mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-30 01:27:26 +08:00
120 lines
4.0 KiB
Go
120 lines
4.0 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 pdf
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import (
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"github.com/xiaoqidun/pdfgo"
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)
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// ShadingPixel 保存抗锯齿覆盖率与混合空间分量
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type ShadingPixel struct {
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Values [4]float64
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Shape float64
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}
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// ShadingColorants 复用原始浓度缓冲及原生通道映射，不跨并发采样共享
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type ShadingColorants struct {
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paint pdfgo.Paint
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Process *pdfgo.ColorantProcess
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tints []float64
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mesh *pdfgo.MeshSampler
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}
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// ShadingColorantSpace 返回渐变的源色料定义，不使用备用颜色推断通道
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// 入参: paint 渐变画刷
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// 返回: *pdfgo.ColorantSpace 原始色料定义，普通渐变为nil
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func ShadingColorantSpace(paint pdfgo.Paint) *pdfgo.ColorantSpace {
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switch {
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case paint.Axial != nil:
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return paint.Axial.ColorantSpace()
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case paint.Radial != nil:
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return paint.Radial.ColorantSpace()
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case paint.Function != nil:
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return paint.Function.ColorantSpace()
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case paint.Mesh != nil:
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return paint.Mesh.ColorantSpace()
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}
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return nil
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}
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// PrepareShadingColorants 为当前组建立原生过程采样，备用色保留原路径
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// 入参: paint 渐变画刷, space 组空间, softMask 是否用于软蒙版
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// 返回: *ShadingColorants 独立采样状态，不可原生映射时为nil
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func PrepareShadingColorants(paint pdfgo.Paint, space *pdfgo.ColorSpace, softMask bool) *ShadingColorants {
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colorants := ShadingColorantSpace(paint)
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process := colorants.PrepareProcess(&pdfgo.ColorantDevice{Space: space}, space, softMask)
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if process == nil || process.Mask() == ([4]bool{}) {
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return nil
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}
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s := &ShadingColorants{paint: paint, Process: process, tints: make([]float64, len(colorants.Names))}
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if paint.Mesh != nil {
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s.mesh = paint.Mesh.NewSampler()
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}
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return s
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}
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// At 在归一化位置求值轴向或径向原始浓度
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// 入参: position 归一化渐变参数
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// 返回: [4]float64 原生过程分量, error 求值错误
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func (s *ShadingColorants) At(position float64) ([4]float64, error) {
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var err error
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if s.paint.Axial != nil {
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err = s.paint.Axial.ColorantValuesAt(position, s.tints)
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} else {
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err = s.paint.Radial.ColorantValuesAt(position, s.tints)
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}
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if err != nil {
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return [4]float64{}, err
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}
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return s.Process.Convert(s.tints)
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}
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// PointAt 在函数定义域内求值原始浓度
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// 入参: point 函数坐标
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// 返回: [4]float64 原生过程分量, error 求值错误
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func (s *ShadingColorants) PointAt(point pdfgo.Point) ([4]float64, error) {
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if err := s.paint.Function.ColorantValuesAt(point, s.tints); err != nil {
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return [4]float64{}, err
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}
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return s.Process.Convert(s.tints)
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}
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// MeshAt 插值网格原始浓度并复用函数结果
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// 入参: patch 网格序号, u 横向参数, v 纵向参数
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// 返回: [4]float64 原生过程分量, error 求值错误
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func (s *ShadingColorants) MeshAt(patch int, u, v float64) ([4]float64, error) {
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if err := s.mesh.ColorantValuesAt(patch, u, v, s.tints); err != nil {
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return [4]float64{}, err
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}
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return s.Process.Convert(s.tints)
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}
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// ShadingPosition 计算渐变参数，未延伸区域及不存在非负圆半径的位置不着色
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// 入参: paint 渐变画刷, point 页面坐标
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// 返回: float64 归一化参数, bool 是否着色
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func ShadingPosition(paint pdfgo.Paint, point pdfgo.Point) (float64, bool) {
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var geometry pdfgo.GradientPosition
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var err error
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if g := paint.Axial; g != nil {
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geometry, err = g.PreparePosition()
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} else {
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geometry, err = paint.Radial.PreparePosition()
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}
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if err != nil {
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return 0, false
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}
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return geometry.PositionAt(point)
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}
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