#!/usr/bin/env python
# $URL: http://pypng.googlecode.com/svn/trunk/code/pipscalez $
# $Rev: 131 $

# pipscalez
# Enlarge an image by an integer factor horizontally and vertically.

def rescale(inp, out, xf, yf):
    from array import array
    import png

    r = png.Reader(file=inp)
    _,_,pixels,meta = r.asDirect()
    typecode = 'BH'[meta['bitdepth'] > 8]
    planes = meta['planes']
    # We are going to use meta in the call to Writer, so expand the
    # size.
    x,y = meta['size']
    x *= xf
    y *= yf
    meta['size'] = (x,y)
    del x
    del y
    # Values per row, target row.
    vpr = meta['size'][0] * planes
    def iterscale():
        for row in pixels:
            bigrow = array(typecode, [0]*vpr)
            row = array(typecode, row)
            for c in range(planes):
                channel = row[c::planes]
                for i in range(xf):
                    bigrow[i*planes+c::xf*planes] = channel
            for _ in range(yf):
                yield bigrow
    w = png.Writer(**meta)
    w.write(out, iterscale())


def main(argv=None):
    import sys

    if argv is None:
        argv = sys.argv
    xf = int(argv[1])
    if len(argv) > 2:
        yf = int(argv[2])
    else:
        yf = xf
    return rescale(sys.stdin, sys.stdout, xf, yf)

if __name__ == '__main__':
    main()
