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############################################################################
#
# File: gifsize.icn
#
# Subject: Procedure to return size of GIF file
#
# Author: Ralph E. Griswold
#
# Date: May 2, 2001
#
############################################################################
#
# This file is in the public domain.
#
############################################################################
#
# This procedure returns the size of a GIF file in the form
# width,height. It fails if the file does not exist or is
# not a valid GIF file.
#
############################################################################
#
# Links: bincvt
#
############################################################################
link bincvt
procedure gifsize(name) #: size of GIF file
local gif, width, height
gif := open(name) | fail
repeat { # only to provide a loop to break out of ...
read(gif) ? {
=("GIF87a" | "GIF89a") | break
width := move(1)
width := move(1) || width
width := unsigned(width) | break
height := move(1)
height := move(1) || height
height := unsigned(height) | break
close(gif)
return width || "," || height
} | break
}
close(gif)
fail
end
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