类的使用demo：
<?php //http://www.cnblogs.com/roucheng/ require_once "roucheng.php"; $gr = new gifresizer; $gr->temp_dir = "keleyi"; $gr->resize("keleyi.gif","keleyi_resized.gif",500,500); ?>
类的源代码,保存为roucheng.php文件：
1 <? 2 /** 3 * 4 * Resizes Animated GIF Files 5 * 6 * ///IMPORTANT NOTE: The script needs a temporary directory where all the frames should be extracted. 7 * Create a directory with a 777 permission level and write the path into $temp_dir variable below. 8 * 9 * Default directory is "frames". 10 */ 11 12 class gifresizer { 13 14 public $temp_dir = "frames"; 15 private $pointer = 0; 16 private $index = 0; 17 private $globaldata = array(); 18 private $imagedata = array(); 19 private $imageinfo = array(); 20 private $handle = 0; 21 private $orgvars = array(); 22 private $encdata = array(); 23 private $parsedfiles = array(); 24 private $originalwidth = 0; 25 private $originalheight = 0; 26 private $wr,$hr; 27 private $props = array(); 28 private $decoding = false; 29 30 /** 31 * Public part of the class 32 * 33 * @orgfile - Original file path 34 * @newfile - New filename with path 35 * @width - Desired image width 36 * @height - Desired image height 37 */ 38 function resize($orgfile,$newfile,$width,$height){ 39 $this->decode($orgfile); 40 $this->wr=$width/$this->originalwidth; 41 $this->hr=$height/$this->originalheight; 42 $this->resizeframes(); 43 $this->encode($newfile,$width,$height); 44 $this->clearframes(); 45 } 46 47 /** 48 * GIF Decoder function. 49 * Parses the GIF animation into single frames. 50 */ 51 private function decode($filename){ 52 $this->decoding = true; 53 $this->clearvariables(); 54 $this->loadfile($filename); 55 $this->get_gif_header(); 56 $this->get_graphics_extension(0); 57 $this->get_application_data(); 58 $this->get_application_data(); 59 $this->get_image_block(0); 60 $this->get_graphics_extension(1); 61 $this->get_comment_data(); 62 $this->get_application_data(); 63 $this->get_image_block(1); 64 while(!$this->checkbyte(0x3b) && !$this->checkEOF()){ 65 $this->get_comment_data(1); 66 $this->get_graphics_extension(2); 67 $this->get_image_block(2); 68 } 69 $this->writeframes(time()); 70 $this->closefile(); 71 $this->decoding = false; 72 } 73 74 /** 75 * GIF Encoder function. 76 * Combines the parsed GIF frames into one single animation. 77 */ 78 private function encode($new_filename,$newwidth,$newheight){ 79 $mystring = ""; 80 $this->pointer = 0; 81 $this->imagedata = array(); 82 $this->imageinfo = array(); 83 $this->handle = 0; 84 $this->index=0; 85 86 $k=0; 87 foreach($this->parsedfiles as $imagepart){ 88 $this->loadfile($imagepart); 89 $this->get_gif_header(); 90 $this->get_application_data(); 91 $this->get_comment_data(); 92 $this->get_graphics_extension(0); 93 $this->get_image_block(0); 94 95 //get transparent color index and color 96 if(isset($this->encdata[$this->index-1])) 97 $gxdata = $this->encdata[$this->index-1]["graphicsextension"]; 98 else 99 $gxdata = null; 100 $ghdata = $this->imageinfo["gifheader"]; 101 $trcolor = ""; 102 $hastransparency=($gxdata[3]&&1==1); 103 104 if($hastransparency){ 105 $trcx = ord($gxdata[6]); 106 $trcolor = substr($ghdata,13+$trcx*3,3); 107 } 108 109 //global color table to image data; 110 $this->transfercolortable($this->imageinfo["gifheader"],$this->imagedata[$this->index-1]["imagedata"]); 111 112 $imageblock = &$this->imagedata[$this->index-1]["imagedata"]; 