mirror of
https://github.com/xiaoqidun/ofdgo.git
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528 lines
16 KiB
Go
528 lines
16 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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"bytes"
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"context"
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"encoding/binary"
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"fmt"
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"image"
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"image/color"
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"io"
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"math"
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)
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// tiffPlaneInput 将单分量目录附加到只读视图，像素仍从原始编码读取
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type tiffPlaneInput struct {
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source, directory []byte
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position int64
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order binary.ByteOrder
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ctx context.Context
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}
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// planarTIFFImage 组合独立分量或映射调色板，不额外分配交错像素缓冲
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type planarTIFFImage struct {
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planes []image.Image
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bounds image.Rectangle
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depth uint32
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packed [4]uint32
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alpha uint32
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gray bool
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palette []color.NRGBA64
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}
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// decodeTIFFImage 按存储方式解码主图并统一显示方向
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// 入参: ctx 取消上下文，可为nil, data TIFF编码, layout 主图布局
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// 返回: image.Image 图像, error 解码或取消错误
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func decodeTIFFImage(ctx context.Context, data []byte, layout tiffImageLayout) (image.Image, error) {
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if layout.compression >= 2 && layout.compression <= 4 {
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pixels, err := decodeTIFFFax(ctx, data, layout)
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if err == nil && layout.orientation != 1 {
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pixels = &orientedTIFFImage{source: pixels, tiffImageLayout: layout}
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}
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return pixels, err
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}
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ranges, err := tiffBitOrderRanges(ctx, data, layout)
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if err != nil {
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return nil, err
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}
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var pixels image.Image
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if layout.planar && layout.samples > 1 || layout.samples == 1 && (layout.depth == 2 || layout.depth == 4) {
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result, directories, err := tiffPlaneDirectories(ctx, data, layout)
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if err != nil {
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return nil, err
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}
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for _, directory := range directories {
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input := &tiffPlaneInput{source: data, directory: directory, order: binary.LittleEndian, ctx: ctx}
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if data[0] == 'M' {
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input.order = binary.BigEndian
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}
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plane, err := decodeTIFFBitOrder(input, ranges)
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if err != nil {
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return nil, err
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}
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result.planes = append(result.planes, plane)
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}
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pixels = result
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} else {
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input := newTIFFDirectoryInput(data, layout.offset)
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input.ctx = ctx
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var err error
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pixels, err = decodeTIFFBitOrder(input, ranges)
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if err != nil {
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return nil, err
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}
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}
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if ctx != nil {
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if err := ctx.Err(); err != nil {
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return nil, err
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}
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}
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if layout.orientation != 1 {
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pixels = &orientedTIFFImage{source: pixels, tiffImageLayout: layout}
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}
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return pixels, nil
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}
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// tiffPlaneDirectories 为颜色、透明度或调色板索引构建单通道TIFF目录
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// 入参: ctx 取消上下文，可为nil, data TIFF编码, layout 已校验的主图布局
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// 返回: *planarTIFFImage 像素布局, [][]byte 各分量目录, error 字段或布局错误
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func tiffPlaneDirectories(ctx context.Context, data []byte, layout tiffImageLayout) (*planarTIFFImage, [][]byte, error) {
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if ctx != nil {
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if err := ctx.Err(); err != nil {
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return nil, nil, err
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}
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}
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if uint64(len(data))+65536*12+8 > math.MaxUint32 {
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return nil, nil, fmt.Errorf("TIFF plane directory offset exceeds format limit")
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}
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var order binary.ByteOrder = binary.LittleEndian
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if data[0] == 'M' {
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order = binary.BigEndian
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}
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offset := int(layout.offset)
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count := int(order.Uint16(data[offset:]))
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entries := make(map[uint16][]byte, count)
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for i := range count {
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entry := data[offset+2+i*12 : offset+14+i*12]
