How to implement image thumbnails in php, _PHP tutorial

How to implement image thumbnails in php,

The functions implemented by this code are as follows:

Supports jpg, jpeg, gif, png, bmp image formats, supports scaling according to the proportion of the original image, you can choose whether to crop the image during the image scaling process, and added image quality control to achieve reduction. Optimize picture quality.

The code of the complete class is as follows:

<&#63;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;
}
}
&#63;>

The usage is very simple and the code is as follows:

$resizeimage=new ResizeImage('upload/abc.bmp', '120', '90', '0', 'upload/xabc.bmp');

The above code is the method of implementing image thumbnails in PHP shared by the editor. I hope it will be helpful to everyone!

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