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【pdf-rs】color.rs 文件解析

news 2025/11/2 7:02:15

color.rs 文件是一个用于PDF处理的颜色空间管理模块，主要实现了PDF标准中定义的各种颜色空间。内容如下：

use datasize::DataSize;
use crate as pdf;
use crate::object::*;
use crate::error::*;#[derive(Object, Debug, DataSize, DeepClone, ObjectWrite)]
pub struct IccInfo {#[pdf(key="N")]pub components: u32,#[pdf(key="Alternate")]pub alternate: Option<Box<ColorSpace>>,#[pdf(key="Range")]pub range: Option<Vec<f32>>,#[pdf(key="Metadata")]pub metadata: Option<Stream<()>>,
}#[derive(Debug, Clone, DeepClone)]
pub enum ColorSpace {DeviceGray,DeviceRGB,DeviceCMYK,DeviceN { names: Vec<Name>, alt: Box<ColorSpace>, tint: Function, attr: Option<Dictionary> },CalGray(Dictionary),CalRGB(Dictionary),CalCMYK(Dictionary),Indexed(Box<ColorSpace>, u8, Arc<[u8]>),Separation(Name, Box<ColorSpace>, Function),Icc(RcRef<Stream<IccInfo>>),Pattern,Named(Name),Other(Vec<Primitive>)
}
impl DataSize for ColorSpace {const IS_DYNAMIC: bool = true;const STATIC_HEAP_SIZE: usize = 0;#[inline]fn estimate_heap_size(&self) -> usize {match *self {ColorSpace::DeviceGray | ColorSpace::DeviceRGB | ColorSpace::DeviceCMYK => 0,ColorSpace::DeviceN { ref names, ref alt, ref tint, ref attr } => {names.estimate_heap_size() +alt.estimate_heap_size() +tint.estimate_heap_size() +attr.estimate_heap_size()}ColorSpace::CalGray(ref d) | ColorSpace::CalRGB(ref d) | ColorSpace::CalCMYK(ref d) => {d.estimate_heap_size()}ColorSpace::Indexed(ref cs, _, ref data) => {cs.estimate_heap_size() + data.estimate_heap_size()}ColorSpace::Separation(ref name, ref cs, ref f) => {name.estimate_heap_size() + cs.estimate_heap_size() + f.estimate_heap_size()}ColorSpace::Icc(ref s) => s.estimate_heap_size(),ColorSpace::Pattern => 0,ColorSpace::Other(ref v) => v.estimate_heap_size(),ColorSpace::Named(ref n) => n.estimate_heap_size()}}
}fn get_index(arr: &[Primitive], idx: usize) -> Result<&Primitive> {arr.get(idx).ok_or(PdfError::Bounds { index: idx, len: arr.len() })
}impl Object for ColorSpace {fn from_primitive(p: Primitive, resolve: &impl Resolve) -> Result<ColorSpace> {ColorSpace::from_primitive_depth(p, resolve, 5)}
}
impl ColorSpace {fn from_primitive_depth(p: Primitive, resolve: &impl Resolve, depth: usize) -> Result<ColorSpace> {let p = p.resolve(resolve)?;if let Ok(name) = p.as_name() {let cs = match name {"DeviceGray" => ColorSpace::DeviceGray,"DeviceRGB" => ColorSpace::DeviceRGB,"DeviceCMYK" => ColorSpace::DeviceCMYK,"Pattern" => ColorSpace::Pattern,name => ColorSpace::Named(name.into()),};return Ok(cs);}let arr = t!(p.into_array());let typ_p = t!(get_index(&arr, 0)).clone().resolve(resolve)?;let typ = t!(typ_p.as_name());if depth == 0 {bail!("ColorSpace base recursion");}match typ {"Indexed" => {let base = Box::new(t!(ColorSpace::from_primitive_depth(t!(get_index(&arr, 1)).clone(), resolve, depth-1)));let hival = t!(t!(get_index(&arr, 2)).as_u8());let lookup = match t!(get_index(&arr, 3)) {&Primitive::Reference(r) => resolve.resolve(r)?,p => p.clone()};let lookup = match lookup {Primitive::String(string) => {let data: Vec<u8> = string.into_bytes().into();data.into()}Primitive::Stream(stream) => {let s: Stream::<()> = Stream::from_stream(stream, resolve)?;t!(s.data(resolve))},p => return Err(PdfError::UnexpectedPrimitive {expected: "String or Stream",found: p.get_debug_name()})};Ok(ColorSpace::Indexed(base, hival, lookup))}"Separation" => {let name = t!(t!(get_index(&arr, 1)).clone().into_name());let alternate = Box::new(t!(ColorSpace::from_primitive_depth(t!(get_index(&arr, 2)).clone(), resolve, depth-1)));let tint = t!(Function::from_primitive(t!(get_index(&arr, 3)).clone(), resolve));Ok(ColorSpace::Separation(name, alternate, tint))}"ICCBased" => {let s = t!(RcRef::from_primitive(t!(get_index(&arr, 1)).clone(), resolve));Ok(ColorSpace::Icc(s))}"DeviceN" => {let names = t!(Object::from_primitive(t!(get_index(&arr, 1)).clone(), resolve));let alt = t!(Object::from_primitive(t!(get_index(&arr, 2)).clone(), resolve));let tint = t!(Function::from_primitive(t!(get_index(&arr, 3)).clone(), resolve));let attr = arr.get(4).map(|p| Dictionary::from_primitive(p.clone(), resolve)).transpose()?;Ok(ColorSpace::DeviceN { names, alt, tint, attr})}"CalGray" => {let dict = Dictionary::from_primitive(t!(get_index(&arr, 1)).clone(), resolve)?;Ok(ColorSpace::CalGray(dict))}"CalRGB" => {let dict = Dictionary::from_primitive(t!(get_index(&arr, 1)).clone(), resolve)?;Ok(ColorSpace::CalRGB(dict))}"CalCMYK" => {let dict = Dictionary::from_primitive(t!(get_index(&arr, 1)).clone(), resolve)?;Ok(ColorSpace::CalCMYK(dict))}"Pattern" => {Ok(ColorSpace::Pattern)}_ => Ok(ColorSpace::Other(arr))}}
}
impl ObjectWrite for ColorSpace {fn to_primitive(&self, update: &mut impl Updater) -> Result<Primitive> {match *self {ColorSpace::DeviceCMYK => Ok(Primitive::name("DeviceCMYK")),ColorSpace::DeviceRGB => Ok(Primitive::name("DeviceRGB")),ColorSpace::Indexed(ref  base, hival, ref lookup) => {let base = base.to_primitive(update)?;let hival = Primitive::Integer(hival.into());let lookup = if lookup.len() < 100 {PdfString::new((**lookup).into()).into()} else {Stream::new((), lookup.clone()).to_primitive(update)?};Ok(Primitive::Array(vec![Primitive::name("Indexed"), base, hival, lookup]))}ref p => {dbg!(p);unimplemented!()}}}
}

