功能：支持jpg,jpeg,gif,png,bmp图片格式，支持按原图片的比例进行缩放，可以选择在图片缩放的过程中是否需要对图片进行裁切，加入了图片质量控制，可以实现缩略图片质量最高化。完整类的代码如下：
<?php
/**
* 功能：php生成缩略图片的类
*/
class ResizeImage{
public $type;//图片类型
public $width;//实际宽度
public $height;//实际高度
public $resize_width;//改变后的宽度
public $resize_height;//改变后的高度
public $cut;//是否裁图
public $srcimg;//源图象
public $dstimg;//目标图象地址
public $im;//临时创建的图象
public $quality;//图片质量
function resizeimage($img,$wid,$hei,$c,$dstpath,$quality=100){
$this->srcimg=$img;
$this->resize_width=$wid;
$this->resize_height=$hei;
$this->cut=$c;
$this->quality=$quality;
$this->type=strtolower(substr(strrchr($this->srcimg,'.'),1));//图片的类型
$this->initi_img();//初始化图象
$this -> dst_img($dstpath);//目标图象地址
@$this->width=imagesx($this->im);
@$this->height=imagesy($this->im);
$this->newimg();//生成图象
@ImageDestroy($this->im);
}
function newimg(){
$resize_ratio=($this->resize_width)/($this->resize_height);//改变后的图象的比例
@$ratio=($this->width)/($this->height);//实际图象的比例
if(($this->cut)=='1'){//裁图
if($img_func==='imagepng'&&(str_replace('.','',PHP_VERSION)>=512)){ //针对php版本大于5.12参数变化后的处理情况
$quality=9;
}
if($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,$this->quality);
}
if($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,$this->quality);
}
}else{//不裁图
if($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,$this->dstimg,$this->quality);
}
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,$this->dstimg,$this->quality);
}
}
}
function initi_img(){//初始化图象
if($this->type=='jpg' || $this->type=='jpeg'){
$this->im=imagecreatefromjpeg($this->srcimg);
}
if($this->type=='gif'){
$this->im=imagecreatefromgif($this->srcimg);
}
if($this->type=='png'){
$this->im=imagecreatefrompng($this->srcimg);
}
if($this->type=='wbm'){
@$this->im=imagecreatefromwbmp($this->srcimg);
}
if($this->type=='bmp'){
$this->im=$this->ImageCreateFromBMP($this->srcimg);
}
}
function dst_img($dstpath){//图象目标地址
$full_length=strlen($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 $this->dstimg;
}
function ImageCreateFromBMP($filename){ //自定义函数处理bmp图片
if(!$f1=fopen($filename,"rb"))returnFALSE;
$FILE=unpack("vfile_type/Vfile_size/Vreserved/Vbitmap_offset",fread($f1,14));
if($FILE['file_type']!=19778)returnFALSE;
$BMP=unpack('Vheader_size/Vwidth/Vheight/vplanes/vbits_per_pixel'.
'/Vcompression/Vsize_bitmap/Vhoriz_resolution'.
'/Vvert_resolution/Vcolors_used/Vcolors_important',fread($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[$COLOR[1]+1];
}
else
returnFALSE;
imagesetpixel($res,$X,$Y,$COLOR[1]);
$X++;
$P+=$BMP['bytes_per_pixel'];
}
$Y--;
$P+=$BMP['decal'];
}
fclose($f1);
return$res;
}
}
?>$resizeimage=new ResizeImage('upload/abc.bmp', '120', '90', '0', 'upload/xabc.bmp');
转：PHP图片的等比缩放和增加Logo水印详细代码和注释
<?php
//PHP图片的等比缩放和增加Logo水印 --->百度 “美日汇”
/**
* 等比缩放函数（以保存的方式实现）
* @param string $picName 被缩放的处理图片源
* @param int $maxx 缩放后图片的最大宽度
* @param int $maxy 缩放后图片的最大高度
* @param string $pre 缩放后图片名的前缀名
* @return String 返回后的图片名称(带路径)，如a.jpg=>s_a.jpg
*/
function imageNewageUpdateSize($picName,$maxx=100,$maxy=100,$pre="s_"){
$imageNewageInfo = getimageNewageSize($picName); //获取图片的基本信息
$w = $imageNewageInfo[0];//获取宽度