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entries[order.Uint16(entry)] = entry
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}
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value := func(tag uint16, fallback uint32) (uint32, error) {
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entry := entries[tag]
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if entry == nil {
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return fallback, nil
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}
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if order.Uint32(entry[4:]) != 1 {
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return 0, fmt.Errorf("invalid TIFF scalar field %d", tag)
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}
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return tiffPlaneValue(data, order, entry, 0)
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}
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samples, err := value(277, 1)
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if err != nil || samples < 1 || samples > 4 {
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return nil, nil, fmt.Errorf("invalid TIFF plane count")
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}
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photo, err := value(262, math.MaxUint32)
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if err != nil || photo > 3 || photo == 3 && samples != 1 {
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return nil, nil, fmt.Errorf("unsupported TIFF planar color model")
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}
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compression, err := value(259, 1)
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if err != nil {
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return nil, nil, err
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}
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fill, err := value(266, 1)
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if err != nil || fill != 1 && (fill != 2 || compression != 1 && compression != 3 && compression != 4) {
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return nil, nil, fmt.Errorf("unsupported TIFF plane fill order")
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}
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predictor, err := value(317, 1)
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if err != nil || predictor != 1 && predictor != 2 {
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return nil, nil, fmt.Errorf("unsupported TIFF plane predictor")
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}
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result := &planarTIFFImage{bounds: image.Rect(0, 0, layout.width, layout.height), gray: photo < 2}
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colors := uint32(3)
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if photo != 2 {
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colors = 1
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}
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if samples != colors {
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result.alpha, err = value(338, 0)
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if err != nil || samples != colors+1 || result.alpha != 1 && result.alpha != 2 {
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return nil, nil, fmt.Errorf("unsupported TIFF extra planes")
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}
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} else if entries[338] != nil {
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return nil, nil, fmt.Errorf("unexpected TIFF extra samples")
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}
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width, err := value(322, 0)
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if err != nil {
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return nil, nil, err
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}
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blocks := uint64(0)
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locations, lengths := uint16(273), uint16(279)
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if width != 0 {
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height, err := value(323, 0)
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if err != nil || height == 0 || width%16 != 0 || height%16 != 0 {
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return nil, nil, fmt.Errorf("invalid TIFF tile dimensions")
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}
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blocks = ((uint64(layout.width)-1)/uint64(width) + 1) * ((uint64(layout.height)-1)/uint64(height) + 1)
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locations, lengths = 324, 325
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} else {
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rows, err := value(278, math.MaxUint32)
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if err != nil || rows == 0 {
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return nil, nil, fmt.Errorf("invalid TIFF rows per strip")
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}
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blocks = (uint64(layout.height)-1)/uint64(rows) + 1
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}
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if blocks > math.MaxUint32/uint64(samples) {
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return nil, nil, fmt.Errorf("too many TIFF plane blocks")
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}
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for _, tag := range []uint16{locations, lengths} {
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entry := entries[tag]
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if entry == nil || uint64(order.Uint32(entry[4:])) != blocks*uint64(samples) || tag == 324 && order.Uint16(entry[2:]) != 4 {
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return nil, nil, fmt.Errorf("invalid TIFF plane block count")
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}
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}
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for i := uint32(0); i < uint32(blocks)*samples; i++ {
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if ctx != nil {
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if err := ctx.Err(); err != nil {
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return nil, nil, err
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}
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}
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at, err := tiffPlaneValue(data, order, entries[locations], i)
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if err != nil {
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return nil, nil, err
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}
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size, err := tiffPlaneValue(data, order, entries[lengths], i)
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if err != nil || size == 0 || uint64(at)+uint64(size) > uint64(len(data)) {
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return nil, nil, fmt.Errorf("truncated TIFF plane block")
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}
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}
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for _, tag := range []uint16{258, 339} {
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if entry := entries[tag]; entry != nil && (order.Uint16(entry[2:]) != 3 || order.Uint32(entry[4:]) != samples) {
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return nil, nil, fmt.Errorf("invalid TIFF sample array")
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}
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}