主要结构

IccInfo 结构体

#[derive(Object, Debug, DataSize, DeepClone, ObjectWrite)]
pub struct IccInfo {#[pdf(key="N")]pub components: u32,#[pdf(key="Alternate")]pub alternate: Option<Box<ColorSpace>>,#[pdf(key="Range")]pub range: Option<Vec<f32>>,#[pdf(key="Metadata")]pub metadata: Option<Stream<()>>,
}

功能：

存储ICC颜色配置文件的元信息
支持PDF对象序列化/反序列化
包含组件数量、备用颜色空间、数值范围和元数据

ColorSpace 枚举

#[derive(Debug, Clone, DeepClone)]
pub enum ColorSpace {DeviceGray,DeviceRGB,DeviceCMYK,DeviceN { names: Vec<Name>, alt: Box<ColorSpace>, tint: Function, attr: Option<Dictionary> },CalGray(Dictionary),CalRGB(Dictionary),CalCMYK(Dictionary),Indexed(Box<ColorSpace>, u8, Arc<[u8]>),Separation(Name, Box<ColorSpace>, Function),Icc(RcRef<Stream<IccInfo>>),Pattern,Named(Name),Other(Vec<Primitive>)
}

颜色空间类型详解

设备颜色空间

DeviceGray - 设备灰度空间
DeviceRGB - 设备RGB颜色空间
DeviceCMYK - 设备CMYK颜色空间

特殊颜色空间

DeviceN - 多组件设备颜色空间
- names: 颜色组件名称
- alt: 备用颜色空间
- tint: 色调变换函数
- attr: 附加属性
Indexed - 索引颜色空间
- 基础颜色空间
- 最大索引值（hival）
- 颜色查找表数据
Separation - 专色分离
- 颜色名称
- 备用颜色空间
- 色调变换函数

基于标准的颜色空间

CalGray - 校准灰度空间（带校准字典）
CalRGB - 校准RGB空间（带校准字典）
CalCMYK - 校准CMYK空间（带校准字典）

其他类型

Icc - ICC基于的颜色空间
Pattern - 图案颜色空间
Named - 命名颜色空间
Other - 其他未实现类型

核心功能实现

内存大小估算

impl DataSize for ColorSpace {const IS_DYNAMIC: bool = true;const STATIC_HEAP_SIZE: usize = 0;fn estimate_heap_size(&self) -> usize {// 为每种变体递归估算堆内存使用match *self {ColorSpace::DeviceGray | ColorSpace::DeviceRGB | ColorSpace::DeviceCMYK => 0,ColorSpace::DeviceN { ref names, ref alt, ref tint, ref attr } => {names.estimate_heap_size() +alt.estimate_heap_size() +tint.estimate_heap_size() +attr.estimate_heap_size()}// ... 其他变体的内存估算}}
}

PDF对象解析

impl Object for ColorSpace {fn from_primitive(p: Primitive, resolve: &impl Resolve) -> Result<ColorSpace> {ColorSpace::from_primitive_depth(p, resolve, 5)}
}

解析特性：

递归解析，最大深度为5层防止无限递归
支持从名称或数组格式解析颜色空间
处理索引颜色空间的查找表数据（字符串或流格式）

主要解析逻辑

名称解析：直接映射标准颜色空间名称
数组解析：根据第一个元素识别颜色空间类型
递归处理：处理嵌套的颜色空间定义
错误处理：完善的边界检查和错误类型

序列化支持

impl ObjectWrite for ColorSpace {fn to_primitive(&self, update: &mut impl Updater) -> Result<Primitive> {match *self {ColorSpace::DeviceCMYK => Ok(Primitive::name("DeviceCMYK")),ColorSpace::DeviceRGB => Ok(Primitive::name("DeviceRGB")),ColorSpace::Indexed(ref base, hival, ref lookup) => {// 将索引颜色空间转换为PDF数组格式let base = base.to_primitive(update)?;let hival = Primitive::Integer(hival.into());let lookup = if lookup.len() < 100 {PdfString::new((**lookup).into()).into()} else {Stream::new((), lookup.clone()).to_primitive(update)?};Ok(Primitive::Array(vec![Primitive::name("Indexed"), base, hival, lookup]))}// ... 其他变体的序列化}}
}