mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-30 01:27:26 +08:00
194 lines
7.0 KiB
Go
194 lines
7.0 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 ofdgo
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import (
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"fmt"
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"math"
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"github.com/xiaoqidun/pdfgo"
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)
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// pdfCompositePattern 保存图案单元的原始图元和独立几何缓存
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type pdfCompositePattern struct {
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nodes []pdfCompositeNode
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local pdfImporter
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box Box
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}
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// tiling 将图案作为非隔离组绘制，保留背景贡献及单元间隙
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// 入参: paint 图案画刷, backdrop 初始背景, space 混合空间
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// 返回: []pdfCompositePixel 去除背景贡献的图案像素, error 解析或绘制错误
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func (c *pdfCompositor) tiling(paint pdfgo.Paint, backdrop []pdfCompositePixel, space *pdfgo.ColorSpace) ([]pdfCompositePixel, error) {
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source := paint.Tiling
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matrix := c.importer.matrix.Mul(source.Matrix)
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inverse, ok := matrix.Inverse()
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if !ok {
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return nil, fmt.Errorf("invalid PDF tiling pattern matrix")
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}
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pattern, err := c.importer.compositePattern(paint)
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if err != nil {
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return nil, err
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}
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xstep, ystep := math.Abs(source.XStep), math.Abs(source.YStep)
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area := pdfBounds([]pdfgo.Point{
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inverse.Apply(pdfgo.Point{X: c.box.X, Y: c.box.Y}), inverse.Apply(pdfgo.Point{X: c.box.X + c.box.W, Y: c.box.Y}),
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inverse.Apply(pdfgo.Point{X: c.box.X + c.box.W, Y: c.box.Y + c.box.H}), inverse.Apply(pdfgo.Point{X: c.box.X, Y: c.box.Y + c.box.H}),
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})
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left, right := math.Ceil((area.X-source.BBox.XMax)/xstep), math.Floor((area.X+area.W-source.BBox.XMin)/xstep)
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top, bottom := math.Ceil((area.Y-source.BBox.YMax)/ystep), math.Floor((area.Y+area.H-source.BBox.YMin)/ystep)
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limit := float64(int(^uint(0) >> 1))
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for _, value := range []float64{left, right, top, bottom} {
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if !finite(value) || value <= -limit || value >= limit {
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return nil, fmt.Errorf("PDF tiling pattern instance range overflow")
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}
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}
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result := make([]pdfCompositePixel, len(backdrop))
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for i, pixel := range backdrop {
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result[i] = pdfCompositePixel{values: pixel.values, alpha: pixel.alpha}
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}
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localInverse, _ := pattern.local.matrix.Inverse()
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for row := int(top); row <= int(bottom); row++ {
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for column := int(left); column <= int(right); column++ {
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if err := c.importer.ctx.Err(); err != nil {
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return nil, err
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}
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x, y := float64(column)*xstep, float64(row)*ystep
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dx, dy := matrix[0]*x+matrix[2]*y+pattern.box.X, matrix[1]*x+matrix[3]*y+pattern.box.Y
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cell := pdfCompositor{importer: &pattern.local, box: Box{X: c.box.X - dx, Y: c.box.Y - dy, W: c.box.W, H: c.box.H},
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width: c.width, height: c.height, inverse: localInverse, cache: pattern.local.compositingCache(), masks: map[*pdfgo.SoftMask][]float64{}}
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if err := cell.draw(pattern.nodes, result, space); err != nil {
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return nil, err
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}
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}
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}
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for i := range result {
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pixel := &result[i]
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if pixel.effect != 0 {
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for j := 0; j < space.Components(); j++ {
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pixel.values[j] = math.Max(0, math.Min(1, (pixel.values[j]*pixel.alpha-backdrop[i].values[j]*backdrop[i].alpha*(1-pixel.effect))/pixel.effect))
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}
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}
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pixel.alpha = pixel.effect
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}
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return result, nil
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}
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// compositePattern 复用图案单元解析及几何上下文，供检查和局部合成共同使用
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// 入参: paint 图案画刷
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// 返回: *pdfCompositePattern 单元内容, error 解析或边界错误
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func (p *pdfImporter) compositePattern(paint pdfgo.Paint) (*pdfCompositePattern, error) {
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paint.Alpha = 1
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cache := p.compositingCache()
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if cache.patterns == nil {
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cache.patterns = make(map[pdfgo.Paint]*pdfCompositePattern)
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}
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if pattern := cache.patterns[paint]; pattern != nil {
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return pattern, nil
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}
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source := paint.Tiling