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var directories [][]byte
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for plane := uint32(0); plane < samples; plane++ {
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depth := uint32(1)
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if entry := entries[258]; entry != nil {
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depth, err = tiffPlaneValue(data, order, entry, plane)
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}
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if err != nil || depth != 1 && depth != 2 && depth != 4 && depth != 8 && depth != 16 {
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return nil, nil, fmt.Errorf("unsupported TIFF plane depth")
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}
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result.depth = max(result.depth, depth)
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if depth < 8 && predictor != 1 {
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return nil, nil, fmt.Errorf("unsupported TIFF packed plane predictor")
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}
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if depth == 2 || depth == 4 {
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result.packed[plane] = depth
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if uint64(layout.width)*uint64(depth) > uint64(math.MaxInt)/uint64(layout.height) || uint64(layout.width)*uint64(depth) > math.MaxUint32 || uint64(width)*uint64(depth) > math.MaxUint32 {
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return nil, nil, fmt.Errorf("TIFF plane dimensions exceed format limit")
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}
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if compression == 2 || compression == 3 || compression == 4 {
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return nil, nil, fmt.Errorf("unsupported TIFF packed plane compression")
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}
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}
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if entry := entries[339]; entry != nil {
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format, err := tiffPlaneValue(data, order, entry, plane)
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if err != nil || format != 1 {
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return nil, nil, fmt.Errorf("unsupported TIFF sample format")
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}
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}
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if photo == 3 {
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entry := entries[320]
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if depth > 8 || entry == nil || order.Uint16(entry[2:]) != 3 || order.Uint32(entry[4:]) != 3<<depth {
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return nil, nil, fmt.Errorf("invalid TIFF color map")
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}
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n := uint32(1) << depth
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result.palette = make([]color.NRGBA64, n)
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for i := range n {
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var components [3]uint16
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for c := range components {
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v, err := tiffPlaneValue(data, order, entry, uint32(c)*n+i)
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if err != nil {
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return nil, nil, err
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}
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components[c] = uint16(v)
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if v%257 != 0 {
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result.depth = 16
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}
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}
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result.palette[i] = color.NRGBA64{R: components[0], G: components[1], B: components[2], A: 65535}
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}
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}
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directory := make([]byte, 2, 6+count*12)
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for i := range count {
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if ctx != nil {
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if err := ctx.Err(); err != nil {
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return nil, nil, err
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}
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}
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entry := bytes.Clone(data[offset+2+i*12 : offset+14+i*12])
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tag := order.Uint16(entry)
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if tag == 338 || tag == 320 {
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continue
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}
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scalar := uint32(0)
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switch tag {
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case 258:
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scalar = depth
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if result.packed[plane] != 0 {
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scalar = 1
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}
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case 256, 322:
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if result.packed[plane] != 0 {
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original, err := tiffPlaneValue(data, order, entry, 0)
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if err != nil {
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return nil, nil, err
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}
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order.PutUint16(entry[2:], 4)
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order.PutUint32(entry[4:], 1)
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order.PutUint32(entry[8:], original*depth)
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}
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case 262:
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scalar = 1
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if result.gray && plane == 0 && photo == 0 {
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scalar = 0
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}
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case 277, 284, 339:
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scalar = 1
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case locations, lengths:
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entry, err = tiffPlaneArray(data, order, entry, uint32(blocks)*plane, uint32(blocks))
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if err != nil {
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return nil, nil, err
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}
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}
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if tag == 258 || tag == 262 || tag == 277 || tag == 284 || tag == 339 {
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order.PutUint16(entry[2:], 3)
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order.PutUint32(entry[4:], 1)
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clear(entry[8:])
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order.PutUint16(entry[8:], uint16(scalar))
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}
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directory = append(directory, entry...)
