apple2_png_to_hgr/pic2hgr.html

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2018-06-17 17:50:44 +00:00
<html>
<head>
<script>
/*
Convert a PNG into raw HGR bytes.
Copyleft 2018 Michaelangel007
Shell:
python -m SimpleHTTPServer
Web Browser:
http://localhost:8000/pic2hgr.html
*/
function main()
{
var canvas = document.getElementById( 'canvas' );
var context = canvas.getContext( '2d' );
var w = canvas.width;
var h = canvas.height;
var pic = new Image();
pic.onload = function()
{
context.drawImage( pic, 0, 0 );
var data = context.getImageData( 0, 0, w, h );
var texels = data.data;
var addr;
var byte = 0;
var bit = 1;
var line = "";
var text = "";
var cr = 0;
var phase = 0;
var hi = 0;
// "Mr. Robot" -> "Mr. Crack"
// X=$00 .. $0D (14 bytes)
var y0 = 0;
var y1 = 44;
console.log( "image.size = " + texels.length );
console.log( "image.w = " + pic.width );
console.log( "image.h = " + pic.height );
for( var y = y0; y < y1; y++ )
{
addr = 0x2000 + ((y/64)&63)*0x28 + (y%8)*0x400 + ((y/8)&7)*0x80;
line = addr.toString( 16 ) + ":";
cr = 0;
phase = 0;
for( var x = 0; x < 280; x++ )
{
j = (y*w + x)*4;
r = texels[ j + 0 ];
g = texels[ j + 1 ];
b = texels[ j + 2 ];
if( b >= 220 )
byte |= bit;
bit <<= 1;
bit &= 0x7F;
if( !bit ) // over-flow to next byte?
{
//hi = ((g > 232) && (b < g) && (r < g)) ? 0 : 0x80;
hi = 0x80; // blue
// hi = 0x00; // green
line = line + (byte | hi).toString( 16 ) + ' ';
cr++;
if( cr % 8 === 0 )
{
addr += 8;
if( cr < 0x28 )
line = line + '\n' + addr.toString( 16 ) + ":";
}
byte = 0;
bit = 1;
}
}
text = text + line + '\n';
}
console.log( text );
var log = document.getElementById( 'log' );
log.innerHTML = text;
};
pic.src = 'mr_crack_and_his_crack_factory_280x192.png';
}
</script>
</head>
<body onload="main();">
<canvas id='canvas' width="280" height="192"></canvas>
<pre id='log'></pre>
</body>
</html>