113 114 //if transparency exists transfer transparency index 115 if($hastransparency){ 116 $haslocalcolortable = ((ord($imageblock[9])&128)==128); 117 if($haslocalcolortable){ 118 //local table exists. determine boundaries and look for it. 119 $tablesize=(pow(2,(ord($imageblock[9])&7)+1)*3)+10; 120 $this->orgvars[$this->index-1]["transparent_color_index"] = 121 ((strrpos(substr($this->imagedata[$this->index-1]["imagedata"],0,$tablesize),$trcolor)-10)/3); 122 }else{ 123 //local table doesnt exist, look at the global one. 124 $tablesize=(pow(2,(ord($gxdata[10])&7)+1)*3)+10; 125 $this->orgvars[$this->index-1]["transparent_color_index"] = 126 ((strrpos(substr($ghdata,0,$tablesize),$trcolor)-10)/3); 127 } 128 } 129 130 //apply original delay time,transparent index and disposal values to graphics extension 131 132 if(!$this->imagedata[$this->index-1]["graphicsextension"]) $this->imagedata[$this->index-1]["graphicsextension"] = chr(0x21).chr(0xf9).chr(0x04).chr(0x00).chr(0x00).chr(0x00).chr(0x00).chr(0x00); 133 134 $imagedata = &$this->imagedata[$this->index-1]["graphicsextension"]; 135 136 $imagedata[3] = chr((ord($imagedata[3]) & 0xE3) | ($this->orgvars[$this->index-1]["disposal_method"] << 2)); 137 $imagedata[4] = chr(($this->orgvars[$this->index-1]["delay_time"] % 256)); 138 $imagedata[5] = chr(floor($this->orgvars[$this->index-1]["delay_time"] / 256)); 139 if($hastransparency){ 140 $imagedata[6] = chr($this->orgvars[$this->index-1]["transparent_color_index"]); 141 } 142 $imagedata[3] = chr(ord($imagedata[3])|$hastransparency); 143 144 //apply calculated left and top offset 145 $imageblock[1] = chr(round(($this->orgvars[$this->index-1]["offset_left"]*$this->wr) % 256)); 146 $imageblock[2] = chr(floor(($this->orgvars[$this->index-1]["offset_left"]*$this->wr) / 256)); 147 $imageblock[3] = chr(round(($this->orgvars[$this->index-1]["offset_top"]*$this->hr) % 256)); 148 $imageblock[4] = chr(floor(($this->orgvars[$this->index-1]["offset_top"]*$this->hr) / 256)); 149 150 if($this->index==1){ 151 if(!isset($this->imageinfo["applicationdata"]) || !$this->imageinfo["applicationdata"]) 152 $this->imageinfo["applicationdata"]=chr(0x21).chr(0xff).chr(0x0b)."NETSCAPE2.0".chr(0x03).chr(0x01).chr(0x00).chr(0x00).chr(0x00); 153 if(!isset($this->imageinfo["commentdata"]) || !$this->imageinfo["commentdata"]) 154 $this->imageinfo["commentdata"] = chr(0x21).chr(0xfe).chr(0x10)."PHPGIFRESIZER1.0".chr(0); 155 $mystring .= $this->orgvars["gifheader"]. $this->imageinfo["applicationdata"].$this->imageinfo["commentdata"]; 156 if(isset($this->orgvars["hasgx_type_0"]) && $this->orgvars["hasgx_type_0"]) $mystring .= $this->globaldata["graphicsextension_0"]; 157 if(isset($this->orgvars["hasgx_type_1"]) && $this->orgvars["hasgx_type_1"]) $mystring .= $this->globaldata["graphicsextension"]; 158 } 159 160 $mystring .= $imagedata . $imageblock; 161 $k++; 162 $this->closefile(); 163 } 164 165 $mystring .= chr(0x3b); 166 167 //applying new width & height to gif header 168 $mystring[6] = chr($newwidth % 256); 169 $mystring[7] = chr(floor($newwidth / 256)); 170 $mystring[8] = chr($newheight % 256); 171 $mystring[9] = chr(floor($newheight / 256)); 172 $mystring[11]= $this->orgvars["background_color"]; 173 //if(file_exists($new_filename)){unlink($new_filename);} 174 file_put_contents($new_filename,$mystring); 175 } 176 177 /** 178 * Variable Reset function 179 * If a instance is used multiple times, it's needed. Trust me. 180 */ 181 private function clearvariables(){ 182 $this->pointer = 0; 183 $this->index = 0; 184 $this->imagedata = array(); 185 $this->imageinfo = array(); 186 $this->handle = 0; 187 $this->parsedfiles = array(); 188 } 189 190 /** 191 * Clear Frames function 192 * For deleting the frames after encoding. 