mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-30 01:27:26 +08:00
295 lines
10 KiB
Go
295 lines
10 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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"context"
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"crypto/sha256"
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"errors"
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"fmt"
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basefont "github.com/xiaoqidun/ofdgo/internal/base/font"
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)
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// FontMetrics 提供不依赖绘图库的字体度量，所有整数尺寸使用字体设计单位
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// VerticalMetrics依次返回非负的上升高度、下降高度和行间隙
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// Write返回独立的SFNT数据，调用方不得修改字体实例
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type FontMetrics interface {
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UnitsPerEm() uint16
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NumGlyphs() uint16
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GlyphIndex(rune) uint16
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GlyphAdvance(uint16) uint16
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VerticalMetrics() (uint16, uint16, uint16)
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Write() []byte
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}
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// FontOutlines 提供基线原点、纵轴向下的字形轮廓，不绑定字体实现
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// GlyphOutline返回只读路径，字号与路径单位为毫米
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type FontOutlines interface {
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FontMetrics
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GlyphOutline(glyph uint16, size float64) (GeometryPath, error)
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}
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// FontOutlineBatch 批量提取指定字形，不经过字符映射或文字塑形
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// 返回路径与输入编号一一对应，允许重复编号和空轮廓，路径只读
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type FontOutlineBatch interface {
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FontOutlines
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GlyphOutlines(glyphs []uint16, size float64) ([]GeometryPath, error)
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}
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// FontGlyphBounds 提供与字形轮廓一致的边界，字号及边界单位为毫米
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// 不使用字体全局边界替代单个字形，空轮廓返回零边界
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type FontGlyphBounds interface {
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FontOutlines
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GlyphBounds(glyph uint16, size float64) (Box, error)
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}
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// FontGlyphDiagnostics 提供已提取字形的恢复提示，不将提示作为轮廓解析失败
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// 字形不存在或不支持的指令仍由GlyphOutline返回错误
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type FontGlyphDiagnostics interface {
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FontMetrics
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GlyphWarning(glyph uint16) error
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}
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// FontShaper 提供可选的横向文字塑形，仅用于显式新建或重排
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// 字形按逻辑簇顺序排列，Cluster使用原文的符文索引，坐标为毫米且纵轴向下
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type FontShaper interface {
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FontMetrics
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ShapeText(value string, size float64) ([]ShapedGlyph, error)
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}
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// TextShapeOptions 指定文字塑形参数，Bidi启用双向及脚本分段，不执行字体回退
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// Direction为空或ltr时从左向右，rtl时从右向左；Script为四字母ISO15924代码，空值自动检测
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// Bidi启用时Direction指定段落方向，各文字片段按双向算法排列
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// Language为语言标签，Features为逗号分隔的全局OpenType特性，如kern=0,liga=1，不接受字符区间
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// 零值保持原有FontShaper行为，非零值要求FontShaperOptions能力
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type TextShapeOptions struct {
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Bidi bool
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Direction string
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Script string
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Language string
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Features string
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}
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// FontShaperOptions 提供显式可配置塑形，簇与坐标遵循FontShaper约定
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// 右向左文字仍按逻辑簇返回，视觉顺序由X和Y保留
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type FontShaperOptions interface {
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FontShaper
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ShapeTextWithOptions(value string, size float64, options TextShapeOptions) ([]ShapedGlyph, error)
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}
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// FontShaperRun 保留完整单行原文的上下文，仅塑形指定区间，不执行字体回退
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// start和end为原文的符文索引，区间左闭右开，返回Cluster仍使用原文索引
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// 调用方负责方向和脚本分段，options.Bidi须为false；坐标相对当前区间的基线起点
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// value为已校验的原文符文序列，调用期间不得修改，返回结果不引用该切片
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type FontShaperRun interface {
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FontShaperOptions
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ShapeTextRun(value []rune, start, end int, size float64, options TextShapeOptions) ([]ShapedGlyph, error)
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}
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// ShapedGlyph 保存塑形后的字形、原文簇和基线定位
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// VisualOrder为簇从左到右的零起始顺序，同簇字形共用顺序
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type ShapedGlyph struct {
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Glyph uint16
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Cluster int
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VisualOrder int
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X, Y, Advance float64
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}
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// ResolvedFont 保存字体来源和只读字体数据，不将外部字体写入文档
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type ResolvedFont struct {
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Data []byte
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Source string