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nodes, err := p.collectCompositeNodes(func(v pdfgo.Visitor) error { return source.Walk(p.ctx, paint, v) })
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if err != nil {
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return nil, err
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}
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matrix := p.matrix.Mul(source.Matrix)
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b := source.BBox
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box := pdfBounds([]pdfgo.Point{
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matrix.Apply(pdfgo.Point{X: b.XMin, Y: b.YMin}), matrix.Apply(pdfgo.Point{X: b.XMax, Y: b.YMin}),
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matrix.Apply(pdfgo.Point{X: b.XMax, Y: b.YMax}), matrix.Apply(pdfgo.Point{X: b.XMin, Y: b.YMax}),
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})
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if box.W <= 0 || box.H <= 0 {
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return nil, fmt.Errorf("invalid PDF tiling pattern bounds")
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}
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local := *p
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local.matrix = matrix
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local.matrix[4] -= box.X
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local.matrix[5] -= box.Y
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local.pageWidth, local.pageHeight = box.W, box.H
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local.compositeCache = nil
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pattern := &pdfCompositePattern{nodes: nodes, local: local, box: box}
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cache.patterns[paint] = pattern
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return pattern, nil
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}
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// directCompositeNode 检查图元及其图案单元能否独立保留，不忽略单元内的背景混合
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// 入参: node 图元, space 混合空间
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// 返回: bool 是否可直接转换, error 图案解析错误
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func (p *pdfImporter) directCompositeNode(node pdfCompositeNode, space *pdfgo.ColorSpace) (bool, error) {
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if !node.opaque(space) && !(space.SRGBEquivalent() && node.direct()) {
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return false, nil
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}
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if node.group != nil {
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for _, child := range node.children {
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if direct, err := p.directCompositeNode(child, space); err != nil || !direct {
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return direct, err
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}
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}
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return true, nil
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}
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style, fill, stroke := node.style()
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for i, paint := range []pdfgo.Paint{style.Fill, style.Stroke} {
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if i == 0 && !fill || i == 1 && !stroke || paint.Tiling == nil {
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continue
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}
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pattern, err := p.compositePattern(paint)
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if err != nil {
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return false, err
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}
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for _, child := range pattern.nodes {
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if direct, err := pattern.local.directCompositeNode(child, space); err != nil || !direct {
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return direct, err
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}
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}
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}
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return true, nil
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}
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// processOverprint 检查图元、透明组和图案单元是否需要设备四色套印
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// 入参: nodes 原始图元
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// 返回: bool 是否需要四色混合, error 图像或图案解析错误
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func (p *pdfImporter) processOverprint(nodes []pdfCompositeNode) (bool, error) {
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for _, node := range nodes {
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if node.group != nil {
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if found, err := p.processOverprint(node.children); err != nil || found {
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return found, err
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}
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continue
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}
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style, fill, stroke := node.style()
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if node.image != nil && style.FillOverprint {
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if _, found, err := pdfImageProcessColorants(node.image.Image); err != nil || found {
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return found, err
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}
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}
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if fill && style.FillOverprint && pdfOverprintNeedsSeparation(style.Fill) || stroke && style.StrokeOverprint && pdfOverprintNeedsSeparation(style.Stroke) {
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return true, nil
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}
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for i, paint := range []pdfgo.Paint{style.Fill, style.Stroke} {
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if i == 0 && !fill || i == 1 && !stroke || paint.Tiling == nil {
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continue
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}
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pattern, err := p.compositePattern(paint)
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if err != nil {
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return false, err
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}
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if found, err := pattern.local.processOverprint(pattern.nodes); err != nil || found {
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return found, err
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}
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}
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}
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return false, nil
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}
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