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ScanlineDecoder

rpdfium_codec::scanline

Trait ScanlineDecoder 

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pub trait ScanlineDecoder {
    // Required methods
    fn width(&self) -> u32;
    fn height(&self) -> u32;
    fn count_comps(&self) -> u8;
    fn bpc(&self) -> u8;
    fn row_stride(&self) -> usize;
    fn decode_scanline(&mut self) -> Result<Option<&[u8]>, DecodeError>;
    fn reset(&mut self) -> Result<(), DecodeError>;
    fn current_line(&self) -> Option<usize>;
}
Expand description

A scanline-based image decoder that yields one row of pixels at a time.

After construction, call decode_scanline repeatedly to get each row. Returns Ok(None) after the last row. Call reset to restart from the first row.

Mirrors PDFium’s ScanlineDecoder base class interface, including the image-geometry accessors GetWidth(), GetHeight(), CountComps(), and GetBPC().

Required Methods§

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fn width(&self) -> u32

Image width in pixels. Mirrors PDFium’s GetWidth().

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fn height(&self) -> u32

Image height in pixels. Mirrors PDFium’s GetHeight().

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fn count_comps(&self) -> u8

Number of color components per pixel (e.g. 1 for gray, 3 for RGB, 4 for CMYK). Mirrors PDFium’s CountComps().

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fn bpc(&self) -> u8

Bits per color component (e.g. 1, 8, 16). Mirrors PDFium’s GetBPC().

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fn row_stride(&self) -> usize

Number of bytes per row: (width * count_comps * bpc + 7) / 8.

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fn decode_scanline(&mut self) -> Result<Option<&[u8]>, DecodeError>

Decode and return the next scanline.

Returns Ok(Some(data)) for each row, Ok(None) when all rows are done.

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fn reset(&mut self) -> Result<(), DecodeError>

Reset the decoder to the first scanline.

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fn current_line(&self) -> Option<usize>

Current line index (0-based), or None if no lines have been read yet.

Implementors§