php生成图片缩略图类程序-php手册-php.cn

缩略图用得最多的是我们上传图片时生成一张小图，这样就可以很好的解决图片大小或影响网站整体美观的问题了，下面介绍的生成图片缩略图类都不支持图片上传，我们要先上传再调用此类来操作。

//使用如下类就可以生成图片缩略图,

代码如下

复制代码

class resizeimage
{
    //图片类型
    var $type;
    //实际宽度
    var $width;
    //实际高度
    var $height;
    //改变后的宽度
    var $resize_width;
    //改变后的高度
    var $resize_height;
    //是否裁图
    var $cut;
    //源图象
    var $srcimg;
    //目标图象地址
    var $dstimg;
    //临时创建的图象
    var $im;

    function resizeimage($img, $wid, $hei,$c,$dstpath)
    {
        $this->srcimg = $img;
        $this->resize_width = $wid;
        $this->resize_height = $hei;
        $this->cut = $c;
        //图片的类型

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

        //初始化图象
        $this->initi_img();
        //目标图象地址
        $this -> dst_img($dstpath);
        //--
        $this->width = imagesx($this->im);
        $this->height = imagesy($this->im);
        //生成图象
        $this->newimg();
        ImageDestroy ($this->im);
    }
    function newimg()
    {
        //改变后的图象的比例
        $resize_ratio = ($this->resize_width)/($this->resize_height);
        //实际图象的比例
        $ratio = ($this->width)/($this->height);
        if(($this->cut)=="1")
        //裁图
        {
            if($ratio>=$resize_ratio)
            //高度优先
            {
                $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);
                imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this-

>resize_height, (($this->height)*$resize_ratio), $this->height);
                ImageJpeg ($newimg,$this->dstimg);
            }
            if($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             {
                $newimg = imagecreatetruecolor(($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;
}
}
?>

类的调用方法

$resizeimage = new resizeimage("图片源文件地址", "200", "100", "0","缩略图地址");

//就只用上面的一句话,就能生成缩略图,其中,源文件和缩略图地址可以相同,200,100分别代表宽和高

实例2

PHP缩略图等比例无损压缩，可填充空白区域补充色

代码如下

复制代码

error_reporting( E_ALL );

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

/*
    php缩略图函数：
        等比例无损压缩，可填充补充色 author: 华仔
    主持格式：
        bmp 、jpg 、gif、png
    param:
        @srcimage : 要缩小的图片
        @dstimage : 要保存的图片
        @dst_width: 缩小宽
        @dst_height: 缩小高
        @backgroundcolor: 补充色如：#FFFFFF 支持 6位不支持3位
*/
function imagezoom( $srcimage, $dstimage, $dst_width, $dst_height, $backgroundcolor ) {

        // 中文件名乱码
        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 "要生成缩略图的文件不存在";
                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)         $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                 $ret .= ord($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']    {
    $PALETTE = unpack('V'.$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         {
         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         {
            $col = imagecolorat ($im, $x, $y);
            fwrite ($f, pack ('V', $col), 3);
        }
        for ($i = 0; $i             fwrite ($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。