使用PHP生成图片的缩略图的方法

本文主要是介绍使用PHP生成图片的缩略图的方法，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

 <?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 ; 
  } 
  
  } 
?>

 

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