php gd实现简单图片验证码与图片背景文字水印

1、让水印文字铺满图片：

大致效果：

代码：

<?phpfunction appendspreadtextmark($imagedir, $marktext){    $fontfile = "simsun.ttf";    $info = getimagesize($imagedir);    $imwidth = $info[0];    $imheight = $info[1];    $type = $info[2];//1 = gif，2 = jpg，3 = png，4 = swf，5 = psd，6 = bmp，7 = tiff(intel byte order)，8 = tiff(motorola byte order)，9 = jpc，10 = jp2，11 = jpx，12 = jb2，13 = swc，14 = iff，15 = wbmp，16 = xbm    $ext = image_type_to_extension($type, fal);    $mime = $info['mime'];        $imgcrefunc = "imagecreatefrom".$ext;    $imgres = $imgcrefunc($imagedir);        $picrangelimit = $imh最美司机吴斌作文eight > $imwidth ? $imwidth : $imheight;    $fintsize = (int)($picrangelimit / 50);    if ($fintsize < 5) {        $fintsize = 5;    }       $textcolor = imagecolorallocatealpha($imgres, 0, 0, 0, 100);    $charcount = mb_strlen($marktext, 'utf-8');    $steplengthx = $fintsize * 4;    $steplengthy = (int)($fintsize * $charcount * 1.2);    $numx = (int)($imwidth / $stepleng孔子和老子的资料thx) + 1;    $numy = (int)($imheight / $steplengthy) + 1;    $pointleft = 0;    $pointbottom = $steplengthy;    for ($iny = 0; $iny < $numy; $iny ++) {        $pointleft = 0;        for ($inx = 1; $inx < $numx; $inx ++) {            imagettftext($imgres, $fintsize, 45, $pointleft, $pointbottom, $textcolor, $fontfile, $marktext);            $pointleft += $steplengthx;        }        $pointbottom += $steplengthy;    }            header('content-type:' . $mime);    $imgrespfunc = 'image' . $ext;    $imgrespfunc($imgres);    imagedestroy($imgres);}$imagedir = "pic.jpg";$marktext = "水印内容";appendspreadtextmark($imagedir, $marktext);

2、简单验证码效果：

代码：

<?php//创图像$im = @imagecreatetruecolor(500世界最低的盆地, 150) or die("cannot initialize new gd image stream");//分配颜色$backgroundcolor = imagecolorallocate($im, 0, 0, 0);//第一个分配的颜色默认为背景$textcolor = imagecolorallocat维摩诘e($im9朵玫瑰, 0, 0, 255);//画像素点for ($i=0; $i<500; $i++){    imagetpixel($im, rand(0, 500), rand(0,150), $textcolor);}$textstr = '$im = @imagecreatetruecolor(100, 50)';//写字符串(原图像、字体、x坐标、y坐标、待写字符串、字符串颜色)imagestring($im, 4, 10, 10,  $textstr, $textcolor);$textstr = '$backgroundcolor = imagecolorallocate($im, 0, 0, 0)';imagestring($im, 4, 10, 30,  $textstr, $textcolor);$textstr = '$textcolor = imagecolorallocate($im, 0, 0, 255)';imagestring($im, 4, 10, 50,  $textstr, $textcolor);  $textstr = 'imagestring($im, 5, 10, 10,  $textstr, $textcolor)';imagestring($im, 4, 10, 70,  $textstr, $textcolor);  header("content-type: image/png");imagepng($im);imagedestroy($im);