$h = $imageNewageInfo[1];//获取高度
//获取图片的类型并为此创建对应图片资源
switch($imageNewageInfo[2]){
case 1: //gif
$imageNew = imageNewagecreatefromgif($picName);
break;
case 2: //jpg
$imageNew = imageNewagecreatefromjpeg($picName);
break;
case 3: //png
$imageNew = imageNewagecreatefrompng($picName);
break;
default:
die("图片类型错误！");
}
//计算缩放比例
if(($maxx/$w)>($maxy/$h)){
$b = $maxy/$h;
}else{
$b = $maxx/$w;
}
//计算出缩放后的尺寸
$nw = floor($w*$b);
$nh = floor($h*$b);
//创建一个新的图像源(目标图像)
$nimageNew = imageNewagecreatetruecolor($nw,$nh);
//执行等比缩放
imageNewagecopyresampled($nimageNew,$imageNew,0,0,0,0,$nw,$nh,$w,$h);
//输出图像（根据源图像的类型，输出为对应的类型）
$picimageNewageInfo = pathimageNewageInfo($picName);//解析源图像的名字和路径信息
$newpicName= $picimageNewageInfo["dirname"]."/".$pre.$picimageNewageInfo["basename"];
switch($imageNewageInfo[2]){
case 1:
imageNewagegif($nimageNew,$newpicName);
break;
case 2:
imageNewagejpeg($nimageNew,$newpicName);
break;
case 3:
imageNewagepng($nimageNew,$newpicName);
break;
}
//释放图片资源
imageNewagedestroy($imageNew);
imageNewagedestroy($nimageNew);
//返回结果
return $newpicName;
}
//调用
echo imageNewageUpdateSize("./imageNewages/leyangjun.jpg",400,400,"ss_"); //你自己要添加的图片
/**
* 为一张图片添加上一个logo图片水印（以保存的方式实现）
* @param string $picName 被处理图片源
* @param string $logo 水印图片
* @param string $pre 处理后图片名的前缀名
* @return String 返回后的图片名称(带路径)，如a.jpg=>n_a.jpg
*/
function imageNewageUpdateLogo($picName,$logo,$pre="n_"){
$picNameimageNewageInfo = getimageNewageSize($picName); //获取图片源的基本信息
$logoimageNewageInfo = getimageNewageSize($logo); //获取logo图片的基本信息
//var_dump($logoimageNewageInfo);
//根据图片类型创建出对应的图片源
switch($picNameimageNewageInfo[2]){
case 1: //gif
$imageNew = imageNewagecreatefromgif($picName);
break;
case 2: //jpg
$imageNew = imageNewagecreatefromjpeg($picName);
break;
case 3: //png
$imageNew = imageNewagecreatefrompng($picName);
break;
default:
die("图片类型错误！");
}
//根据logo图片类型创建出对应的图片源
switch($logoimageNewageInfo[2]){
case 1: //gif
$logoimageNew = imageNewagecreatefromgif($logo);
break;
case 2: //jpg
$logoimageNew = imageNewagecreatefromjpeg($logo);
break;
case 3: //png
$logoimageNew = imageNewagecreatefrompng($logo);
break;
default:
die("logo图片类型错误！");
}
//执行图片水印处理 源图的高-logo图的高 源图的宽-logo图的宽
imageNewagecopyresampled($imageNew,$logoimageNew,$picNameimageNewageInfo[0]-$logoimageNewageInfo[0],$picNameimageNewageInfo[1]-$logoimageNewageInfo[1],0,0,$logoimageNewageInfo[0],$logoimageNewageInfo[1],$logoimageNewageInfo[0],$logoimageNewageInfo[1]);
//输出图像（根据源图像的类型，输出为对应的类型）
$picimageNewageInfo = pathimageNewageInfo($picName);//解析源图像的名字和路径信息
$newpicName= $picimageNewageInfo["dirname"]."/".$pre.$picimageNewageInfo["basename"];
switch($picNameimageNewageInfo[2]){
case 1:
imageNewagegif($imageNew,$newpicName);
break;
case 2:
imageNewagejpeg($imageNew,$newpicName);
break;
case 3:
imageNewagepng($imageNew,$newpicName);
break;
}
//释放图片资源
imageNewagedestroy($imageNew);
imageNewagedestroy($logoimageNew);
//返回结果
return $newpicName;
}
//测试
//echo imageNewageUpdateLogo("./imageNewages/leyangjun.jpg","./imageNewages/logo.png"); //对应添加你的图片，和你的logo水印图片 OK
来源：oschina
链接：https://my.oschina.net/u/778827/blog/159686