mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 17:27:08 +08:00
46 lines
1.5 KiB
Go
46 lines
1.5 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 "github.com/xiaoqidun/pdfgo"
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// halftone 检查连续色调转换及不可忽略的传递函数，避免将打印网屏误用于屏幕显示
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// 入参: style 图形状态
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// 返回: error 严格模式或非恒等传递函数无法表达
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func (p *pdfImporter) halftone(style pdfgo.Style) error {
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h := style.Halftone
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if h == nil || h.Type == 0 {
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return nil
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}
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identity, err := h.IdentityTransfer(p.reader)
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if err != nil {
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return err
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}
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if !identity {
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return &pdfgo.UnsupportedError{Feature: "halftone transfer function conversion"}
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}
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if p.warning == nil {
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return &pdfgo.UnsupportedError{Feature: "device halftone conversion"}
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}
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if p.halftoneWarnings == nil {
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p.halftoneWarnings = make(map[*pdfgo.Halftone]bool)
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}
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if !p.halftoneWarnings[h] {
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p.halftoneWarnings[h] = true
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p.warning(pdfgo.Diagnostic{Message: "PDF continuous-tone appearance retained; device halftone not transferred to OFD"})
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}
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return nil
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}
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