php bmp转jpg的实现方法

<?php 
$srcFile ='test.bmp';//需要转换的图片$info = getimagesize($srcFile);    
$srcFileExt=$info['mime'];//判断是否是bmp格式if($srcFileExt=='image/x-ms-bmp'){    $result = changeBMPtoJPG($srcFile);    if($result){        echo $result;
    }else{        echo "转换失败!";
    }
}else{    echo "该图片不是bmp格式";
} 
exit;function ImageCreateFromBMP_private($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 < $BMP['width']) {            switch ($BMP['bits_per_pixel']) {                case 32:                    $COLOR = unpack("V", substr($IMG, $P, 3) . $VIDE);                    break;                case 24:                    $COLOR = unpack("V", substr($IMG, $P, 3) . $VIDE);                    break;                case 16:                    $COLOR = unpack("n", substr($IMG, $P, 2));                    $COLOR[1] = $PALETTE[$COLOR[1] + 1];                    break;                case 8:                    $COLOR = unpack("n", $VIDE . substr($IMG, $P, 1));                    $COLOR[1] = $PALETTE[$COLOR[1] + 1];                    break;                case 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];                    break;                case 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];                    break;                default:                    return false;                    break;
            }

            imagesetpixel($res, $X, $Y, $COLOR[1]);            $X++;            $P += $BMP['bytes_per_pixel'];
        }        $Y--;        $P+=$BMP['decal'];
    }    fclose($f1);    return $res;
}function changeBMPtoJPG($srcPathName){    $srcFile=$srcPathName;  
    $dstFile = str_replace('.bmp', '.jpg', $srcPathName);    $photoSize = GetImageSize($srcFile);  
    $pw = $photoSize[0];  
    $ph = $photoSize[1];    $dstImage = ImageCreateTrueColor($pw, $ph);  
    $white = imagecolorallocate($dstImage, 255, 255, 255);    //用 $white 颜色填充图像
    imagefill( $dstImage, 0, 0, $white);    //读取图片  
    $srcImage = ImageCreateFromBMP_private($srcFile); 
    //合拼图片  
    imagecopyresampled($dstImage, $srcImage, 0, 0, 0, 0, $pw, $ph, $pw, $ph);  
    $judge = imagejpeg($dstImage, $dstFile, 90);  
    imagedestroy($dstImage);    if($judge){        return $dstFile;
    }else{        return false;
    }
}?>