下面贴处理的源代码：
<?php
require_once("gifencoder.php"); //载入编码 文件
$gif = new GIFEncoder(); //实例化gif解码对象
$gif->load("test.gif"); //载入要解码的gif图像
for($i=0;$i<sizeof($gif->IMGS["frames"]);$i++){ //根据 gif图像的帧数获取每帧的图像数据
$im = imagecreatefromstring($gif->getgif($i)); //利用GD库函数将GIF转得标准些
imagegif($im, $i.".gif"); //用文件形式保存生成的每帧图像数据，当然也可以用变量
}
imagedestroy($im);
ob_start();
for($i=0;sizeof($gif->IMGS["frames"]);$i++){
$im=imagecreatefromgif("0.gif"); //根据每帧的图片创建图像
if($i>0){ //不是第一帧 复制图片和第一帧合并
$frame=imagecreatefromgif("$i.gif"); //读取当前帧的图像
$w = imagesx($frame); //获取图像宽度
$y= imagesy($frame); //获取图像高度
imagecopy($im,$frame,0,0,0,0,$w,$y); //把当前帧图像和第一帧图像复制合并
imagedestroy($frame); //销毁当前图像
}
imagejpeg($im,$i."frame.jpg"); //合并后保存为jpg格式
$im=imagecreatefromjpeg($i."frame.jpg"); //从jpg格式重新创建图像
imagegif($im); //转为gif格式
imagedestroy($im); //销毁图像
$imagedata[] = ob_get_contents(); //创建这一帧的图像数据
ob_clean();
}
$diy[]=0;//开始延迟时间
$gif = new GIFEncoder($imagedata,$diy,0,2,0,0,0,"bin"); //实例化gif编码对象
ob_start();
Header ('Content-type:image/gif');
echo $gif->GetAnimation();
?>
以上代码 基本就是一个完整的 读取一个gif图片，对其进行解码，然后再编码成gif图片的完整过程了..
有了这个就可以在网上随意抓取gif图片然后进行修改。甚至直接用php就可以自己制作一些gif图片.
GIFEncoder类源码：
<?php
Class GIFEncoder {
var $GIF = "GIF89a"; /* GIF header 6 bytes */
var $VER = "GIFEncoder V2.06"; /* Encoder version */
var $BUF = Array ( );
var $LOP = 0;
var $DIS = 2;
var $COL = -1;
var $IMG = -1;
var $ERR = Array (
'ERR00' =>"Does not supported function for only one image!",
'ERR01' =>"Source is not a GIF image!",
'ERR02' =>"Unintelligible flag ",
'ERR03' =>"Could not make animation from animated GIF source",
);
/*
:::::::::::::::::::::::::::::::::::::::::::::::::::
::
:: GIFEncoder...
::
*/
function GIFEncoder (
$GIF_src, $GIF_dly, $GIF_lop, $GIF_dis,
$GIF_red, $GIF_grn, $GIF_blu, $GIF_mod
) {
if ( ! is_array ( $GIF_src ) && ! is_array ( $GIF_tim ) ) {
printf ( "%s: %s", $this->VER, $this->ERR [ 'ERR00' ] );
exit ( 0 );
}
$this->LOP = ( $GIF_lop > -1 ) ? $GIF_lop : 0;
$this->DIS = ( $GIF_dis > -1 ) ? ( ( $GIF_dis < 3 ) ? $GIF_dis : 3 ) : 2;
$this->COL = ( $GIF_red > -1 && $GIF_grn > -1 && $GIF_blu > -1 ) ?
( $GIF_red | ( $GIF_grn << 8 ) | ( $GIF_blu << 16 ) ) : -1;
for ( $i = 0; $i < count ( $GIF_src ); $i++ ) {
if ( strToLower ( $GIF_mod ) == "url" ) {
$this->BUF [ ] = fread ( fopen ( $GIF_src [ $i ], "rb" ), filesize ( $GIF_src [ $i ] ) );
}
else if ( strToLower ( $GIF_mod ) == "bin" ) {
$this->BUF [ ] = $GIF_src [ $i ];
}
else {
printf ( "%s: %s ( %s )!", $this->VER, $this->ERR [ 'ERR02' ], $GIF_mod );
exit ( 0 );
}
if ( substr ( $this->BUF [ $i ], 0, 6 ) != "GIF87a" && substr ( $this->BUF [ $i ], 0, 6 ) != "GIF89a" ) {
printf ( "%s: %d %s", $this->VER, $i, $this->ERR [ 'ERR01' ] );
exit ( 0 );
}
for ( $j = ( 13 + 3 * ( 2 << ( ord ( $this->BUF [ $i ] { 10 } ) & 0x07 ) ) ), $k = TRUE; $k; $j++ ) {
switch ( $this->BUF [ $i ] { $j } ) {
case "!":
if ( ( substr ( $this->BUF [ $i ], ( $j + 3 ), 8 ) ) == "NETSCAPE" ) {
printf ( "%s: %s ( %s source )!", $this->VER, $this->ERR [ 'ERR03' ], ( $i + 1 ) );
exit ( 0 );
}
break;
case ";":
$k = FALSE;
break;
}
}
}
GIFEncoder::GIFAddHeader ( );
for ( $i = 0; $i < count ( $this->BUF ); $i++ ) {
GIFEncoder::GIFAddFrames ( $i, $GIF_dly [ $i ] );
}
GIFEncoder::GIFAddFooter ( );
}
/*
:::::::::::::::::::::::::::::::::::::::::::::::::::
::
:: GIFAddHeader...
