mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 17:27:08 +08:00
65 lines
2.3 KiB
Go
65 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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"errors"
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"fmt"
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"image"
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"image/color"
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"math"
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"github.com/xiaoqidun/pdfgo"
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)
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// rasterMaskAllowed 仅对不可矢量表达的蒙版启用显式局部合成，格式错误仍返回
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// 入参: err 蒙版转换错误
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// 返回: bool 是否允许局部合成
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func (p *pdfImporter) rasterMaskAllowed(err error) bool {
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var unsupported *pdfgo.UnsupportedError
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return p.warning != nil && errors.As(err, &unsupported)
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}
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// applySoftMask 按原始颜色分量计算蒙版，逐块应用透明度及亮度传递
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// 入参: source 源图像, box 页面区域, mask PDF软蒙版
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// 返回: image.Image 合成图像, error 蒙版解释或渲染错误
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func (p *pdfImporter) applySoftMask(source image.Image, box Box, mask *pdfgo.SoftMask) (image.Image, error) {
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inverse, ok := p.matrix.Inverse()
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if !ok {
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return nil, fmt.Errorf("invalid PDF mask transform")
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}
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out := image.NewNRGBA(source.Bounds())
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w, h := out.Rect.Dx(), out.Rect.Dy()
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step := 25.4 / p.rasterDPI
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cache := p.compositingCache()
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for y := 0; y < h; y += 256 {
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for x := 0; x < w; x += 256 {
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width, height := min(256, w-x), min(256, h-y)
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c := pdfCompositor{importer: p, box: Box{X: box.X + float64(x)*step, Y: box.Y + float64(y)*step, W: float64(width) * step, H: float64(height) * step}, width: width, height: height, inverse: inverse, cache: cache, masks: map[*pdfgo.SoftMask][]float64{}}
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alpha, err := c.mask(mask, &pdfgo.ColorSpace{Model: "DeviceRGB"})
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if err != nil {
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return nil, err
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}
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for i, opacity := range alpha {
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px, py := out.Rect.Min.X+x+i%width, out.Rect.Min.Y+y+i/width
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pixel := color.NRGBAModel.Convert(source.At(px, py)).(color.NRGBA)
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pixel.A = uint8(math.Round(float64(pixel.A) * opacity))
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out.SetNRGBA(px, py, pixel)
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}
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}
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}
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return out, nil
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}
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