mirror of
https://github.com/xiaoqidun/ofdgo.git
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101 lines
3.2 KiB
Go
101 lines
3.2 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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"slices"
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)
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// RasterScene 固定尺寸、DPI、字体和资源的可重复绘制场景
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// 每次Render返回独立图像；源图像只读借用，修改页面或配置后应重新准备
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type RasterScene interface {
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Render() (image.Image, error)
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}
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// RasterSceneBackend 可选的光栅预编译能力，不改变后端选择
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type RasterSceneBackend interface {
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RasterBackend
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Prepare(page *RasterPage) (RasterScene, error)
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}
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// PreparePage 编译并准备当前配置的页面场景，不自动跟踪后续编辑
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// 入参: page 源页面
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// 返回: RasterScene 可重复绘制场景, error 编译或准备错误
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func (r *Renderer) PreparePage(page *PageContent) (RasterScene, error) {
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if r.backends.Raster == nil {
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return nil, fmt.Errorf("raster scene: %w", ErrBackendUnavailable)
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}
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compiled, err := r.CompilePage(page)
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if err != nil {
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return nil, err
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}
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return PrepareRasterScene(r.backends.Raster, compiled)
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}
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// PrepareRasterScene 准备绘制快照，未实现预编译的后端复用公共指令
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// 入参: backend 光栅后端, page 绘制页面
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// 返回: RasterScene 可重复绘制场景, error 准备错误
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func PrepareRasterScene(backend RasterBackend, page *RasterPage) (RasterScene, error) {
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if backend == nil {
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return nil, fmt.Errorf("raster scene: %w", ErrBackendUnavailable)
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}
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if _, _, err := page.PixelSize(); err != nil {
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return nil, err
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}
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if provider, ok := backend.(RasterSceneBackend); ok {
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return provider.Prepare(page)
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}
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return &rasterScene{backend: backend, page: cloneRasterPage(page)}, nil
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}
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// rasterScene 复用后端无关指令，图片保持只读引用
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type rasterScene struct {
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backend RasterBackend
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page *RasterPage
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}
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// Render 绘制固定快照
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// 返回: image.Image 独立图像, error 绘制错误
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func (s *rasterScene) Render() (image.Image, error) { return s.backend.Render(s.page) }
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// cloneRasterPage 隔离可变指令，源图片按接口约定只读借用
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// 入参: page 绘制页面
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// 返回: *RasterPage 指令快照
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func cloneRasterPage(page *RasterPage) *RasterPage {
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result := *page
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result.Commands = slices.Clone(page.Commands)
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for i := range result.Commands {
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cmd := &result.Commands[i]
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cmd.Path, cmd.Clip = slices.Clone(cmd.Path), slices.Clone(cmd.Clip)
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if cmd.Stroke != nil {
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stroke := *cmd.Stroke
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stroke.Dashes = slices.Clone(stroke.Dashes)
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cmd.Stroke = &stroke
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}
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if cmd.Paint.Gradient != nil {
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gradient := *cmd.Paint.Gradient
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gradient.Stops = slices.Clone(gradient.Stops)
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if gradient.Spread != nil {
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spread := *gradient.Spread
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gradient.Spread = &spread
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}
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cmd.Paint.Gradient = &gradient
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}
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}
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return &result
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}
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