ImageCode函数通过GIFEncoder类实现的GIF动画的PHP源代码，有兴趣的朋友可以研究一下。
有关GIFEncoder类。 具体代码入如下：
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/** * ImageCode 生成GIF图片验证 * @param $string 字符串 * @param $width 宽度 * @param $height 高度 * */ function ImageCode($string = '', $width = 75, $height = 25) { $authstr = $string ? $string : ((time() % 2 == 0) ? mt_rand(1000, 9999) : mt_rand(10000, 99999)); $board_width = $width; $board_height = $height; // 生成一个32帧的GIF动画 for($i = 0; $i < 32; $i++) { ob_start(); $image = imagecreate($board_width, $board_height); imagecolorallocate($image, 0,0,0); // 设定文字颜色数组 $colorList[] = ImageColorAllocate($image, 15,73,210); $colorList[] = ImageColorAllocate($image, 0,64,0); $colorList[] = ImageColorAllocate($image, 0,0,64); $colorList[] = ImageColorAllocate($image, 0,128,128); $colorList[] = ImageColorAllocate($image, 27,52,47); $colorList[] = ImageColorAllocate($image, 51,0,102); $colorList[] = ImageColorAllocate($image, 0,0,145); $colorList[] = ImageColorAllocate($image, 0,0,113); $colorList[] = ImageColorAllocate($image, 0,51,51); $colorList[] = ImageColorAllocate($image, 158,180,35); $colorList[] = ImageColorAllocate($image, 59,59,59); $colorList[] = ImageColorAllocate($image, 0,0,0); $colorList[] = ImageColorAllocate($image, 1,128,180); $colorList[] = ImageColorAllocate($image, 0,153,51); $colorList[] = ImageColorAllocate($image, 60,131,1); $colorList[] = ImageColorAllocate($image, 0,0,0); $fontcolor = ImageColorAllocate($image, 0,0,0); $gray = ImageColorAllocate($image, 245,245,245); $color = imagecolorallocate($image, 255,255,255); $color2 = imagecolorallocate($image, 255,0,0); imagefill($image, 0, 0, $gray); $space = 15;// 字符间距 if($i > 0) // 屏蔽第一帧 { for ($k = 0; $k < strlen($authstr); $k++) { $colorRandom = mt_rand(0,sizeof($colorList)-1); $float_top = rand(0,4); $float_left = rand(0,3); imagestring($image, 6, $space * $k, $top + $float_top, substr($authstr, $k, 1), $colorList[$colorRandom]); } } for ($k = 0; $k < 20; $k++) { $colorRandom = mt_rand(0,sizeof($colorList)-1); imagesetpixel($image, rand()%70 , rand()%15 , $colorList[$colorRandom]); } // 添加干扰线 for($k = 0; $k < 3; $k++) { $colorRandom = mt_rand(0, sizeof($colorList)-1); // $todrawline = rand(0,1); $todrawline = 1; if($todrawline) { imageline($image, mt_rand(0, $board_width), mt_rand(0,$board_height), mt_rand(0,$board_width), mt_rand(0,$board_height), $colorList[$colorRandom]); } else { $w = mt_rand(0,$board_width); $h = mt_rand(0,$board_width); imagearc($image, $board_width - floor($w / 2) , floor($h / 2), $w, $h, rand(90,180), rand(180,270), $colorList[$colorRandom]); } } imagegif($image); imagedestroy($image); $imagedata[] = ob_get_contents(); ob_clean(); ++$i; } $gif = new GIFEncoder($imagedata); Header ('Content-type:image/gif'); echo $gif->GetAnimation(); } /** * 调用示例 * */ session_start(); $authstr = mt_rand(1000, 9999); // 生成随机字符串 $_SESSION['verify'] = $authstr; // 记录session ImageCode($authstr, 60); // 显示GIF动画