GD imagecreatefrombmp,GD库支持32位BMP图片.

大部分代码来源于互联网,但是一般不支持32位的BMP图片.小生稍微修改了一点点,使其支持32位的bmp图片.

使PHP的GD库支持bmp图片,imagecreatefrombmp.

/**
 * 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['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'] == 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['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;
}