wml2 0.0.22

Pure Rust multi-format image decoding and encoding library supporting JPEG, PNG, GIF, WebP, TIFF and PC-98 legacy formats (MAG, MAKI, PI, PIC)
Documentation 
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//! Metadata value types shared by image decoders and encoders.

use crate::error::{ImgError, ImgErrorKind};
#[cfg(feature = "exif")]
use crate::tiff::header::TiffHeaders;
#[cfg(feature = "exif")]
use crate::tiff::header::exif_to_bytes;
use std::collections::HashMap;

/// A map of metadata keys to typed values.
pub type Metadata = HashMap<String, DataMap>;

/// A typed metadata value.
#[derive(Debug, Clone, PartialEq)]
pub enum DataMap {
    UInt(u64),
    SInt(i64),
    Float(f64),
    UIntAllay(Vec<u64>),
    SIntAllay(Vec<i64>),
    FloatAllay(Vec<f64>),
    Raw(Vec<u8>),
    Ascii(String),
    I18NString(String),
    SJISString(Vec<u8>),
    #[cfg(feature = "exif")]
    Exif(TiffHeaders),
    ICCProfile(Vec<u8>),
    None,
}

impl DataMap {
    /// Converts the metadata value to a display-oriented string.
    pub fn to_string(&self) -> String {
        match self {
            DataMap::UInt(d) => d.to_string(),
            DataMap::SInt(d) => d.to_string(),
            DataMap::Float(d) => d.to_string(),
            DataMap::UIntAllay(d) => {
                format!("{:?}", d)
            }
            DataMap::SIntAllay(d) => {
                format!("{:?}", d)
            }
            DataMap::FloatAllay(d) => {
                format!("{:?}", d)
            }
            DataMap::Raw(d) => {
                format!("{:?}", d)
            }
            DataMap::Ascii(d) => d.to_string(),
            DataMap::I18NString(d) => d.to_string(),
            DataMap::SJISString(d) => {
                format!("{:?}", d)
            }
            #[cfg(feature = "exif")]
            DataMap::Exif(header) => header.to_string(),
            DataMap::ICCProfile(iccprofile) => {
                format!("{:?}", iccprofile)
            }
            DataMap::None => "none".to_owned(),
        }
    }
}

/// Extracts a serialized EXIF payload from metadata when present.
///
/// This accepts decoded TIFF-style metadata (`"Tiff headers"`), generic EXIF
/// metadata (`"EXIF"`), or an already serialized fallback (`"EXIF Raw"`).
pub fn get_exif(
    metadata: Option<&Metadata>,
) -> Result<Option<Vec<u8>>, Box<dyn std::error::Error>> {
    let Some(metadata) = metadata else {
        return Ok(None);
    };

    #[cfg(feature = "exif")]
    match metadata.get("EXIF") {
        Some(DataMap::Exif(headers)) => return exif_to_bytes(headers).map(Some),
        Some(DataMap::Raw(bytes)) => return Ok(Some(bytes.clone())),
        Some(_) => {
            return Err(Box::new(ImgError::new_const(
                ImgErrorKind::InvalidParameter,
                "EXIF metadata is not serializable".to_string(),
            )));
        }
        None => {}
    }

    #[cfg(feature = "exif")]
    match metadata.get("Tiff headers") {
        Some(DataMap::Exif(headers)) => return exif_to_bytes(headers).map(Some),
        Some(_) => {
            return Err(Box::new(ImgError::new_const(
                ImgErrorKind::InvalidParameter,
                "Tiff headers metadata is not serializable".to_string(),
            )));
        }
        None => {}
    }

    match metadata.get("EXIF Raw") {
        Some(DataMap::Raw(bytes)) => Ok(Some(bytes.clone())),
        Some(_) => Err(Box::new(ImgError::new_const(
            ImgErrorKind::InvalidParameter,
            "EXIF Raw metadata is not raw bytes".to_string(),
        ))),
        None => Ok(None),
    }
}

fn find_exif_option<'a>(options: Option<&'a Metadata>) -> Option<&'a DataMap> {
    let options = options?;
    options
        .get("exif")
        .or_else(|| options.get("exif "))
        .or_else(|| {
            options
                .iter()
                .find(|(key, _)| key.trim().eq_ignore_ascii_case("exif"))
                .map(|(_, value)| value)
        })
}

/// Resolves an EXIF payload from encoder options.
///
/// Supported option forms:
/// - `{"exif": Raw(bytes)}`: use serialized EXIF/TIFF bytes directly
/// - `{"exif": Exif(headers)}`: serialize [`TiffHeaders`] on demand
/// - `{"exif": Ascii("copy")}`: copy EXIF from source metadata
pub fn get_exif_option(
    options: Option<&Metadata>,
    metadata: Option<&Metadata>,
) -> Result<Option<Vec<u8>>, Box<dyn std::error::Error>> {
    let Some(value) = find_exif_option(options) else {
        return Ok(None);
    };

    match value {
        DataMap::Raw(bytes) => Ok(Some(bytes.clone())),
        #[cfg(feature = "exif")]
        DataMap::Exif(headers) => exif_to_bytes(headers).map(Some),
        DataMap::Ascii(value) if value.trim().eq_ignore_ascii_case("copy") => get_exif(metadata),
        DataMap::Ascii(_) => Err(Box::new(ImgError::new_const(
            ImgErrorKind::InvalidParameter,
            "exif option must be Raw(bytes), Exif(headers), or Ascii(\"copy\")".to_string(),
        ))),
        _ => Err(Box::new(ImgError::new_const(
            ImgErrorKind::InvalidParameter,
            "exif option must be Raw(bytes), Exif(headers), or Ascii(\"copy\")".to_string(),
        ))),
    }
}