php中从bmp文件创建图像ImageCreateFromBMP

[code]function ImageCreateFromBMP($filename)

{

if (! $f1 = fopen($filename,"rb")) return FALSE;

$FILE = unpack("vfile_type/Vfile_size/Vreserved/Vbitmap_offset", fread($f1,14));

if ($FILE['file_type'] != 19778) return FALSE;

$BMP = unpack('Vheader_size/Vwidth/Vheight/vplanes/vbits_per_pixel'.

'/Vcompression/Vsize_bitmap/Vhoriz_resolution'.

'/Vvert_resolution/Vcolors_used/Vcolors_important', fread($f1,40));

$BMP['colors'] = pow(2,$BMP['bits_per_pixel']);

if ($BMP['size_bitmap'] == 0) $BMP['size_bitmap'] = $FILE['file_size'] - $FILE['bitmap_offset'];

$BMP['bytes_per_pixel'] = $BMP['bits_per_pixel']/8;

$BMP['bytes_per_pixel2'] = ceil($BMP['bytes_per_pixel']);

$BMP['decal'] = ($BMP['width']*$BMP['bytes_per_pixel']/4);

$BMP['decal'] -= floor($BMP['width']*$BMP['bytes_per_pixel']/4);

$BMP['decal'] = 4-(4*$BMP['decal']);

if ($BMP['decal'] == 4) $BMP['decal'] = 0;

$PALETTE = array();

if ($BMP['colors'] < 16777216)

{

$PALETTE = unpack('V'.$BMP['colors'], fread($f1,$BMP['colors']*4));

}

$IMG = fread($f1,$BMP['size_bitmap']);

$VIDE = chr(0);

$res = imagecreatetruecolor($BMP['width'],$BMP['height']);

$P = 0;

$Y = $BMP['height']-1;

while ($Y >= 0)

{

$X=0;

while ($X < $BMP['width'])

{

if ($BMP['bits_per_pixel'] == 24)

$COLOR = unpack("V",substr($IMG,$P,3).$VIDE);

elseif ($BMP['bits_per_pixel'] == 16)

{

$COLOR = unpack("n",substr($IMG,$P,2));

$COLOR[1] = $PALETTE[$COLOR[1]+1];

}

elseif ($BMP['bits_per_pixel'] == 8)

{

$COLOR = unpack("n",$VIDE.substr($IMG,$P,1));

$COLOR[1] = $PALETTE[$COLOR[1]+1];

}

elseif ($BMP['bits_per_pixel'] == 4)

{

$COLOR = unpack("n",$VIDE.substr($IMG,floor($P),1));

if (($P*2)%2 == 0) $COLOR[1] = ($COLOR[1] >> 4) ; else $COLOR[1] = ($COLOR[1] & 0x0F);

$COLOR[1] = $PALETTE[$COLOR[1]+1];

}

elseif ($BMP['bits_per_pixel'] == 1)

{

$COLOR = unpack("n",$VIDE.substr($IMG,floor($P),1));

if (($P*8)%8 == 0) $COLOR[1] = $COLOR[1] >>7;

elseif (($P*8)%8 == 1) $COLOR[1] = ($COLOR[1] & 0x40)>>6;

elseif (($P*8)%8 == 2) $COLOR[1] = ($COLOR[1] & 0x20)>>5;

elseif (($P*8)%8 == 3) $COLOR[1] = ($COLOR[1] & 0x10)>>4;

elseif (($P*8)%8 == 4) $COLOR[1] = ($COLOR[1] & 0x8)>>3;

elseif (($P*8)%8 == 5) $COLOR[1] = ($COLOR[1] & 0x4)>>2;

elseif (($P*8)%8 == 6) $COLOR[1] = ($COLOR[1] & 0x2)>>1;

elseif (($P*8)%8 == 7) $COLOR[1] = ($COLOR[1] & 0x1);

$COLOR[1] = $PALETTE[$COLOR[1]+1];

}

else

return FALSE;

imagesetpixel($res,$X,$Y,$COLOR[1]);

$X++;

$P += $BMP['bytes_per_pixel'];

}

$Y--;

$P+=$BMP['decal'];

}

fclose($f1);

return $res;

}[/code]