::
*/
function GIFAddHeader ( ) {
$cmap = 0;
if ( ord ( $this->BUF [ 0 ] { 10 } ) & 0x80 ) {
$cmap = 3 * ( 2 << ( ord ( $this->BUF [ 0 ] { 10 } ) & 0x07 ) );
$this->GIF .= substr ( $this->BUF [ 0 ], 6, 7 );
$this->GIF .= substr ( $this->BUF [ 0 ], 13, $cmap );
$this->GIF .= "!/377/13NETSCAPE2.0/3/1" . GIFEncoder::GIFWord ( $this->LOP ) . "/0";
}
}
/*
:::::::::::::::::::::::::::::::::::::::::::::::::::
::
:: GIFAddFrames...
::
*/
function GIFAddFrames ( $i, $d ) {
$Locals_str = 13 + 3 * ( 2 << ( ord ( $this->BUF [ $i ] { 10 } ) & 0x07 ) );
$Locals_end = strlen ( $this->BUF [ $i ] ) - $Locals_str - 1;
$Locals_tmp = substr ( $this->BUF [ $i ], $Locals_str, $Locals_end );
$Global_len = 2 << ( ord ( $this->BUF [ 0 ] { 10 } ) & 0x07 );
$Locals_len = 2 << ( ord ( $this->BUF [ $i ] { 10 } ) & 0x07 );
$Global_rgb = substr ( $this->BUF [ 0 ], 13,
3 * ( 2 << ( ord ( $this->BUF [ 0 ] { 10 } ) & 0x07 ) ) );
$Locals_rgb = substr ( $this->BUF [ $i ], 13,
3 * ( 2 << ( ord ( $this->BUF [ $i ] { 10 } ) & 0x07 ) ) );
$Locals_ext = "!/xF9/x04" . chr ( ( $this->DIS << 2 ) + 0 ) .
chr ( ( $d >> 0 ) & 0xFF ) . chr ( ( $d >> 8 ) & 0xFF ) . "/x0/x0";
if ( $this->COL > -1 && ord ( $this->BUF [ $i ] { 10 } ) & 0x80 ) {
for ( $j = 0; $j < ( 2 << ( ord ( $this->BUF [ $i ] { 10 } ) & 0x07 ) ); $j++ ) {
if (
ord ( $Locals_rgb { 3 * $j + 0 } ) == ( $this->COL >> 0 ) & 0xFF &
ord ( $Locals_rgb { 3 * $j + 1 } ) == ( $this->COL >> 8 ) & 0xFF &
ord ( $Locals_rgb { 3 * $j + 2 } ) == ( $this->COL >> 16 ) & 0xFF
) {
$Locals_ext = "!/xF9/x04" . chr ( ( $this->DIS << 2 ) + 1 ) .
chr ( ( $d >> 0 ) & 0xFF ) . chr ( ( $d >> 8 ) & 0xFF ) . chr ( $j ) . "/x0";
break;
}
}
}
switch ( $Locals_tmp { 0 } ) {
case "!":
$Locals_img = substr ( $Locals_tmp, 8, 10 );
$Locals_tmp = substr ( $Locals_tmp, 18, strlen ( $Locals_tmp ) - 18 );
break;
case ",":
$Locals_img = substr ( $Locals_tmp, 0, 10 );
$Locals_tmp = substr ( $Locals_tmp, 10, strlen ( $Locals_tmp ) - 10 );
break;
}
if ( ord ( $this->BUF [ $i ] { 10 } ) & 0x80 && $this->IMG > -1 ) {
if ( $Global_len == $Locals_len ) {
if ( GIFEncoder::GIFBlockCompare ( $Global_rgb, $Locals_rgb, $Global_len ) ) {
$this->GIF .= ( $Locals_ext . $Locals_img . $Locals_tmp );
}
else {
$byte = ord ( $Locals_img { 9 } );
$byte |= 0x80;
$byte &= 0xF8;
$byte |= ( ord ( $this->BUF [ 0 ] { 10 } ) & 0x07 );
$Locals_img { 9 } = chr ( $byte );
$this->GIF .= ( $Locals_ext . $Locals_img . $Locals_rgb . $Locals_tmp );
}
}
else {
$byte = ord ( $Locals_img { 9 } );
$byte |= 0x80;
$byte &= 0xF8;
$byte |= ( ord ( $this->BUF [ $i ] { 10 } ) & 0x07 );
$Locals_img { 9 } = chr ( $byte );
$this->GIF .= ( $Locals_ext . $Locals_img . $Locals_rgb . $Locals_tmp );
}
}
else {
$this->GIF .= ( $Locals_ext . $Locals_img . $Locals_tmp );
}
$this->IMG = 1;
}
/*
:::::::::::::::::::::::::::::::::::::::::::::::::::
::
:: GIFAddFooter...
::
*/
function GIFAddFooter ( ) {
$this->GIF .= ";";
}
/*
:::::::::::::::::::::::::::::::::::::::::::::::::::
::
:: GIFBlockCompare...
::
*/
function GIFBlockCompare ( $GlobalBlock, $LocalBlock, $Len ) {
for ( $i = 0; $i < $Len; $i++ ) {
if (
$GlobalBlock { 3 * $i + 0 } != $LocalBlock { 3 * $i + 0 } ||
$GlobalBlock { 3 * $i + 1 } != $LocalBlock { 3 * $i + 1 } ||
$GlobalBlock { 3 * $i + 2 } != $LocalBlock { 3 * $i + 2 }
) {
return ( 0 );
}
}
return ( 1 );
}
/*
:::::::::::::::::::::::::::::::::::::::::::::::::::
::
:: GIFWord...
::
*/
function GIFWord ( $int ) {
return ( chr ( $int & 0xFF ) . chr ( ( $int >> 8 ) & 0xFF ) );
}
/*
:::::::::::::::::::::::::::::::::::::::::::::::::::
::
:: GetAnimation...
::
*/
function GetAnimation ( ) {
return ( $this->GIF );
}
}
?>