Read a bitmap file with APL

bitmap.dyalog

:Class Bitmap

    :Field Public FileTie
    :Field Public BMPHeader
    :Field Public DIPHeader
    :Field Public ImageTable
    :Field Public ImageWidth
    :Field Public ImageHeight
    :Field Public ImageDataOffset
    :Field Public Bytes

    ∇ open path;offset;w;h;bytes;data;size;DIPHeaderSize
        :Implements Constructor
        :Access Public

        FileTie←path ⎕NTIE 0

        BMPHeader←⎕NREAD FileTie 83 14 0
        DIPHeaderSize←1⊃⎕NREAD FileTie 323 1 14
        DIPHeader←⎕NREAD FileTie 83 DIPHeaderSize 14

        offset←1⊃⎕NREAD FileTie 323 1 10
        w←1⊃⎕NREAD FileTie 323 1 18
        h←1⊃⎕NREAD FileTie 323 1 22
        bytes←(1⊃⎕NREAD FileTie 163 1 28)÷8
        size←bytes×h×w

        data←⎕NREAD FileTie 83 size offset
        ImageWidth←w
        ImageHeight←h
        ImageDataOffset←offset
        Bytes←bytes

        ImageTable←256|bytes h w⍴⍉(h×w) bytes⍴data

        ⎕NUNTIE FileTie
    ∇
    
:EndClass