縮略圖用得最多的是我們上傳圖片時生成一張小圖，這樣就可以很好的解決圖片大小或影響網站整體美觀的問題了，下面介紹的生成圖片縮略圖類都不支持圖片上傳，我們要先上傳再調用此類來操作。
//使用如下類就可以生成圖片縮略圖,
代碼如下 復制代碼<?php
class resizeimage
{
//圖片類型
var $type;
//實際寬度
var $width;
//實際高度
var $height;
//改變後的寬度
var $resize_width;
//改變後的高度
var $resize_height;
//是否裁圖
var $cut;
//源圖象
var $srcimg;
//目標圖象地址
var $dstimg;
//臨時創建的圖象
var $im;
function resizeimage($img, $wid, $hei,$c,$dstpath)
{
$this->srcimg = $img;
$this->resize_width = $wid;
$this->resize_height = $hei;
$this->cut = $c;
//圖片的類型
$this->type = strtolower(substr(strrchr($this->srcimg,"."),1));
//初始化圖象
$this->initi_img();
//目標圖象地址
$this -> dst_img($dstpath);
//--
$this->width = imagesx($this->im);
$this->height = imagesy($this->im);
//生成圖象
$this->newimg();
ImageDestroy ($this->im);
}
function newimg()
{
//改變後的圖象的比例
$resize_ratio = ($this->resize_width)/($this->resize_height);
//實際圖象的比例
$ratio = ($this->width)/($this->height);
if(($this->cut)=="1")
//裁圖
{
if($ratio>=$resize_ratio)
//高度優先
{
$newimg = imagecreatetruecolor($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<$resize_ratio)
//寬度優先
{
$newimg = imagecreatetruecolor($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,$this->dstimg);
}
}
else
//不裁圖
{
if($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,$this->dstimg);
}
}
}
//初始化圖象
function initi_img()
{
if($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);
}
}
//圖象目標地址
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;
}
}
?>
類的調用方法
$resizeimage = new resizeimage("圖片源文件地址", "200", "100", "0","縮略圖地址");
//就只用上面的一句話,就能生成縮略圖,其中,源文件和縮略圖地址可以相同,200,100分別代表寬和高
實例2
PHP縮略圖 等比例無損壓縮，可填充空白區域補充色
代碼如下 復制代碼<?php
error_reporting( E_ALL );
// 測試
imagezoom('1.jpg', '2.jpg', 400, 300, '#FFFFFF');
/*
php縮略圖函數：
等比例無損壓縮，可填充補充色 author: 華仔
主持格式：
bmp 、jpg 、gif、png
param:
@srcimage : 要縮小的圖片
@dstimage : 要保存的圖片
@dst_width: 縮小寬
@dst_height: 縮小高
@backgroundcolor: 補充色 如：#FFFFFF 支持 6位 不支持3位
*/
function imagezoom( $srcimage, $dstimage, $dst_width, $dst_height, $backgroundcolor ) {
// 中文件名亂碼
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 "要生成縮略圖的文件不存在";
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) < 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 "保存的文件名錯誤";
exit;
} else {
eval( $arr[$suffix] . '($dstimg, "'.$dstimage.'");' );
}
imagejpeg($dstimg, $dstimage);
imagedestroy($dstimg);
imagedestroy($srcimg);
}
function getcreatemethod( $file ) {
$arr = array(
'474946' => "imagecreatefromgif('$file')"
, 'FFD8FF' => "imagecreatefromjpeg('$file')"
, '424D' => "imagecreatefrombmp('$file')"
, '89504E' => "imagecreatefrompng('$file')"
);
$fd = fopen( $file, "rb" );
$data = fread( $fd, 3 );
$data = str2hex( $data );
if ( array_key_exists( $data, $arr ) ) {
return $arr[$data];
} elseif ( array_key_exists( substr($data, 0, 4), $arr ) ) {
return $arr[substr($data, 0, 4)];
} else {
return false;
}
}
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( $ret );
}
// BMP 創建函數 php本身無
function imagecreatefrombmp($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 $res;
}
// BMP 保存函數，php本身無
function imagebmp ($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;
}
?>
總結，第一個類文件不如第二個好，因為第一個生成圖之後圖片會有點變模糊哦，後面這個生成類是高質量的。
