The GIF animation is created with the following BASH script. Another way is to use freetype. But the stock freetype excutables are not quite scriptable. This script is terribly slow. The better way is to create a large EPS file and to use ImageMagick to scroll the clipping window.
#!/bin/bash

start_y=0
# total height is 180+35 = 215
total_height=215
num_images=50

fileno=1
for i in `jot $num_images $start_y $total_height`
do
    filename=`printf hb%02d.ppm $fileno`

    end_y=$(($i+35))
    fileno=$(($fileno+1))
    echo $i,$end_y

sed -e "s/START_Y/$i/" -e "s/END_Y/${end_y}/" <<end_of_eps |gs -q -dNOPAUSE -dBATCH 
-r72 -dEPSCrop -dTextAlphaBits=4 -sDEVICE=ppm -sOutputFile=$filename -
%!PS-Adobe-2.0 EPSF-2.0
%%BoundingBox: 0 START_Y 60 END_Y 
/SimSun-Medium-GBK-EUC-H
findfont 30 scalefont setfont
0 5 moveto (║˙Ýš) show
/Fang-Medium-GBK-EUC-H
findfont 30 scalefont setfont
0 35 moveto (║˙Ýš) show
/Kai-Medium-GBK-EUC-H
findfont 30 scalefont setfont
0 70 moveto (║˙Ýš) show
/Hei-Medium-GBK-EUC-H
findfont 30 scalefont setfont
0 105 moveto (║˙Ýš) show
/Li-Medium-GBK-EUC-H
findfont 30 scalefont setfont
0 145 moveto (║˙Ýš) show
/You-Medium-GBK-EUC-H
findfont 30 scalefont setfont
0 180 moveto (║˙Ýš) show
end_of_eps
done