php实现图片缩略图的方法
发布:smiling 来源: PHP粉丝网 添加日期:2021-07-22 11:33:44 浏览: 评论:0
本文使用php实现的图片缩略图,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,需要的朋友可以参考下本段代码。
本段代码实现功能有这些:
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;
- }
- }
- ?>
使用方法很简单代码如下:
$resizeimage=new ResizeImage('upload/abc.bmp', '120', '90', '0', 'upload/xabc.bmp');
以上代码是小编给大家分享的php实现图片缩略图的方法,希望对大家有所帮助!
Tags: php图片缩略图
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