php實現圖片縮圖的方法，_PHP教程

php實現圖片縮圖的方法，

本段代碼實現功能有這些：

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];}elsereturnFALSE;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');

以上代碼是小編給大家分享的php實現圖片縮圖的方法，希望對大家有所協助！

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