mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 08:46:55 +08:00
107 lines
3.4 KiB
Go
107 lines
3.4 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/tdewolff/canvas"
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"github.com/tdewolff/canvas/renderers/rasterizer"
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)
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// CanvasBackend canvas页面编译与绘制适配器，ColorSpace仅影响光栅输出
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type CanvasBackend struct {
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ColorSpace canvas.ColorSpace
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}
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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 (CanvasBackend) Name() string { return "canvas" }
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// Render 绘制已编译页面，不修改输入数据
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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 (b CanvasBackend) 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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img := image.NewRGBA(image.Rect(0, 0, w, h))
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space := b.ColorSpace
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if space == nil {
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space = canvas.DefaultColorSpace
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}
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r := rasterizer.FromImage(img, canvas.DPMM(page.DPI/25.4), space)
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for i, cmd := range page.Commands {
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if cmd.Image != nil {
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source := cmd.Image
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if _, linear := space.(canvas.LinearColorSpace); !linear {
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converted := image.NewRGBA(source.Bounds())
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for y := source.Bounds().Min.Y; y < source.Bounds().Max.Y; y++ {
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for x := source.Bounds().Min.X; x < source.Bounds().Max.X; x++ {
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converted.SetRGBA(x, y, space.ToLinear(color.RGBAModel.Convert(source.At(x, y)).(color.RGBA)))
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}
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}
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source = converted
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}
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drawRasterImage(img, source, page.PixelTransform(cmd.Transform, h))
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continue
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}
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p := &canvas.Path{}
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for _, s := range cmd.Path {
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switch s.Verb {
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case RasterMove:
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p.MoveTo(s.End.X, s.End.Y)
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case RasterLine:
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p.LineTo(s.End.X, s.End.Y)
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case RasterQuad:
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p.QuadTo(s.Control1.X, s.Control1.Y, s.End.X, s.End.Y)
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case RasterCubic:
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p.CubeTo(s.Control1.X, s.Control1.Y, s.Control2.X, s.Control2.Y, s.End.X, s.End.Y)
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case RasterClose:
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p.Close()
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default:
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return nil, fmt.Errorf("canvas command %d: unsupported path verb %d", i, s.Verb)
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}
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}
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paint := canvas.Paint{Color: cmd.Paint.Color}
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if g := cmd.Paint.Gradient; g != nil {
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stops := make(canvas.Grad, len(g.Stops))
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for j, stop := range g.Stops {
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stops[j] = canvas.Stop{Offset: stop.Offset, Color: stop.Color}
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}
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start, end := canvas.Point{X: g.Start.X, Y: g.Start.Y}, canvas.Point{X: g.End.X, Y: g.End.Y}
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switch g.Kind {
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case RasterLinear:
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paint = canvas.Paint{Gradient: stops.ToLinear(start, end)}
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case RasterRadial:
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paint = canvas.Paint{Gradient: stops.ToRadial(start, g.R0, end, g.R1)}
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default:
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return nil, fmt.Errorf("canvas command %d: unsupported gradient %d", i, g.Kind)
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}
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}
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style := canvas.Style{Fill: paint, FillRule: canvas.NonZero}
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if cmd.EvenOdd {
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style.FillRule = canvas.EvenOdd
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}
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m := cmd.Transform
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r.RenderPath(p, style, canvas.Matrix{{m[0], m[2], m[4]}, {-m[1], -m[3], page.Height - m[5]}})
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}
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r.Close()
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return img, nil
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}
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