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}
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order.PutUint16(directory, uint16((len(directory)-2)/12))
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directories = append(directories, append(directory, 0, 0, 0, 0))
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}
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return result, directories, nil
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}
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// tiffPlaneValue 读取SHORT或LONG数组中的一项，校验完整数组范围
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// 入参: data 原编码, order 字节序, entry 目录项, index 元素序号
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// 返回: uint32 元素值, error 类型或越界错误
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func tiffPlaneValue(data []byte, order binary.ByteOrder, entry []byte, index uint32) (uint32, error) {
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kind, count := order.Uint16(entry[2:]), order.Uint32(entry[4:])
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if kind != 3 && kind != 4 || index >= count {
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return 0, fmt.Errorf("invalid TIFF plane array")
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}
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size := uint64(2)
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if kind == 4 {
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size = 4
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}
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values := entry[8:]
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if size*uint64(count) > 4 {
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at := uint64(order.Uint32(values))
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if at+size*uint64(count) > uint64(len(data)) {
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return 0, fmt.Errorf("truncated TIFF plane array")
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}
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values = data[at:]
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}
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if size == 2 {
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return uint32(order.Uint16(values[uint64(index)*size:])), nil
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}
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return order.Uint32(values[uint64(index)*size:]), nil
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}
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// tiffPlaneArray 将块索引缩减为指定分量的范围，较长数组继续借用原编码
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// 入参: data 原编码, order 字节序, entry 目录项副本, first 起始序号, count 元素数
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// 返回: []byte 修改后的目录项, error 类型或越界错误
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func tiffPlaneArray(data []byte, order binary.ByteOrder, entry []byte, first, count uint32) ([]byte, error) {
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if _, err := tiffPlaneValue(data, order, entry, first+count-1); err != nil {
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return nil, err
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}
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size := uint32(2)
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if order.Uint16(entry[2:]) == 4 {
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size = 4
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}
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if uint64(count)*uint64(size) <= 4 {
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var values [4]byte
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for i := uint32(0); i < count; i++ {
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value, _ := tiffPlaneValue(data, order, entry, first+i)
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if size == 2 {
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order.PutUint16(values[i*size:], uint16(value))
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} else {
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order.PutUint32(values[i*size:], value)
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}
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}
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copy(entry[8:], values[:])
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} else {
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order.PutUint32(entry[8:], order.Uint32(entry[8:])+first*size)
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}
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order.PutUint32(entry[4:], count)
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return entry, nil
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}
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// Read 从组合视图顺序读取
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// 入参: data 接收缓冲
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// 返回: int 字节数, error 读取或取消错误
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func (r *tiffPlaneInput) Read(data []byte) (int, error) {
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n, err := r.ReadAt(data, r.position)
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r.position += int64(n)
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return n, err
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}
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// ReadAt 从原始编码或附加目录读取并替换首目录指针
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// 入参: data 接收缓冲, offset 文件偏移
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// 返回: int 字节数, error 读取或取消错误
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func (r *tiffPlaneInput) ReadAt(data []byte, offset int64) (int, error) {
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if r.ctx != nil {
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if err := r.ctx.Err(); err != nil {
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return 0, err
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}
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}
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if offset < 0 {
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return 0, fmt.Errorf("negative TIFF read offset")
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}
