PHP program to generate image thumbnails_PHP tutorial-PHP Tutorial-php.cn

The most commonly used thumbnail is to generate a small image when we upload an image. This can effectively solve the problem of image size or affecting the overall beauty of the website. The generated image thumbnail class introduced below does not support image uploading. We need to upload first and then call this class to operate.

//Use the following class to generate image thumbnails,

The code is as follows

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class resizeimage
{
//Image type
var $type;
//Actual width
var $width;
//Actual height
var $height;
//Changed width
var $resize_width;
//Height after change
var $resize_height;
//Whether to crop the image
var $cut;
//Source image
var $srcimg;
//Target image address
var $dstimg;
//Temporarily created image
var $im;

function resizeimage($img, $wid, $hei,$c,$dstpath)
{
           $this->srcimg = $img;
            $this->resize_width = $wid;
            $this->resize_height = $hei;
           $this->cut = $c;
//Type of picture

$this->type = strtolower(substr(strrchr($this->srcimg,"."),1));

//Initialize image
           $this->initi_img();
//Target image address
          $this -> dst_img($dstpath);
            //--
           $this->width = imagesx($this->im);
          $this->height = imagesy($this->im);
//Generate image
$this->newimg();
ImageDestroy ($this->im);
}
Function newimg()
{
//The proportion of the changed image
          $resize_ratio = ($this->resize_width)/($this->resize_height);
//Proportion of actual image
          $ratio = ($this->width)/($this->height);
           if(($this->cut)=="1")
// Creed            {
If($ratio>=$resize_ratio)
//High priority
                {
$newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);
Imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this-

>resize_height, (($this->height)*$resize_ratio), $this->height);
                ImageJpeg ($newimg,$this->dstimg);
            }
            if($ratio<$resize_ratio)
            //宽度优先
            {
                $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);
                imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this-

>resize_height, $this->width, (($this->width)/$resize_ratio));
                ImageJpeg ($newimg,$this->dstimg);
            }
        }
        else
        //不裁图
        {
            if($ratio>=$resize_ratio)
            {
                $newimg = imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio);
                imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this-

>resize_width)/$ratio, $this->width, $this->height);
                ImageJpeg ($newimg,$this->dstimg);
            }
            if($ratio<$resize_ratio)
            {
                $newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height);
                imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height)*$ratio,

$this->resize_height, $this->width, $this->height);
                ImageJpeg ($newimg,$this->dstimg);
            }
        }
    }
    //初始化图象
    function initi_img()
    {
        if($this->type=="jpg")
        {
            $this->im = imagecreatefromjpeg($this->srcimg);
        }
        if($this->type=="gif")
        {
            $this->im = imagecreatefromgif($this->srcimg);
        }
        if($this->type=="png")
        {
            $this->im = imagecreatefrompng($this->srcimg);
        }
    }
    //图象目标地址
    function dst_img($dstpath)
    {
        $full_length = strlen($this->srcimg);

$type_length = strlen($this->type);
$name_length = $full_length-$type_length;

$name = substr($this->srcimg,0,$name_length-1);
$this->dstimg = $dstpath;

//echo $this->dstimg;
}
}
?>

Call method of class

$resizeimage = new resizeimage("Image source file address", "200", "100", "0","Thumbnail address");

// Just use the above sentence to generate a thumbnail. The source file and thumbnail addresses can be the same, 200 and 100 represent the width and height respectively

Example 2

PHP thumbnails are compressed losslessly in equal proportions and can fill blank areas with supplementary colors

The code is as follows

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error_reporting( E_ALL );

//Test
imagezoom('1.jpg', '2.jpg', 400, 300, '#FFFFFF');

/*
php thumbnail function:
Lossless compression with equal ratio, can be filled with complementary colors author: Andy Lau
Hosting format:
           bmp, jpg, gif, png
Param:
@Srcimage: The picture to be reduced
           @dstimage: Picture to be saved
           @dst_width: Reduce width
           @dst_height: Reduce height
@backgroundcolor: Supplementary color such as: #FFFFFF supports 6 bits but does not support 3 bits
*/
function imagezoom( $srcimage, $dstimage, $dst_width, $dst_height, $backgroundcolor ) {

