mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 16:59:27 +08:00
71 lines
2.3 KiB
Go
71 lines
2.3 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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"crypto/sha256"
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"encoding/binary"
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"math"
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"github.com/tdewolff/canvas"
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)
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// canvasGeometryDigest 按完整坐标、路径顺序及几何容差计算摘要
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// 入参: paths 非空路径序列
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// 返回: [32]byte 几何摘要
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func canvasGeometryDigest(paths ...*canvas.Path) [32]byte {
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hash := sha256.New()
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var data [512]byte
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binary.LittleEndian.PutUint64(data[:8], math.Float64bits(canvas.Tolerance))
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binary.LittleEndian.PutUint64(data[8:16], math.Float64bits(canvas.Epsilon))
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binary.LittleEndian.PutUint64(data[16:24], math.Float64bits(canvas.BentleyOttmannEpsilon))
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hash.Write(data[:24])
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for _, path := range paths {
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values := path.Data()
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binary.LittleEndian.PutUint64(data[:8], uint64(len(values)))
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hash.Write(data[:8])
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for len(values) > 0 {
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count := min(len(values), len(data)/8)
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for i, value := range values[:count] {
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binary.LittleEndian.PutUint64(data[i*8:], math.Float64bits(value))
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}
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hash.Write(data[:count*8])
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values = values[count:]
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}
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}
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var key [32]byte
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hash.Sum(key[:0])
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return key
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}
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// settleCanvasPath 复用复杂路径的填充规范化结果，返回独立副本
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// 入参: path 页面坐标路径, rule 填充规则
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// 返回: *canvas.Path 规范化填充轮廓
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func (r *Renderer) settleCanvasPath(path *canvas.Path, rule canvas.FillRule) *canvas.Path {
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if len(path.Data()) < 256 {
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return path.Settle(rule)
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}
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key := canvasFillKey{digest: canvasGeometryDigest(path), rule: rule}
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cache := r.canvasSettledPaths()
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if result, ok := cache.get(key); ok {
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return result.Copy()
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}
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result := path.Settle(rule)
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if cost := len(result.Data())*8 + 256; cost <= cache.limit {
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cache.put(key, result.Copy(), cost)
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}
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return result
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}
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