193 */ 194 private function clearframes(){ 195 foreach($this->parsedfiles as $temp_frame){ 196 unlink($temp_frame); 197 } 198 } 199 200 /** 201 * Frame Writer 202 * Writes the GIF frames into files. 203 */ 204 private function writeframes($prepend){ 205 for($i=0;$i<sizeof($this->imagedata);$i++){ 206 file_put_contents($this->temp_dir."/frame_".$prepend."_".str_pad($i,2,"0",STR_PAD_LEFT).".gif",$this->imageinfo["gifheader"].$this->imagedata[$i]["graphicsextension"].$this->imagedata[$i]["imagedata"].chr(0x3b)); 207 $this->parsedfiles[]=$this->temp_dir."/frame_".$prepend."_".str_pad($i,2,"0",STR_PAD_LEFT).".gif"; 208 } 209 } 210 211 /** 212 * Color Palette Transfer Device 213 * Transferring Global Color Table (GCT) from frames into Local Color Tables in animation. 214 */ 215 private function transfercolortable($src,&$dst){ 216 //src is gif header,dst is image data block 217 //if global color table exists,transfer it 218 if((ord($src[10])&128)==128){ 219 //Gif Header Global Color Table Length 220 $ghctl = pow(2,$this->readbits(ord($src[10]),5,3)+1)*3; 221 //cut global color table from gif header 222 $ghgct = substr($src,13,$ghctl); 223 //check image block color table length 224 if((ord($dst[9])&128)==128){ 225 //Image data contains color table. skip. 226 }else{ 227 //Image data needs a color table. 228 //get last color table length so we can truncate the dummy color table 229 $idctl = pow(2,$this->readbits(ord($dst[9]),5,3)+1)*3; 230 //set color table flag and length 231 $dst[9] = chr(ord($dst[9]) | (0x80 | (log($ghctl/3,2)-1))); 232 //inject color table 233 $dst = substr($dst,0,10).$ghgct.substr($dst,-1*strlen($dst)+10); 234 } 235 }else{ 236 //global color table doesn't exist. skip. 237 } 238 } 239 240 /** 241 * GIF Parser Functions. 242 * Below functions are the main structure parser components. 243 */ 244 private function get_gif_header(){ 245 $this->p_forward(10); 246 if($this->readbits(($mybyte=$this->readbyte_int()),0,1)==1){ 247 $this->p_forward(2); 248 $this->p_forward(pow(2,$this->readbits($mybyte,5,3)+1)*3); 249 }else{ 250 $this->p_forward(2); 251 } 252 253 $this->imageinfo["gifheader"]=$this->datapart(0,$this->pointer); 254 if($this->decoding){ 255 $this->orgvars["gifheader"]=$this->imageinfo["gifheader"]; 256 $this->originalwidth = ord($this->orgvars["gifheader"][7])*256+ord($this->orgvars["gifheader"][6]); 257 $this->originalheight = ord($this->orgvars["gifheader"][9])*256+ord($this->orgvars["gifheader"][8]); 258 $this->orgvars["background_color"]=$this->orgvars["gifheader"][11]; 259 } 260 261 } 262 //------------------------------------------------------- 263 private function get_application_data(){ 264 $startdata = $this->readbyte(2); 265 if($startdata==chr(0x21).chr(0xff)){ 266 $start = $this->pointer - 2; 267 $this->p_forward($this->readbyte_int()); 268 $this->read_data_stream($this->readbyte_int()); 269 $this->imageinfo["applicationdata"] = $this->datapart($start,$this->pointer-$start); 270 }else{ 271 $this->p_rewind(2); 272 } 273 } 274 //------------------------------------------------------- 275 private function get_comment_data(){ 276 $startdata = $this->readbyte(2); 277 if($startdata==chr(0x21).chr(0xfe)){ 278 $start = $this->pointer - 2; 279 $this->read_data_stream($this->readbyte_int()); 280 $this->imageinfo["commentdata"] = $this->datapart($start,$this->pointer-$start); 281 }else{ 282 $this->p_rewind(2); 283 } 284 } 285 //------------------------------------------------------- 286 private function get_graphics_extension($type){ 287 $startdata = $this->readbyte(2); 288 if($startdata==chr(0x21).chr(0xf9)){ 289 $start = $this->pointer - 2; 290 $this->p_forward($this->readbyte_int()); 291 $this->p_forward(1); 292 if($type==2){ 293 $this->imagedata[$this->index]["graphicsextension"] = $this->datapart($start,$this->pointer-$start); 294 }else if($type==1){ 295 $this->orgvars["hasgx_type_1"] = 1; 296 $this->globaldata["graphicsextension"] = $this->datapart($start,$this->pointer-$start); 297 }else if($type==0 && $this->decoding==false){ 298 $this->encdata[$this->index]["graphicsextension"] = $this->datapart($start,$this->pointer-$start); 299 }else if($type==0 && $this->decoding==true){ 300 $this->orgvars["hasgx_type_0"] = 1; 301 $this->globaldata["graphicsextension_0"] = $this->datapart($start,$this->pointer-$start); 302 } 303 }else{ 304 $this->p_rewind(2); 305 } 306 } 307 //------------------------------------------------------- 308 private function get_image_block($type){ 309 if($this->checkbyte(0x2c)){ 310 $start = $this->pointer; 311 $this->p_forward(9); 312 if($this->readbits(($mybyte=$this->readbyte_int()),0,1)==1){ 313 $this->p_forward(pow(2,$this->readbits($mybyte,5,3)+1)*3); 314 } 315 $this->p_forward(1); 316 $this->read_data_stream($this->readbyte_int()); 317 $this->imagedata[$this->index]["imagedata"] = $this->datapart($start,$this->pointer-$start); 318 319 if($type==0){ 320 $this->orgvars["hasgx_type_0"] = 0; 321 if(isset($this->globaldata["graphicsextension_0"])) 322 $this->imagedata[$this->index]["graphicsextension"]=$this->globaldata["graphicsextension_0"]; 323 else 324 $this->imagedata[$this->index]["graphicsextension"]=null; 325 unset($this->globaldata["graphicsextension_0"]); 326 }elseif($type==1){ 327 if(isset($this->orgvars["hasgx_type_1"]) && $this->orgvars["hasgx_type_1"]==1){ 328 $this->orgvars["hasgx_type_1"] = 0; 329 $this->imagedata[$this->index]["graphicsextension"]=$this->globaldata["graphicsextension"]; 330 unset($this->globaldata["graphicsextension"]); 331 }else{ 332 $this->orgvars["hasgx_type_0"] = 0; 333 $this->imagedata[$this->index]["graphicsextension"]=$this->globaldata["graphicsextension_0"]; 334 unset($this->globaldata["graphicsextension_0"]); 335 } 336 } 337 338 $this->parse_image_data(); 339 $this->index++; 340 341 } 342 } 343 //------------------------------------------------------- 344 private function parse_image_data(){ 345 $this->imagedata[$this->index]["disposal_method"] = $this->get_imagedata_bit("ext",3,3,3); 346 $this->imagedata[$this->index]["user_input_flag"] = $this->get_imagedata_bit("ext",3,6,1); 347 $this->imagedata[$this->index]["transparent_color_flag"] = $this->get_imagedata_bit("ext",3,7,1); 348 $this->imagedata[$this->index]["delay_time"] = $this->dualbyteval($this->get_imagedata_byte("ext",4,2)); 349 $this->imagedata[$this->index]["transparent_color_index"] = ord($this->get_imagedata_byte("ext",6,1)); 350 $this->imagedata[$this->index]["offset_left"] = $this->dualbyteval($this->get_imagedata_byte("dat",1,2)); 351 $this->imagedata[$this->index]["offset_top"] = $this->dualbyteval($this->get_imagedata_byte("dat",3,2)); 352 $this->imagedata[$this->index]["width"] = $this->dualbyteval($this->get_imagedata_byte("dat",5,2)); 353 $this->imagedata[$this->index]["height"] = $this->dualbyteval($this->get_imagedata_byte("dat",7,2)); 354 $this->imagedata[$this->index]["local_color_table_flag"] = $this->get_imagedata_bit("dat",9,0,1); 355 $this->imagedata[$this->index]["interlace_flag"] = $this->get_imagedata_bit("dat",9,1,1); 356 $this->imagedata[$this->index]["sort_flag"] = $this->get_imagedata_bit("dat",9,2,1); 357 $this->imagedata[$this->index]["color_table_size"] = pow(2,$this->get_imagedata_bit("dat",9,5,3)+1)*3; 358 $this->imagedata[$this->index]["color_table"] = substr($this->imagedata[$this->index]["imagedata"],10,$this->imagedata[$this->index]["color_table_size"]); 359 $this->imagedata[$this->index]["lzw_code_size"] = ord($this->get_imagedata_byte("dat",10,1)); 360 if($this->decoding){ 361 $this->orgvars[$this->index]["transparent_color_flag"] = $this->imagedata[$this->index]["transparent_color_flag"]; 362 $this->orgvars[$this->index]["transparent_color_index"] = $this->imagedata[$this->index]["transparent_color_index"]; 363 $this->orgvars[$this->index]["delay_time"] = $this->imagedata[$this->index]["delay_time"]; 364 $this->orgvars[$this->index]["disposal_method"] = $this->imagedata[$this->index]["disposal_method"]; 365 $this->orgvars[$this->index]["offset_left"] = $this->imagedata[$this->index]["offset_left"]; 366 $this->orgvars[$this->index]["offset_top"] = $this->imagedata[$this->index]["offset_top"]; 367 } 368 } 369 //------------------------------------------------------- 370 private function get_imagedata_byte($type,$start,$length){ 371 if($type=="ext") 372 return substr($this->imagedata[$this->index]["graphicsextension"],$start,$length); 373 elseif($type=="dat") 374 return substr($this->imagedata[$this->index]["imagedata"],$start,$length); 375 } 376 //------------------------------------------------------- 377 private function get_imagedata_bit($type,$byteindex,$bitstart,$bitlength){ 378 if($type=="ext") 379 return $this->readbits(ord(substr($this->imagedata[$this->index]["graphicsextension"],$byteindex,1)),$bitstart,$bitlength); 380 elseif($type=="dat") 381 return $this->readbits(ord(substr($this->imagedata[$this->index]["imagedata"],$byteindex,1)),$bitstart,$bitlength); 382 } 383 //------------------------------------------------------- 384 private function dualbyteval($s){ 385 $i = ord($s[1])*256 + ord($s[0]); 386 return $i; 387 } 388 //------------ Helper Functions --------------------- 389 private function read_data_stream($first_length){ 390 $this->p_forward($first_length); 391 $length=$this->readbyte_int(); 392 if($length!=0) { 393 while($length!