php 圖片縮圖的實現方法，_PHP教程

php 圖片縮圖的實現方法，

功能：支援jpg,jpeg,gif,png,bmp圖片格式，支援按原圖片的比例進行縮放，可以選擇在圖片縮放的過程中是否需要對圖片進行裁切，加入了圖片品質控制，可以實現縮圖片品質最高化。完整類的代碼如下：

php/** * 功能：php產生縮圖片的類 */ class ResizeImage{  public $type;//圖片類型  public $width;//實際寬度  public $height;//實際高度  public $resize_width;//改變後的寬度  public $resize_height;//改變後的高度  public $cut;//是否裁圖  public $srcimg;//源圖象   public $dstimg;//靶心圖表象地址  public $im;//臨時建立的圖象  public $quality;//圖片品質  function resizeimage($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));//圖片的類型   $this->initi_img();//初始化圖象   $this -> dst_img($dstpath);//靶心圖表象地址   @$this->width=imagesx($this->im);   @$this->height=imagesy($this->im);   $this->newimg();//產生圖象   @ImageDestroy($this->im);  }  function newimg(){   $resize_ratio=($this->resize_width)/($this->resize_height);//改變後的圖象的比例   @$ratio=($this->width)/($this->height);//實際圖象的比例   if(($this->cut)=='1'){//裁圖    if($img_func==='imagepng'&&(str_replace('.','',PHP_VERSION)>=512)){ //針對php版本大於5.12參數變化後的處理情況     $quality=9;    }    if($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,$this->quality);    }    if($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,$this->quality);    }   }else{//不裁圖    if($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,$this->dstimg,$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(){//初始化圖象   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){//圖象目標地址   $full_length=strlen($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){ //自訂函數處理bmp圖片   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;  }     }?>

使用方法很簡單代碼如下：

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

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