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Face *FontFace
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Exact bool
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}
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// PreparedFont 保存绘制用字体及GID、CID到包装字符的映射，所有数据只读
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// Data可与源编码不同，原始资源仍由ResolveFont和Reader保留
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type PreparedFont struct {
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ResolvedFont
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Glyphs map[uint16]rune
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CIDs map[uint16]rune
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digest [32]byte
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}
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// FontBackend 统一字体来源与度量，exact禁止使用无关回退字体
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// ResolveFont不得递归调用Renderer.ResolveFont，OpenFont不得修改输入数据
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type FontBackend interface {
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Backend
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ResolveFont(renderer *Renderer, id string, exact bool) (ResolvedFont, error)
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OpenFont(data []byte) (FontMetrics, error)
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}
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// resolvedFontKey 区分只读资源的字体标识与精确匹配要求
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type resolvedFontKey struct {
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id string
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exact bool
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definition *Font
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}
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// resolvedFontResult 缓存字体解析结果及不可用原因
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type resolvedFontResult struct {
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font ResolvedFont
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err error
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}
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// fontDataKey 区分只读字体的起点和长度，指针保留源数据直到预算淘汰
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type fontDataKey struct {
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data *byte
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size int
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}
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// ResolveFont 使用配置的字体后端解析资源，保留精确匹配与回退的区别
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// 页面取消及后端取消、超时结果不缓存，后续调用可重试
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// 入参: id 字体资源标识, exact 是否要求精确匹配
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// 返回: ResolvedFont 字体与来源, error 解析错误
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func (r *Renderer) ResolveFont(id string, exact bool) (ResolvedFont, error) {
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if r.pageContext != nil {
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if err := r.pageContext.Err(); err != nil {
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return ResolvedFont{}, err
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}
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}
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if r.backends.Fonts == nil {
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return ResolvedFont{}, fmt.Errorf("fonts: %w", ErrBackendUnavailable)
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}
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key := resolvedFontKey{id: id, exact: exact, definition: r.Reader.fontDefinition(id)}
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if key.definition != nil && key.definition.ID != "" {
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key.id = key.definition.ID
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}
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if cached, ok := r.resolvedFonts[key]; ok {
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return cached.font, cached.err
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}
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resolved, err := r.backends.Fonts.ResolveFont(r, key.id, exact)
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if r.pageContext != nil {
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if err := r.pageContext.Err(); err != nil {
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return ResolvedFont{}, err
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}
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}
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if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
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return ResolvedFont{}, err
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}
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key.definition = r.Reader.fontDefinition(id)
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if key.definition != nil && key.definition.ID != "" {
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key.id = key.definition.ID
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}
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r.resolvedFonts[key] = resolvedFontResult{font: resolved, err: err}
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return resolved, err
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}
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// PrepareFont 统一处理内嵌字体包装和索引映射，供各编译器复用
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// 子渲染器按原始内容复用只读包装结果，各文档保留独立的来源信息
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// 入参: id 字体资源标识
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// 返回: *PreparedFont 绘制字体, error 字体解析错误
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func (r *Renderer) PrepareFont(id string) (*PreparedFont, error) {
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if r.pageContext != nil {
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if err := r.pageContext.Err(); err != nil {
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return nil, err
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}
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}
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if definition := r.Reader.fontDefinition(id); definition != nil && definition.ID != "" {
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id = definition.ID
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}
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if cached := r.preparedFonts[id]; cached != nil {
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return cached, nil
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}
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resolved, err := r.ResolveFont(id, false)
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if err != nil {
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return nil, err
