nd2-rs 0.1.6

Pure Rust library for reading Nikon ND2 microscopy files
Documentation 
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use crate::error::{Nd2Error, Result};
use crate::parse::ClxValue;
use crate::types::{Attributes, CompressionType, PixelDataType};

pub fn parse_attributes(clx: ClxValue) -> Result<Attributes> {
    let root = clx
        .as_object()
        .ok_or_else(|| Nd2Error::file_metadata("Expected object for attributes".to_string()))?;

    // The attributes are nested inside "SLxImageAttributes" key
    let obj = root
        .get("SLxImageAttributes")
        .and_then(|v| v.as_object())
        .ok_or_else(|| Nd2Error::file_metadata("Missing SLxImageAttributes object".to_string()))?;

    let get_u32 = |key: &str| -> Result<u32> {
        // Try the key as-is first, then try with type suffixes
        obj.get(key)
            .or_else(|| obj.get(&format!("{}_u32", key)))
            .or_else(|| obj.get(&format!("{}_i32", key)))
            .and_then(|v| v.as_u64().or_else(|| v.as_i64().map(|i| i as u64)))
            .map(|v| v as u32)
            .ok_or_else(|| Nd2Error::file_metadata(format!("Missing or invalid {}", key)))
    };

    let get_opt_u32 = |key: &str| -> Option<u32> {
        obj.get(key)
            .or_else(|| obj.get(&format!("{}_u32", key)))
            .or_else(|| obj.get(&format!("{}_i32", key)))
            .and_then(|v| v.as_u64().or_else(|| v.as_i64().map(|i| i as u64)))
            .map(|v| v as u32)
    };

    let get_opt_f64 = |key: &str| -> Option<f64> { obj.get(key).and_then(|v| v.as_f64()) };

    let pixel_data_type = obj
        .get("uiCompBPC")
        .and_then(|v| v.as_u64())
        .map(|v| {
            if v == 3 {
                PixelDataType::Float
            } else {
                PixelDataType::Unsigned
            }
        })
        .unwrap_or(PixelDataType::Unsigned);

    let compression_type = obj
        .get("eCompression")
        .and_then(|v| v.as_str())
        .map(|s| match s {
            "lossless" => CompressionType::Lossless,
            "lossy" => CompressionType::Lossy,
            _ => CompressionType::None,
        });

    Ok(Attributes {
        bits_per_component_in_memory: get_u32("uiBpcInMemory")?,
        bits_per_component_significant: get_u32("uiBpcSignificant")?,
        component_count: get_u32("uiComp")?,
        height_px: get_u32("uiHeight")?,
        pixel_data_type,
        sequence_count: get_u32("uiSequenceCount")?,
        width_bytes: get_opt_u32("uiWidthBytes"),
        width_px: get_opt_u32("uiWidth"),
        compression_level: get_opt_f64("dCompressionParam"),
        compression_type,
        tile_height_px: get_opt_u32("uiTileHeight"),
        tile_width_px: get_opt_u32("uiTileWidth"),
        channel_count: get_opt_u32("uiChannelCount"),
    })
}