// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package ofdgo

import (
	"image"

	"github.com/tdewolff/canvas"
)

// canvasBackendState 保存Canvas字体、字形和编码图片适配缓存
type canvasBackendState struct {
	images             map[*EncodedImage]image.Image
	fontMap            map[string]*canvas.FontFamily
	svgFontCache       map[*canvas.Font]SVGFont
	textGlyphPathCache map[textGlyphPathCacheKey]textGlyphPathCacheValue
	fontOutlines       map[*canvas.Font]*sfntOutliner
}

// canvasState 获取当前渲染器的Canvas私有缓存，按需创建且不向其他后端暴露
// 返回: *canvasBackendState Canvas缓存
func (r *Renderer) canvasState() *canvasBackendState {
	key := CanvasBackend{}
	if state, ok := r.backendStates[key]; ok {
		return state.(*canvasBackendState)
	}
	state := &canvasBackendState{
		images: make(map[*EncodedImage]image.Image),
	}
	state.resetFonts()
	r.backendStates[key] = state
	return state
}

// resetFonts 清除Canvas字体及字形缓存，保留编码图片适配对象
func (s *canvasBackendState) resetFonts() {
	s.fontMap = make(map[string]*canvas.FontFamily)
	s.svgFontCache = make(map[*canvas.Font]SVGFont)
	s.textGlyphPathCache = make(map[textGlyphPathCacheKey]textGlyphPathCacheValue)
	s.fontOutlines = make(map[*canvas.Font]*sfntOutliner)
}