=0){ 394 $this->p_forward($length); 395 $length=$this->readbyte_int(); 396 } 397 } 398 return true; 399 } 400 //------------------------------------------------------- 401 private function loadfile($filename){ 402 $this->handle = fopen($filename,"rb"); 403 $this->pointer = 0; 404 } 405 //------------------------------------------------------- 406 private function closefile(){ 407 fclose($this->handle); 408 $this->handle=0; 409 } 410 //------------------------------------------------------- 411 private function readbyte($byte_count){ 412 $data = fread($this->handle,$byte_count); 413 $this->pointer += $byte_count; 414 return $data; 415 } 416 //------------------------------------------------------- 417 private function readbyte_int(){ 418 $data = fread($this->handle,1); 419 $this->pointer++; 420 return ord($data); 421 } 422 //------------------------------------------------------- 423 private function readbits($byte,$start,$length){ 424 $bin = str_pad(decbin($byte),8,"0",STR_PAD_LEFT); 425 $data = substr($bin,$start,$length); 426 return bindec($data); 427 } 428 //------------------------------------------------------- 429 private function p_rewind($length){ 430 $this->pointer-=$length; 431 fseek($this->handle,$this->pointer); 432 } 433 //------------------------------------------------------- 434 private function p_forward($length){ 435 $this->pointer+=$length; 436 fseek($this->handle,$this->pointer); 437 } 438 //------------------------------------------------------- 439 private function datapart($start,$length){ 440 fseek($this->handle,$start); 441 $data = fread($this->handle,$length); 442 fseek($this->handle,$this->pointer); 443 return $data; 444 } 445 //------------------------------------------------------- 446 private function checkbyte($byte){ 447 if(fgetc($this->handle)==chr($byte)){ 448 fseek($this->handle,$this->pointer); 449 return true; 450 }else{ 451 fseek($this->handle,$this->pointer); 452 return false; 453 } 454 } 455 //------------------------------------------------------- 456 private function checkEOF(){ 457 if(fgetc($this->handle)===false){ 458 return true; 459 }else{ 460 fseek($this->handle,$this->pointer); 461 return false; 462 } 463 } 464 //------------------------------------------------------- 465 /** 466 * Debug Functions. keleyi.com 467 * Parses the GIF animation into single frames. 468 */ 469 private function debug($string){ 470 echo "<pre>"; 471 for($i=0;$i<strlen($string);$i++){ 472 echo str_pad(dechex(ord($string[$i])),2,"0",STR_PAD_LEFT). " "; 473 } 474 echo "</pre>"; 475 } 476 //------------------------------------------------------- 477 private function debuglen($var,$len){ 478 echo "<pre>"; 479 for($i=0;$i<$len;$i++){ 480 echo str_pad(dechex(ord($var[$i])),2,"0",STR_PAD_LEFT). " "; 481 } 482 echo "</pre>"; 483 } 484 //------------------------------------------------------- 485 private function debugstream($length){ 486 $this->debug($this->datapart($this->pointer,$length)); 487 } 488 //------------------------------------------------------- 489 /** 490 * GD Resizer Device 491 * Resizes the animation frames 492 */ 493 private function resizeframes(){ 494 $k=0; 495 foreach($this->parsedfiles as $img){ 496 $src = imagecreatefromgif($img); 497 $sw = $this->imagedata[$k]["width"]; 498 $sh = $this->imagedata[$k]["height"]; 499 $nw = round($sw * $this->wr); 500 $nh = round($sh * $this->hr); 501 $sprite = imagecreatetruecolor($nw,$nh); 502 $trans = imagecolortransparent($sprite); 503 imagealphablending($sprite, false); 504 imagesavealpha($sprite, true); 505 imagepalettecopy($sprite,$src); 506 imagefill($sprite,0,0,imagecolortransparent($src)); 507 imagecolortransparent($sprite,imagecolortransparent($src)); 508 imagecopyresized($sprite,$src,0,0,0,0,$nw,$nh,$sw,$sh); 509 imagegif($sprite,$img); 510 imagedestroy($sprite); 511 imagedestroy($src); 512 $k++; 513 } 514 } 515 } 516 517 518 ?>