color为空、Size为0时保留原值
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// Size单位为毫米，Color为OFD的RGB分量字符串，保留原颜色透明度
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type TextStyle struct {
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Font string
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Size float64
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Color string
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}
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// StyleText 原子更新同页文字样式，全部校验通过后提交一次撤销记录
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// 已知段落重新排版；原布局未知时替换字体和颜色保留坐标，不允许自动调整字号
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// 入参: page 页面索引, ids 文字对象标识, style 样式增量
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// 返回: error 错误信息
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func (e *Editor) StyleText(page int, ids []string, style TextStyle) error {
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objects, _, err := e.selectedObjects(page, ids)
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if err != nil {
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return err
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}
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updates, err := e.styleTextObjects(objects, style)
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if err != nil {
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return err
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}
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return e.UpdateObjects(page, updates)
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}
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// styleTextObjects 生成文字样式副本，不提交文档或历史
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// 入参: objects 原文字对象, style 样式增量
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// 返回: []GraphicObject 更新对象, error 错误信息
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func (e *Editor) styleTextObjects(objects []GraphicObject, style TextStyle) ([]GraphicObject, error) {
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updates := make([]GraphicObject, len(objects))
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for i, object := range objects {
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id := editorObjectID(object)
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if object.Type != "TextObject" {
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return nil, fmt.Errorf("object %q is not text", id)
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}
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updates[i] = cloneEditorData(object)
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text := &updates[i].TextObject
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value, layout := text.TextLayout()
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known := e.objectOrigin(id) == nil || text.layout != nil
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fontChanged := style.Font != "" && style.Font != text.Font
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sizeChanged := style.Size != 0 && style.Size != text.Size
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if sizeChanged && !known {
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return nil, &EditError{Code: EditUnsupportedObject, Err: fmt.Errorf("object %q requires explicit paragraph layout before changing size", id)}
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}
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if fontChanged {
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text.Font = style.Font
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}
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if sizeChanged {
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text.Size = style.Size
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}
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if known && (fontChanged || sizeChanged) {
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if err := e.LayoutText(text, value, layout); err != nil {
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return nil, err
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}
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}
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if style.Color != "" {
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if err := creationColor(&FillColor{Value: style.Color}); err != nil {
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return nil, err
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}
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var r, g, b float64
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fmt.Sscan(style.Color, &r, &g, &b)
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value, err := e.RGBColor(color.NRGBA{R: uint8(r), G: uint8(g), B: uint8(b), A: 255})
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if err != nil {
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return nil, err
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}
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if text.FillColor != nil {
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value.Alpha = text.FillColor.Alpha
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}
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text.FillColor = value
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}
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}
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return updates, nil
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}
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// textLayout 保存编辑中的原文与选项，不写入OFD，也不参与渲染
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type textLayout struct {
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value string
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options TextLayout
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}
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// TextLayout 获取最近一次排版的原文与选项，区分软换行和显式换行
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// 信息仅在当前编辑过程保留，读取OFD时返回定位后的文字和默认选项
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// 返回: string 原文, TextLayout 排版选项
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func (obj TextObject) TextLayout() (string, TextLayout) {
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if obj.layout != nil {
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return obj.layout.value, obj.layout.options
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}
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return obj.Text(), TextLayout{}
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}
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// breakTextLines 优先使用Unicode断行机会，过长词仅在字素边界折行，不丢弃空白
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// 入参: runes 段落字符, advances 含字距的字符步进, width 本地排版宽度, wrap 是否自动折行, spacing 附加字距, indent 首行缩进
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// 返回: [][2]int 各行的字符起止索引，左闭右开
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func breakTextLines(runes []rune, advances []float64, width float64, wrap bool, spacing, indent float64) [][2]int {
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if !wrap || len(runes) == 0 {
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return [][2]int{{0, len(runes)}}
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}
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var seg segmenter.Segmenter
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seg.Init(runes)
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breaks := make([]bool, len(runes)+1)
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for it := seg.LineIterator(); it.Next(); {
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line := it.Line()
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breaks[line.Offset+len(line.Text)] = true
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}
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var ends []int
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for it := seg.GraphemeIterator(); it.Next(); {
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cluster := it.Grapheme()
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ends = append(ends, cluster.Offset+len(cluster.Text))
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}
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sums := make([]float64, len(runes)+1)
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for i, advance := range advances {
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sums[i+1] = sums[i] + advance
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}
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var lines [][2]int
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for start, cursor := 0, 0; start < len(runes); {
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available := width
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if start == 0 {
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available -= indent
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}
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end, legal, next := start, start, cursor
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for next < len(ends) {
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candidate := ends[next]
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visible := candidate
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for visible > start && runes[visible-1] == ' ' {
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visible--
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}
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length := sums[visible] - sums[start]
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if visible > start {
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length -= spacing
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}
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if length > available && end > start {
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break
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}
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end = candidate
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next++
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if breaks[end] {
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legal = end
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}
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if length > available {
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break
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}
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}
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if end < len(runes) && legal > start {
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end = legal
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}
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lines = append(lines, [2]int{start, end})
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start = end
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for cursor < len(ends) && ends[cursor] <= start {
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cursor++
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}
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}
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return lines
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}
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// alignTextLine 将段落对齐转换为标准X和DeltaX，两端对齐保留段落末行左对齐
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// 入参: runes 行内字符, advances 含字距的字符步进, width 本地排版宽度, alignment 对齐方式, justify 是否允许本行两端对齐, spacing 附加字距
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// 返回: float64 行首X坐标, string 字符间的DeltaX序列
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func alignTextLine(runes []rune, advances []float64, width float64, alignment string, justify bool, spacing float64) (float64, string) {
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end := len(runes)
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for end > 0 && runes[end-1] == ' ' {
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end--
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}
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length := 0.0
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for _, advance := range advances[:end] {
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length += advance
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}
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if end > 0 {
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length -= spacing
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}
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x, extra := 0.0, max(0, width-length)
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if alignment == "center" {
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x = extra / 2
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} else if alignment == "right" {
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x = extra
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}
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gaps := make(map[int]bool)
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if alignment == "justify" && justify && extra > 0 {
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var seg segmenter.Segmenter
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seg.Init(runes[:end])
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for it := seg.LineIterator(); it.Next(); {
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line := it.Line()
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at := line.Offset + len(line.Text)
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if at < end {
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gaps[at-1] = true
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}
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}
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}
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deltas := make([]string, max(0, len(runes)-1))
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for i := range deltas {
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advance := advances[i]
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if gaps[i] {
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advance += extra / float64(len(gaps))
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}
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deltas[i] = ofdNumber(advance)
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}
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return x, strings.Join(deltas, " ")
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}
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// spaceTextAdvances 将字距加入各字素末尾，不拆散组合字符
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// 入参: runes 段落字符, advances 待更新的字符步进, spacing 附加毫米字距
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func spaceTextAdvances(runes []rune, advances []float64, spacing float64) {
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if spacing == 0 {
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return
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}
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var seg segmenter.Segmenter
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seg.Init(runes)
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for it := seg.GraphemeIterator(); it.Next(); {
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cluster := it.Grapheme()
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advances[cluster.Offset+len(cluster.Text)-1] += spacing
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}
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}
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