imagecreatefrombmp,GD库支持32位BMP图片.-PHP源码

/**
 * BMP 创建函数
 * @author simon
 * @param string $filename path of bmp file
 * @example who use,who knows
 * @return resource of GD
 */ 
function imagecreatefrombmp( $filename ){
	if ( !$f1 = fopen( $filename, "rb" ) )
		return FALSE;
	
	$FILE = unpack( "vfile_type/Vfile_size/Vreserved/Vbitmap_offset", fread( $f1, 14 ) );
	if ( $FILE[&＃39;file_type&＃39;] != 19778 )
		return FALSE;
	
	$BMP = unpack( &＃39;Vheader_size/Vwidth/Vheight/vplanes/vbits_per_pixel&＃39; . &＃39;/Vcompression/Vsize_bitmap/Vhoriz_resolution&＃39; . &＃39;/Vvert_resolution/Vcolors_used/Vcolors_important&＃39;, fread( $f1, 40 ) );
	$BMP[&＃39;colors&＃39;] = pow( 2, $BMP[&＃39;bits_per_pixel&＃39;] );
	if ( $BMP[&＃39;size_bitmap&＃39;] == 0 )
		$BMP[&＃39;size_bitmap&＃39;] = $FILE[&＃39;file_size&＃39;] - $FILE[&＃39;bitmap_offset&＃39;];
	$BMP[&＃39;bytes_per_pixel&＃39;] = $BMP[&＃39;bits_per_pixel&＃39;] / 8;
	$BMP[&＃39;bytes_per_pixel2&＃39;] = ceil( $BMP[&＃39;bytes_per_pixel&＃39;] );
	$BMP[&＃39;decal&＃39;] = ($BMP[&＃39;width&＃39;] * $BMP[&＃39;bytes_per_pixel&＃39;] / 4);
	$BMP[&＃39;decal&＃39;] -= floor( $BMP[&＃39;width&＃39;] * $BMP[&＃39;bytes_per_pixel&＃39;] / 4 );
	$BMP[&＃39;decal&＃39;] = 4 - (4 * $BMP[&＃39;decal&＃39;]);
	if ( $BMP[&＃39;decal&＃39;] == 4 )
		$BMP[&＃39;decal&＃39;] = 0;
	
	$PALETTE = array();
	if ( $BMP[&＃39;colors&＃39;] <16777216 ){
		$PALETTE = unpack( &＃39;V&＃39; . $BMP[&＃39;colors&＃39;], fread( $f1, $BMP[&＃39;colors&＃39;] * 4 ) );
	}
	
	$IMG = fread( $f1, $BMP[&＃39;size_bitmap&＃39;] );
	$VIDE = chr( 0 );
	
	$res = imagecreatetruecolor( $BMP[&＃39;width&＃39;], $BMP[&＃39;height&＃39;] );
	$P = 0;
	$Y = $BMP[&＃39;height&＃39;] - 1;
	while( $Y >= 0 ){
		$X = 0;
		while( $X <$BMP[&＃39;width&＃39;] ){
			if ( $BMP[&＃39;bits_per_pixel&＃39;] == 32 ){
				$COLOR = unpack( "V", substr( $IMG, $P, 3 ) );
				$B = ord(substr($IMG, $P,1));
				$G = ord(substr($IMG, $P+1,1));
				$R = ord(substr($IMG, $P+2,1));
				$color = imagecolorexact( $res, $R, $G, $B );
				if ( $color == -1 )
					$color = imagecolorallocate( $res, $R, $G, $B );
				$COLOR[0] = $R*256*256+$G*256+$B;
				$COLOR[1] = $color;
			}elseif ( $BMP[&＃39;bits_per_pixel&＃39;] == 24 )
				$COLOR = unpack( "V", substr( $IMG, $P, 3 ) . $VIDE );
			elseif ( $BMP[&＃39;bits_per_pixel&＃39;] == 16 ){
				$COLOR = unpack( "n", substr( $IMG, $P, 2 ) );
				$COLOR[1] = $PALETTE[$COLOR[1] + 1];
			}elseif ( $BMP[&＃39;bits_per_pixel&＃39;] == 8 ){
				$COLOR = unpack( "n", $VIDE . substr( $IMG, $P, 1 ) );
				$COLOR[1] = $PALETTE[$COLOR[1] + 1];
			}elseif ( $BMP[&＃39;bits_per_pixel&＃39;] == 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[&＃39;bits_per_pixel&＃39;] == 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[&＃39;bytes_per_pixel&＃39;];
		}
		$Y--;
		$P += $BMP[&＃39;decal&＃39;];
	}
	fclose( $f1 );
	
	return $res;
}