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start := int64(len(r.source))
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directory := start + start%2
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written := 0
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if offset < start {
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written = copy(data, r.source[offset:])
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}
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if offset+int64(written) == start && start != directory && written < len(data) {
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data[written] = 0
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written++
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}
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if at := offset + int64(written) - directory; at >= 0 && at < int64(len(r.directory)) {
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written += copy(data[written:], r.directory[at:])
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}
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var pointer [4]byte
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r.order.PutUint32(pointer[:], uint32(directory))
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for i, value := range pointer {
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if at := int64(4+i) - offset; at >= 0 && at < int64(written) {
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data[at] = value
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}
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}
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if written != len(data) {
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return written, io.EOF
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}
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return written, nil
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}
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// Bounds 返回存储坐标范围
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// 返回: image.Rectangle 图像范围
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func (p *planarTIFFImage) Bounds() image.Rectangle { return p.bounds }
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// ColorModel 按透明度类型和最高分量精度返回颜色模型
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// 返回: color.Model 颜色模型
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func (p *planarTIFFImage) ColorModel() color.Model {
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if p.gray && p.alpha == 0 {
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if p.depth > 8 {
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return color.Gray16Model
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}
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return color.GrayModel
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}
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if p.alpha == 1 {
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if p.depth > 8 {
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return color.RGBA64Model
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}
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return color.RGBAModel
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}
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if p.depth > 8 {
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return color.NRGBA64Model
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}
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return color.NRGBAModel
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}
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// components 直接读取灰度分量，保留原始透明度语义
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// 入参: x 横坐标, y 纵坐标
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// 返回: [4]uint16 红、绿、蓝和透明度分量
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func (p *planarTIFFImage) components(x, y int) [4]uint16 {
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if !image.Pt(x, y).In(p.bounds) {
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return [4]uint16{}
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}
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values := [4]uint16{0, 0, 0, 65535}
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for i, plane := range p.planes {
|
|
var value uint16
|
|
switch plane := plane.(type) {
|
|
case *image.Gray:
|
|
if bits := p.packed[i]; bits != 0 {
|
|
for bit := range int(bits) {
|
|
value = value<<1 | uint16(plane.GrayAt(x*int(bits)+bit, y).Y>>7)
|
|
}
|
|
value *= 65535 / uint16(1<<bits-1)
|
|
} else {
|
|
value = uint16(plane.GrayAt(x, y).Y) * 257
|
|
}
|
|
case *image.Gray16:
|
|
value = plane.Gray16At(x, y).Y
|
|
default:
|
|
v, _, _, _ := plane.At(x, y).RGBA()
|
|
value = uint16(v)
|
|
}
|
|
if len(p.palette) != 0 {
|
|
c := p.palette[uint32(value)*uint32(len(p.palette)-1)/65535]
|
|
return [4]uint16{c.R, c.G, c.B, c.A}
|
|
}
|
|
if p.gray && i == 0 {
|
|
values[0], values[1], values[2] = value, value, value
|
|
} else if p.gray {
|
|
values[3] = value
|
|
} else {
|
|
values[i] = value
|
|
}
|
|
}
|
|
return values
|
|
}
|
|
|
|
// At 返回组合后的颜色，关联透明度保留预乘语义
|
|
// 入参: x 横坐标, y 纵坐标
|
|
// 返回: color.Color 像素颜色
|
|
func (p *planarTIFFImage) At(x, y int) color.Color {
|
|
values := p.components(x, y)
|
|
if p.alpha == 1 {
|
|
return color.RGBA64{R: values[0], G: values[1], B: values[2], A: values[3]}
|
|
}
|
|
return color.NRGBA64{R: values[0], G: values[1], B: values[2], A: values[3]}
|
|
}
|
|
|
|
// NRGBA64At 读取独立透明度颜色，保留非预乘分量中的隐藏颜色
|
|
// 入参: x 横坐标, y 纵坐标
|
|
// 返回: color.NRGBA64 像素颜色
|
|
func (p *planarTIFFImage) NRGBA64At(x, y int) color.NRGBA64 {
|
|
values := p.components(x, y)
|
|
if p.alpha == 1 && values[3] != 65535 {
|
|
if values[3] == 0 {
|
|
return color.NRGBA64{}
|
|
}
|
|
for i := range 3 {
|
|
values[i] = uint16(uint32(values[i]) * 65535 / uint32(values[3]))
|
|
}
|
|
}
|
|
return color.NRGBA64{R: values[0], G: values[1], B: values[2], A: values[3]}
|
|
}
|
|
|
|
// RGBA64At 返回预乘十六位颜色，不分配临时颜色对象
|
|
// 入参: x 横坐标, y 纵坐标
|
|
// 返回: color.RGBA64 像素颜色
|
|
func (p *planarTIFFImage) RGBA64At(x, y int) color.RGBA64 {
|
|
values := p.components(x, y)
|
|
if p.alpha != 1 && values[3] != 65535 {
|
|
for i := range 3 {
|
|
values[i] = uint16(uint32(values[i]) * uint32(values[3]) / 65535)
|
|
}
|
|
}
|
|
return color.RGBA64{R: values[0], G: values[1], B: values[2], A: values[3]}
|
|
}
|