mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 08:46:55 +08:00
104 lines
3.1 KiB
Go
104 lines
3.1 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"
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"image/color"
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"github.com/gogpu/gg"
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)
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// GGBackend 提供字体、页面编译和CPU绘制，不注册全局GPU设备或隐式切换后端
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type GGBackend struct{}
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// Name 返回后端标识
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// 返回: string 后端标识
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func (GGBackend) Name() string { return "gg" }
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// Render 绘制已编译页面，使用自有双圆渐变语义保持原有定位
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// 入参: page 只读页面
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// 返回: image.Image 图像, error 绘制错误
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func (GGBackend) Render(page *RasterPage) (image.Image, error) {
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w, h, err := page.PixelSize()
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if err != nil {
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return nil, err
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}
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pixmap := gg.NewPixmap(w, h)
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img := pixmap.ImageView()
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raster := gg.NewSoftwareRenderer(w, h)
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for i, cmd := range page.Commands {
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m := page.PixelTransform(cmd.Transform, h)
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if cmd.Image != nil {
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if err := drawRasterImageCommand(GGBackend{}, page, img, imagePixelSource(cmd.Image), cmd); err != nil {
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return nil, err
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}
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continue
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}
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path := gg.NewPath()
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for _, s := range cmd.Path {
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end, c1, c2 := m.Apply(s.End), m.Apply(s.Control1), m.Apply(s.Control2)
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switch s.Verb {
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case RasterMove:
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path.MoveTo(end.X, end.Y)
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case RasterLine:
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path.LineTo(end.X, end.Y)
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case RasterQuad:
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path.QuadraticTo(c1.X, c1.Y, end.X, end.Y)
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case RasterCubic:
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path.CubicTo(c1.X, c1.Y, c2.X, c2.Y, end.X, end.Y)
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case RasterClose:
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path.Close()
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default:
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return nil, fmt.Errorf("gg command %d: unsupported path verb %d", i, s.Verb)
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}
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}
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paint := gg.NewPaint()
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paint.SetFillBrush(gg.SolidBrush{Color: ggRGBA(cmd.Paint.Color)})
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if g := cmd.Paint.Gradient; g != nil {
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if g.Kind != RasterLinear && g.Kind != RasterRadial {
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return nil, fmt.Errorf("gg command %d: unsupported gradient %d", i, g.Kind)
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}
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inverse, err := m.Inverse()
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if err != nil {
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return nil, fmt.Errorf("gg command %d: %w", i, err)
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}
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paint.SetFillBrush(gg.NewCustomBrush(func(x, y float64) gg.RGBA {
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p := inverse.Apply(RasterPoint{X: x, Y: y})
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return ggRGBA(g.At(p.X, p.Y))
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}))
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}
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if cmd.EvenOdd {
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paint.FillRule = gg.FillRuleEvenOdd
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}
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if err := raster.Fill(pixmap, path, paint); err != nil {
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return nil, fmt.Errorf("gg command %d: %w", i, err)
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}
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}
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return img, nil
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}
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// ggRGBA 将标准库预乘颜色转换为gg的非预乘颜色
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// 入参: c 预乘颜色
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// 返回: gg.RGBA 非预乘颜色
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func ggRGBA(c color.RGBA) gg.RGBA {
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if c.A == 0 {
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return gg.Transparent
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}
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a := float64(c.A)
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return gg.RGBA{R: float64(c.R) / a, G: float64(c.G) / a, B: float64(c.B) / a, A: a / 255}
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}
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