mirror of
https://github.com/xiaoqidun/ofdgo.git
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101 lines
3.3 KiB
Go
101 lines
3.3 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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"github.com/tdewolff/canvas"
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"github.com/tdewolff/font"
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)
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// canvasFontMetrics 保留默认字体度量，写出时不更新原始时间
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type canvasFontMetrics struct {
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*font.SFNT
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*fontShaper
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outlines *sfntOutliner
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}
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// ResolveFont 按需加载字体资源，保留内嵌数据及外部字体的名称、样式和集合索引匹配
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// 入参: r 渲染器, id 字体标识, exact 是否禁止无关回退
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// 返回: ResolvedFont 字体与来源, error 字体不可用错误
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func (b CanvasBackend) ResolveFont(r *Renderer, id string, exact bool) (ResolvedFont, error) {
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return r.resolveFontSource(b, id, exact)
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}
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// OpenFont 解析独立SFNT数据，度量与原有编辑排版保持一致
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// 入参: data 字体数据
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// 返回: FontMetrics 字体度量, error 解析错误
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func (CanvasBackend) OpenFont(data []byte) (FontMetrics, error) {
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sfnt, err := font.ParseSFNT(data, 0)
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if err != nil {
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return nil, err
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}
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metrics := &canvasFontMetrics{SFNT: sfnt, outlines: &sfntOutliner{font: sfnt}}
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metrics.fontShaper = &fontShaper{metrics: metrics}
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return metrics, nil
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}
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// Write 返回字体数据，不修改字体元信息
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// 返回: []byte 独立SFNT数据
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func (f canvasFontMetrics) Write() []byte {
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return fontSFNTData(f.SFNT)
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}
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// GlyphOutline 返回基线原点、纵轴向下的字形轮廓
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// 入参: glyph 字形编号, size 字号，单位为毫米
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// 返回: GeometryPath 字形路径, error 字形解析错误
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func (f canvasFontMetrics) GlyphOutline(glyph uint16, size float64) (GeometryPath, error) {
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if !rasterPositive(size) || glyph >= f.NumGlyphs() {
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return nil, fmt.Errorf("invalid glyph or size")
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}
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path := &canvas.Path{}
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if err := f.outlines.path(path, glyph, size/float64(f.UnitsPerEm())); err != nil {
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return nil, err
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}
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return *geometryFromCanvasPath(path), nil
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}
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// GlyphWarning 返回字形指令栈下溢后保留设计轮廓的提示，原始字体不变
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// 入参: glyph 字形编号
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// 返回: error 恢复原因，无恢复时为空
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func (f canvasFontMetrics) GlyphWarning(glyph uint16) error {
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return f.outlines.glyphWarning(glyph)
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}
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// GlyphOutlines 批量提取字形轮廓，重复编号只解析一次
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// 入参: glyphs 字形编号, size 毫米字号
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// 返回: []GeometryPath 同序只读轮廓, error 轮廓错误
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func (f canvasFontMetrics) GlyphOutlines(glyphs []uint16, size float64) ([]GeometryPath, error) {
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if !rasterPositive(size) {
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return nil, fmt.Errorf("invalid glyph size")
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}
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result := make([]GeometryPath, len(glyphs))
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paths := make(map[uint16]GeometryPath, len(glyphs))
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for i, glyph := range glyphs {
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path, ok := paths[glyph]
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if !ok {
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var err error
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path, err = f.GlyphOutline(glyph, size)
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if err != nil {
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return nil, err
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}
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paths[glyph] = path
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}
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result[i] = path
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}
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return result, nil
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}
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