read-png-chunks ( loading-png -- loading-png )

Vocabulary

images.png

Inputs

loading-png

an object

Outputs

loading-png

an object

Definition

USING: accessors checksums checksums.crc32 endian io
io.encodings.ascii io.encodings.string kernel math sequences ;

IN: images.png

: read-png-chunks ( loading-png -- loading-png )
    <png-chunk> 4 read be> 4 + read dup crc32 checksum-bytes
    4 read = [ bad-checksum ] unless 4 cut-slice
    [ ascii decode >>type ] [ B{ } like >>data ] bi*
    [ over chunks>> push ] [ type>> ] bi "IEND" =
    [ read-png-chunks ] unless ;