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}
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definition := r.Reader.fontDefinition(id)
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if definition != nil && definition.ID != "" {
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id = definition.ID
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}
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prepared := &PreparedFont{ResolvedFont: resolved}
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if definition != nil && definition.FontFile != "" {
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key := r.fontDigest(resolved.Data)
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if content, ok := r.fontPreparations.get(key); ok {
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prepared.Data, prepared.Glyphs, prepared.CIDs, prepared.digest = content.Data, content.Glyphs, content.CIDs, content.digest
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r.preparedFonts[id] = prepared
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return prepared, nil
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}
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prepared.CIDs = basefont.GetCFFCIDRuneMap(resolved.Data)
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if _, data, mapping, _, err := FixFontDataAggressive(resolved.Data, true, true); err == nil {
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prepared.Data = data
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if mapping != nil {
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prepared.Glyphs = make(map[uint16]rune)
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for character, glyph := range mapping {
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if character == basefont.PackedGlyphRune(glyph) {
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prepared.Glyphs[glyph] = character
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}
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}
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for character, glyph := range mapping {
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if _, ok := prepared.Glyphs[glyph]; !ok {
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prepared.Glyphs[glyph] = character
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}
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}
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}
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}
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prepared.digest = r.fontDigest(prepared.Data)
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if r.pageContext != nil {
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if err := r.pageContext.Err(); err != nil {
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return nil, err
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}
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}
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cost := min(len(prepared.Data), r.fontPreparations.limit)*2 + (len(prepared.Glyphs)+len(prepared.CIDs))*48 + 256
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r.fontPreparations.put(key, PreparedFont{ResolvedFont: ResolvedFont{Data: prepared.Data}, Glyphs: prepared.Glyphs, CIDs: prepared.CIDs, digest: prepared.digest}, cost)
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}
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r.preparedFonts[id] = prepared
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return prepared, nil
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}
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// fontDigest 在预算内复用只读字体摘要，内容副本仍按摘要复用解析结果
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// 入参: data 不得修改的字体数据
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// 返回: [32]byte 字体摘要
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func (r *Renderer) fontDigest(data []byte) [32]byte {
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if len(data) == 0 {
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return sha256.Sum256(nil)
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}
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key := fontDataKey{data: &data[0], size: len(data)}
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if digest, ok := r.fontDigests.get(key); ok {
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return digest
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}
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digest := sha256.Sum256(data)
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r.fontDigests.put(key, digest, min(cap(data), r.fontDigests.limit)+256)
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return digest
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}
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// resetFontCache 重置字体解析及字形缓存，保留图片和非字体后端状态
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func (r *Renderer) resetFontCache() {
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r.fontSourcesCache = newFontSourceCache()
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r.resetFontBackendCache()
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}
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// resetFontBackendCache 清理后端字体对象，保留字体文件和图片缓存
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func (r *Renderer) resetFontBackendCache() {
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r.sharedBackendStates = make(map[any]any)
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r.preparedFonts = make(map[string]*PreparedFont)
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r.fontDigests = &renderCache[fontDataKey, [32]byte]{limit: 4 << 20}
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r.fontPreparations = &renderCache[[32]byte, PreparedFont]{limit: 16 << 20}
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r.resolvedFonts = make(map[resolvedFontKey]resolvedFontResult)
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if r.fontSourcesCache != nil {
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r.fontSourcesCache.fallback = ResolvedFont{}
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r.fontSourcesCache.fallbackRead = false
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}
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r.fontMetrics = &renderCache[[32]byte, FontMetrics]{limit: 32 << 20}
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r.glyphOutlines = &renderCache[glyphOutlineKey, GeometryPath]{limit: 16 << 20}
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for _, state := range r.backendStates {
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if fonts, ok := state.(interface{ resetFonts() }); ok {
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fonts.resetFonts()
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}
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}
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}
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