mirror of
https://github.com/xiaoqidun/ofdgo.git
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118 lines
4.3 KiB
Go
118 lines
4.3 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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"bytes"
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"fmt"
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"math"
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ggtext "github.com/gogpu/gg/text"
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)
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// ResolveFont 使用公共字体来源匹配，不创建Canvas字体
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// 入参: r 渲染器, id 字体ID, exact 是否禁止无关回退
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// 返回: ResolvedFont 字体及来源, error 解析错误
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func (b GGBackend) 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 通过GG解析独立字体，保留原始SFNT编码
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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 (GGBackend) OpenFont(data []byte) (FontMetrics, error) {
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data = bytes.Clone(data)
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source, err := ggtext.NewFontSource(data)
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if err != nil {
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return nil, err
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}
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return &ggFontMetrics{font: source.Parsed(), data: data}, nil
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}
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// ggFontMetrics 适配GG设计单位度量与字形轮廓
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type ggFontMetrics struct {
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font ggtext.ParsedFont
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data []byte
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}
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// UnitsPerEm 返回字体设计单位
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// 返回: uint16 每字单位数
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func (f *ggFontMetrics) UnitsPerEm() uint16 { return uint16(f.font.UnitsPerEm()) }
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// NumGlyphs 返回字形数量
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// 返回: uint16 字形数量
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func (f *ggFontMetrics) NumGlyphs() uint16 { return uint16(f.font.NumGlyphs()) }
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// GlyphIndex 返回字符对应的字形编号
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// 入参: character 字符
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// 返回: uint16 字形编号
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func (f *ggFontMetrics) GlyphIndex(character rune) uint16 { return f.font.GlyphIndex(character) }
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// GlyphAdvance 返回字形设计单位推进宽度
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// 入参: glyph 字形编号
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// 返回: uint16 推进宽度
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func (f *ggFontMetrics) GlyphAdvance(glyph uint16) uint16 {
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return uint16(math.Round(f.font.GlyphAdvance(glyph, float64(f.font.UnitsPerEm()))))
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}
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// VerticalMetrics 返回非负的上升、下降与行间隙
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// 返回: uint16 上升高度, uint16 下降高度, uint16 行间隙
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func (f *ggFontMetrics) VerticalMetrics() (uint16, uint16, uint16) {
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m := f.font.Metrics(float64(f.font.UnitsPerEm()))
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return uint16(math.Round(math.Max(0, m.Ascent))), uint16(math.Round(math.Max(0, -m.Descent))), uint16(math.Round(math.Max(0, m.LineGap)))
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}
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// Write 返回独立字体数据，不更新字体元信息
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// 返回: []byte SFNT数据
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func (f *ggFontMetrics) Write() []byte { return bytes.Clone(f.data) }
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// GlyphOutline 返回基线原点、纵轴向下的字形路径
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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 轮廓解析错误
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func (f *ggFontMetrics) GlyphOutline(glyph uint16, size float64) (GeometryPath, error) {
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if !rasterPositive(size) || int(glyph) >= f.font.NumGlyphs() {
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return nil, fmt.Errorf("invalid glyph or size")
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}
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outline, err := ggtext.NewOutlineExtractor().ExtractOutline(f.font, ggtext.GlyphID(glyph), size)
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if err != nil || outline == nil {
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return nil, err
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}
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result := make(GeometryPath, 0, len(outline.Segments)+1)
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point := func(p ggtext.OutlinePoint) Point { return Point{X: float64(p.X), Y: float64(p.Y)} }
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for _, s := range outline.Segments {
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segment := GeometrySegment{End: point(s.Points[0])}
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switch s.Op {
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case ggtext.OutlineOpMoveTo:
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if len(result) > 0 {
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result = append(result, GeometrySegment{Verb: GeometryClose})
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}
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segment.Verb = GeometryMove
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case ggtext.OutlineOpLineTo:
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segment.Verb = GeometryLine
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case ggtext.OutlineOpQuadTo:
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segment.Verb, segment.Control1, segment.End = GeometryQuad, point(s.Points[0]), point(s.Points[1])
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case ggtext.OutlineOpCubicTo:
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segment.Verb, segment.Control1, segment.Control2, segment.End = GeometryCubic, point(s.Points[0]), point(s.Points[1]), point(s.Points[2])
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default:
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return nil, fmt.Errorf("unsupported GG outline command %d", s.Op)
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}
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result = append(result, segment)
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}
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if len(result) > 0 {
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result = append(result, GeometrySegment{Verb: GeometryClose})
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}
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return result, nil
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}
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