// The file name is garbled
             if (PHP_OS == 'WINNT') {
                    $srcimage = iconv('UTF-8', 'GBK', $srcimage);
                   $dstimage = iconv('UTF-8', 'GBK', $dstimage);
}

$dstimg = imagecreatetruecolor( $dst_width, $dst_height );
$color = imagecolorallocate($dstimg
, hexdec(substr($backgroundcolor, 1, 2))
, hexdec(substr($backgroundcolor, 3, 2))
, hexdec(substr($backgroundcolor, 5, 2))
);
Imagefill($dstimg, 0, 0, $color);

If ( !$arr=getimagesize($srcimage) ) {
echo "The file to generate thumbnails does not exist";
exit;
}

$src_width = $arr[0];
$src_height = $arr[1];
$srcimg = null;
$method = getcreatemethod( $srcimage );
If ( $method ) {
          eval( '$srcimg = ' . $method . ';' );
}

$dst_x = 0;
$dst_y = 0;
$dst_w = $dst_width;
$dst_h = $dst_height;
If ( ($dst_width / $dst_height - $src_width / $src_height) > 0 ) {
           $dst_w = $src_width * ( $dst_height / $src_height );
           $dst_x = ( $dst_width - $dst_w ) / 2;
} elseif ( ($dst_width / $dst_height - $src_width / $src_height) < 0 ) {
           $dst_h = $src_height * ( $dst_width / $src_width );
          $dst_y = ( $dst_height - $dst_h ) / 2;
}

    imagecopyresampled($dstimg, $srcimg, $dst_x
        , $dst_y, 0, 0, $dst_w, $dst_h, $src_width, $src_height);

    // 保存格式
    $arr = array(
        'jpg' => 'imagejpeg'
        , 'jpeg' => 'imagejpeg'
        , 'png' => 'imagepng'
        , 'gif' => 'imagegif'
        , 'bmp' => 'imagebmp'
    );
    $suffix = strtolower( array_pop(explode('.', $dstimage ) ) );
    if (!in_array($suffix, array_keys($arr)) ) {
        echo "保存的文件名错误";
        exit;
    } else {
        eval( $arr[$suffix] . '($dstimg, "'.$dstimage.'");' );
    }

    imagejpeg($dstimg, $dstimage);

    imagedestroy($dstimg);
    imagedestroy($srcimg);

}

function str2hex( $str ) {
        $ret = "";

        for( $i = 0; $i < strlen( $str ) ; $i++ ) {
                $ret .= ord($str[$i]) >= 16 ? strval( dechex( ord($str[$i]) ) )
                        : '0'. strval( dechex( ord($str[$i]) ) );
        }

        return strtoupper( $ret );
}

// BMP 创建函数 php本身无
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 $res;
}
// BMP 保存函数，php本身无
function imagebmp ($im, $fn = false)
{
    if (!$im) return false;

    if ($fn === false) $fn = 'php://output';
    $f = fopen ($fn, "w");
    if (!$f) return false;

    $biWidth = imagesx ($im);
    $biHeight = imagesy ($im);
    $biBPLine = $biWidth * 3;
    $biStride = ($biBPLine + 3) & ~3;
    $biSizeImage = $biStride * $biHeight;
    $bfOffBits = 54;
    $bfSize = $bfOffBits + $biSizeImage;

    fwrite ($f, 'BM', 2);
    fwrite ($f, pack ('VvvV', $bfSize, 0, 0, $bfOffBits));

    fwrite ($f, pack ('VVVvvVVVVVV', 40, $biWidth, $biHeight, 1, 24, 0, $biSizeImage, 0, 0, 0, 0));

    $numpad = $biStride - $biBPLine;
    for ($y = $biHeight - 1; $y >= 0; --$y)
    {
        for ($x = 0; $x < $biWidth; ++$x)
        {
            $col = imagecolorat ($im, $x, $y);
            fwrite ($f, pack ('V', $col), 3);
        }
        for ($i = 0; $i < $numpad; ++$i)
            fwrite ($f, pack ('C', 0));
    }
    fclose ($f);
    return true;
}

总结，第一个类文件不如第二个好，因为第一个生成图之后图片会有点变模糊哦，后面这个生成类是高质量的。